CN116601303A

CN116601303A - Analyte sensor with metal-containing redox mediator and method of use thereof

Info

Publication number: CN116601303A
Application number: CN202280008621.7A
Authority: CN
Inventors: 弗乌·勒; 约翰·V·拉图尔; 凯文·P·沃利斯; 乌多·霍斯
Original assignee: Abbott Diabetes Care Inc
Current assignee: Abbott Diabetes Care Inc
Priority date: 2020-12-31
Filing date: 2022-01-03
Publication date: 2023-08-15

Abstract

The present disclosure provides redox mediators having two tridentate ligands and analyte sensors comprising such redox mediators. The present disclosure further provides methods of detecting one or more analytes present in a biological sample of a subject using such analyte sensors.

Description

Analyte sensor with metal-containing redox mediator and method of use thereof

Cross Reference to Related Applications

The present application claims priority from U.S. provisional application No. 63/132,901 filed on 31 of 12 in 2020 and U.S. provisional application No. 63/188,765 filed on 14 of 5 in 2021, each of which is incorporated herein by reference in its entirety for each priority.

Technical Field

The subject matter described herein relates to analyte sensors including one or more redox mediators and methods of use thereof.

Background

Detection of various analytes within an individual is sometimes critical to monitoring their health condition, as deviations from normal analyte levels may be indicative of physiological conditions. For example, monitoring glucose levels may enable a person with diabetes to take appropriate corrective action, including administering a drug or eating a particular food or beverage product, to avoid serious physiological injury. Other analytes may be required to monitor other physiological conditions. In some cases, it may be desirable to monitor more than one analyte to monitor multiple physiological conditions, particularly when a person has a complication that results in simultaneous imbalance of two or more analytes in combination with each other.

Many analytes represent interesting targets for physiological analysis, provided that the appropriate detection chemistry can be determined. For this reason, enzyme-based amperometric sensors configured for continuous glucose determination in vivo have been developed and improved in recent years to aid in monitoring the health of diabetic individuals. Other analytes that are commonly co-deregulated with glucose in diabetic individuals include, for example, lactate, oxygen, A1c, ketones, and the like. It may also be desirable to monitor these and other analytes independently of glucose imbalance. Analyte sensors configured to detect analytes other than glucose in the body are known, but are currently quite inadequate. For example, poor sensitivity of low abundance analytes can be particularly problematic.

Analyte monitoring in an individual may be performed periodically or continuously over a period of time. Periodic analyte monitoring may be performed by taking samples of bodily fluid (e.g., blood or urine) at set time intervals and performing an ex vivo analysis. Periodic ex vivo analyte monitoring may be sufficient to determine the physiological condition of many individuals. However, in some cases, ex vivo analyte monitoring may be inconvenient or painful. Furthermore, if analyte measurements are not obtained at the appropriate time, lost data cannot be recovered. Continuous analyte monitoring may be performed using one or more sensors implanted at least partially within the tissue of the individual (e.g., dermis, subcutaneous, or intravenous) so that analysis may be performed in vivo. The implanted sensor may collect analyte data on a set schedule or continuously as needed, depending on the particular health needs of the individual and/or the analyte level previously measured. For individuals with severe analyte imbalance and/or rapid fluctuations in analyte levels, monitoring the analyte using an in vivo implanted sensor may be a more desirable approach, although it may also be beneficial for other individuals. Since implanted analyte sensors typically remain within the individual's tissue for a long period of time, it may be highly desirable for such analyte sensors to be made of stable materials that exhibit a high degree of biocompatibility.

An analyte sensor (e.g., an electrochemical sensor) for measuring various analytes in a fluid may include two or more electrodes, including, for example, at least one working (or measuring) electrode and one reference electrode. The electrodes are connected by an electrical circuit, such as a potentiostat. When an electric current is passed through the working electrode, the oxidoreductase is electrooxidized or electroreduced. The oxidoreductase is specific for the analyte to be detected or the product of the analyte. The turnover rate of an enzyme is typically related to the concentration of the analyte itself or its products in the fluid. The presence of a redox mediator may promote electro-oxidation or electro-reduction of the enzyme. The redox mediator facilitates electrical communication between the working electrode and the enzyme. Analyte sensors can be manufactured, for example, by coating an electrode with a membrane comprising a redox mediator and an enzyme, wherein the enzyme is catalytically specific for the desired analyte or product thereof. When the substrate of the enzyme is electrooxidized, the redox mediator transfers electrons from the enzyme reduced by the substrate to the electrode; and when the substrate is electrically reduced, the redox mediator transfers electrons from the electrode to the enzyme that oxidizes the substrate.

Various redox mediators have been explored, such as monomeric ferrocenes, quinones (including quinines (e.g., benzoquinone)), cyclamate nickel, and ruthenium amine. However, these compounds often exhibit insufficient stability and thus limit the lifetime of the sensor. Accordingly, there is a need in the art to develop analyte sensors that not only have the desired electrochemical properties (e.g., are capable of rapid electron exchange), but also exhibit chemical, optical, thermal, and/or pH stability.

Disclosure of Invention

Objects and advantages of the disclosed subject matter will be set forth in and apparent from the description that follows, and will be learned by practice of the disclosed subject matter. Additional advantages of the disclosed subject matter will be realized and attained by the apparatus particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purpose of the disclosed subject matter, as embodied and broadly described, the disclosed subject matter includes an analyte sensor comprising a sensor tail including at least a first working electrode and a first active region disposed on a surface of the first working electrode and responsive to a first analyte, wherein the first active region includes a first polymer, a first redox mediator covalently bound to the first polymer, and at least one enzyme covalently bound to the first polymer and responsive to the first analyte. In certain embodiments, the first redox mediator has the following structure:

wherein M is iron, ruthenium, osmium, cobalt or vanadium, wherein n is I, II, II, IV or V, wherein R ₁ 、R ₃ 、R’ ₁ And R'. ₃ Independently selected from H, alkylamido (alkylamido), alkylamino, alkoxy or alkyl, wherein R ₂ And R'. ₂ Independently selected from H, electron donating groups or linking groups. In certain embodiments, the linking group will be the firstThe redox mediator is covalently bonded to the first polymer. In certain embodiments, the analyte sensor further comprises at least a mass transfer limiting membrane covering the first active region, the membrane being permeable to the first analyte.

In certain embodiments of the present disclosure, the at least one enzyme comprises an enzyme system comprising a plurality of enzymes having a common response to the first analyte.

In certain embodiments, the first analyte comprises glucose.

In certain embodiments, the mass transfer limiting membranes of the analyte sensors disclosed herein comprise a membrane polymer crosslinked with a branched crosslinking agent comprising two or more or three or more crosslinkable groups. In certain embodiments, the mass transfer limiting film comprises a polyvinylpyridine-based polymer, polyvinylimidazole, polyacrylate, polyurethane, polyether urethane (polyether urethane), silicone, or a combination thereof. In certain embodiments, the mass transfer limiting film comprises polyvinylpyridine or polyvinylimidazole. In certain embodiments, wherein the mass transfer limiting film comprises a copolymer of vinylpyridine and styrene. In certain embodiments, the branched crosslinking agent comprises polyethylene glycol diglycidyl ether or polyethylene glycol tetraglycidyl ether.

In certain embodiments, M of the redox mediators of the analyte sensors disclosed herein is osmium (Os).

In certain embodiments, when the redox mediator includes a linking group, the linking group includes an amide bond.

In certain embodiments, the analyte sensors disclosed herein further comprise a second working electrode and a second active region disposed on a surface of the second working electrode and responsive to a second analyte different from the first analyte, wherein the second active region comprises a second polymer, a second redox mediator covalently bonded to the second polymer different from the first redox mediator, and at least one enzyme covalently bonded to the second polymer and responsive to the second analyte, wherein a second portion of the mass transfer limiting membrane covers the second active region.

In certain embodiments, the at least one enzyme responsive to the second analyte comprises an enzyme system comprising a plurality of enzymes having a common response to the second analyte.

In certain embodiments, the second analyte comprises a ketone.

In certain embodiments, the first active region of the analyte sensor disclosed herein is responsive to the first analyte at a potential that is about-80 mV higher than the redox potential of the first redox mediator and lower than the Ag/AgCl reference.

Certain other aspects of the disclosure include a method comprising providing an analyte sensor comprising (a) a sensor tail comprising at least a first working electrode, (b) a sensor tail comprising at least a first working electrode that is responsive to a first analyte, wherein a first active region comprises a first polymer, a first redox mediator covalently bound to the first polymer, and at least one enzyme covalently bound to the first polymer that is responsive to the first analyte, wherein the first redox mediator has the structure:

wherein M is iron, ruthenium, osmium, cobalt or vanadium, wherein n is I, II, III, IV or V, wherein R ₁ 、R ₃ 、R’ ₁ And R'. ₃ Independently selected from H, alkylamide, alkylamino, alkoxy or alkyl, wherein R ₂ And R'. ₂ Independently selected from H, an electron donating group, or a linking group, wherein the linking group covalently bonds the first redox mediator to the first polymer; and (c) a mass transfer limiting membrane permeable to the first analyte, the mass transfer limiting membrane covering at least the first active region, wherein the method further comprises applying an electrical potential to the first working electrode, obtaining a first signal at or above the redox potential of the first active region, the first signal being associated with a fluid contacting the first active region Is proportional to the concentration of the first analyte in the fluid, and correlates the first signal to the concentration of the first analyte in the fluid.

In certain embodiments, the at least one enzyme comprises an enzyme system comprising a plurality of enzymes having a common response to the first analyte.

In certain embodiments, the first analyte comprises glucose.

In certain embodiments, the transport-limiting membrane of the analyte sensor used in the methods disclosed herein comprises a membrane polymer crosslinked with a branched crosslinking agent comprising two or more or three or more crosslinkable groups. In certain embodiments, the mass transfer limiting film comprises a polyvinyl pyridine-based polymer, polyvinyl imidazole, polyacrylate, polyurethane, polyether urethane, silicone, or a combination thereof. In certain embodiments, the mass transfer limiting film comprises polyvinylpyridine or polyvinylimidazole. In certain embodiments, the mass transfer limiting film comprises a copolymer of vinylpyridine and styrene. In certain embodiments, the branched crosslinking agent comprises polyethylene glycol diglycidyl ether or polyethylene glycol tetraglycidyl ether.

In certain embodiments, the potential of the first active region of the analyte sensor used in the methods disclosed herein is higher than the redox potential of the first redox mediator and is about-80 mV lower relative to the Ag/AgCl reference.

In certain embodiments, an analyte sensor for use in the methods disclosed herein includes (d) a second working electrode and a second active region disposed on a surface of the second working electrode and responsive to a second analyte different from the first analyte, wherein the second active region includes a second polymer, a second redox mediator covalently bonded to the second polymer different from the first redox mediator, and at least one enzyme covalently bonded to the second polymer and responsive to the second analyte, wherein a second portion of the mass transfer limiting membrane covers the second active region.

In certain embodiments, the second analyte comprises a ketone.

In certain embodiments, the first redox mediators of the analyte sensors disclosed herein have the following structure:

wherein n is II or III.

Drawings

The following drawings are included to illustrate certain aspects of the disclosure and should not be taken as exclusive implementations. The disclosed subject matter is capable of modifications, alterations, combinations, and equivalents in form and function, without departing from the scope of the disclosure.

Fig. 1A is a system overview of a sensor applicator, reader device, monitoring system, network, and remote system.

FIG. 1B is a diagram illustrating an operating environment for an example analyte monitoring system for use with the techniques described herein.

Fig. 2A is a block diagram depicting an example implementation of a reader device.

Fig. 2B is a block diagram illustrating an example data receiving device for communicating with a sensor in accordance with an example embodiment of the disclosed subject matter.

Fig. 2C and 2D are block diagrams depicting example embodiments of a sensor control device.

FIG. 2E is a block diagram illustrating an example analyte sensor in accordance with an exemplary embodiment of the disclosed subject matter.

Fig. 3A is a proximal perspective view depicting an example embodiment of a tray that a user prepares for assembly.

Fig. 3B is a side view depicting an exemplary embodiment of an applicator device that a user prepares for assembly.

Fig. 3C is a proximal perspective view depicting an exemplary embodiment of a user inserting an applicator device into a tray during assembly.

Fig. 3D is a proximal perspective view depicting an exemplary embodiment of a user removing the applicator device from the tray during assembly.

Fig. 3E is a proximal perspective view depicting an exemplary embodiment of an administration sensor for a patient using an applicator device.

Fig. 3F is a proximal perspective view depicting an exemplary embodiment of a patient having an applied sensor and an applicator device in use.

Fig. 4A is a side view depicting an exemplary embodiment of an applicator device coupled to a cap.

Fig. 4B is a side perspective view depicting an exemplary embodiment of a separate applicator device and cap.

Fig. 4C is a perspective view depicting an exemplary embodiment of the applicator device and the distal end of the electronics housing.

Fig. 4D is a top perspective view of an exemplary applicator device according to the disclosed subject matter.

Fig. 4E is a bottom perspective view of the applicator device of fig. 4D.

Fig. 4F is an exploded view of the applicator device of fig. 4D.

Fig. 4G is a side cross-sectional view of the applicator device of fig. 4D.

Fig. 5 is a proximal perspective view depicting an example embodiment of a tray with a sterilization cover attached thereto.

Fig. 6A is a perspective cutaway view depicting an example embodiment of a tray with a sensor delivery assembly.

Fig. 6B is a proximal perspective view depicting a sensor delivery assembly.

Fig. 7A and 7B are isometric exploded top and bottom views, respectively, of an exemplary sensor control device.

Fig. 8A-8C are an assembly view and a cross-sectional view of an on-body device including an integrated connector for a sensor assembly.

Fig. 9A and 9B are side and cross-sectional side views, respectively, of the exemplary embodiment of the sensor applicator of fig. 1A with the cap of fig. 2C attached thereto.

Fig. 10A and 10B are isometric and side views, respectively, of another example sensor control device.

Fig. 11A-11C are progressive cross-sectional side views illustrating assembly of the sensor applicator with the sensor control device of fig. 10A-10B.

Fig. 12A-12C are progressive cross-sectional side views showing assembly and disassembly of the sensor applicator with an example embodiment of the sensor control device of fig. 10A-10B.

Fig. 13A-13F show cross-sectional views depicting example embodiments of applicators during a deployment phase.

FIG. 14 is a graph depicting an example of in vitro sensitivity of an analyte sensor.

Fig. 15 is a diagram illustrating an example operational state of a sensor in accordance with an example embodiment of the disclosed subject matter.

FIG. 16 is a diagram illustrating example operations and data flows for wireless programming of sensors in accordance with the disclosed subject matter.

Fig. 17 is a diagram illustrating an example data flow for securely exchanging data between two devices in accordance with the disclosed subject matter.

Fig. 18A-18C show cross-sectional views of an analyte sensor that includes a single active area.

Fig. 19A-19C show cross-sectional views of an analyte sensor that includes two active regions.

FIG. 20 shows a cross-sectional view of an analyte sensor including two active regions.

Fig. 21A-21C show perspective views of an analyte sensor including two active regions on separate working electrodes.

FIGS. 22A-22C show diagrams of enzyme systems that can be used to detect ketones in analyte sensors.

FIG. 23A provides the chemical structure of an exemplary redox mediator of the present disclosure in free form.

FIG. 23B shows a cyclic voltammogram of the exemplary redox mediator of FIG. 23A.

FIG. 24A provides the chemical structure of an exemplary redox mediator of the present disclosure in free form.

FIG. 24B shows a cyclic voltammogram of the exemplary redox mediator of FIG. 24A.

FIG. 25A provides a chemical structure of an exemplary redox mediator of the present disclosure in free form.

FIG. 25B shows a cyclic voltammogram of the exemplary redox mediator of FIG. 25A.

FIG. 26A provides a chemical structure of an exemplary redox mediator of the present disclosure in free form.

FIG. 26B shows a cyclic voltammogram of the exemplary redox mediator of FIG. 26A.

FIG. 27A provides a chemical structure of an exemplary redox mediator of the present disclosure in free form.

FIG. 27B shows a cyclic voltammogram of the exemplary redox mediator of FIG. 27A.

FIG. 28A provides the chemical structure of an exemplary redox mediator of the present disclosure in free form.

FIG. 28B shows a cyclic voltammogram of the exemplary redox mediator of FIG. 28A.

FIG. 29A provides chemical structures of an exemplary redox mediator of the present disclosure in free form.

FIG. 29B shows a cyclic voltammogram of the exemplary redox mediator of FIG. 29A.

FIG. 30 provides chemical structures of an exemplary redox mediator of the present disclosure in free form.

FIG. 31A provides a chemical structure of an exemplary redox mediator of the present disclosure covalently bonded to a polymer.

FIG. 31B shows a cyclic voltammogram of the exemplary redox mediator of FIG. 31A.

FIG. 32A shows a graph of current versus time for a glucose sensor incorporating the exemplary redox mediator of FIG. 25A at various working electrode potentials.

FIG. 32B shows a graph of current versus glucose for a glucose sensor incorporating the exemplary redox mediator of FIG. 25A at various working electrode potentials.

FIG. 33A shows a graph of current versus time for a glucose sensor incorporating the exemplary redox mediator of FIG. 31A at various working electrode potentials.

FIG. 33B shows a graph of current versus glucose for a glucose sensor incorporating the exemplary redox mediator of FIG. 31A at various working electrode potentials.

Detailed Description

The present disclosure provides transition metal complexes (transition metal complexe, transition metal complexes) and the use of such complexes as redox mediators in analyte sensors. The present disclosure generally describes analyte sensors suitable for in vivo use, and more particularly, analyte sensors that include the redox mediators disclosed herein. Depending on the sensor configuration, the analyte sensors of the present disclosure may be configured to detect one analyte or multiple analytes simultaneously or nearly simultaneously.

Various analyte sensor assemblies can pose certain difficulties in monitoring some analytes or combinations of analytes. Redox mediators used to facilitate electron transfer to the working electrode may require the analyte sensor to operate at a relatively high potential, which may lead to electrochemical side reactions that complicate the detection of certain low abundance analytes. Furthermore, operation of an analyte sensor under certain conditions (e.g., prolonged use) may cause the redox mediator to decompose and affect the sensitivity of the analyte sensor.

To address the above-described need, the present disclosure provides redox mediators for facilitating electron transfer at lower working electrode potentials than are commonly used. The usual working electrode potential is typically in the range of 0 to 300mV relative to the Ag/AgCl reference. The use of such "low potential" redox mediators can reduce the occurrence of electrochemical side reactions and can detect low abundance analytes, such as ketones, more readily than at higher working electrode potentials. Such low potential redox mediators may also be advantageous when used in conjunction with detection of multiple analytes, as discussed further below. In addition, the redox mediators disclosed herein include a transition metal surrounded by two tridentate ligands, which provide the redox mediators with increased structural stability. Increased stability may result in extended wear times for analyte sensors including the redox mediators of the present disclosure.

In certain embodiments, analyte sensors incorporating one or more redox mediators of the present disclosure are capable of operating at a wide range of potentials, such as ranging from about-300 mV to about +200mV, for example from about-270 mV to about +130mV, measured relative to an Ag/AgCl reference. In certain embodiments, analyte sensors incorporating one or more redox mediators of the present disclosure are capable of low potential operation. As used herein, the term "low potential" refers to a potential that is higher than the redox potential of the first redox mediator and less than about +200mV, including less than about +100mV, less than about-50 mV, less than about-80 mV, or less than about-100 mV, as measured with respect to an Ag/AgCl reference. In certain embodiments, the redox potential of the first redox mediator that may facilitate operation at such working electrode potentials may be less than about-200 mV, such as about-400 mV to about-200 mV, or about-350 mV to about-250 mV, or about-300 mV to about-250 mV, as measured relative to an Ag/AgCl reference.

For clarity, but not by way of limitation, the detailed description of the presently disclosed subject matter is divided into the following subsections:

I. definition;

an analyte sensor;

1. the general structure of the analyte sensor system;

2. a redox mediator;

3. a polymer backbone;

4. an enzyme;

5. a mass transfer limiting membrane;

6. an interference domain;

III, a using method; and

exemplary embodiments.

I. Definition of the definition

The terms used in the present specification generally have their ordinary meaning in the art in the context of the present disclosure and in the specific context in which each term is used. Certain terms are discussed below or elsewhere in the specification to provide additional guidance to the practitioner in describing the compositions and methods of the disclosure and how to make and use them.

As used herein, the use of the terms "a" or "an" when used in conjunction with the term "comprising" in the claims and/or specification may mean "one" but it is also consistent with "one or more", "at least one", and "one or more".

As used herein, the terms "comprises," "comprising," "includes," "including," "having," "can," "containing," and variations thereof are intended to be open-ended terms, or words that do not exclude additional acts or structures. The present disclosure also contemplates other embodiments "comprising" the embodiments or elements presented herein, "consisting of" and "consisting essentially of, whether or not explicitly stated.

The term "about" or "approximately" means within an acceptable error range for a particular value as determined by one of ordinary skill in the art, depending in part on how the value is measured or determined, i.e., the limitations of the measurement system. For example, according to practice in the art, "about" may mean within 3 standard deviations or more than 3 standard deviations. Alternatively, "about" may mean a range of up to 20%, preferably up to 10%, more preferably up to 5%, and still more preferably up to 1% of a given value. Alternatively, particularly with respect to biological systems or processes, the term may mean within an order of magnitude of a value, preferably within 5 times a value, and more preferably within 2 times a value.

As used herein, the term "alkyl" refers to a straight or branched chain saturated aliphatic hydrocarbon. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, and the like. Unless otherwise indicated, the term "alkyl" includes alkyl and cycloalkyl.

As used herein, the term "alkoxy" refers to an alkyl group attached to the remainder of the structure through an oxygen atom. Examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, n-propoxy, isopropoxy, butoxy, tert-butoxy, and the like. Furthermore, unless otherwise indicated, the term "alkoxy" includes alkoxy and cycloalkoxy.

As used herein, the term "alkenyl" refers to an unsaturated straight or branched chain aliphatic hydrocarbon having at least one carbon-carbon double bond. Non-limiting examples of alkenyl groups include vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-methyl-1-propenyl, and the like.

As used herein, an "analyte sensor" or "sensor" may refer to any device capable of receiving sensor information from a user, including, for illustrative purposes, but not limited to, a body temperature sensor, a blood pressure sensor, a pulse or heart rate sensor, a glucose level sensor, an analyte sensor, a physical activity (physical activity) sensor, a body movement (body movement) sensor, or any other sensor for collecting physical or biological information. Analytes measured by the analyte sensor may include, for example, but are not limited to, glutamate, glucose, ketone, lactate, oxygen, hemoglobin A1C, albumin, alcohol, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, hematein nitrogen, calcium, carbon dioxide, chloride, creatinine, hematocrit, aspartate, asparagine, magnesium, oxygen, pH, phosphorus, potassium, sodium, total protein, uric acid, and the like.

As used herein, the term "reactive group" refers to a functional group of a molecule that is capable of reacting with another compound to couple at least a portion of the other compound to the molecule. Non-limiting examples of reactive groups include carboxyl groups, reactive ester groups, sulfonyl halide groups, sulfonate groups, isocyanate groups, isothiocyanate groups, epoxy groups, aziridine groups, halogen groups (halos), aldehyde groups, ketone groups, amine groups, acrylamide groups, thiol groups, acyl azide groups, acyl halide groups, hydrazine groups, hydroxylamine groups, alkyl halide groups, imidazole groups, pyridine groups, phenol groups, alkyl sulfonate groups, halotriazine groups, imino ester groups, maleimide groups, hydrazide groups, hydroxyl groups, and photoreactive azidoaryl groups. As used herein and understood in the art, activated esters include, but are not limited to, esters of succinimidyl, benzotriazole or aryl groups substituted with electron withdrawing groups such as sulfo, nitro, cyano or halogen groups; or carboxylic acids activated by carbodiimides.

As used herein, the term "substituted functional group" (e.g., substituted alkyl, alkenyl, or alkoxy) includes, but is not limited to, at least one substituent selected from the group consisting of: halogen, alkoxy, mercapto, aryl, alkoxycarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, -OH, -NH ₂ Alkylamino, dialkylamino, trialkylammonio, alkanoylamino, arylcarboxamide, hydrazino, alkylthio, alkenyl, and reactive groups.

As used herein, the term "biological fluid" refers to any body fluid or body fluid derivative in which an analyte may be measured. Non-limiting examples of biological fluids include dermal fluid, interstitial fluid, plasma, blood, lymphatic fluid, synovial fluid, cerebrospinal fluid, saliva, bronchoalveolar lavage, amniotic fluid, sweat, tears, and the like. In certain embodiments, the biological fluid is dermal or interstitial fluid.

As used herein, the term "polyvinylpyridine-based polymer" refers to a polymer or copolymer comprising polyvinylpyridine (e.g., poly (2-vinylpyridine) or poly (4-vinylpyridine)) or a derivative thereof.

As used herein, the term "redox mediator" refers to an electron transfer agent for carrying electrons between an analyte or analyte-reduced or analyte-oxidized enzyme and an electrode, either directly or via one or more other electron transfer agents. In certain embodiments, a redox mediator comprising a polymeric backbone may also be referred to as a "redox polymer".

As used herein, the term "electrolysis" refers to the electrooxidation or electroreduction of a compound directly at an electrode or by means of one or more electron transfer agents (e.g., redox mediators or enzymes).

As used herein, the term "reference electrode" may refer to a reference electrode or an electrode that serves as both a reference and a counter electrode. Similarly, as used herein, the term "counter electrode" may refer to a counter electrode and a counter electrode that also serves as a reference electrode.

As used herein, the term "tridentate ligand" refers to a ligand having three donor atoms capable of forming a coordination bond with a central metal atom or ion.

As used herein, the term "multicomponent film" refers to a film that includes two or more types of film polymers.

As used herein, the term "monocomponent film" refers to a film comprising one type of film polymer.

Analyte sensor

1. General architecture of analyte sensor systems

Before the present subject matter is described in detail, it is to be understood that this disclosure is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.

The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the disclosure is not entitled to antedate such publication by virtue of prior disclosure. Furthermore, the dates of publication provided may be different from the actual publication dates, which may need to be independently confirmed.

In general, embodiments of the present disclosure include systems, devices, and methods for inserting an applicator using an analyte sensor for use with an in vivo analyte monitoring system. The applicator may be provided to the user in a sterile package containing the electronic enclosure of the sensor control device therein. According to some embodiments, a structure separate from the applicator, such as a container, may also be provided to the user as a sterile package having the sensor module and the sharps module contained therein. The user may connect the sensor module to the electronics housing and may connect the sharps to the applicator using an assembly process that involves inserting the applicator into the container in a particular manner. In other embodiments, the applicator, sensor control device, sensor module, and sharps module may be provided in a single package. The applicator may be used to position the sensor control device on a person, wherein the sensor is in contact with the body fluid of the wearer. An improvement of the embodiments provided herein is to reduce the likelihood of the sensor being improperly inserted or damaged, or causing adverse physiological reactions. Other improvements and advantages are also provided. Various configurations of these devices will be described in detail by way of example only.

Further, many embodiments include an in vivo analyte sensor that is structurally configured such that at least a portion of the sensor is or can be located within a user's body to obtain information about at least one analyte of the body. However, it should be noted that embodiments disclosed herein may be used with in vivo analyte monitoring systems that incorporate in vitro capabilities as well as purely in vitro or ex vivo analyte monitoring systems (including systems that are entirely non-invasive).

Further, for each and every embodiment of the methods disclosed herein, systems and devices capable of performing each of those embodiments are encompassed within the scope of the present disclosure. For example, embodiments of sensor control devices are disclosed and these devices may have one or more sensors, analyte monitoring circuitry (e.g., analog circuitry), memory (e.g., for storing instructions), power supply, communication circuitry, transmitters, receivers, processors and/or controllers (e.g., for executing instructions) that may perform or facilitate the performance of any and all of the method steps. These sensor control device embodiments may be, and can be used to implement, those steps from any and all methods described herein that are performed by the sensor control device.

Furthermore, the systems and methods presented herein may be used for operation of sensors used in analyte monitoring systems, such as, but not limited to, general health, wellness, diet, research, information, or any purpose involving analyte sensing over time. As used herein, an "analyte sensor" or "sensor" may refer to any device capable of receiving sensor information from a user, including, for illustrative purposes, but not limited to, a body temperature sensor, a blood pressure sensor, a pulse or heart rate sensor, a glucose level sensor, an analyte sensor, a physical activity sensor, a body movement sensor, or any other sensor for collecting physical or biological information. In certain embodiments, the analyte sensors of the present disclosure may further measure analytes including, but not limited to, glutamic acid, glucose, ketones, lactic acid, oxygen, hemoglobin A1C, albumin, alcohol, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, hematin nitrogen, calcium, carbon dioxide, chloride, creatinine, hematocrit, magnesium, oxygen, pH, phosphorus, potassium, sodium, total protein, uric acid, and the like.

As mentioned, various embodiments of systems, devices, and methods are described herein that provide improved assembly and use of dermal sensor insertion devices for use with in vivo analyte monitoring systems. In particular, embodiments of the present disclosure are designed to improve sensor insertion methods with respect to in vivo analyte monitoring systems, and in particular to prevent premature retraction of the insertion sharp during sensor insertion. For example, some embodiments include a dermal sensor insertion mechanism with increased firing speed and delayed sharps retraction. In other embodiments, the sharps retraction mechanism may be actuated in motion such that the sharps is not retracted until the user pulls the applicator away from the skin. Thus, these embodiments may reduce the likelihood of prematurely retracting the insertion sharp during sensor insertion; reducing the possibility of improper sensor insertion; and reduces the likelihood of damaging the sensor during sensor insertion, to name a few. Embodiments of the present disclosure also provide improved insertion sharps modules to address the relatively shallow insertion paths that exist in small dermal sensors and subject dermis layers. Furthermore, embodiments of the present disclosure are designed to prevent undesired axial and/or rotational movement of the applicator member during sensor insertion. Thus, these embodiments may reduce the likelihood of instability of the positioned dermal sensor, irritation of the insertion site, damage to surrounding tissue, and capillary rupture (resulting in contamination of the dermal fluid with blood), to name a few. Further, to mitigate inaccurate sensor readings that may be caused by trauma at the insertion site, various embodiments of the present disclosure may reduce needle tip depth penetration relative to the sensor tip during insertion.

Before describing these aspects of the embodiments in detail, however, it is first desirable to describe examples of devices that may be present, for example, within an in vivo analyte monitoring system, as well as examples of their operation, all of which may be used with the embodiments described herein.

There are various types of in vivo analyte monitoring systems. For example, a "continuous analyte monitoring" system (or "continuous glucose monitoring" system) may automatically transmit data continuously from the sensor control device to the reader device without prompting, e.g., according to a schedule. As another example, a "rapid analyte monitoring" system (or "rapid glucose monitoring" system or simply "rapid" system) may transmit data from a sensor control device in response to a scan or data request by a reading device, for example using Near Field Communication (NFC) or Radio Frequency Identification (RFID) protocols. In vivo analyte monitoring systems may also operate without the need for finger stick calibration.

In vivo analyte monitoring systems can be distinguished from "in vitro" systems that contact biological samples outside of the body (or "ex vivo"), which typically include a meter device having a port for receiving an analyte test strip that carries a user's body fluid, which can be analyzed to determine the user's blood analyte level.

The in-vivo monitoring system may include a sensor that, when positioned in the body, contacts the body fluid of the user and senses the level of analyte contained therein. The sensor may be part of a sensor control device that resides on the user's body and contains electronics and power supply that enable and control analyte sensing. For example, the sensor control devices and variations thereof may also be referred to as "sensor control units," "on-body electronics" devices or units, "on-body" devices or units, or "sensor data communication" devices or units.

The in-vivo monitoring system may also include a device that receives sensed analyte data from the sensor control device and processes and/or displays the sensed analyte data to a user in any number of forms. For example, the device and its variants may be referred to as a "handheld reader device," "reader device" (or simply "reader"), "handheld electronic device" (or simply "handheld device"), "portable data processing" device or unit, "data receiver," "receiver" device or unit (or simply "receiver"), or "remote" device or unit. Other devices such as personal computers have also been used with or incorporated into in vivo and in vitro monitoring systems.

A. Exemplary in vivo analyte monitoring System

Fig. 1A is a conceptual diagram depicting an example embodiment of an analyte monitoring system 100 including a sensor applicator 150, a sensor control device 102, and a reader device 120. Here, the sensor applicator 150 may be used to deliver the sensor control device 102 to a monitoring location on the user's skin where the sensor 104 is held in place by the adhesive patch 105 for a period of time. The sensor control device 102 is further described in fig. 2B and 2C, and may communicate with the reader device 120 via a communication path or link 140 using wired or wireless, unidirectional or bidirectional, and encrypted or unencrypted technologies. Example wireless protocols include bluetooth, bluetooth low energy (BLE, BTLE, smart bluetooth, etc.), near Field Communication (NFC), etc. The user may monitor applications installed in memory on reader device 120 using screen 122 and input 121 and may charge the device battery using power port 123. More details regarding reader device 120 are set forth below with reference to fig. 2A. According to some embodiments, reader device 120 may constitute an output medium for viewing analyte concentrations and alarms or notifications determined by sensor 104 or a processor associated therewith, as well as allowing one or more user inputs. The reader device 120 may be a multi-purpose smart phone or a dedicated electronic reader instrument. Although only one reader device 120 is shown, in some cases, multiple reader devices 120 may be present.

The reader device 120 may communicate with the local computer system 170 via a communication path 141, which communication path 141 may also be wired or wireless, unidirectional or bidirectional, and encrypted or unencrypted. The local computer system 170 may include one or more of a laptop, desktop, tablet, smart phone (phaset), smart phone, set top box, video game console (video game console ), remote terminal, or other computing device, and the wireless communication may include any of a number of suitable wireless network protocols, including bluetooth, bluetooth low energy (BTLE), wi-Fi, or others. The local computer system 170 may communicate with the network 190 via the communication path 143 by wired or wireless techniques as previously described, similar to how the reader device 120 may communicate with the network 190 via the communication path 142. The network 190 may be any of a number of networks, such as private and public networks, local or wide area networks, and the like. Trusted computer system 180 may include a server and may provide authentication services and secure data storage and may communicate with network 190 via communication path 144 by wired or wireless techniques. According to some embodiments, the local computer system 170 and/or the trusted computer system 180 may be accessed by individuals other than the primary user who are interested in the user's analyte level. The reader device 120 may include a display 122 and an optional input component 121. According to some implementations, the display 122 may include a touch screen interface.

The sensor control device 102 includes a sensor housing that can house circuitry and a power source for operating the sensor 104. Alternatively, the power supply and/or active circuitry may be omitted. A processor (not shown) may be communicatively connected to the sensor 104, wherein the processor is physically located within the sensor housing or reader device 120. According to some embodiments, the sensor 104 protrudes from the underside of the sensor housing and extends through an adhesive layer 105, the adhesive layer 105 being adapted to adhere the sensor housing to a tissue surface, such as skin.

FIG. 1B illustrates an operating environment of an analyte monitoring system 100a capable of embodying the techniques described herein. The analyte monitoring system 100a may include a component system designed to provide monitoring of a parameter of the human or animal body (e.g., analyte level), or may provide other operations based on the configuration of various components. As embodied herein, the system may include a low power analyte sensor 110, or simply a "sensor" that is worn by a user or attached to the body where information is to be collected. As embodied herein, the analyte sensor 110 may be a sealed disposable device having a predetermined effective useful life (e.g., 1 day, 14 days, 30 days, etc.). The sensor 110 may be applied to the skin of the user's body and remain adhered during the life of the sensor, or may be designed to be selectively removed and remain functional upon re-application. The low power analyte monitoring system 100a may further include a data reading device 120 or a multi-purpose data receiving device 130 configured as described herein to facilitate retrieval and delivery of data, including analyte data, from the analyte sensor 110.

As embodied herein, analyte monitoring system 100a may include a software or firmware library or application provided to a third party, for example, through remote application server 150 or application storefront server 160, and incorporated into multipurpose hardware device 130, for example, a mobile phone, tablet, personal computing device, or other similar computing device capable of communicating with analyte sensor 110 over a communication link. The multi-purpose hardware may further include an embedded device, including but not limited to an insulin pump or insulin pen, having an embedded library configured to communicate with the analyte sensor 110. While the illustrated embodiment of analyte monitoring system 100a includes only one of each of the illustrated devices, the present disclosure contemplates analyte monitoring system 100a incorporating a plurality of each component that interact throughout the system. For example, and without limitation, as embodied herein, the data reading device 120 and/or the multi-purpose data receiving device 130 may include a plurality of each. As embodied herein, the plurality of data receiving devices 130 may communicate directly with the sensor 110 as described herein. Additionally or alternatively, the data receiving device 130 may communicate with an auxiliary data receiving device 130 to provide visualization or analysis of the analyte data or data for auxiliary display to a user or other authorized party.

The sensor 104 of fig. 1A is adapted to be at least partially inserted into a tissue of interest, such as a dermis layer or subcutaneous layer of skin. The sensor 104 may include a sensor tail of sufficient length for insertion to a desired depth into a given tissue. The sensor tail may include at least one working electrode. In certain configurations, the sensor tail may include an active region for detecting an analyte, which in certain cases may include a low potential redox mediator, as discussed further herein. The counter electrode may be present in combination with at least one working electrode. The specific electrode configuration on the sensor tail is described in more detail below. One or more mass transfer limiting films may cover the active region, as described in further detail below.

The active region may be configured to detect a particular analyte as described herein. For example, but not limited to, analytes may include glutamic acid, glucose, ketone, lactic acid, oxygen, hemoglobin A1C, albumin, alcohol, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, blood urea nitrogen, calcium, carbon dioxide, chloride, creatinine, hematocrit, lactic acid, magnesium, oxygen, pH, asparagine, aspartic acid, phosphorus, potassium, sodium, total protein, uric acid, and the like. In certain embodiments, the active area of the presently disclosed sensor is configured to detect glucose. In certain embodiments, the active area of the presently disclosed sensor is configured to detect lactic acid. In certain embodiments, the active area of the presently disclosed sensor is configured to detect alcohol. In certain embodiments, the active region of the presently disclosed sensor is configured to detect ketones. For example, and without limitation, the glucose-responsive active region can include a glucose-responsive enzyme, the lactate-responsive active region can include a lactate-responsive enzyme, and the ketone-responsive active region can include an enzyme system that includes at least two enzymes that can cooperate to facilitate ketone detection. Suitable enzyme systems for detecting ketones are further described below with reference to FIGS. 22A-22C. In certain embodiments, the active area of the presently disclosed sensor is configured to detect creatinine. In certain embodiments, the active area of the presently disclosed sensor is configured to detect alcohol, such as ethanol, for example by including an alcohol responsive enzyme. In certain embodiments, the active region of the presently disclosed sensor is configured to detect glutamate, for example by including a glutamate responsive enzyme. In certain embodiments, the active region of the presently disclosed sensor is configured to detect aspartic acid, such as by including an aspartate responsive enzyme. In certain embodiments, the active region of the presently disclosed sensor is configured to detect asparagine, for example, by including an asparagine-responsive enzyme. According to various embodiments, each active region may include a polymer to which at least some of the enzyme is covalently bonded.

In certain embodiments of the present disclosure, one or more analytes in any biological fluid of interest, such as dermal fluid, interstitial fluid, plasma, blood, lymph fluid, synovial fluid, cerebrospinal fluid, saliva, bronchoalveolar lavage, amniotic fluid, and the like, may be monitored. In certain particular embodiments, the analyte sensors of the present disclosure may be adapted to determine dermal or interstitial fluid to determine the concentration of one or more analytes in the body. In certain embodiments, the biological fluid is interstitial fluid.

An introducer (introducer) may be temporarily present to facilitate introduction of the sensor 104 into tissue. In certain example embodiments, the introducer may comprise a needle or similar sharp. As one skilled in the art will readily recognize, other types of introducers, such as sheaths or blades, may be present in alternative embodiments. More specifically, a needle or other introducer may reside temporarily near sensor 104 prior to tissue insertion and then be retracted thereafter. When present, a needle or other introducer may facilitate insertion of the sensor 104 into tissue by opening an access path for the sensor 104 to follow. For example, and not by way of limitation, according to one or more embodiments, a needle may facilitate penetration of the epidermis as an access path to the dermis to allow implantation of sensor 104. After opening the access path, the needle or other introducer may be retracted so as not to pose a sharp hazard. In certain embodiments, suitable needles may be solid or hollow in cross-section, beveled or beveled, and/or rounded or non-rounded. In more specific embodiments, a suitable needle may be comparable to an acupuncture needle in cross-sectional diameter and/or tip design, which may have a cross-sectional diameter of about 250 microns. However, a suitable needle may have a larger or smaller cross-sectional diameter if desired for certain specific applications.

In some embodiments, the tip of the needle (when present) may be angled over the end of the sensor 104 such that the needle first penetrates the tissue and opens an access path for the sensor 104. In some embodiments, the sensor 104 may reside within a lumen or recess of a needle, where the needle similarly opens an access path for the sensor 104. In either case, the needle is then withdrawn after facilitating sensor insertion.

B. Exemplary reader device

Fig. 2A is a block diagram depicting an example implementation of a reader device configured as a smartphone. Here, reader device 120 may include a display 122, an input component 121, and a processing core 206, processing core 206 including a communication processor 222 coupled to a memory 223 and an application processor 224 coupled to a memory 225. A separate memory 230, an RF transceiver 228 with an antenna 229, and a power supply 226 with a power management module 238 may also be included. A multi-function transceiver 232 may be further included that may communicate with an antenna 234 through Wi-Fi, NFC, bluetooth, BTLE, and GPS. As will be appreciated by those skilled in the art, these components are electrically and communicatively connected in a manner that constitutes a functional device.

C. Exemplary data receiving device architecture

For purposes of illustration and not limitation, reference is made to the exemplary embodiment of the data receiving device 120 shown in fig. 2B for use with the disclosed subject matter. The data receiving device 120 and associated multi-purpose data receiving device 130 include components closely related to the discussion of the analyte sensor 110 and its operation, and may include additional components. In particular embodiments, the data receiving device 120 and the multi-purpose data receiving device 130 may be or include components provided by a third party, and are not necessarily limited to including devices manufactured by the same manufacturer as the sensor 110.

As shown in fig. 2B, the data receiving device 120 includes an ASIC 4000, and the ASIC 4000 includes a microcontroller 4010, a memory 4020, and a storage 4030 and is communicatively connected to the communication module 4040. Power for components of the data receiving device 120 may be delivered by the power module 4050, as embodied herein, the power module 4050 may include a rechargeable battery. The data receiving device 120 may further include a display 4070 for facilitating viewing of analyte data received from the analyte sensor 110 or other device (e.g., the user device 140 or the remote application server 150). The data receiving device 120 may include separate user interface components (e.g., physical keys), light sensors, microphones, etc.).

The communication module 4040 may include a BLE module 4041 and an NFC module 4042. Data receiving device 120 may be configured to wirelessly connect with analyte sensor 110 and send commands to analyte sensor 110 and receive data from analyte sensor 110. As embodied herein, the data receiving device 120 may be configured to operate as an NFC scanner and BLE endpoint via a particular module of the communication module 4040 (e.g., BLE module 4042 or NFC module 4043) relative to the analyte sensor 110 described herein. For example, the data receiving device 120 can issue a command to the analyte sensor 110 (e.g., an activation command for a data broadcast mode of the sensor; a pairing command identifying the data receiving device 120) using a first module of the communication module 4040, and receive data from the analyte sensor 110 and transmit data to the analyte sensor 110 using a second module of the communication module 4040. The data receiving device 120 may be configured to communicate with the user device 140 via a Universal Serial Bus (USB) module 4045 of the communication module 4040.

As another example, the communication module 4040 may include, for example, a cellular radio module 4044. The cellular radio module 4044 may include one or more radio transceivers for communicating using a broadband cellular network including, but not limited to, third generation (3G), fourth generation (4G), and fifth generation (5G) networks. In addition, the communication module 4040 of the data receiving device 120 may include a Wi-Fi radio module 4043 for communicating using a wireless local area network in accordance with one or more of the IEEE 802.11 standards (e.g., 802.11a, 802.11b, 802.11g, 802.11n (also referred to as Wi-Fi 4), 802.11ac (also referred to as Wi-Fi 5), 802.11ax (also referred to as Wi-Fi 6)). Using cellular radio module 4044 or Wi-Fi radio module 4043, data receiving device 120 may communicate with remote application server 150 to receive analyte data or to provide updates or inputs received from a user (e.g., through one or more user interfaces). Although not shown, the communication module 5040 of the analyte sensor 120 may similarly include a cellular radio module or a Wi-Fi radio module.

As embodied herein, an on-board memory (on-board storage) 4030 of the data receiving device 120 may store analyte data received from the analyte sensor 110. Further, the data receiving device 120, the multipurpose data receiving device 130, or the user device 140 may be configured to communicate with the remote application server 150 via a wide area network. As embodied herein, the analyte sensor 110 may provide data to the data receiving device 120 or the multi-purpose data receiving device 130. The data receiving device 120 may transmit the data to the user computing device 140. The user computing device 140 (or the multi-purpose data receiving device 130) may in turn transmit the data to the remote application server 150 for processing and analysis.

As embodied herein, the data receiving device 120 may further include sensing hardware 4060 that is similar to or extends from the sensing hardware 5060 of the analyte sensor 110. In particular embodiments, data receiving device 120 may be configured to operate in conjunction with analyte sensor 110 and based on analyte data received from analyte sensor 110. As an example, where the analyte sensor 110 is a glucose sensor, the data receiving device 120 may be or include an insulin pump or insulin injection pen. In combination, the compatible device 130 may adjust the insulin dosage for the user based on the glucose value received from the analyte sensor.

D. Exemplary sensor control apparatus

Fig. 2C and 2D are block diagrams depicting an example embodiment of the sensor control device 102 with the analyte sensor 104 and sensor electronics 160 (including analyte monitoring circuitry), which may have a majority of the processing power to cause the final result data to be displayed to a user. In fig. 2C, a single semiconductor chip 161, which may be a custom application-specific integrated circuit (ASIC), is depicted. Shown within ASIC 161 are certain high-level functional units including an Analog Front End (AFE) 162, a power management (or control) circuit 164, a processor 166, and a communication circuit 168 (which may be implemented as a transmitter, receiver, transceiver, passive circuit, or other manner according to a communication protocol). In this embodiment, both AFE 162 and processor 166 function as analyte monitoring circuitry, but in other embodiments either circuitry may perform analyte monitoring functions. The processor 166 may include one or more processors, microprocessors, controllers, and/or microcontrollers, each of which may be a discrete chip or distributed among (and a portion of) a number of different chips.

Memory 163 is also included within ASIC 161 and may be shared by various functional units present within ASIC 161, or may be distributed among two or more of them. The memory 163 may also be a separate chip. Memory 163 may be volatile and/or nonvolatile memory. In this embodiment, ASIC 161 is connected to a power source 170, and power source 170 may be a button cell or the like. AFE 162 interacts with in-vivo analyte sensor 104 and receives measurement data therefrom and outputs the data in digital form to processor 166, which processor 166 in turn processes the data to obtain final results glucose discrete values and trend values, and the like. This data may then be provided to communication circuitry 168 for transmission via antenna 171 to reader device 120 (not shown), for example, where the resident software application requires minimal further processing to display the data.

Fig. 2D is similar to fig. 2C, but instead includes two discrete semiconductor chips 162 and 174, which may be packaged together or separately. Here, AFE 162 resides on ASIC 161. The processor 166 is integrated with the power management circuitry 164 and the communication circuitry 168 on a chip 174. AFE 162 includes memory 163 and chip 174 includes memory 165, which may be isolated or distributed therein. In one example embodiment, AFE 162 is combined with power management circuit 164 and processor 166 on one chip, while communication circuit 168 is on a separate chip. In another example embodiment, AFE 162 and communication circuit 168 are on one chip and processor 166 and power management circuit 164 are on another chip. It should be noted that other chip combinations are possible, including three or more chips, each chip being responsible for the separate functions described, or sharing one or more functions to achieve fail-safe redundancy.

For purposes of illustration and not limitation, reference is made to an exemplary embodiment of an analyte sensor 110 for use with the disclosed subject matter shown in FIG. 2E. FIG. 2E illustrates a block diagram of an example analyte sensor 110 according to an example embodiment compatible with the security architectures and communication schemes described herein.

As embodied herein, the analyte sensor 110 may include an application specific integrated circuit ("ASIC") 5000 communicatively connected to the communication module 5040. ASIC 5000 may include a microcontroller core 5010, an on-board memory 5020, and a storage memory 5030. Storage memory 5030 may store data for authentication and encryption security architecture. Storage memory 5030 may store programming instructions for sensor 110. As embodied herein, certain communication chipsets may be embedded in an ASIC 5000 (e.g., NFC transceiver 5025). The ASIC 5000 may receive power from a power module 5050 (e.g., an on-board battery) or from NFC pulses. The storage memory 5030 of the ASIC 5000 may be programmed to include information such as an identifier of the sensor 110 for identification and tracking purposes. Storage memory 5030 may also be programmed with configuration or calibration parameters for use by sensor 110 and its various components. Storage memory 5030 may include a rewritable or one-time programmable (OTP) memory. Storage memory 5030 may be updated using the techniques described herein to extend the usefulness of sensor 110.

As embodied herein, the communication module 5040 of the sensor 100 may be or include one or more modules to support the analyte sensor 110 to communicate with other devices of the analyte monitoring system 100. By way of example only and not limitation, the example communication module 5040 may include a bluetooth low energy ("BLE") module 5041. As used throughout this disclosure, bluetooth low energy ("BLE") refers to a short range communication protocol that is optimized to enable an end user to easily pair bluetooth devices. The communication module 5040 may transmit and receive data and commands via interactions of the communication module similar to the functions of the data receiving device 120 or the user device 140. The communication module 5040 may include additional or alternative chipsets for short-range-like communication schemes such as personal area networks according to the IEEE 802.15 protocol, IEEE 802.11 protocol, infrared communication according to the infrared data association standard (IrDA), and so forth.

To perform its function, the sensor 100 may further comprise suitable sensing hardware 5060 adapted to its function. As embodied herein, the sensing hardware 5060 may include an analyte sensor positioned percutaneously or subcutaneously in contact with a bodily fluid of a subject. The analyte sensor may generate sensor data containing values corresponding to one or more analyte levels within the bodily fluid.

E. Exemplary assembly procedure of sensor control device

The components of the sensor control device 102 may be available to the user in a plurality of packages requiring final assembly by the user prior to delivery to the appropriate user location. Fig. 3A-3D depict an example embodiment of a user's assembly process of the sensor control device 102, including connecting components after preparing individual components in order to prepare the sensor for delivery. Fig. 3E-3F depict example embodiments of delivering the sensor control device 102 to an appropriate user location by selecting an appropriate delivery location and applying the device 102 to that location.

Fig. 3A is a proximal perspective view depicting an example embodiment of a container 810 that a user prepares for an assembly process, where the container 810 is configured as a tray (although other packages may be used). The user may complete the preparation by removing the cover 812 from the tray 810 to expose the platform 808, for example by peeling the non-adhered portion of the cover 812 from the tray 810 such that the adhered portion of the cover 812 is removed. Removal of the cover 812 may be appropriate in various embodiments as long as the platform 808 is sufficiently exposed within the tray 810. The cover 812 may then be set aside.

Fig. 3B is a side view depicting an exemplary embodiment of an applicator device 150 that a user is ready for assembly. The applicator device 150 may be provided in a sterile package sealed by a cap 708. Preparation of the applicator device 150 may include separating the housing 702 from the cap 708 to expose the sheath 704 (fig. 3C). This may be accomplished by unscrewing (or otherwise separating) the cap 708 from the housing 702. Cap 708 may then be set aside.

Fig. 3C is a proximal perspective view depicting an example embodiment in which a user inserts the applicator device 150 into the tray 810 during assembly. Initially, after aligning the housing orientation features 1302 (or slots or grooves) and the tray orientation features 924 (standoffs or detents), the user may insert the sheath 704 into the platform 808 within the tray 810. Insertion of the sheath 704 into the platform 808 temporarily unlocks the sheath 704 relative to the housing 702 and also temporarily unlocks the platform 808 relative to the tray 810. At this stage, removal of the applicator device 150 from the tray 810 will result in the same condition as before the initial insertion of the applicator device 150 into the tray 810 (i.e., the process may be reversed or aborted at this point and then repeated without any consequences).

Sheath 704 may remain positioned within platform 808 relative to housing 702 while housing 702 is advanced distally, connecting with platform 808 to advance platform 808 distally relative to tray 810. This step unlocks and collapses (collapse) the platform 808 within the tray 810. The sheath 704 may contact and disengage a locking feature (not shown) within the tray 810 that unlocks the sheath 704 relative to the housing 702 and prevents the sheath 704 from moving (relatively), while the housing 702 continues to advance the platform 808 distally. At the end of the advancement of the housing 702 and platform 808, the sheath 704 is permanently unlocked relative to the housing 702. At the end of distal advancement of the housing 702, a sharp and sensor (not shown) within the tray 810 may be connected with an electronics housing (not shown) within the housing 702. The operation and interaction of the applicator device 150 and the tray 810 are further described below.

Fig. 3D is a proximal perspective view depicting an exemplary embodiment of a user removing the applicator device 150 from the tray 810 during assembly. The user may remove the applicator 150 from the tray 810 by pushing the housing 702 proximally relative to the tray 810 or other motion having the same end effect of separating the applicator 150 and the tray 810. The applicator device 150 is removed, wherein the sensor control device 102 (not shown) has been fully assembled (sharp, sensor, electronics) and positioned for delivery.

Fig. 3E is a proximal perspective view depicting an example embodiment of a patient using the application device 150 to apply the sensor control device 102 to a target area of skin, for example, on the abdomen or other suitable location. Distally advancing the housing 702 collapses the sheath 704 within the housing 702 and applies the sensor to the target site such that the adhesive layer on the underside of the sensor control device 102 adheres to the skin. When the housing 702 is fully advanced, the sharps are automatically retracted while a sensor (not shown) remains in place to measure the analyte level.

Fig. 3F is a proximal perspective view depicting an example embodiment of a patient having a sensor control device 102 in an administration position. The user may then remove the applicator 150 from the application site.

The system 100 described with reference to fig. 3A-3F and elsewhere herein may provide a reduced or eliminated opportunity for accidental breakage, permanent deformation, or improper assembly of the applicator assembly as compared to prior art systems. Because the applicator housing 702 directly engages the platform 808 while the sheath 704 is unlocked, rather than indirectly engaging through the sheath 704, the relative angle between the sheath 704 and the housing 702 does not result in breakage or permanent deformation of the arm or other component. The likelihood of relatively high forces during assembly (e.g., in conventional devices) will be reduced, which in turn reduces the likelihood of unsuccessful assembly by the user.

F. Exemplary sensor applicator apparatus

Fig. 4A is a side view depicting an exemplary embodiment of an applicator device 150 coupled to a screw cap 708. This is an example of how the applicator 150 may be shipped to and received by a user before the user assembles the sensor. Fig. 4B is a side perspective view depicting the applicator 150 and cap 708 after separation. Fig. 4C is a perspective view depicting an example embodiment of the distal end of the applicator device 150 with the electronics housing 706 and adhesive patch 105 removed from their position held within the sensor carrier 710 of the sheath 704 when the cap 708 is in place.

Referring to fig. 4D-G, for purposes of illustration and not limitation, the applicator device 20150 may be provided to a user as a single integrated assembly. Fig. 4D and 4E provide top and bottom perspective views, respectively, of an applicator device 20150, fig. 4F provides an exploded view of the applicator device 20150 and fig. 4G provides a side cross-sectional view. The perspective view illustrates how the applicator 20150 is delivered to and received by a user. The exploded and cross-sectional views show the components of the applicator device 20150. The applicator device 20150 may include a housing 20702, a liner 20701, a sheath 20704, a sharps carrier 201102, a spring 205612, a sensor carrier 20710 (also referred to as a "puck" carrier), a sharps hub 205014, a sensor control device (also referred to as a "puck") 20102, an adhesive patch 20105, a desiccant 20502, a cap 20708, a serial number label 20709, and tamper evidence features 20712. When received by the user, only the outer shell 20702, cap 20708, tamper evidence feature 20712, and tag 20709 are visible. The tamper evidence feature 20712 may be, for example, a decal attached to each of the casing 20702 and the cap 20708, and the tamper evidence feature 20712 may be irreparably damaged, for example, by separating the casing 20702 and the cap 20708, thereby indicating to the user that the casing 20702 and the cap 20708 were previously separated. These features are described in more detail below.

G. Exemplary tray and sensor Module Assembly

Fig. 5 is a proximal perspective view depicting an exemplary embodiment of tray 810, wherein sterilization cover 812 is removably attached to tray 810, which may represent how packages are shipped to and received by a user prior to assembly.

Fig. 6A is a perspective cutaway view depicting the proximal end of the sensor delivery assembly within tray 810. Platform 808 is slidably coupled within tray 810. The desiccant 502 is stationary relative to the tray 810. The sensor module 504 is mounted within a tray 810.

Fig. 6B is a proximal perspective view depicting the sensor module 504 in more detail. Here, the retaining arm extension 1834 of the platform 808 releasably secures the sensor module 504 in place. The module 2200 is connected with the connector 2300, the sharps module 2500, and a sensor (not shown) so that they can be removed together as the sensor module 504 during assembly.

H. Exemplary applicators and sensor control devices for one-piece architectures

Referring briefly again to fig. 1A and 3A-3G, for a two-piece architecture system, the sensor tray 202 and sensor applicator 102 are provided to the user as separate packages, thus requiring the user to open each package and ultimately assemble the system. In some applications, the separate sealed packages allow the sensor tray 202 and sensor applicator 102 to be sterilized in a separate sterilization process that is unique to the contents of each package and otherwise incompatible with the contents of the other. More specifically, sensor tray 202, including plug assembly 207, includes sensor 110 and sharps 220, which may be sterilized using radiation sterilization, such as electron beam (or "e-beam") irradiation. Suitable radiation sterilization processes include, but are not limited to, electron beam (e-beam) radiation, gamma radiation, X-ray radiation, or any combination thereof. However, radiation sterilization can damage electronic components disposed within the electronic enclosure of the sensor control device 102. Thus, if it is desired to sterilize the sensor applicator 102 containing the electronic housing of the sensor control device 102, it may be sterilized by another method, such as chemical sterilization using a gas such as ethylene oxide. However, gas chemical sterilization may damage enzymes or other chemicals and biological products included on the sensor 110. Because of this sterilization incompatibility, the sensor tray 202 and sensor applicator 102 are typically sterilized and then individually packaged in separate sterilization processes, which requires the user to ultimately assemble the components for use.

Fig. 7A and 7B are exploded top and bottom views, respectively, of a sensor control device 3702 in accordance with one or more embodiments. The housing 3706 and mount 3708 operate as opposing clamshell halves that enclose or substantially encase the various electronic components of the sensor control device 3702. As shown, the sensor control device 3702 may include a Printed Circuit Board Assembly (PCBA) 3802 including a Printed Circuit Board (PCB) 3804 having a plurality of electronic modules 3806 connected thereto. Example electronic modules 3806 include, but are not limited to, resistors, transistors, capacitors, inductors, diodes, and switches. Existing sensor control devices typically stack PCB assemblies on only one side of the PCB. Conversely, PCB assembly 3806 in sensor control device 3702 may be dispersed over surface areas (i.e., top and bottom surfaces) on both sides of PCB 3804.

In addition to the electronic module 3806, the PCBA3802 may also include a data processing unit 3808 mounted to the PCB 3804. The data processing unit 3808 can include, for example, an Application Specific Integrated Circuit (ASIC) configured to implement one or more functions or routines associated with operation of the sensor control device 3702. More specifically, the data processing unit 3808 may be configured to perform data processing functions, wherein such functions may include, but are not limited to, filtering and encoding of data signals, each of which corresponds to a user's sampled analyte level. The data processing unit 3808 can also include or be in communication with an antenna for communicating with the reader device 106 (fig. 1A).

A battery aperture 3810 may be defined in the PCB 3804 and sized to receive and house a battery 3812, the battery 3812 configured to power the sensor control device 3702. Axial battery contact 3814a and radial battery contact 3814b may be connected to PCB 3804 and extend into battery aperture 3810 to facilitate transmission of power from battery 3812 to PCB 3804. As the name suggests, the axial battery contact 3814a may be configured to provide axial contact for the battery 3812, while the radial battery contact 3814b may provide radial contact for the battery 3812. Positioning the battery 3812 within the battery aperture 3810 with the battery contacts 3814a, b helps reduce the height H of the sensor control device 3702, which allows the PCB 3804 to be centered and its components to be dispersed on both sides (i.e., top and bottom surfaces). This also helps to facilitate the provision of a chamfer 3718 on the electronics housing 3704.

The sensor 3716 may be centrally located relative to the PCB 3804 and includes a tail 3816, a flag 3818, and a neck 3820 interconnecting the tail 3816 and the flag 3818. The tail 3816 may be configured to extend through the central aperture 3720 of the mount 3708 to be received percutaneously under the skin of a user. In addition, enzymes or other chemicals may be included on tail 3816 to help facilitate analyte monitoring.

The flag 3818 may include a generally planar surface on which one or more sensor contacts 3822 (three shown in fig. 7B) are disposed. The sensor contacts 3822 may be configured to align with and engage corresponding one or more circuit contacts 3824 (three shown in fig. 7A) provided on the PCB 3804. In some embodiments, the sensor contacts 3822 may include a carbon impregnated polymer printed or digitally applied to the flag 3818. Existing sensor control devices typically include a connector made of silicone rubber that encapsulates one or more compliant carbon impregnated polymer modules that serve as conductive contacts between the sensor and the PCB. In contrast, the presently disclosed sensor contact 3822 provides a direct connection between the sensor 3716 and PCB 3804 connections, which eliminates the need for prior art connectors and advantageously reduces the height H. Furthermore, eliminating the compliant carbon impregnated polymer module eliminates significant circuit resistance and thus improves circuit conductivity.

The sensor control device 3702 may further include a compliant member 3826, which may be configured to insert the flag 3818 and an inner surface of the housing 3706. More specifically, when the housing 3706 and the mount 3708 are assembled to one another, the compliant member 3826 can be configured to provide a passive biasing load against the flag 3818, forcing the sensor contacts 3822 into continuous engagement with the respective circuit contacts 3824. In an exemplary embodiment, the compliant member 3826 is an elastomeric O-ring, but may alternatively include any other type of biasing device or mechanism, such as a compression spring or the like, without departing from the scope of the present disclosure.

The sensor control device 3702 may further include one or more electromagnetic shields, shown as a first shield 3828a and a second shield. The housing 3706 may provide or define a first clock (clocking) socket 3830a (fig. 7B) and a second clock socket 3830B (fig. 7B), and the mount 3708 may provide or define a first clock post 3832a (fig. 7A) and a second clock post 3832B (fig. 7A). Mating the first and second clock sockets 3830a, b with the first and second clock posts 3832a, b, respectively, properly aligns the housing 3706 to the mount 3708.

Referring specifically to fig. 7A, an inner surface of mount 3708 can provide or define a plurality of pockets or recesses configured to house various component parts of sensor control device 3702 when housing 3706 is mated with mount 3708. For example, an inner surface of the mount 3708 can define a battery locator 3834 configured to receive a portion of the battery 3812 when the sensor control device 3702 is assembled. The adjacent contact pocket 3836 may be configured to receive a portion of the axial contact 3814 a.

In addition, a plurality of module pockets 3838 may be defined in the inner surface of the mount 3708 to accommodate various electronic modules 3806 disposed at the bottom of the PCB 3804. Further, a shield locator 3840 may be defined in an inner surface of the mount 3708 to accommodate at least a portion of the second shield 3828b when the sensor control device 3702 is assembled. The battery locator 3834, contact pocket 3836, module pocket 3838, and shield locator 3840 all extend a small distance into the inner surface of the mount 3708 and thus the overall height H of the sensor control device 3702 can be reduced as compared to existing sensor control devices. The module pocket 3838 may also help minimize the diameter of the PCB 3804 by allowing the PCB assembly to be disposed on both sides (i.e., top and bottom surfaces).

Referring also to fig. 7A, the mount 3708 can further include a plurality of carrier grasping features 3842 (two shown) defined about an outer periphery of the mount 3708. The carrier gripping feature 3842 is axially offset from the bottom 3844 of the mount 3708 where a transfer adhesive (not shown) may be applied during assembly. In contrast to existing sensor control devices that generally include a conical carrier gripping feature intersecting the bottom of the mount, the presently disclosed carrier gripping feature 3842 is offset from the plane of the application transfer adhesive (i.e., the bottom 3844). This may prove advantageous in helping to ensure that the delivery system does not inadvertently adhere to the transfer adhesive during assembly. In addition, the presently disclosed carrier gripping feature 3842 eliminates the need for a fan-shaped transfer adhesive, which simplifies the manufacture of the transfer adhesive and eliminates the need for accurate timing of the transfer adhesive relative to the mount 3708. This also increases the adhesive area and thus the adhesive strength.

Referring to fig. 7B, the bottom 3844 of the mount 3708 can provide or define a plurality of grooves 3846, which can be defined at or near the outer periphery of the mount 3708 and equally spaced from one another. A transfer adhesive (not shown) may be connected to the bottom 3844 and the recess 3846 may be configured to facilitate the transfer of moisture from the sensor control device 3702 and toward the periphery of the mount 3708 during use. In some embodiments, the spacing of the grooves 3846 may be inserted into a module pocket 3838 defined on the opposite side (inner surface) of the mount 3708 (fig. 7A). As will be appreciated, the location of alternating grooves 3846 and module pockets 3838 ensures that the opposing features on either side of the mount 3708 do not extend into each other. This may help to maximize the use of the material of the mount 3708 and thereby help to maintain the minimum height H of the sensor control device 3702. The modular pocket 3838 can also significantly reduce mold sagging and improve the flatness of the bottom 3844 to which the transfer adhesive is adhered.

Referring also to fig. 7B, the inner surface of the housing 3706 may also provide or define a plurality of pockets or recesses configured to house various component parts of the sensor control device 3702 when the housing 3706 is mated with the mount 3708. For example, an inner surface of the housing 3706 may define opposing battery locators 3848, which may be disposed opposite the battery locators 3834 (fig. 7A) of the mount 3708, and configured to receive a portion of the battery 3812 when the sensor control device 3702 is assembled. The opposing battery locator 3848 extends a small distance into the inner surface of the housing 3706, which helps reduce the overall height H of the sensor control device 3702.

The sharp and sensor locator 3852 may also be provided by or defined on the inner surface of the housing 3706. The sharp and sensor locator 3852 may be configured to receive a portion of the sharp (not shown) and sensor 3716. Further, the sharp and sensor positioner 3852 can be configured to align and/or mate with a corresponding sharp and sensor positioner 2054 (fig. 7A) disposed on an inner surface of the mount 3708.

An alternative sensor assembly/electronic assembly connection method is shown in fig. 8A-8C, according to an embodiment of the present disclosure. As shown, the sensor assembly 14702 includes a sensor 14704, a connector support 14706, and a sharp 14708. Notably, a recess or socket 14710 can be defined in the bottom of the mount of the electronic assembly 14712 and provide a location where the sensor assembly 14702 can be received and connected to the electronic assembly 14712 and thereby fully assemble the sensor control device. The sensor assembly 14702 may be contoured to mate with or be shaped in a complementary manner to the socket 14710, with the socket 14710 including an elastomeric sealing member 14714 (including conductive material connected to the circuit board and aligned with the electrical contacts of the sensor 14704). Thus, when the sensor assembly 14702 is snap-fit or adhered to the electronic assembly 14712 by driving the sensor assembly 14702 into the integrally formed recess 14710 in the electronic assembly 14712, the on-body apparatus 14714 depicted in fig. 8C is formed. This embodiment provides an integrated connector for the sensor assembly 14702 within the electronic assembly 14712.

Additional information regarding the sensor assembly is provided in U.S. publication No. 2013/0150691 and U.S. publication No. 2021/0204841, each of which is incorporated herein by reference in its entirety.

According to embodiments of the present disclosure, the sensor control device 102 may be modified to provide a one-piece architecture that may be subject to sterilization techniques specifically designed for one-piece architecture sensor control devices. The one-piece architecture allows the sensor applicator 150 and the sensor control device 102 to be shipped to a user in a single sealed package that does not require any end user assembly steps. Instead, the user need only open one package and then deliver the sensor control device 102 to the target monitoring location. The one-piece system architecture described herein may prove advantageous in eliminating component parts, various manufacturing process steps, and user assembly steps. Thus, packaging and wastage are reduced, and the likelihood of user error or system contamination is lessened.

Fig. 9A and 9B are side and cross-sectional side views, respectively, of an exemplary embodiment of a sensor applicator 102 having an applicator cap 210 attached thereto. More specifically, fig. 9A depicts how the sensor applicator 102 is delivered to and received by a user, and fig. 9B depicts a sensor control device 4402 disposed within the sensor applicator 102. Thus, the fully assembled sensor control device 4402 may have been assembled and installed within the sensor applicator 102 prior to delivery to a user, thus eliminating any other assembly steps that a user would have to perform.

The fully assembled sensor control device 4402 may be loaded into the sensor applicator 102, and the applicator cap 210 may then be connected to the sensor applicator 102. In some embodiments, the applicator cap 210 may be threadably connected to the housing 208 and include a theft prevention ring 4702. Upon rotation (e.g., unscrewing) of the applicator cap 210 relative to the housing 208, the anti-theft ring 4702 may shear and thereby release the applicator cap 210 from the sensor applicator 102.

In accordance with the present disclosure, when loaded in the sensor applicator 102, the sensor control device 4402 may be subjected to gaseous chemical sterilization 4704 configured to sterilize the electronics housing 4404 and any other exposed portions of the sensor control device 4402. To achieve this, a chemical may be injected into the sterilization chamber 4706 defined collectively by the sensor applicator 102 and the interconnect cap 210. In some applications, chemicals may be injected into the sterilization chamber 4706 via one or more vents 4708 defined in the applicator cap 210 at the proximal end 610 thereof. Exemplary chemicals that may be used in gaseous chemical sterilization 4704 include, but are not limited to, ethylene oxide, vaporized hydrogen peroxide, nitrogen oxides (e.g., nitrous oxide, nitrogen dioxide, etc.), and steam.

Because the distal portion of sensor 4410 and sharp 4412 are sealed within sensor cap 4416, chemicals used in the gaseous chemical sterilization process do not interact with enzymes, chemicals, and biological products provided on tail 4524 and other sensor components (e.g., a membrane coating that regulates the inflow of analytes).

Once the desired level of sterility assurance is achieved within the sterilization chamber 4706, the gaseous solution can be removed and the sterilization chamber 4706 can be inflated. Aeration may be achieved by a series of vacuums and then circulating a gas (e.g., nitrogen) or filtered air through the sterilization chamber 4706. Once the sterilization chamber 4706 is properly inflated, the vent 4708 may be closed with a seal 4712 (shown in phantom).

In some embodiments, the seal 4712 may include two or more layers of different materials. The first layer may be made of a synthetic material (e.g., flash spun high density polyethylene fibers), e.g., fromAvailable-> Is very durable and puncture resistant and allows vapor permeation. Can be applied before the gaseous chemical sterilization processA layer, and after a gaseous chemical sterilization process, can be in +.>A layer of seal (e.g., heat seal) foil or other vapor and moisture resistant material is applied to prevent contaminants and moisture from entering the sterilization chamber 4706. In other embodiments, the seal 4712 may include only a single protective layer applied to the applicator cap 210. In such embodiments, the monolayer may be breathable to the sterilization process, but may also be able to prevent moisture and other deleterious elements once the sterilization process is completed.

With seal 4712 in place, applicator cap 210 provides a barrier against external contamination and thereby maintains a sterile environment for assembled sensor control device 4402 until the user removes (loosens) applicator cap 210. The applicator cap 210 may also create a dust-free environment during shipping and storage to prevent the adhesive patch 4714 from becoming dirty.

Fig. 10A and 10B are an isometric view and a side view, respectively, of another example sensor control device 5002 in accordance with one or more embodiments of the present disclosure. The sensor control device 5002 may be similar in some respects to the sensor control device 102 of fig. 1A and may therefore be best understood with reference thereto. Furthermore, the sensor control device 5002 can replace the sensor control device 102 of fig. 1A and can therefore be used in conjunction with the sensor applicator 102 of fig. 1A, the sensor applicator 102 can deliver the sensor control device 5002 to a target monitoring location on the user's skin.

However, unlike the sensor control device 102 of fig. 1A, the sensor control device 5002 may include a one-piece system architecture, eliminating the need for a user to open multiple packages and ultimately assemble the sensor control device 5002 prior to application. Instead, upon receipt by the user, the sensor control device 5002 may have been fully assembled and properly positioned within the sensor applicator 150 (fig. 1A). To use the sensor control device 5002, the user need only open one barrier (e.g., the applicator cap 708 of fig. 3B) and then immediately deliver the sensor control device 5002 to the target monitoring location for use.

As shown, the sensor control device 5002 includes an electronic housing 5004 that is generally disk-shaped and may have a circular cross-section. However, in other embodiments, the electronic enclosure 5004 may take on other cross-sectional shapes, such as oval or polygonal, without departing from the scope of the present disclosure. The electronics housing 5004 can be configured to house or contain various electronic components for operating the sensor control device 5002. In at least one embodiment, an adhesive patch (not shown) may be provided at the bottom of the electronics housing 5004. The adhesive patch may be similar to adhesive patch 105 of fig. A1, and thus may aid in adhering sensor control device 5002 to the skin of a user for use.

As shown, the sensor control device 5002 includes an electronic housing 5004, the electronic housing 5004 including a housing 5006 and a mount 5008 mateable with the housing 5006. The housing 5006 can be secured to the mount 5008 by a variety of means, such as a snap fit engagement, an interference fit, sonic welding, one or more mechanical fasteners (e.g., screws), washers, adhesive, or any combination thereof. In some cases, the housing 5006 can be secured to the mount 5008 such that a sealing interface is created therebetween.

The sensor control device 5002 can further include a sensor 5010 (partially visible) and a sharp 5012 (partially visible) for facilitating transdermal delivery of the sensor 5010 under the skin of a user during application of the sensor control device 5002. As shown, the sensor 5010 and the corresponding portion of the sharpener 5012 extend distally from the bottom of the electronics housing 5004 (e.g., mount 5008). The sharps 5012 may include a sharps hub 5014 configured to secure and carry the sharps 5012. As best shown in fig. 10B, the sharps hub 5014 may include or define a mating member 5016. To connect the sharpener 5012 to the sensor control apparatus 5002, the sharpener 5012 can be axially advanced through the electronic housing 5004 until the sharpener hub 5014 engages the upper surface of the housing 5006 and the mating member 5016 extends distally from the bottom of the mount 5008. When the sharps 5012 penetrate the electronic housing 5004, the exposed portions of the sensor 5010 can be received within the hollow or concave (arcuate) portions of the sharps 5012. The remainder of the sensor 5010 is disposed within the electronics housing 5004.

The sensor control device 5002 can further include a sensor cap 5018, shown exploded or separated from the electronics housing 5004 in fig. 10A-10B. The sensor cap 5016 can be connected to the sensor control device 5002 (e.g., the electronics housing 5004) at or near the bottom of the mount 5008. The sensor cap 5018 can help provide a sealing barrier that surrounds and protects the exposed portions of the sensor 5010 and the sharps 5012 from the gaseous chemical sterilization. As shown, the sensor cap 5018 can include a generally cylindrical body having a first end 5020a and a second end 5020b opposite the first end 5020 a. The first end 5020a can be open to provide access to an interior chamber 5022 defined within the body. Conversely, the second end 5020b can be closed and can provide or define engagement features 5024. As described herein, the engagement feature 5024 can facilitate mating the sensor cap 5018 to a cap (e.g., the applicator cap 708 of fig. 3B) of a sensor applicator (e.g., the sensor applicator 150 of fig. 1A and 3A-3G) and can facilitate removing the sensor cap 5018 from the sensor control device 5002 when the cap is removed from the sensor applicator.

The sensor cap 5018 can be removably connected to the electronics housing 5004 at or near the bottom of the mount 5008. More specifically, the sensor cap 5018 can be removably connected to the mating member 5016 that extends distally from the bottom of the mount 5008. In at least one embodiment, for example, the mating member 5016 can define a set of external threads 5026a (fig. 10B) that can mate with a set of internal threads 5026B (fig. 10A) defined by the sensor cap 5018. In some embodiments, the external and internal threads 5026a, b can include flat thread designs (e.g., without helical curvature), which can prove advantageous when molding components. Alternatively, the external and internal threads 5026a, b can comprise a helical threaded engagement. Thus, the sensor cap 5018 can be threaded to the sensor control device 5002 at the mating member 5016 of the sharp hub 5014. In other embodiments, the sensor cap 5018 can be removably connected to the mating member 5016 by other types of engagement including, but not limited to, interference or friction fits, or frangible members or substances that can be broken with minimal separation forces (e.g., axial forces or rotational forces).

In some embodiments, the sensor cap 5018 can include a monolithic (unitary) structure extending between the first end 5020a and the second end 5020 b. However, in other embodiments, the sensor cap 5018 can include two or more component parts. In an exemplary embodiment, for example, the sensor cap 5018 can include a sealing ring 5028 positioned at the first end 5020a and a desiccant cap 5030 disposed at the second end 5020 b. The sealing ring 5028 can be configured to facilitate sealing the inner chamber 5022, as described in more detail below. In at least one embodiment, the seal ring 5028 can comprise an elastomeric O-ring. The desiccant cap 5030 may contain or include a desiccant to help maintain a preferred humidity level within the interior chamber 5022. The desiccant cap 5030 may also define or provide engagement features 5024 of the sensor cap 5018.

Fig. 11A-11C are progressive cross-sectional side views showing assembly of the sensor applicator 102 with the sensor control device 5002 in accordance with one or more embodiments. Once the sensor control device 5002 is fully assembled, it can be loaded into the sensor applicator 102. Referring to fig. 11A, the sharps hub 5014 can include or define hub snap fingers 5302, the hub snap fingers 5302 configured to facilitate connection of the sensor control device 5002 to the sensor applicator 102. More specifically, the sensor control device 5002 can be advanced into the interior of the sensor applicator 102 and the hub snap jaws 5302 can be received by the corresponding arms 5304 of the sharps carrier 5306 positioned within the sensor applicator 102.

In fig. 11B, the sensor control device 5002 is shown as being received by the sharps carrier 5306 and thus secured within the sensor applicator 102. Once the sensor control device 5002 is loaded into the sensor applicator 102, the applicator cap 210 can be connected to the sensor applicator 102. In some embodiments, the applicator cap 210 and the housing 208 may have opposing matable sets of threads 5308 that enable the applicator cap 210 to be screwed onto the housing 208 in a clockwise (or counter-clockwise) direction and thereby secure the applicator cap 210 to the sensor applicator 102.

As shown, the sheath 212 is also positioned within the sensor applicator 102, and the sensor applicator 102 may include a sheath locking mechanism 5310, the sheath locking mechanism 5310 being configured to ensure that the sheath 212 does not collapse prematurely during an impact event. In an exemplary embodiment, the sheath locking mechanism 5310 may include a threaded engagement between the applicator cap 210 and the sheath 212. More specifically, one or more internal threads 5312a may be defined or disposed on an inner surface of the applicator cap 210 and one or more external threads 5312b may be defined or disposed on the sheath 212. The internal and external threads 5312a, b may be configured to be threaded into engagement when the applicator cap 210 is threaded onto the sensor applicator 102 at threads 5308. The internal and external threads 5312a, b may have the same pitch as the threads 5308, enabling the applicator cap 210 to be screwed onto the housing 208.

In fig. 11C, the applicator cap 210 is shown as being fully threaded (connected) to the housing 208. As shown, the applicator cap 210 may further provide or define a cap post 5314, the cap post 5314 being centrally located inside the applicator cap 210 and extending proximally from the bottom thereof. The cap post 5314 may be configured to receive at least a portion of the sensor cap 5018 when the applicator cap 210 is screwed onto the housing 208.

With the sensor control device 5002 loaded within the sensor applicator 102 and the applicator cap 210 properly secured, the sensor control device 5002 can then be subjected to gaseous chemical sterilization configured to sterilize the electronics housing 5004 and any other exposed portions of the sensor control device 5002. Because the distal portion of the sensor 5010 and the sharps 5012 are sealed within the sensor cap 5018, the chemicals used in the gaseous chemical sterilization process cannot interact with enzymes, chemicals, and biological products provided on the tail 5104 and other sensor components (e.g., the membrane coating that regulates the flow of analytes).

Fig. 12A-12C are progressive cross-sectional side views illustrating assembly and disassembly of the sensor applicator 102 with alternative embodiments of the sensor control device 5002, in accordance with one or more other embodiments. The fully assembled sensor control device 5002 can be loaded into the sensor applicator 102 by connecting the hub snap fingers 5302 into the arms 5304 of the sharps carrier 5306 positioned within the sensor applicator 102, as generally described above.

In an exemplary embodiment, the sheath arm 5604 of the sheath 212 may be configured to interact with a first detent 5702a and a second detent 5702b defined inside the housing 208. The first pawl 5702a may alternatively be referred to as a "locking" pawl, and the second pawl 5702b may alternatively be referred to as a "firing" pawl. When the sensor control device 5002 is initially installed in the sensor applicator 102, the sheath arm 5604 can be received within the primary pawl 5702 a. As discussed below, the sheath 212 may be actuated to move the sheath arm 5604 to the second detent 5702b, which places the sensor applicator 102 in the firing position.

In fig. 12B, the applicator cap 210 is aligned with the housing 208 and advanced toward the housing 208 such that the sheath 212 is received within the applicator cap 210. Instead of rotating the applicator cap 210 relative to the housing 208, the threads of the applicator cap 210 may snap onto corresponding threads of the housing 208 to connect the applicator cap 210 to the housing 208. An axial cutout or slot 5703 (one shown) defined in the applicator cap 210 may allow portions of the applicator cap 210 proximate the threads thereof to flex outwardly to engage the threads of the housing 208. When the applicator cap 210 is snapped into the housing 208, the sensor cap 5018 can correspondingly snap into the cap post 5314.

Similar to the embodiment of fig. 11A-11C, the sensor applicator 102 may include a sheath locking mechanism configured to ensure that the sheath 212 does not collapse prematurely during an impact event. In an exemplary embodiment, the sheath locking mechanism includes one or more ribs 5704 (one shown) and a shoulder 5708 defined near the base of the applicator cap 210, the one or more ribs 5704 being defined near the base of the sheath 212 and configured to interact with the one or more ribs 5706 (two shown). The rib 5704 may be configured to interlock between the rib 5706 and the shoulder 5708 when the applicator cap 210 is attached to the housing 208. More specifically, once the applicator cap 210 is snapped onto the housing 208, the applicator cap 210 may be rotated (e.g., clockwise) which positions the ribs 5704 of the sheath 212 between the ribs 5706 and the shoulders 5708 of the applicator cap 210 and thereby "locks" the applicator cap 210 in place until the user counter-rotates the applicator cap 210 to remove the applicator cap 210 for use. Engaging the rib 5704 between the rib 5706 and the shoulder 5708 of the applicator cap 210 may also prevent the sheath 212 from collapsing prematurely.

In fig. 12C, the applicator cap 210 is removed from the housing 208. As with the embodiment of fig. 12A-12C, the applicator cap 210 may be removed by counter-rotating the applicator cap 210, which in turn rotates the cap post 5314 in the same direction and causes the sensor cap 5018 to be released from the mating member 5016 as generally described above. Further, removal of the sensor cap 5018 from the sensor control apparatus 5002 exposes the distal portion of the sensor 5010 and the sharps 5012.

When the applicator cap 210 is unscrewed from the housing 208, the ribs 5704 defined on the sheath 212 may slidably engage the tops of the ribs 5706 defined on the applicator cap 210. The top of the rib 5706 may provide a corresponding sloped surface that causes the sheath 212 to displace upward as the applicator cap 210 rotates, and moving the sheath 212 upward causes the sheath arm 5604 to flex out of engagement with the first detent 5702a to be received within the second detent 5702 b. As the sheath 212 moves to the second detent 5702b, the radial shoulder 5614 moves out of radial engagement with the carrier arm 5608, which allows the passive spring force of the spring 5612 to push the sharps carrier 5306 upward and force the carrier arm 5608 out of engagement with the recess 5610. As the sharps carrier 5306 moves upwardly within the housing 208, the mating member 5016 may retract accordingly until it becomes flush, substantially flush, or sub-flush with the bottom of the sensor control device 5002. At this point, the sensor applicator 102 is in the firing position. Accordingly, in this embodiment, removal of the applicator cap 210 correspondingly causes retraction of the mating member 5016.

I. Exemplary firing mechanism for one-piece and two-piece applicators

Fig. 13A-13F illustrate example details of an embodiment of an internal device mechanism to "fire" the applicator 216 to apply the sensor control device 222 to a user and include safely retracting the sharps 1030 into the applicator 216 in use. In summary, these figures represent an example sequence of driving the sharp 1030 (supporting the sensor connected to the sensor control device 222) into the user's skin, withdrawing the sharp while leaving the sensor in active contact with the interstitial fluid of the user, and adhering the sensor control device to the user's skin with an adhesive. Modifications of this activity may be understood by those skilled in the art with reference to the same content for use with alternative applicator assembly embodiments and assemblies. Further, the applicator 216 may be a sensor applicator having a one-piece architecture or a two-piece architecture as disclosed herein.

Turning now to fig. 13A, a sensor 1102 is supported within a sharpener 1030 just above the user's skin 1104. The rails 1106 of the upper guide section 1108 (optionally three of them) may be provided to control the movement of the applicator 216 relative to the sheath 318. The sheath 318 is held by the detent feature 1110 within the applicator 216 such that a proper downward force along the longitudinal axis of the applicator 216 will cause the resistance provided by the detent feature 1110 to be overcome such that the sharp 1030 and the sensor control device 222 can translate into (and onto) the user's skin 1104 along the longitudinal axis. Further, the gripping arms 1112 of the sensor carrier 1022 engage the sharpener retraction assembly 1024 to hold the sharpener 1030 in place relative to the sensor control device 222.

In fig. 13B, a user force is applied to overcome or override the detent feature 1110 and the sheath 318 collapses into the housing 314, driving the sensor control device 222 (with associated components) to translate down the longitudinal axis as indicated by arrow L. The inner diameter of the upper guide section 1108 of the sheath 318 limits the position of the carrier arm 1112 throughout the stroke of the sensor/sharps insertion procedure. The stop surface 1114 of the carrier arm 1112 maintains the position of the components against the complementary face 1116 of the sharps retraction assembly 1024 and the return spring 1118 is fully energized. According to an embodiment, rather than using a user force to drive sensor control device 222 to translate downward along a longitudinal axis as indicated by arrow L, housing 314 may include a button (e.g., without limitation, a key) that activates a drive spring (e.g., without limitation, a coil spring) to drive sensor control device 222.

In fig. 13C, sensor 1102 and sharp 1030 have reached full insertion depth. In so doing, the carrier arm 1112 is clear of the inner diameter of the upper guide section 1108. The compressive force of the helical return spring 1118 then drives the angled stop surface 1114 radially outward, and the release force drives the sharps carrier 1102 of the sharps retraction assembly 1024 to pull the (slotted or configured) sharps 1030 out of the user and away from the sensor 1102 as indicated by arrow R in fig. 13D.

With the sharps 1030 fully retracted as shown in fig. 13E, the upper guide section 1108 of the sheath 318 is provided with a final locking feature 1120. As shown in fig. 13F, the used applicator assembly 216 is removed from the insertion position, leaving the sensor control device 222, and the sharps 1030 securely fixed within the applicator assembly 216. The used applicator assembly 216 may now be discarded.

The operation of the applicator 216 when the sensor control device 222 is applied is designed to provide the user with a sensation that insertion and retraction of the sharp 1030 is both automatically performed by the internal mechanisms of the applicator 216. In other words, the present invention avoids the user experiencing the sensation that he is manually driving the sharp 1030 to his skin. Thus, once the user applies sufficient force to overcome the resistance from the detent feature of the applicator 216, the final action of the applicator 216 is perceived as an automatic response to the applicator being "triggered". Although all of the driving force is provided by the user and no additional biasing/driving means are used to insert the sharp 1030, the user does not perceive that he is providing additional force to drive the sharp 1030 to pierce his skin. Retraction of the sharp 1030 is automatically accomplished by the helical return spring 1118 of the applicator 216, as detailed above in fig. 13C.

With respect to any of the applicator embodiments described herein and any components thereof, including but not limited to sharp, sharp module, and sensor module embodiments, those of skill in the art will appreciate that the embodiments may be sized and configured for use with a sensor configured to sense an analyte level in a bodily fluid in the epidermis, dermis, or subcutaneous tissue of a subject. In some embodiments, for example, both the sharp and distal portions of the analyte sensors disclosed herein can be sized and configured to be positioned at a particular tip depth (i.e., the furthest penetration point of a subject's body tissue or layer, e.g., in the epidermis, dermis, or subcutaneous tissue). With respect to some applicator embodiments, those skilled in the art will appreciate that certain embodiments of the sharps may be sized and configured to be positioned at different tip depths in the subject's body relative to the final tip depth of the analyte sensor. In some embodiments, for example, the sharp may be positioned at a first end depth in the subject's epidermis before retraction, while the distal portion of the analyte sensor may be positioned at a second end depth in the subject's dermis. In other embodiments, the sharp instrument may be positioned at a first end depth in the dermis of the subject prior to retraction, and the distal portion of the analyte sensor may be positioned at a second end depth in the subcutaneous tissue of the subject. In still other embodiments, the sharps may be positioned at a first end depth and the analyte sensor may be positioned at a second end depth prior to retraction, wherein both the first end depth and the second end depth are in the same layer or tissue of the subject's body.

Further, with respect to any of the applicator embodiments described herein, those skilled in the art will appreciate that the analyte sensor and one or more structural components (including, but not limited to, one or more spring mechanisms) connected thereto may be disposed within the applicator in an eccentric position with respect to one or more axes of the applicator. In some applicator embodiments, for example, the analyte sensor and spring mechanism may be disposed on a first side of the applicator in a first eccentric position relative to the axis of the applicator, and the sensor electronics may be disposed on a second side of the applicator in a second eccentric position relative to the axis of the applicator. In other applicator embodiments, the analyte sensor, spring mechanism, and sensor electronics may be disposed on the same side in an eccentric position relative to the axis of the applicator. Those skilled in the art will appreciate that other arrangements and configurations are possible and well within the scope of the present disclosure, wherein any or all of the analyte sensor, spring mechanism, sensor electronics, and other sets of components of the applicator are disposed in a centered or eccentric position relative to one or more axes of the applicator.

Further details of suitable devices, systems, methods, components, and operations thereof, and their associated features, are given in International publication No. WO 2018/136898 to Rao et al, international publication No. WO 2019/236850 to Thomas et al, international publication No. WO 2019/23689 to Thomas et al, international publication No. WO 2019/236876 to Thomas et al, and U.S. patent publication No. 2020/0196919 filed 6/2019, each of which is incorporated herein by reference in its entirety. Further details regarding embodiments of applicators, their components, and variants thereof are described in U.S. patent publication nos. 2013/0150691, 2016/0331283, and 2018/0235218, all of which are incorporated herein by reference in their entirety for all purposes. Further details regarding the implementation of the sharps module, sharps, their components, and variants thereof are described in U.S. patent publication No. 2014/0171771, which is incorporated herein by reference in its entirety for all purposes.

J. Exemplary methods of calibrating analyte sensors

A biochemical sensor may be described by one or more sensing characteristics. A common sensing characteristic is known as the sensitivity of a biochemical sensor, which is a measure of the responsiveness of the sensor to the concentration of chemicals or components it is designed to detect. For electrochemical sensors, this response may be in the form of current (amperes) or charge (coulombs). For other types of sensors, the response may be of different forms, such as photon intensity (e.g., visible light). The sensitivity of a biochemical analyte sensor may vary depending on a variety of factors, including whether the sensor is in an in vitro state or an in vivo state.

Fig. 14 is a graph depicting the in vitro sensitivity of an amperometric analyte sensor. In vitro sensitivity can be obtained by in vitro testing of the sensor at various analyte concentrations, and then regression (e.g., linear or nonlinear) or other curve fitting of the resulting data. In this example, the sensitivity of the analyte sensor is linear, or substantially linear, and can be modeled according to the equation y = mx+b, where y is the electrical output current of the sensor, x is the analyte level (or concentration), m is the slope of the sensitivity and b is the intercept of the sensitivity, where the intercept generally corresponds to the background signal (e.g., noise). For a sensor with a linear or substantially linear response, the analyte level corresponding to a given current may be determined from the slope and intercept of the sensitivity. A sensor with nonlinear sensitivity requires additional information to determine the analyte level derived from the output current of the sensor and one of ordinary skill in the art is familiar with ways to simulate nonlinear sensitivity. In certain embodiments of the in vivo sensor, the in vitro sensitivity may be the same as the in vivo sensitivity, but in other embodiments, a transfer (or conversion) function is used to convert the in vitro sensitivity to an in vivo sensitivity suitable for the sensor to be used in vivo.

Calibration is a technique to improve or maintain accuracy by adjusting the measured output of the sensor to reduce the variance from the expected output of the sensor. One or more parameters describing the sensing characteristics of the sensor, such as its sensitivity, are established for calibration adjustment.

Some in vivo analyte monitoring systems require calibration in an automated fashion by user interaction or the system itself after the sensor is implanted in the user or patient. For example, when user interaction is required, the user performs an in vitro measurement (e.g., blood Glucose (BG) measurement using a finger stick and an in vitro test strip) and inputs it into the system while the analyte sensor is implanted. The system then compares the in vitro measurements with the in vivo signals and determines an estimate of the in vivo sensitivity of the sensor using differentiation. The in vivo sensitivity may then be used in an algorithmic process to convert the data collected with the sensor into a value indicative of the user's analyte level. This process and other processes that require user action to perform calibration are referred to as "user calibration". Because the sensitivity of the sensor is unstable, such that the sensitivity may drift or change over time, the system may require user calibration. Thus, multiple user calibrations (e.g., according to a periodic (e.g., daily) schedule, variable schedule, or as needed) may be required to maintain accuracy. While the embodiments described herein may incorporate some degree of user calibration for a particular implementation, this is generally not preferred because it requires the user to perform painful or burdensome BG measurements and may introduce user errors.

Some in vivo analyte monitoring systems may adjust the calibration parameters periodically by using automatic measurements of sensor characteristics by the system itself (e.g., processing circuitry executing software). Repeatedly adjusting the sensitivity of the sensor based on the variables measured by the system (rather than the user) is often referred to as "system" (or automatic) calibration, and may be performed using user calibration (e.g., early BG measurements) or not using user calibration. As with repeated user calibration, sensor sensitivity drift over time typically requires repeated system calibration. Thus, while the embodiments described herein may be used with a degree of automated system calibration, preferably the sensitivity of the sensor is relatively stable over time such that post-implantation calibration is not required.

Some in vivo analyte monitoring systems operate using factory calibrated sensors. Factory calibration refers to determining or estimating one or more calibration parameters prior to distribution to a user or a Health Care Professional (HCP). The calibration parameters may be determined by the sensor manufacturer (or the manufacturer of other components of the sensor control device if the two entities are different). Many in vivo sensor manufacturing processes manufacture sensors in groups or batches, referred to as production batches, manufacturing stage batches, or simple batches. A single batch may include thousands of sensors.

The sensor may include calibration codes or parameters that may be derived or determined during one or more sensor manufacturing processes and encoded or programmed in a data processing device of the analyte monitoring system or provided on the sensor itself as part of the manufacturing process, for example as a bar code, laser tag, RFID tag or other machine readable information provided on the sensor. If the code is provided to the receiver (or other data processing device), user calibration during in-vivo use of the sensor may be avoided or in-vivo calibration frequency during sensor wear may be reduced. In embodiments where the calibration code or parameter is provided on the sensor itself, the calibration code or parameter may be automatically transmitted or provided to a data processing device in the analyte monitoring system prior to or upon initiation of sensor use.

Some in vivo analyte monitoring systems operate using sensors that may be one or more of factory calibration, system calibration, and/or user calibration. For example, the sensor may be provided with calibration codes or parameters that allow factory calibration. If information is provided to the receiver (e.g., entered by a user), the sensor may operate as a factory calibration sensor. If no information is provided to the receiver, the sensor may operate as a user calibration sensor and/or a system calibration sensor.

In yet another aspect, programmable instructions may be provided or stored in a data processing device and/or receiver/controller unit of the analyte monitoring system to provide a time-varying adjustment algorithm to the in-vivo sensor during use. For example, based on retrospective statistical analysis of analyte sensors used in vivo and corresponding glucose level feedback, a time-based predetermined or analytical curve or database may be generated and configured to provide additional adjustments to one or more in vivo sensor parameters to compensate for potential sensor drift in terms of stability attributes or other factors.

In accordance with the disclosed subject matter, an analyte monitoring system can be configured to compensate or adjust sensor sensitivity based on sensor drift properties. The time-varying parameter β (t) may be defined or determined based on analysis of sensor behavior during in vivo use, and the time-varying drift properties may be determined. In certain aspects, compensation or adjustment of sensor sensitivity may be programmed in a receiver unit, controller, or data processor of the analyte monitoring system such that compensation or adjustment, or both, may be performed automatically and/or iteratively upon receiving sensor data from the analyte sensor. In accordance with the disclosed subject matter, the adjustment or compensation algorithm may be initiated or executed by the user (rather than self-initiated or executed) such that the adjustment or compensation of the analyte sensor sensitivity attribute is performed or executed after the user initiates or activates the corresponding function or routine, or after the user enters the sensor calibration code.

In accordance with the disclosed subject matter, each sensor in a sensor batch (excluding sample sensors for in vitro testing in some cases) may be non-destructively inspected to determine or measure its characteristics, such as film thickness at one or more points of the sensor, and other characteristics may be measured or determined, including physical characteristics such as surface area/volume of the active region. Such measurements or determinations may be made in an automated manner using, for example, an optical scanner or other suitable measuring device or system, and the determined sensor characteristics of each sensor in the sensor batch are compared to a corresponding average value based on the sample sensor for possible correction of the calibration parameters or codes assigned to each sensor. For example, for a calibration parameter defined as sensor sensitivity, the sensitivity is approximately inversely proportional to the film thickness, such that, for example, with a sensor measuring approximately 4% of the film thickness as a sensor over the average film thickness of sampled sensors from the same sensor lot, then in one embodiment the sensitivity assigned to that sensor is the average sensitivity determined from the sampled sensors divided by 1.04. Similarly, since the sensitivity is approximately proportional to the active area of the sensor, there is a sensor with a measured active area that is about 3% lower than the average active area of the sampled sensors from the same sensor batch, and the sensitivity assigned to that sensor is the average sensitivity multiplied by 0.97. By continuously adjusting the sensor a number of times per check or measurement, the assigned sensitivity can be determined from the average sensitivity of the sampled sensor. In certain embodiments, the inspection or measurement of each sensor may additionally include measurement of film consistency or texture in addition to the film thickness and/or surface area or volume of the active sensing region.

Additional information regarding sensor calibration is provided in U.S. publication No. 2010/00230285 and U.S. publication No. 2019/0274598, each of which is incorporated herein by reference in its entirety.

K. Exemplary Bluetooth communication protocol

The storage memory 5030 of the sensor 110 may include software building blocks related to the communication protocol of the communication module. For example, storage memory 5030 may include a BLE service software building block having functionality to provide an interface to make BLE module 5041 available to computing hardware of sensor 110. These software functions may include BLE logical interfaces and interface parsers. BLE services provided by communication module 5040 may include universal access protocol services, universal attribute services, universal access services, device information services, data transfer services, and security services. The data transmission service may be a primary service for transmitting data such as sensor control data, sensor status data, analyte measurement data (historical and current) and event log data. The sensor state data may include error data, current activity time, and software state. The analyte measurement data may include information such as current and historical raw measurements, current and historical values processed using appropriate algorithms or models, predictions and trends of measurement levels, comparisons of other values to patient-specific averages, action invocations determined by algorithms or models, and other similar types of data.

In accordance with aspects of the disclosed subject matter, and as embodied herein, the sensor 110 may be configured to communicate with multiple devices simultaneously by adapting features of a communication protocol or medium supported by the hardware and radio of the sensor 110. As an example, BLE module 5041 of communication module 5040 may be provided with software or firmware to enable multiple concurrent connections between sensor 110 as a central device and other devices as peripheral devices, or as peripheral devices, wherein the other devices are central devices.

The connection between two devices using a communication protocol such as BLE and subsequent communication sessions may be characterized by a similar physical channel running between the two devices (e.g., sensor 110 and data receiving device 120). The physical channels may comprise a single channel or a series of channels including, for example and without limitation, using an agreed-upon series of channels determined by a common clock and channel or frequency hopping sequence. The communication sessions may use a similar amount of available communication spectrum, and a plurality of such communication sessions may exist adjacently. In some embodiments, each set of devices in a communication session uses a different physical channel or series of channels to manage interference for devices of the same proximity.

For purposes of illustration and not limitation, reference is made to exemplary embodiments of a program for sensor-receiver connection for use with the disclosed subject matter. First, the sensor 110 repeatedly publishes its connection information to its environment in the search data reception apparatus 120. The sensor 110 may be repeatedly published periodically until a connection is established. The data receiving device 120 detects the publishing packet and scans and filters the sensors 120 to be connected by the data provided in the publishing packet. Next, the data receiving device 120 sends a scan request command and the sensor 110 responds with a scan response packet that provides additional details. Then, the data reception device 120 transmits a connection request using the bluetooth device address associated with the data reception device 120. The data receiving device 120 may also continually request to use a particular bluetooth device address to establish a connection with the sensor 110. The devices then establish an initial connection allowing them to begin exchanging data. The device starts a process of initializing the data exchange service and performing the mutual authentication procedure.

During a first connection between the sensor 110 and the data receiving device 120, the data receiving device 120 may initiate a service, characteristic, and attribute discovery procedure. The data receiving device 120 can evaluate these features of the sensor 110 and store them for use during a subsequent connection. Next, the device enables notification of customized security services for mutual authentication of the sensor 110 and the data receiving device 120. The mutual authentication procedure may be automated and no user interaction is required. After successful completion of the mutual authentication procedure, the sensor 110 sends a connection parameter update to request the data receiving device 120 to use the connection parameter settings that the sensor 110 prefers and is configured to have the longest lifetime.

The data receiving device 120 then executes the sensor control program to backfill the historical data, current data, event logs, and plant data. As an example, for each type of data, the data receiving device 120 sends a request to initiate the backfill process. The request may specify a recording range defined based on, for example, a measurement value, a time stamp, or the like as the case may be. The sensor 110 responds with the requested data until all previously unsent data in the memory of the sensor 110 is transferred to the data receiving device 120. The sensor 110 may respond to a backfill request that all data from the data receiving device 120 have been sent. Once backfilling is complete, the data receiving device 120 can notify the sensor 110 that it is ready to receive periodic measurement readings. The sensor 110 may send readings across multiple notification results on a recurring basis. As embodied herein, the plurality of notifications may be redundant notifications to ensure that the data is properly transmitted. Alternatively, multiple notifications may constitute a single payload.

For purposes of illustration and not limitation, reference is made to an exemplary embodiment of a program that sends a close command to sensor 110. If the sensor 110 is in, for example, an error state, an insertion failure state, or a sensor expiration state, a shutdown operation is performed. If the sensor 110 is not in those states, the sensor 110 may record a command and perform a shutdown when the sensor 110 transitions to an error state or a sensor expiration state. The data receiving device 120 sends a properly formatted shutdown command to the sensor 110. If the sensor 110 is actively processing another command, the sensor 110 will respond with a standard error response, indicating that the sensor 110 is busy. Otherwise, the sensor 110 sends a response upon receiving the command. In addition, the sensor 110 sends a success notification through the sensor control feature to confirm that the sensor 110 has received the command. The sensor 110 records a shutdown command. At the next appropriate opportunity (e.g., depending on the current sensor state, as described herein), sensor 110 will be turned off.

L. exemplary sensor State and activation

For purposes of illustration and not limitation, the exemplary embodiment described at a high level with reference to the state machine representation 6000 of actions that may be taken by the sensor 110 shown in FIG. 15. After initialization, the sensor enters state 6005, state 6005 involves the manufacture of sensor 110. In manufacturing state 6005, sensor 110 may be configured for operation, e.g., storage memory 5030 may be written to. At a different time in state 6005, sensor 110 checks the received command to enter storage state 6015. Upon entering the storage state 6015, the sensor performs a software integrity check. While in storage state 6015, the sensor may also receive an activation request command before proceeding to insertion detection state 6025.

Upon entering state 6025, the sensor 110 may store information about the device that is verified to be in communication with the sensor, as set during activation, or initialize algorithms related to making and interpreting measurements from the sensing hardware 5060. The sensor 110 may also initialize a lifecycle timer responsible for maintaining an activity count of the operational time of the sensor 110 and beginning to communicate with the authenticated device to transmit the recorded data. While in the insertion detection state 6025, the sensor may enter a state 6030 in which the sensor 110 checks whether the operation time is equal to a predetermined threshold. The operating time threshold may correspond to a timeout function used to determine whether an insertion has been successful. If the operating time has reached a threshold, the sensor 110 proceeds to state 6035 where the sensor 110 checks whether the average data read is greater than a threshold amount corresponding to the expected data read volume for triggering a successful insertion detection. If the data read volume is below the threshold in state 6035, the sensor proceeds to state 6040, corresponding to an insertion failure. If the data read volume meets the threshold, the sensor proceeds to an active pairing state 6055.

The active pairing state 6055 of the sensors 110 reflects the state of the sensors 110 as they normally operate by recording measurements, processing the measurements, and reporting them appropriately. While in the active pairing state 6055, the sensor 110 transmits a measurement result or attempts to establish a connection with the receiving device 120. The sensor 110 also increases the operating time. Once the sensor 110 reaches a predetermined threshold operating time (e.g., once the operating time reaches a predetermined threshold), the sensor 110 transitions to the active expiration state 6065. The activity expiration state 6065 of the sensor 110 reflects the state when the sensor 110 has been operating for its maximum predetermined amount of time.

While in the active expiration state 6065, the sensor 110 may typically perform operations related to rolling down operations and ensure that the collected measurements have been securely transmitted to the receiving device as needed. For example, while in the active expiration state 6065, the sensor 110 may transmit collected data and if no connection is available, effort may be increased to discover and establish a connection with nearby authenticated devices. Upon expiration of the active state 6065, the sensor 110 may receive a shutdown command at state 6070. If no shutdown command is received, the sensor 110 may also check in state 6075 if the operation time has exceeded a final operation threshold. The final operating threshold may be based on the battery life of the sensor 110. The normal end state 6080 corresponds to the final operation of the sensor 110 and eventually turns off the sensor 110.

The ASIC 5000 is in a low power storage mode state prior to activating the sensor. For example, when an incoming RF field (e.g., NFC field) drives the supply voltage of the ASIC 5000 above a reset threshold, then the activation process may begin, which causes the sensor 110 to enter an awake state. Upon the wake-up state, the ASIC 5000 enters an active sequence state. The ASIC 5000 then wakes up the communication module 5040. The communication module 5040 is initialized, triggering a power-on self-test. The power-on self test may include communicating with the communication module 5040 using a specified read and write data sequence ASIC 5000 to verify that the memory and one-time programmable memory are not corrupted.

When the ASIC 5000 first enters the measurement mode, an insertion detection sequence is performed to verify that the sensor 110 has been properly mounted to the patient's body before appropriate measurements can be made. First, the sensor 110 interprets a command to activate the measurement configuration process, causing the ASIC 5000 to enter a measurement command mode. The sensor 110 then temporarily enters a measurement lifecycle state to run a number of consecutive measurements to test whether the insertion has been successful. The communication module 5040 or ASIC 5000 evaluates the measurement to determine that the insertion was successful. When the insertion is deemed successful, the sensor 110 enters a measurement state in which the sensor 110 begins to make periodic measurements using the sensing hardware 5060. If the sensor 110 determines that the insertion was unsuccessful, the sensor 110 is triggered into an insertion failure mode, wherein the ASIC 5000 is commanded back to storage mode, while the communication module 5040 disables itself.

M. exemplary over-the-air (over-the-air) update

FIG. 1B further illustrates an example operating environment for providing over-the-air ("OTA") updates for use with the techniques described herein. An operator of analyte monitoring system 100 may bundle updates of data receiving device 120 or sensor 110 into updates of an application executing on multipurpose data receiving device 130. Using the available communication channels between the data receiving device 120, the multipurpose data receiving device 130, and the sensor 110, the multipurpose data receiving device 130 may receive periodic updates for the data receiving device 120 or the sensor 110 and initiate installation of updates with respect to the data receiving device 120 or the sensor 110. The multipurpose data receiving device 130 acts as an installation or update platform for the data receiving device 120 or sensor 110 in that applications that enable the multipurpose data receiving device 130 to communicate with the analyte sensor 110, the data receiving device 120, and/or the remote application server 150 can update software or firmware on the data receiving device 120 or sensor 110 without wide area network capability.

As embodied herein, a remote application server 150 operated by the manufacturer of analyte sensor 110 and/or the operator of analyte monitoring system 100 may provide software and firmware updates to the devices of analyte monitoring system 100. In particular embodiments, remote application server 150 may provide updated software and firmware to user device 140 or directly to the multipurpose data receiving device. As embodied herein, remote application server 150 may also provide application software updates to application storefront server 160 using an interface provided by the application storefront. The multipurpose data sink device 130 can periodically contact the application storefront server 160 to download and install updates.

After the multipurpose data receiving device 130 downloads an application update including a firmware or software update to the data receiving device 120 or the sensor 110, the data receiving device 120 or the sensor 110 establishes a connection with the multipurpose data receiving device 130. The multipurpose data receiving device 130 determines that a firmware or software update is available to the data receiving device 120 or the sensor 110. The multipurpose data receiving device 130 may prepare software or firmware updates for transmission to the data receiving device 120 or the sensor 110. As an example, the multipurpose data receiving device 130 may compress or segment data associated with the software or firmware update, may encrypt or decrypt the firmware or software update, or may perform an integrity check of the firmware or software update. The multipurpose data receiving device 130 transmits data for firmware or software update to the data receiving device 120 or the sensor 110. The multipurpose data receiving device 130 may also send commands to the data receiving device 120 or the sensor 110 to initiate an update. Additionally or alternatively, the multipurpose data receiving device 130 may provide a notification to a user of the multipurpose data receiving device 130 and include instructions for facilitating the update, such as instructions to keep the data receiving device 120 and the multipurpose data receiving device 130 connected to a power source and in proximity until the update is completed.

The data receiving device 120 or the sensor 110 receives data for update and a command to start update from the multipurpose data receiving device 130. The data receiving device 120 may then install the firmware or software update. To install the update, the data receiving device 120 or the sensor 110 may place itself in or reboot into a so-called "safe" mode with limited operational capabilities. Once the update is complete, the data receiving device 120 or sensor 110 re-enters or resets to the standard operating mode. The data receiving device 120 or the sensor 110 may perform one or more self-tests to determine that the firmware or software update has been successfully installed. The multipurpose data receiving device 130 may receive a notification of a successful update. The multipurpose data receiving device 130 may then report a confirmation of successful update to the remote application server 150.

In a particular embodiment, the storage memory 5030 of the sensor 110 includes one-time programmable (OTP) memory. The term OTP memory may refer to memory that includes access restrictions and security to facilitate writing to a particular address or segment in the memory a predetermined number of times. Memory 5030 may be pre-configured as a plurality of pre-allocated memory blocks or containers. The containers are pre-allocated to a fixed size. If storage memory 5030 is a one-time programmable memory, then the container may be considered to be in an unprogrammed state. Other containers that have not been written to may be placed in a programmable or writable state. Containerizing storage memory 5030 in this manner may improve the transmissibility of code and data to be written to storage memory 5030. Updating the software of a device stored in OTP memory (e.g., a sensor device as described herein) may be performed by replacing code in a particular previously written container or containers with only updated code written to the new container or containers, rather than replacing the entire code in memory. In a second embodiment, the memory is not pre-arranged. Instead, the space allocated for the data is dynamically allocated or determined as needed. Incremental updates may be published because containers of different sizes may be defined where updates are expected.

Fig. 16 is a diagram illustrating example operations and data flow for over-the-air (OTA) programming of storage memory 5030 in sensor device 100 and use of memory after OTA programming during execution by sensor device 110 in accordance with the disclosed subject matter. In the example OTA programming 500 shown in fig. 5, a request is sent from an external device (e.g., the data receiving device 130) to initiate OTA programming (or reprogramming). At 511, the communication module 5040 of the sensor device 110 receives the OTA programming command. The communication module 5040 sends OTA programming commands to the microcontroller 5010 of the sensor device 110.

After receiving the OTA programming command, the microcontroller 5010 verifies the OTA programming command at 531. For example, the microcontroller 5010 can determine whether the OTA programming command is signed with an appropriate digital signature token. Upon determining that the OTA programming command is valid, the microcontroller 5010 can set the sensor device to the OTA programming mode. At 532, the microcontroller 5010 can verify the OTA programming data. At 533, the microcontroller 5010 can reset the sensor device 110 to reinitialize the sensor device 110 to the programmed state. Once the sensor device 110 has transitioned to the OTA programming state, the microcontroller 5010 can begin writing data to the sensor device's rewritable memory 540 (e.g., memory 5020) at 534 and to the sensor device's OTP memory 550 (e.g., memory 5030) at 535. The data written by the microcontroller 5010 may be based on the verified OTA programming data. The microcontroller 5010 can write data such that one or more programming blocks or areas of the OTP memory 550 are marked as invalid or inaccessible. The data written to the free or unused portion of OTP memory may be used to replace an invalid or inaccessible programming block of OTP memory 550. After the microcontroller 5010 writes the data to the corresponding memories at 534 and 535, the microcontroller 5010 may perform one or more software integrity checks to ensure that no errors are introduced into the programming blocks during the writing process. Once the microcontroller 5010 can determine that data has been written without error, the microcontroller 5010 can resume standard operation of the sensor device.

In the execution mode, at 536, the microcontroller 5010 may retrieve a programming list or configuration file from the rewritable memory 540. The programming manifest or configuration file may include a list of valid software programming blocks and may include guidelines for program execution of sensor 110. By following a programming list or configuration file, the microcontroller 5010 can determine which memory blocks of the OTP memory 550 are suitable for execution and avoid execution of obsolete or invalid programming blocks or references to obsolete data. At 537, the microcontroller 5010 may selectively retrieve memory blocks from the OTP memory 550. At 538, the microcontroller 5010 may use the retrieved memory block by executing stored program code or using variables stored in memory.

N. exemplary security and other architectural features

As embodied herein, a first layer for communication security between analyte sensor 110 and other devices may be established based on a security protocol specified by and integrated in a communication protocol used for communication. Another layer of security may be based on the communication protocol that requires the communication device to be in close proximity. In addition, certain data packets and/or certain data included in data packets may be encrypted, while other data packets and/or data in data packets may or may not be encrypted. Additionally or alternatively, application layer encryption may be used with one or more block ciphers or stream ciphers to establish mutual authentication and communication encryption with other devices in analyte monitoring system 100.

The ASIC 5000 of the analyte sensor 110 may be configured to dynamically generate authentication and encryption keys using data retained in the storage memory 5030. Storage memory 5030 may also be preprogrammed with a valid set of authentication and encryption keys for use with a particular class of devices. The ASIC 5000 may be further configured to perform a verification procedure using the received data with other devices and to apply the generated keys to the sensitive data before transmitting the sensitive data. The generated key may be unique to analyte sensor 110, to a pair of devices, to a communication session between analyte sensor 110 and other devices, to a message sent during the communication session, or to a block of data included in the message.

Both the sensor 110 and the data receiving device 120 may ensure authorization of the other party in the communication session, such as issuing a command or receiving data. In a specific embodiment, identity authentication may be performed by two features. First, the party that declares its identity provides a valid certificate signed by the device manufacturer or operator of analyte monitoring system 100. Second, authentication may be implemented by using public and private keys established by the devices of analyte monitoring system 100 or established by the operator of analyte monitoring system 100 and sharing secrets derived therefrom. To confirm the identity of the other party, the party may provide proof that the party has control of its private key.

The manufacturer of the analyte sensor 110, the data receiving device 120, or the provider of the application of the multipurpose data receiving device 130 may provide the information and programming necessary for the device to communicate securely through secure programming and updating. For example, the manufacturer may provide information that may be used to generate encryption keys for each device, including a secure root key for analyte sensor 110 and optionally for data receiving device 120, which may be used in conjunction with device specific information and operational data (e.g., entropy-based random values) to generate device, session, or data transmission unique encryption values as desired.

Analytical data associated with the user is at least partially sensitive data, as this information can be used for a variety of purposes, including health monitoring and drug dosage decisions. In addition to user data, analyte monitoring system 100 may enforce security enhancements against the efforts of external parties in reverse engineering. The communication connection may be encrypted using a device-unique or session-unique encryption key. A transmission integrity check built into the communication may be used to verify encrypted or unencrypted communications between any two devices. The operation of analyte sensor 110 may be protected from tampering by restricting access to read and write functions of memory 5020 through a communication interface. The sensor may be configured to grant access only to known or "trusted" devices that are provided in a "whitelist," or to devices that may provide a predetermined code associated with the manufacturer or other authenticated user. The whitelist may represent an exclusive range, meaning that no connection identifier other than the connection identifier included in the whitelist is used, or a priority range, in which the whitelist is searched first, but other devices may be used. If the requestor is unable to complete the login process through the communication interface within a predetermined period of time (e.g., within four seconds), the sensor 110 may further reject and close the connection request. These features may protect against specific denial of service attacks and in particular against denial of service attacks on the BLE interface.

As embodied herein, the analyte monitoring system 100 may employ periodic key rotation to further reduce the likelihood of key compromise and exploitation. The key rotation strategy employed by the analyte monitoring system 100 may be designed to support backward compatibility of field deployment or distributed devices. As an example, analyte monitoring system 100 may employ a key for a downstream device (e.g., a device in the field or a device that cannot practically provide an update) that is designed to be compatible with the multi-generation key used by the upstream device.

For purposes of illustration and not limitation, reference is made to an exemplary embodiment of a message sequence chart 600 for use with the disclosed subject matter shown in fig. 17, and an example data exchange between a pair of devices (particularly sensor 110 and data receiving device 120) is illustrated. As embodied herein, the data receiving device 120 may be the data receiving device 120 or the multi-purpose data receiving device 130. In step 605, the data receiving device 120 can send a sensor activation command 605 to the sensor 110, for example via a short range communication protocol. Prior to step 605, the sensor 110 may be in a primary sleep state, preserving its battery until full activation is required. After activation at step 610, the sensor 110 may collect data or perform other operations appropriate to the sensing hardware 5060 of the sensor 110. At step 615, the data receiving device 120 may initiate an authentication request command 615. In response to the authentication request command 615, both the sensor 110 and the data receiving device 120 may participate in a mutual authentication process 620. The mutual authentication process 620 may involve the transmission of data, including challenge parameters that allow the sensor 110 and the data receiving device 120 to ensure that another device is sufficiently capable of adhering to the agreed upon security framework described herein. Mutual authentication may be based on a mechanism whereby two or more entities mutually authenticate with or without the establishment of a challenge-response authentication key by an online trusted third party. Mutual authentication may be performed using two, three, four, or five authentications or similar versions thereof.

After a successful mutual authentication procedure 620, the sensor 110 may provide the sensor secret 625 to the data receiving device 120 at step 625. The sensor secret may contain a sensor unique value and be derived from a random value generated during the manufacturing process. The sensor secret may be encrypted prior to or during transmission to prevent access to the secret by a third party. The sensor secret 625 may be encrypted via one or more keys generated by or in response to the mutual authentication process 620. In step 630, the data receiving device 120 can derive a sensor-unique encryption key from the sensor secret. The sensor-unique encryption key may further be session-unique. In this way, a sensor-unique encryption key may be determined by each device without transmission between the sensor 110 or the data receiving device 120. At step 635, the sensor 110 may encrypt data to be included in the payload. At step 640, the sensor 110 may transmit the encrypted payload 640 to the data receiving device 120 using a communication link established between the sensor 110 and an appropriate communication model of the data receiving device 120. At step 645, the data receiving device 120 can decrypt the payload using the sensor-unique encryption key derived during step 630. After step 645, the sensor 110 may transmit additional (including newly collected) data and the data receiving device 120 may process the received data appropriately.

As discussed herein, the sensor 110 may be a device with limited processing power, battery supply, and storage. The encryption technique (e.g., a cryptographic algorithm or selection of an algorithmic implementation) used by the sensor 110 may be selected based at least in part on these constraints. The data receiving device 120 may be a more powerful device with fewer limitations of this nature. Thus, the data receiving device 120 may employ more complex computationally intensive encryption techniques, such as cryptographic algorithms and implementations.

Exemplary payload/communication frequency

Analyte sensor 110 may be configured to change its discoverability behavior in an attempt to increase the probability that the receiving device receives the appropriate data packet and/or to provide an acknowledgement signal or to reduce the limit that may result in an acknowledgement signal being unable to be received. Changing the discoverability behavior of analyte sensor 110 may include, for example, but not limited to, changing the frequency at which connection data is included in the data packets, changing the frequency at which data packets are typically transmitted, extending or shortening the publication window of the data packets, changing the amount of time for analyte sensor 110 to listen for acknowledgement or scanning signals after publication, including directing transmission to one or more devices that have previously communicated with analyte sensor 110 (e.g., through one or more attempted transmissions) and/or directing transmission to one or more devices on a whitelist, changing the transmission power associated with the communication module when data packets are published (e.g., to increase the scope of publication or reduce the energy consumed and extend the life of the analyte sensor battery), changing the rate at which data packets are prepared and published, or a combination of one or more other changes. Additionally or alternatively, the receiving device may similarly adjust parameters related to the listening behavior of the device to increase the likelihood of receiving a data packet including connection data.

As embodied herein, the analyte sensor 110 may be configured to publish data packets using two types of windows. The first window refers to the rate at which analyte sensor 110 is configured to operate the communication hardware. The second window refers to the rate at which the analyte sensor 110 is configured to actively transmit data packets (e.g., publish). As an example, the first window may instruct the analyte sensor 110 to operate the communication hardware to send and/or receive data packets (including connection data) during the first 2 seconds of each 60 second cycle. The second window may indicate that the analyte sensor 110 transmits data packets every 60 milliseconds during each 2 second window. During the remainder of the 2 second window, analyte sensor 110 is scanning. Analyte sensor 110 may extend or shorten either window to modify the discoverability behavior of analyte sensor 110.

In particular embodiments, the discoverability behavior of the analyte sensor may be stored in a discoverability profile and may be changed based on one or more factors, such as the state of analyte sensor 110 and/or by applying rules based on the state of analyte sensor 110. For example, when the battery level of analyte sensor 110 is below a certain amount, the rule may cause analyte sensor 110 to reduce the power consumed by the publication process. As another example, configuration settings associated with publishing or transmitting data packets may be adjusted based on ambient temperature, the temperature of analyte sensor 110, or the temperature of certain components of the communication hardware of analyte sensor 110. In addition to modifying the transmission power, other parameters associated with the transmission capabilities or processes of the communication hardware of analyte sensor 110 may be modified, including but not limited to transmission rate, frequency, and timing. As another example, when the analyte data indicates that the subject is experiencing or is about to experience a negative health event, the rules may cause the analyte sensor 110 to increase its discoverability to alert the receiving device to the negative health event.

P. exemplary sensor sensitivity initialization/adjustment features

As embodied herein, certain calibration features of the sensing hardware 5060 of the analyte sensor 110 may be adjusted based on external or intermittent environmental features, as well as compensating for attenuation of the sensing hardware 5060 during prolonged periods of inactivity (e.g., a "shelf life" prior to use). The calibration characteristics of sensing hardware 5060 may be adjusted autonomously by sensor 110 (e.g., by operation of ASIC 5000 to modify characteristics in memory 5020 or storage 5030) or may be adjusted by other devices of analyte monitoring system 100.

As an example, the sensor sensitivity of the sensing hardware 5060 may be adjusted based on external temperature data or time since manufacture. The disclosed subject matter can adaptively change the compensation for the sensor sensitivity over time as the device experiences changing storage conditions when monitoring external temperatures during storage of the sensor. For purposes of illustration and not limitation, adaptive sensitivity adjustment may be performed in an "active" storage mode in which analyte sensor 110 periodically wakes up to measure temperature. These features may save the battery of the analyte device and extend the life of the analyte sensor. At each temperature measurement, the analyte sensor 110 may calculate a sensitivity adjustment for the time period based on the measured temperature. The temperature weighting adjustments may then be accumulated during the active storage mode to calculate a total sensor sensitivity adjustment value at the end of the active storage mode (e.g., at the time of insertion). Similarly, upon insertion, the sensor 110 may determine the time difference between the sensor 110 fabrication (which may be written to the memory 5030 of the ASIC 5000) or the sensing hardware 5060, and modify the sensor sensitivity or other calibration characteristics according to one or more known decay rates or formulas.

Further, for purposes of illustration and not limitation, as embodied herein, sensor sensitivity adjustment may take into account other sensor conditions, such as sensor drift. Sensor sensitivity adjustment may be hard coded into sensor 110 during manufacturing, for example, in the case of sensor drift, based on an estimate of how much the average sensor will drift. The sensor 110 may use a calibration function with a time-varying function of sensor offset and gain, which may account for drift during sensor wear. Thus, the sensor 110 may utilize a function used to convert the interstitial current to interstitial glucose that is combined with a baseline of the glucose spectrum using a device-dependent function that describes the sensor 110's drift over time, and the device-dependent function may represent sensor sensitivity and may be device-specific. Such a function that accounts for sensor sensitivity and drift may improve the accuracy of the sensor 110 during wear and eliminate the need for user calibration.

Analyte measurement based on exemplary models

The sensor 110 detects raw measurements from the sensing hardware 5060. On-sensor processing may be performed, for example, by one or more models trained to interpret raw measurements. The model may be a machine learning model that is trained off-site to detect, predict, or interpret raw measurements to detect, predict, or interpret levels of one or more analytes. Additional trained models may operate on the output of the machine learning model trained to interact with the raw measurements. As an example, the model may be used to detect, predict, or recommend events based on raw measurements and the type of analyte detected by sensing hardware 5060. Events may include the start or completion of physical activity, the use of meals, medical or pharmaceutical applications, emergency health events, and other events of similar nature.

The model may be provided to the sensor 110, the data receiving device 120, or the multi-purpose data receiving device 130 during manufacturing or during a firmware or software update. The model may be periodically refined, for example, by the manufacturer of the sensor 110 or by an operator of the analyte monitoring system 100, based on data received from the sensor 110 and a data receiving device common to the single user or multiple users. In some implementations, the sensor 110 includes sufficient computing components to assist in further training or improving the machine learning model, for example, based on unique features of the user to which the sensor 110 is attached. The machine learning model may include, for example, but is not limited to, models trained using or encompassing decision tree analysis, gradient boosting, ada boosting, artificial neural networks or variants thereof, linear discriminant analysis, nearest neighbor analysis, support vector machines, supervised or unsupervised classification, and the like. In addition to machine learning models, the models may also include algorithm or rule based models. Upon receiving data from the sensor 110 (or other downstream device), the model-based processing may be performed by other devices, including the data receiving device 120 or the multi-purpose data receiving device 130.

R. exemplary alert feature

The data transmitted between the sensor 110 and the data receiving device 120 may include raw or processed measurements. The data transmitted between the sensor 110 and the data receiving device 120 may further include an alarm or notification for display to the user. The data receiving device 120 may display or transmit a notification to the user based on the raw or processed measurements, or may display an alarm upon receipt from the sensor 110. Alarms that may be triggered to display to a user include alarms based on direct analyte values (e.g., one-time readings that exceed a threshold or fail to meet a threshold), analyte value trends (e.g., average readings over a set period of time that exceed a threshold or fail to meet a threshold; slope); analyte value prediction (e.g., algorithm calculations based on analyte values that exceed a threshold or fail to meet a threshold), sensor alarms (e.g., suspected faults are detected), communication alarms (e.g., no communication between sensor 110 and data receiving device 120 for a threshold period of time; unknown devices attempt or fail to initiate a communication session with sensor 110), reminders (e.g., reminder to charge data receiving device 120; reminder to take medications or perform other activities), and other alarms of similar nature. For purposes of illustration and not limitation, as embodied herein, the alert parameters described herein may be configured by a user or may be fixed during manufacture, or a combination of user-settable parameters and non-user-settable parameters.

S. exemplary electrode configuration

Sensor configurations having a single active region configured for detection of a respective single analyte may employ a two-electrode or three-electrode detection motif, as further described herein with reference to fig. 18A-18C. Sensor configurations having two different active regions on different working electrodes or on the same working electrode for detecting the same or different analytes will be described below with reference to fig. 19A-21C, respectively. A sensor configuration with multiple working electrodes may be particularly advantageous for incorporating two different active regions into the same sensor tail, as the signal contribution from each active region may be more easily determined.

When a single working electrode is present in the analyte sensor, the three-electrode sensor configuration can include a working electrode, a counter electrode, and a reference electrode. A related dual electrode sensor configuration may include a working electrode and a second electrode, where the second electrode may serve as a counter electrode and a reference electrode (i.e., counter/reference electrode). The various electrodes may be at least partially stacked (layered) on top of each other and/or laterally spaced from each other on the sensor tail. Suitable sensor configurations may be substantially flat in shape, substantially cylindrical in shape, or any suitable shape. In any of the sensor configurations disclosed herein, the electrodes may be electrically isolated from each other by a dielectric material or similar insulator.

An analyte sensor having a plurality of working electrodes may similarly include at least one additional electrode. When present, one additional electrode can serve as a counter/reference electrode for each of the plurality of working electrodes. When two additional electrodes are present, one of the additional electrodes may serve as a counter electrode for each of the plurality of working electrodes and the other of the additional electrodes may serve as a reference electrode for each of the plurality of working electrodes.

Fig. 18A shows a diagram of an exemplary dual electrode analyte sensor configuration suitable for use in the present disclosure. As shown, analyte sensor 200 includes a substrate 30212 disposed between a working electrode 214 and a counter/reference electrode 30216. Alternatively, the working electrode 214 and the counter/reference electrode 30216 may be located on the same side of the substrate 30212 with a dielectric material interposed therebetween (configuration not shown). The active region 218 is provided as at least one layer over at least a portion of the working electrode 214. The active region 218 may include multiple spots or a single spot configured for detection of an analyte at a low working electrode potential, as discussed further herein. In certain embodiments, the active region 218 may include an electron transfer agent as described herein.

Still referring to fig. 18A, a film 220 covers at least the active region 218. In certain embodiments, the membrane 220 may also cover some or all of the working electrode 214 and/or the counter/reference electrode 30216, or the entire analyte sensor 200. One or both sides of analyte sensor 200 may be covered with a membrane 220. The membrane 220 may comprise one or more polymeric membrane materials that have the ability to limit the flow of the analyte to the active region 218 (i.e., the membrane 220 is a mass transport limiting membrane that has some permeability to the analyte of interest). In accordance with the disclosure herein, the membrane 220 may be crosslinked with a branched crosslinking agent in certain specific sensor configurations. For example, and without limitation, the film 220 is crosslinked with a crosslinking agent such as a branched glycidyl ether (e.g., polyethylene glycol tetraglycidyl ether). The composition and thickness of the membrane 220 may be varied to facilitate the desired analyte flow to the active region 218 to provide the desired signal strength and stability. Analyte sensor 200 may be operable to determine an analyte by any of coulombic, amperometric, voltammetric, or potentioelectrochemical detection techniques.

Fig. 18B and 18C illustrate diagrams of exemplary three-electrode analyte sensor configurations, which are also suitable for use in the present disclosure. The three-electrode analyte sensor configuration may be similar to that shown for analyte sensor 200 in fig. 18A, except that additional electrodes 217 (fig. 18B and 18C) are included in analyte sensors 201 and 202. In the case of the use of the additional electrode 217, the counter/reference electrode 30216 may be used as a counter electrode or reference electrode, and the additional electrode 217 performs other electrode functions not considered. The working electrode 214 continues to perform its original function. Additional electrodes 217 may be provided on working electrode 214 or electrode 30216 with a separation layer of dielectric material in between. For example, and without limitation, as shown in fig. 18B, dielectric layers 219a, 219B, and 219c separate electrodes 214, 30216, and 217 from one another and provide electrical isolation. Alternatively, at least one of the electrodes 214, 30216, and 217 may be located on an opposite side of the substrate 30212, as shown in fig. 18C. Thus, in certain embodiments, electrode 214 (the working electrode) and electrode 30216 (the counter electrode) may be located on opposite sides of substrate 30212, with electrode 217 (the reference electrode) being located on one of electrodes 214 or 30216 and spaced apart therefrom by a dielectric material. A layer of reference material 230 (e.g., ag/AgCl) may be present on the electrode 217, the location of the layer of reference material 230 not being limited to the location depicted in fig. 18B and 18C. As with the sensor 200 shown in fig. 18A, the active regions 218 in the analyte sensors 201 and 202 may include multiple spots or a single spot. In certain embodiments, the active region 218 can include a redox mediator as disclosed herein. Additionally, analyte sensors 201 and 202 may be operable to determine analytes by any of coulombic, amperometric, voltammetric, or potentioelectrochemical detection techniques.

As with analyte sensor 200, membrane 220 may also cover active area 218 and other sensor components in analyte sensors 201 and 202, thereby acting as a mass transfer limiting membrane. In some embodiments, the additional electrode 217 may be covered with a film 220. While fig. 18B and 18C have depicted electrodes 214, 30216, and 217 as being covered by film 220, it should be appreciated that in some embodiments, only working electrode 214 is covered. Further, the thickness of the film 220 at each of the electrodes 214, 30216, and 217 may be the same or different. As in the dual electrode analyte sensor configuration (fig. 18A), in the sensor configurations of fig. 18B and 18C, one or both sides of analyte sensors 201 and 202 may be covered by film 220, or the entire analyte sensors 201 and 202 may be covered. Accordingly, the three-electrode sensor configuration shown in fig. 18B and 18C should be understood to not limit the embodiments disclosed herein, and alternative electrode and/or layer configurations are still within the scope of the present disclosure.

Fig. 19A shows an exemplary configuration of a sensor 203, the sensor 203 having a single working electrode with two different active areas disposed thereon. Fig. 19A is similar to fig. 18A, except that there are two active regions on the working electrode 214: a first active region 218a and a second active region 218b that are responsive to the same or different analytes and are laterally spaced apart from each other on the surface of the working electrode 214. The active regions 218a and 218b may include multiple spots or a single spot configured to detect each analyte. The composition of the film 220 may vary or be compositionally the same at the active regions 218a and 218 b. The first active region 218a and the second active region 218b may be configured to detect their corresponding analytes at different working electrode potentials than each other, as discussed further below.

Fig. 19B and 19C show cross-sectional views of exemplary three-electrode sensor configurations of sensors 204 and 205, respectively, each having a single working electrode with a first active region 218a and a second active region 218B disposed thereon. Fig. 19B and 19C are similar to fig. 18B and 18C and can be better understood with reference thereto. As shown in fig. 19A, the composition of the film 220 may vary or be compositionally the same at the active regions 218a and 218b. In certain embodiments, any of the active regions 218a and 218b can comprise a redox mediator as described herein. In certain embodiments, only one of the active regions 218a and 218b may include a redox mediator as described herein. For example, and without limitation, only the active region 218a includes the redox mediators described herein. In certain embodiments, only the active region 218b includes the redox mediators described herein. In certain embodiments, both active regions 218a and 218b comprise a redox mediator as described herein. In certain embodiments, the electron transfer agent present in the active region 218a differs from the redox mediator present in 218b. Alternatively, the electron transfer agent present in the active region 218a is the same as the redox mediator present in 218b.

An exemplary sensor configuration having a plurality of working electrodes (particularly two working electrodes) is described in further detail with reference to fig. 20-21C. Although the following description is primarily directed to a sensor configuration having two working electrodes, it should be understood that more than two working electrodes may be incorporated by extending the disclosure herein. In addition to the first analyte and the second analyte, additional working electrodes may be used to impart additional sensing capabilities to the analyte sensor.

Fig. 20 shows a cross-sectional view of an exemplary analyte sensor configuration having two working, reference and counter electrodes, which is suitable for use in the present disclosure. As shown, analyte sensor 300 includes working electrodes 304 and 306 disposed on opposite sides of a substrate 302. The first active region 310a is disposed on the surface of the working electrode 304 and the second active region 310b is disposed on the surface of the working electrode 306. Counter electrode 320 is electrically isolated from working electrode 304 by dielectric layer 322, and reference electrode 321 is electrically isolated from working electrode 306 by dielectric layer 323. Outer dielectric layers 30230 and 332 are positioned over reference electrode 321 and counter electrode 320, respectively. According to various embodiments, the membrane 340 may cover at least the active areas 310a and 310b, including other components of the analyte sensor 300 or the entire analyte sensor 300.

In certain embodiments, the membrane 340 may be continuous, but compositionally varied over the active region 310a and/or the active region 310b to provide different permeability values for differentially modulating analyte flux at each location. For example, and without limitation, one or more electrodes may be covered with first membrane portion 340a and/or second membrane portion 340 b. In certain embodiments, different film formulations may be sprayed and/or printed onto opposite sides of the analyte sensor 300. Dip coating techniques may also be suitable, particularly for depositing at least a portion of the bilayer film on one of the active regions 310a and 310 b. In certain embodiments, the composition of the film 340 at the active regions 310a and 310b may be the same or vary. For example, and without limitation, the membrane 340 may include a bilayer covering active area 310a and be a homogeneous membrane covering active area 310b, or the membrane 340 may include a bilayer covering active area 310b and be a homogeneous membrane covering active area 310a. In certain embodiments, according to particular embodiments of the present disclosure, one of the first film portion 340a and the second film portion 340b may comprise a bilayer film, while the other of the first film portion 340a and the second film portion 340b may comprise a single film polymer. In certain embodiments, the analyte sensor may include more than one membrane 340, such as two or more membranes. For example, and without limitation, an analyte sensor may include a membrane covering one or more active areas (e.g., 310a and 310 b), as well as additional membranes covering the entire sensor, as shown in fig. 20. In such a configuration, a bilayer film may be formed over one or more active regions (e.g., 310a and 310 b). In certain embodiments, either of the active regions 310a and 310b can include an electron transfer agent as described herein. In certain embodiments, only one of the active regions 310a and 310b may include a redox mediator as described herein. For example, and without limitation, only active region 310a includes a redox mediator as described herein. In certain embodiments, only the active region 310b includes the redox mediators described herein. In certain embodiments, both active regions 310a and 310b comprise a redox mediator as described herein. In certain embodiments, the redox mediator present in the active region 310a is different from the electron transfer agent present in 310 b. Alternatively, the redox mediator present in the active region 310a is the same as the electron transfer agent present in 310 b.

As with analyte sensors 200, 201, and 202, analyte sensor 300 is operable to determine ketones (and/or a second analyte) by any of coulombic, amperometric, voltammetric, or potentiometric electrochemical detection techniques. In certain embodiments, the analyte sensor may include more than one membrane 340, such as two or more membranes.

Alternative sensor configurations having multiple working electrodes and differing from the configuration shown in fig. 20 may have counter/reference electrodes instead of separate counter and reference electrodes 320, 321, and/or have layer and/or membrane arrangements differing from those explicitly described. For example, and without limitation, the positioning of counter electrode 320 and reference electrode 321 may be reversed from that depicted in fig. 20. Furthermore, the working electrodes 304 and 306 do not have to reside on opposite sides of the substrate 302 in the manner shown in FIG. 20.

While suitable sensor configurations may have substantially planar electrodes, it should be understood that sensor configurations having non-planar electrodes may be advantageous and particularly well suited for use in the disclosure herein. In particular, substantially cylindrical electrodes disposed concentrically with respect to one another may facilitate deposition of a mass transfer limiting film, as described below. For example, and without limitation, concentric working electrodes spaced along the length of the sensor tail may facilitate film deposition by a sequential dip coating operation in a manner similar to that described above for a substantially planar sensor configuration. Fig. 21A-21C show perspective views of an analyte sensor having two working electrodes disposed concentrically with respect to each other. It should be understood that a sensor configuration having a concentric electrode arrangement but lacking a second working electrode is also possible in the present disclosure.

Fig. 21A shows a perspective view of an exemplary sensor configuration in which a plurality of electrodes are substantially cylindrical and are disposed concentrically relative to one another about a central substrate. As shown, analyte sensor 400 includes a central substrate 402 about which all electrodes and dielectric layers are disposed concentrically with respect to one another. In particular, the working electrode 410 is disposed on a surface of the central substrate 402, and the dielectric layer 412 is disposed on a portion of the working electrode 410 remote from the sensor tip 404. The working electrode 420 is disposed on the dielectric layer 412, and the dielectric layer 422 is disposed on a portion of the working electrode 420 distal from the sensor tip 404. The counter electrode 430 is disposed on the dielectric layer 422, and the dielectric layer 432 is disposed on a portion of the counter electrode 430 remote from the sensor tip 404. A reference electrode 440 is disposed on dielectric layer 432 and a dielectric layer 442 is disposed on a portion of reference electrode 440 remote from sensor tip 404. In this way, the exposed surfaces of working electrode 410, working electrode 420, counter electrode 430, and reference electrode 440 are spaced apart from one another along longitudinal axis B of analyte sensor 400.

Still referring to fig. 21A, a first active region 414a and a second active region 414b, which are responsive to different analytes, are disposed on the exposed surfaces of working electrodes 410 and 420, respectively, allowing contact with a fluid for sensing. Although the active regions 414a and 414b are depicted in FIG. 21A as three discrete spots, it should be appreciated that there may be fewer or more than three spots in alternative sensor configurations, including a continuous active region layer. In certain embodiments, either of the active regions 414a and 414b may include an electron transfer agent as described herein. In certain embodiments, only one of the active regions 414a and 414b may include a redox mediator as described herein. For example, and without limitation, only the active region 414a includes the redox mediators described herein. In certain embodiments, only the active region 414b includes the redox mediators described herein. In certain embodiments, both active regions 414a and 414b comprise a redox mediator as described herein. In certain embodiments, the redox mediator present in the active region 414a is different from the electron transfer agent present in 414 b. Alternatively, the redox mediator present in the active region 414a is the same as the electron transfer agent present in 414 b.

In fig. 21A, sensor 400 is partially coated with a film 450 over working electrodes 410 and 420 and active areas 414a and 414b disposed thereon. Fig. 21B shows an alternative sensor configuration in which substantially the entire sensor 401 is covered with a membrane 450. The composition of the film 450 at the active regions 414a and 414b may be the same or vary. For example, the membrane 450 may include a bilayer covering the active region 414a and be a homogeneous membrane covering the active region 414b.

It should also be appreciated that the positioning of the electrodes in fig. 21A and 21B may be different than explicitly described. For example, the positions of counter electrode 430 and reference electrode 440 can be reversed from the configuration shown in fig. 21A and 21B. Similarly, the positions of working electrodes 410 and 420 are not limited to those explicitly depicted in fig. 21A and 21B. Fig. 21C shows an alternative sensor configuration to that shown in fig. 21B, wherein sensor 405 includes counter electrode 430 and reference electrode 440 positioned closer to sensor tip 404 and working electrodes 410 and 420 positioned further from sensor tip 404. Sensor configurations in which working electrodes 410 and 420 are positioned further from sensor tip 404 may be advantageous by providing a greater surface area to deposit active regions 414a and 414b (five discrete sensing spots exemplarily shown in fig. 21C), thereby facilitating increased signal strength in some cases. Similarly, the central substrate 402 may be omitted in any of the concentric sensor configurations disclosed herein, wherein the innermost electrode may instead support a subsequently deposited layer.

In certain embodiments, one or more electrodes of the analyte sensors described herein are wire electrodes, e.g., permeable wire electrodes. In certain embodiments, the sensor tail includes a working electrode and a reference electrode spirally wound around the working electrode. In certain embodiments, an insulator is disposed between the working electrode and the reference electrode. In certain embodiments, portions of the electrodes are exposed to allow one or more enzymes to react with analytes on the electrodes. In certain embodiments, each electrode is formed from a thin wire having a diameter of about 0.001 inch or less to about 0.010 inch or more. In certain embodiments, the working electrode has a diameter of about 0.001 inch or less to about 0.010 inch or greater, such as about 0.002 inch to about 0.008 inch or about 0.004 inch to about 0.005 inch. In certain embodiments, the electrodes are formed of a plated insulator, plated wire, or bulk conductive material. In certain embodiments, the working electrode comprises wires formed of a conductive material (e.g., platinum-iridium, palladium, graphite, gold, carbon, conductive polymers, alloys, etc.). In certain embodiments, the conductive material is a permeable conductive material. In certain embodiments, the electrodes may be formed by a variety of manufacturing techniques (e.g., bulk metal processing, metal deposition onto a substrate, etc.), and the electrodes may be formed from plated wires (e.g., platinum on steel wire) or bulk metal (e.g., platinum wire). In certain embodiments, the electrodes are formed from tantalum wire, e.g., covered with platinum.

In certain embodiments, the reference electrode, which may be used as a reference electrode alone or as dual reference and counter electrodes, is formed of silver, silver/silver chloride, or the like. In certain embodiments, the reference electrode is juxtaposed with and/or wound with or around the working electrode. In certain embodiments, the reference electrode is spirally wound around the working electrode. In some embodiments, the wire assembly may be coated with or adhered together with an insulating material to provide an insulating attachment.

In some embodiments, additional electrodes may be included in the sensor tail. Such as, but not limited to, a three-electrode system (working electrode, reference electrode, and counter electrode) and/or additional working electrodes (e.g., electrodes for detecting a second analyte). In certain embodiments where the sensor includes two working electrodes, the two working electrodes may be juxtaposed with the reference electrode disposed therearound (e.g., spirally wound around the two or more working electrodes). In some embodiments, two or more working electrodes may extend parallel to each other. In some embodiments, the reference electrode is coiled around the working electrode and extends toward the distal end of the sensor tail (i.e., the in-body end). In certain embodiments, the reference electrode extends (e.g., spirals) to an exposed region of the working electrode.

In certain embodiments, one or more working electrodes are helically wound around the reference electrode. In some embodiments where two or more working electrodes are provided, the working electrodes may be formed in a double helix, triple helix, quad helix or larger helix configuration (e.g., around a reference electrode, insulating rod or other support structure) along the length of the sensor tail. In certain embodiments, the electrodes, e.g., two or more working electrodes, are formed coaxially. For example, but not by way of limitation, the electrodes all share the same central axis.

In certain embodiments, the working electrode comprises a tube with a reference electrode disposed or coiled therein, including an insulator therebetween. Alternatively, the reference electrode comprises a tube with a working electrode disposed or coiled inside, with an insulator included therebetween. In certain embodiments, a polymer (e.g., insulating) rod is provided, with one or more electrodes (e.g., one or more electrode layers) disposed thereon (e.g., by electroplating). In certain embodiments, a metal (e.g., steel or tantalum) rod or wire is provided, coated with an insulating material (described herein), on which one or more working and reference electrodes are disposed. For example, and without limitation, the present disclosure provides a sensor, such as a sensor tail, comprising one or more tantalum wires, wherein a conductive material is disposed on a portion of the one or more tantalum wires to function as a working electrode. In certain embodiments, the platinum-coated tantalum wire is covered with an insulating material, wherein the insulating material is partially covered with a silver/silver chloride composition to serve as a reference and/or counter electrode.

In certain embodiments in which an insulator is disposed on the working electrode (e.g., on the platinum surface of the electrode), a portion of the insulator may be stripped or otherwise removed to expose the electroactive surface of the working electrode. For example, but not by way of limitation, a portion of the insulator may be removed by hand, excimer laser, chemical etching, laser ablation, sand blasting, and the like. Alternatively, a portion of the electrode may be masked prior to depositing the insulator to maintain the exposed electroactive surface area. In certain embodiments, the portion of the insulation that is stripped and/or removed may be about 0.1mm or less to about 2mm or more in length, for example about 0.5mm to about 0.75mm in length. In certain embodiments, the insulator is a non-conductive polymer. In certain embodiments, the insulator comprises parylene, fluorinated polymers, polyethylene terephthalate, polyvinylpyrrolidone, polyurethane, polyimide, and other non-conductive polymers. In certain embodiments, glass or ceramic materials may also be used for the insulating layer. In certain embodiments, the insulator comprises parylene. In certain embodiments, the insulator comprises polyurethane. In certain embodiments, the insulator comprises polyurethane and polyvinylpyrrolidone.

Several parts of the sensor, including the active region, are described further below.

2. Redox mediators

The present disclosure provides transition metal complexes suitable for use as redox mediators. In certain embodiments, the transition metal complexes described herein include a metal center surrounded by one or more tridentate ligands (e.g., two tridentate ligands).

In certain embodiments, the tridentate ligands of the present disclosure include at least one pyridine, imidazole, or combination thereof. For example, but not by way of limitation, the tridentate ligands of the present disclosure have an imidazole-pyridine-imidazole structure. In certain embodiments, the tridentate ligand has a pyridine-pyridine structure. In certain embodiments, the tridentate ligand has a pyridine-imidazole structure. In certain embodiments, the tridentate ligand has a pyridine-imidazole structure. In certain embodiments, the tridentate ligand has an imidazole-imidazole structure. In certain embodiments, the tridentate ligand has a pyridine-imidazole-pyridine structure.

In certain embodiments, a tridentate ligand having an imidazole-pyridine-imidazole structure is represented by formula I:

in certain embodiments, a tridentate ligand having an imidazole-pyridine-imidazole structure is represented by formula II:

In certain embodiments, the tridentate ligand having the imidazole-pyridine-imidazole structure is represented by formula III:

in certain embodiments, the tridentate ligand having the imidazole-pyridine-imidazole structure is represented by formula IV:

in certain embodiments, the tridentate ligand having a pyridine-pyridine structure is represented by formula V:

in certain embodiments, the tridentate ligand having a pyridine-pyridine structure is represented by formula VI:

in certain embodiments, the tridentate ligand having a pyridine-pyridine structure is represented by formula VII:

in certain embodiments, a tridentate ligand having a pyridine-imidazole structure is represented by formula VIII:

in certain embodiments, the tridentate ligand having a pyridine-imidazole structure is represented by formula IX:

in certain embodiments, a tridentate ligand having a pyridine-imidazole structure is represented by formula X-a:

in certain embodiments, a tridentate ligand having a pyridine-imidazole structure is represented by formula X-B:

in certain embodiments, a tridentate ligand having a pyridine-imidazole structure is represented by formula XI-a:

in certain embodiments, a tridentate ligand having a pyridine-imidazole structure is represented by formula XI-B:

in certain embodiments, the tridentate ligand having a pyridine-imidazole structure is represented by formula XII-a:

In certain embodiments, the tridentate ligand having a pyridine-imidazole structure is represented by formula XII-B:

in certain embodiments, the tridentate ligand having a pyridine-imidazole structure is represented by formula XIII-a:

in certain embodiments, the tridentate ligand having a pyridine-imidazole structure is represented by formula XIII-B:

in certain embodiments, the tridentate ligand having the imidazole-imidazole structure is represented by formula XIV:

in certain embodiments, the tridentate ligand having the imidazole-imidazole structure is represented by formula XV:

in certain embodiments, the tridentate ligand having the imidazole-imidazole structure is represented by formula XVI:

in certain embodiments, the tridentate ligand having the imidazole-imidazole structure is represented by formula XVII:

in certain embodiments, the tridentate ligand having a pyridine-imidazole-pyridine structure is represented by formula XVIII:

in certain embodiments, the tridentate ligand having a pyridine-imidazole-pyridine structure is represented by formula XIX:

in certain embodiments, the tridentate ligand having a pyridine-imidazole-pyridine structure is represented by formula XX:

in certain embodiments, the tridentate ligand having a pyridine-imidazole-pyridine structure is represented by formula XXI:

In certain embodiments, R of formulas I-XXI ₁ And R is ₃ Independently selected from H, alkoxy, alkyl, alkylamide, alkylamino, or a linking group. In certain embodiments, the linking group is capable of bonding the redox mediator to the polymer. In certain embodiments, the linking group is capable of linking two ligands (e.g., two ligands of formula I) together. In certain embodiments, R ₁ And/or R ₃ Can be an alkyl group. Non-limiting examples of alkyl groups include methyl or ethyl. In certain embodiments, alkyl is C ₁ -C ₁₂ Linear or branched alkyl. In certain embodiments, R ₁ And/or R ₃ May be a polyether group, such as a polyethylene oxide (polyethylene oxide ) group. In certain embodiments, R ₁ And/or R ₃ Can be an alkoxy group. Non-limiting examples of alkoxy groups include methoxy and ethoxy.

In certain embodiments, R of formulas I-XXI ₂ Selected from H, electron donating groups or linking groups capable of bonding the redox mediator to the polymer.

In certain embodiments, R of formulas I-XXI ₂ Is an electron donating group. An electron donating group is an atom or group that releases electron density from itself to an adjacent atom by resonance or induction effect. In certain embodiments, the electron donating group is a hydroxyl, alkoxy, amino, alkyl, acetamido, alkylamide, alkylamino, or polyether group. Non-limiting examples of alkoxy groups include methoxy and ethoxy, and non-limiting examples of alkylamino groups include methylamino, ethylamino and dialkylamino groups, such as dimethylamino and diethylamino. In certain embodiments, the electron donating group is NR ₇ R ₈ Wherein R is ₇ And R is ₈ Independently selected from H or alkyl. In certain embodiments, alkyl is C ₁ -C ₆ An alkyl group. In certain embodiments, the alkyl group is methyl. In certain embodiments, R ₂ Is dimethylamino.

In certain embodiments, R of formulas I-XXI ₂ Is a linking group capable of binding a redox mediator to a polymer. In certain embodiments, the linking group may include a functional group that is capable of facilitating covalent bonding with the polymer by reaction with a functional group disposed on or within the polymer precursor. In certain embodiments, the linking group may comprise an amide group, a substituted amine group, or a urea group. In certain embodiments, the linking group is a linking group compatible with click chemistry, such as an alkynyl or azido group.

In certain embodiments, the tridentate ligand has a structure represented by formula XXII:

in certain embodiments, the tridentate ligand has a structure represented by formula XXIII:

in certain embodiments, the tridentate ligand has a structure represented by formula XXIV:

in certain embodiments, the tridentate ligand has a structure represented by formula XXV:

in certain embodiments, the tridentate ligand has a structure represented by formula XXVI:

In certain embodiments, the tridentate ligand has a structure represented by formula XXVII:

in certain embodiments, the tridentate ligand has a structure represented by formula XXVIII:

in certain embodiments, the tridentate ligand has a structure represented by formula XXIX:

in certain embodiments, the tridentate ligand has a structure represented by formula XXX:

in certain embodiments, the tridentate ligand has a structure represented by formula XXXI:

in certain embodiments, the tridentate ligand has a structure represented by formula XXXII:

in certain embodiments, the tridentate ligand has a structure represented by formula XXXIII:

in certain embodiments, the tridentate ligand has a structure represented by formula XXXIV:

in certain embodiments, the tridentate ligand has a structure represented by formula XXXV:

in certain embodiments, the tridentate ligand has the structure represented by formula XXXVI:

in certain embodiments, the tridentate ligand has the structure represented by formula XXXVII:

in certain embodiments, the tridentate ligand has the structure represented by formula XXXVIII:

in certain embodiments, the tridentate ligand has a structure represented by formula XXXIX:

in certain embodiments, the tridentate ligand has the structure represented by formula XL:

In certain embodiments, the redox mediators of the present disclosure may include one or more tridentate ligands of formulas I-XXI. In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formulas I-XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula I. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula I and a tridentate ligand of formula II. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula I and a tridentate ligand of formula III. In certain embodiments, the redox mediators of the present disclosure can include tridentate ligands of formula I and tridentate ligands of formula IV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula I and a tridentate ligand of formula V. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula I and a tridentate ligand of formula VI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula I and a tridentate ligand of formula VII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula I and a tridentate ligand of formula VIII. In certain embodiments, the redox mediators of the present disclosure can include tridentate ligands of formula I and tridentate ligands of formula IX. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula I and a tridentate ligand of formula X. In certain embodiments, the redox mediators of the present disclosure can include tridentate ligands of formula I and tridentate ligands of formula XI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula I and a tridentate ligand of formula XII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula I and a tridentate ligand of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula I and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure can include tridentate ligands of formula I and tridentate ligands of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula I and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula I and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula I and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula I and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula I and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure can include tridentate ligands of formula I and tridentate ligands of formula XXI.

In certain embodiments, the redox mediators of the present disclosure can include two tridentate ligands of formula II. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula III. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula IV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula V. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula VI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula VII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula VIII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula IX. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula X. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula XI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula II and a tridentate ligand of formula XII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula II and a tridentate ligand of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula II and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula II and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula II and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula II and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula II and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula III. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula III and a tridentate ligand of formula IV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula III and a tridentate ligand of formula V. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula III and a tridentate ligand of formula VI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula III and a tridentate ligand of formula VII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula III and a tridentate ligand of formula VIII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula III and a tridentate ligand of formula IX. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula III and a tridentate ligand of formula X. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula III and a tridentate ligand of formula XI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula III and a tridentate ligand of formula XII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula III and a tridentate ligand of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula III and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula III and a tridentate ligand of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula III and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula III and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula III and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula III and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula III and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula III and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure can include two tridentate ligands of formula IV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IV and a tridentate ligand of formula V. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IV and a tridentate ligand of formula VI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IV and a tridentate ligand of formula VII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IV and a tridentate ligand of formula VIII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IV and a tridentate ligand of formula IX. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IV and a tridentate ligand of formula X. In certain embodiments, the redox mediators of the present disclosure can include tridentate ligands of formula IV and tridentate ligands of formula XI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IV and a tridentate ligand of formula XII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IV and a tridentate ligand of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IV and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IV and a tridentate ligand of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IV and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IV and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IV and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IV and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IV and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IV and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula V. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula V and a tridentate ligand of formula VI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula V and a tridentate ligand of formula VII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula V and a tridentate ligand of formula VIII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula V and a tridentate ligand of formula IX. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula V and a tridentate ligand of formula X. In certain embodiments, the redox mediators of the present disclosure can include tridentate ligands of formula V and tridentate ligands of formula XI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula V and a tridentate ligand of formula XII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula V and a tridentate ligand of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula V and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure can include tridentate ligands of formula V and tridentate ligands of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula V and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula V and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula V and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula V and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula V and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula V and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula VI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VI and a tridentate ligand of formula VII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VI and a tridentate ligand of formula VIII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VI and a tridentate ligand of formula IX. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VI and a tridentate ligand of formula X. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VI and a tridentate ligand of formula XI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VI and a tridentate ligand of formula XII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VI and a tridentate ligand of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VI and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VI and a tridentate ligand of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VI and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VI and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VI and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VI and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VI and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VI and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula VII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VII and a tridentate ligand of formula VIII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VII and a tridentate ligand of formula IX. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VII and a tridentate ligand of formula X. In certain embodiments, the redox mediators of the present disclosure can include tridentate ligands of formula VII and tridentate ligands of formula XI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VII and a tridentate ligand of formula XII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VII and a tridentate ligand of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VII and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VII and a tridentate ligand of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VII and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VII and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VII and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VII and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VII and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VII and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula VIII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VIII and a tridentate ligand of formula IX. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VIII and a tridentate ligand of formula X. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VIII and a tridentate ligand of formula XI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VIII and a tridentate ligand of formula XII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VIII and a tridentate ligand of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VIII and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VIII and a tridentate ligand of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VIII and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VIII and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula VIII and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VIII and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VIII and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula VIII and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may comprise two tridentate ligands of formula IX. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IX and a tridentate ligand of formula X. In certain embodiments, the redox mediators of the present disclosure can include tridentate ligands of formula IX and tridentate ligands of formula XI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IX and a tridentate ligand of formula XII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IX and a tridentate ligand of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IX and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IX and a tridentate ligand of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IX and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IX and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula IX and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IX and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula IX and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure can include tridentate ligands of formula IX and tridentate ligands of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula X. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula X and a tridentate ligand of formula XI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula X and a tridentate ligand of formula XII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula X and a tridentate ligand of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula X and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula X and a tridentate ligand of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula X and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula X and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula X and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula X and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula X and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula X and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure can include two tridentate ligands of formula XI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XI and a tridentate ligand of formula XII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XI and a tridentate ligand of formula XIII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XI and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XI and a tridentate ligand of formula XV. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XI and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XI and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XI and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XI and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XI and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure can include tridentate ligands of formula XI and tridentate ligands of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula XII. In certain embodiments, the redox mediators of the present disclosure may include tridentate ligands of formula XII and tridentate ligands of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XII and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XII and a tridentate ligand of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XII and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XII and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XII and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XII and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XII and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XII and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIII and a tridentate ligand of formula XIV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula xiiiixiii and a tridentate ligand of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIII and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIII and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIII and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIII and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIII and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIII and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula XIV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIV and a tridentate ligand of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIV and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIV and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIV and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIV and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIV and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIV and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula XV. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XV and a tridentate ligand of formula XVI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XV and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XV and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XV and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XV and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XV and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula XVI. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XVI and a tridentate ligand of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XVI and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XVI and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XVI and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XVI and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula XVII. In certain embodiments, the redox mediators of the present disclosure can include a tridentate ligand of formula XVII and a tridentate ligand of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XVII and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XVII and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XVII and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XVIII and a tridentate ligand of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XVIII and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XVIII and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula XIX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIX and a tridentate ligand of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XIX and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula XX. In certain embodiments, the redox mediators of the present disclosure may include a tridentate ligand of formula XX and a tridentate ligand of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may comprise two tridentate ligands of formula XXI.

In certain embodiments, the redox mediators of the present disclosure may include one or more tridentate ligands of formula I-XL. In certain embodiments, the redox mediators of the present disclosure may include two tridentate ligands of formula I-XL. In certain embodiments, the redox mediators of the present disclosure may include one or more tridentate ligands of formula XXII-XL. For example, and without limitation, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula I, e.g., two tridentate ligands having the structure of formula I. In certain embodiments, the redox mediators of the present disclosure can include at least one tridentate ligand having the structure of formula II, e.g., two tridentate ligands having the structure of formula II. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula III, e.g., two tridentate ligands having the structure of formula III. In certain embodiments, the redox mediators of the present disclosure can include at least one tridentate ligand having the structure of formula IV, e.g., two tridentate ligands having the structure of formula IV. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula V, e.g., two tridentate ligands having the structure of formula V. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula VI, e.g., two tridentate ligands having the structure of formula VI. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula VII, e.g., two tridentate ligands having the structure of formula VII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula VIII, e.g., two tridentate ligands having the structure of formula VIII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula IX, e.g., two tridentate ligands having the structure of formula IX. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula X, e.g., two tridentate ligands having the structure of formula X. In certain embodiments, the redox mediators of the present disclosure can include at least one tridentate ligand having the structure of formula XI, e.g., two tridentate ligands having the structure of formula XI. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XII, e.g., two tridentate ligands having the structure of formula XII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XIII, e.g., two tridentate ligands having the structure of formula XIII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XIV, e.g., two tridentate ligands having the structure of formula XIV. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XV, e.g., two tridentate ligands having the structure of formula XV. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XVI, e.g., two tridentate ligands having the structure of formula XVI. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XVII, e.g., two tridentate ligands having the structure of formula XVII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XVIII, e.g., two tridentate ligands having the structure of formula XVIII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XIX, e.g., two tridentate ligands having the structure of formula XIX. In certain embodiments, a redox mediator of the present disclosure may include at least one tridentate ligand having the structure of formula XX, e.g., two tridentate ligands having the structure of formula XX. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXI, e.g., two tridentate ligands having the structure of formula XXI. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXII, e.g., two tridentate ligands having the structure of formula XXII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXIII, e.g., two tridentate ligands having the structure of formula XXIII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXIV, e.g., two tridentate ligands having the structure of formula XXIV. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXV, e.g., two tridentate ligands having the structure of formula XXV. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXVI, e.g., two tridentate ligands having the structure of formula XXVI. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXVII, e.g., two tridentate ligands having the structure of formula XXVII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXVIII, e.g., two tridentate ligands having the structure of formula XXVIII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXIX, e.g., two tridentate ligands having the structure of formula XXIX. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXX, e.g., two tridentate ligands having the structure of formula XXX. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXXI, e.g., two tridentate ligands having the structure of formula XXXI. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXXII, e.g., two tridentate ligands having the structure of formula XXXII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXXIII, e.g., two tridentate ligands having the structure of formula XXXIII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXXIV, e.g., two tridentate ligands having the structure of formula XXXIV. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXXV, e.g., two tridentate ligands having the structure of formula XXXV. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXXVI, e.g., two tridentate ligands having the structure of formula XXXVI. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXXVII, e.g., two tridentate ligands having the structure of formula XXXVII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXXVIII, e.g., two tridentate ligands having the structure of formula XXXVIII. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XXXIX, e.g., two tridentate ligands having the structure of formula XXXIX. In certain embodiments, the redox mediators of the present disclosure may include at least one tridentate ligand having the structure of formula XL, e.g., two tridentate ligands having the structure of formula XL.

In certain embodiments, the redox mediators disclosed herein can have a structure represented by formula XLI:

in certain embodiments, R of formula XLI ₁ 、R ₃ 、R’ ₁ And R'. ₃ Independently selected from H, alkoxy, alkyl, alkylamide, alkylamino, or a linking group. In certain embodiments, alkyl is C ₁ -C ₁₂ Linear or branched alkyl. In certain embodiments, R ₁ 、R ₃ 、R’ ₁ And R'. ₃ Is methyl. In certain embodiments, R ₁ 、R ₃ 、R’ ₁ And/or R' ₃ May be an alkyl group. Non-limiting examples of alkyl groups include methyl or ethyl. In certain embodiments, alkyl is C ₁ -C ₁₂ Linear or branched alkyl. In certain embodiments, R ₁ 、R ₃ 、R’ ₁ And/or R' ₃ May be an alkoxy group. Non-limiting examples of alkoxy groups include methoxy and ethoxy. In certain embodiments, R ₁ 、R ₃ 、R’ ₁ And/or R' ₃ May be a polyether group such as polyethylene oxide groups.

In certain embodiments, R of formula XLI ₂ And R'. ₂ Independently selected from H, an electron donating group, or a linking group capable of bonding a redox mediator to the polymer.

In certain embodiments, R of formula XLI ₂ And/or R' ₂ Is an electron donating group. In certain embodiments, the electron donating group is a hydroxyl, alkoxy, amino, alkyl, acetamido, alkylamide, alkylamino, or polyether group. Non-limiting examples of alkoxy groups include methoxy and ethoxy, and non-limiting examples of alkylamino groups include methylamino, ethylamino and dialkylamino groups, such as dimethylamino and diethylamino. In certain embodiments, the electron donating group is NR ₇ R ₈ Wherein R is ₇ And R is ₈ Independently selected from H or alkyl. In certain embodiments, alkyl is C ₁ -C ₆ An alkyl group. In certain embodiments, the alkyl group is methyl. In certain embodiments, R of formula XLI ₂ And/or R' ₂ Is dimethylamino.

In certain embodiments, R of formula XLI ₂ And/or R' ₂ Is a linking group capable of bonding a redox mediator to the polymer. In certain embodiments, the linking group may contain a functional group that is capable of facilitating covalent bonding with the polymer by reaction with a functional group disposed on or within the polymer precursor. In certain embodiments, the linking group may comprise an amide group, a substituted amine group, or a urea group. In certain embodiments, the linking group is a linking group compatible with click chemistry, such as an alkynyl or azido group.

In certain embodiments, R ₂ Is an electron donating group, such as dimethylamino, and R' ₂ Is a linking group.

"M" in the formula XLI represents a transition metal. The transition metal is not particularly limited as long as it has at least two stable and (electro) chemically reversible redox states. In certain embodiments, the transition metal is iron, ruthenium, osmium, cobalt, or vanadium. In certain particular embodiments, the transition metal is osmium. In certain embodiments, the transition metal of the redox mediators of the present disclosure may be positively charged, as indicated by "n" on formula XLI. In certain embodiments, n is I, II, III, IV or V.

In certain embodiments, the redox mediators disclosed herein can have a structure represented by formula XLII:

R ₁ 、R’ ₁ 、R ₂ 、R’ ₂ 、R ₃ 、R’ ₃ m and n may be defined as described for formula XLI.

In certain embodiments, the redox mediator may have a structure represented by formula XLIII:

R ₂ 、R’ ₂ and n may be defined as described for formula XLI. For example, but not limiting of, R ₂ And R'. ₂ Independently selected from H, an electron donating group, or a linking group capable of bonding a redox mediator to the polymer. In certain embodiments, R ₂ Is an electron donating group, such as dimethylamino, and R' ₂ Is a linking group.

In certain embodiments, the redox mediator may have a structure represented by the formula XLIV:

R’ ₂ may be defined as described for formula XLI. In certain embodiments, R' ₂ Selected from H, electron donating groups or linking groups capable of bonding the redox mediator to the polymer. In certain embodiments, R' ₂ Is capable of oxidizing and returningThe original mediator is bound to a linking group of a polymer (e.g., a polymer of the active region of the sensor). For example, but not limited to, R' ₂ May contain an amide group. Non-limiting examples of polymers (also referred to herein as "polymer backbones") covalently bonded to redox mediators are disclosed below.

In certain embodiments, the redox mediator may have a structure represented by formula XLV.

In certain embodiments, the redox mediator may have a structure represented by formula XLVI.

In certain embodiments, the redox mediator may have a structure represented by formula xlviii.

In certain embodiments, the redox mediator may have a structure represented by the formula XLIX.

In certain embodiments, the redox mediator may have a structure represented by formula L.

In certain embodiments, the redox mediator may have a structure represented by formula LI.

In certain embodiments, the redox mediator may have a structure represented by formula LII.

In certain embodiments, the redox mediator may have a structure represented by formula LIII.

In certain embodiments, the redox mediator may have a structure represented by the formula LIV.

In certain embodiments, the redox mediator may have a structure represented by formula LV.

In certain embodiments, the redox mediator may have an overall positive charge. In certain embodiments, the redox mediator has a total charge of +1 to +5. In certain other embodiments, the redox mediator has an overall negative charge if the ligand or backbone is derivatized with a sufficient number of negatively charged functional groups, such as, but not limited to carboxylate, phosphate or sulfonate groups. In certain embodiments, the redox mediator has a total negative charge from-1 to-5.

In certain embodiments, when the redox mediator has a total positive charge, a counter anion may be present to balance the charge. A variety of anions may be incorporated to balance the charge. In certain particular embodiments, the anion is a halide (fluoride, chloride, bromide, or iodide), sulfate, phosphate, hexafluorophosphate, acetate, trifluoroacetate, or tetrafluoroborate.

In certain embodiments, when the redox mediator has a total negative charge, a counter cation may be present to balance the charge. A variety of cations may be incorporated to balance the charge. In certain particular embodiments, the cation is lithium, sodium, potassium, tetraalkylammonium, or ammonium.

The present disclosure provides analyte sensors that include one or more redox mediators, including structures of any of formulas I-LV. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula XLI-LV. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula XLI. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula XLII. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula XLIII. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula XLIV. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula XLV. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula XLVI. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula xlviii. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula XLVIII. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula XLIX. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula L. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula LI. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula LII. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula LIII. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula LIV. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula LV.

In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators comprising a structure of any of formulas I-LV, wherein the redox mediators are attached to a polymer. In certain embodiments, an analyte sensor of the present disclosure includes one or more redox mediators of formula XLI-LV, wherein the redox mediators are attached to a polymer. For example, but not by way of limitation, the redox mediator may be covalently bonded to the polymer.

In certain embodiments, a redox mediator of the present disclosure, such as a redox mediator comprising the structure of any of formulas I-LV, is disposed on or near the working electrode (e.g., in a surrounding solution). Redox mediators transfer electrons between the working electrode and the analyte, and in certain embodiments, enzymes are also included to facilitate transfer. For example, and without limitation, a redox mediator transfers electrons (typically by an enzyme) between a working electrode and glucose in an enzyme-catalyzed reaction of glucose. In certain embodiments, the redox mediators of the present disclosure are disposed on a working electrode within a composition comprising an enzyme that is responsive to an analyte.

In certain embodiments, the transition metal complexes disclosed herein can achieve accurate, reproducible, and rapid or continuous assays. The transition metal complex redox mediator accepts electrons from or transfers electrons to the enzyme or analyte at a high rate and also rapidly exchanges electrons with the electrode. In general, the rate of self-exchange (the process in which the reduced redox mediator transfers electrons to the oxidized redox mediator) is rapid. At a defined redox mediator concentration, this provides for faster electron transport between the enzyme (or analyte) and the electrode and thus shortens the response time of the sensor. Furthermore, the novel transition metal complex redox mediators of the present disclosure are stable under ambient light and at temperatures encountered during use, storage and transportation. In certain embodiments, the transition metal complex redox mediator does not undergo chemical changes other than oxidation and reduction during use or under storage conditions, although the redox mediator may be designed to be activated by reaction with water or an analyte, for example. The characteristics of the disclosed redox mediators may allow for extended wear of analyte sensors incorporating these redox mediators and extended storage/shelf life of such analyte sensors. For example, and without limitation, the analyte sensors of the present disclosure may be used for a wear period of greater than about 5 days, greater than about 6 days, greater than about 7 days, greater than about 8 days, greater than about 9 days, greater than about 10 days, greater than about 11 days, greater than about 12 days, greater than about 13 days, greater than about 14 days, greater than about 15 days, greater than about 16 days, greater than about 17 days, greater than about 18 days, greater than about 19 days, greater than about 20 days, greater than about 21 days, greater than about 22 days, greater than about 23 days, greater than about 24 days, greater than about 25 days, greater than about 26 days, greater than about 27 days, greater than about 28 days, greater than about 29 days, or greater than about 30 days.

Other redox mediators may also be used with the analyte sensor systems disclosed herein. For example, and without limitation, one or more additional redox mediators may be included in the second active site, such as in a sensor configured to detect two or more analytes. In certain embodiments, redox mediators for inclusion in the second active site can include osmium complexes and other transition metal complexes, such as those described in U.S. patent nos. 6,134,461 and 6,605,200, which are incorporated herein by reference in their entirety. Other examples of suitable redox mediators include those described in U.S. patent nos. 6,736,957, 7,501,053, and 7,754,093, the disclosures of each of which are also incorporated herein by reference in their entirety. Other examples of suitable redox mediators include metal compounds or complexes of ruthenium, osmium, iron (e.g., polyvinylferrocene or hexacyanoferrite) or cobalt, including, for example, metallocene compounds thereof. Suitable ligands for the metal complex may also include, for example, bidentate or higher number ligands such as bipyridine, biimidazole, phenanthroline or pyridinyl (imidazole). Other suitable bidentate ligands may include, for example, amino acids, oxalic acid, acetylacetone, diaminoalkanes (diaminoalkanes) or o-diaminoarenes. Any combination of monodentate, bidentate, tridentate, tetradentate or higher number of ligands can be present in the metal complex, e.g., osmium complex, to achieve a fully coordinated layer. In certain embodiments, the redox mediator is an osmium complex. In certain embodiments, the redox mediator is osmium complexed with a bidentate ligand. In certain embodiments, the redox mediator is osmium complexed with a tridentate ligand. In certain embodiments, the redox mediator is a bidentate osmium complex bonded to a polymer described herein (e.g., a polymer backbone described herein). Suitable non-limiting examples of polymer-bonded redox mediators include those described in U.S. patent nos. 8,444,834, 8,268,143, and 6,605,201, the disclosures of which are incorporated herein by reference in their entirety. In certain embodiments, the polymer-bonded redox mediators shown in fig. 3 of us patent No. 8,444,834 can be used with the sensors of the present disclosure, for example at a second active site.

In certain embodiments, when the sensor comprises two or more active regions, at least one of the active sites comprises a redox mediator comprising any of the structures of formulas I-LV. In certain embodiments, when the sensor comprises two or more active regions, at least one of the active sites comprises a redox mediator of any of the formulas XLI-LV. For example, but not by way of limitation, when the sensor includes two or more active regions, at least one of the active sites includes a redox mediator of formula XLI, XLII, XLIII, XLIV, XLV, XLVI, XLVII, XLVIII, XLIX, L, LI, LII, LIII, LIV, LV or a combination thereof. In certain embodiments, the two active sites comprise a redox mediator of formula XLI, XLII, XLIII, XLIV, XLV, XLVI, XLVII, XLVIII, XLIX, L, LI, LII, LIII, LIV, LV or a combination thereof.

In certain embodiments, an analyte of the present disclosure can include (i) a sensor tail including at least a first working electrode; (ii) A first active region disposed on a surface of the first working electrode and responsive to a first analyte, for example, at a low potential; and (iii) a first analyte-permeable mass transport limiting membrane covering at least the first active region. In certain embodiments, the first active region comprises a first redox mediator and at least one enzyme responsive to a first analyte. In certain embodiments, the first active region comprises a first polymer, a first redox mediator covalently bound to the first polymer, and at least one enzyme responsive to a first analyte covalently bound to the first polymer. In certain embodiments, the at least one enzyme responsive to the first analyte may comprise an enzyme system comprising a plurality of enzymes having a common response to the first analyte.

In certain embodiments, the analyte sensors of the present disclosure may be further configured to analyze a second or subsequent analyte in addition to the analyte detectable in the first active region, e.g., at a low potential. To facilitate detection of a second analyte, the analyte sensor of the present disclosure may further include (iv) a second working electrode, and (v) a second active region disposed on a surface of the second working electrode and responsive to a second analyte different from the first analyte. In certain embodiments, the second active region includes a second redox mediator different from the first redox mediator and at least one enzyme responsive to the second analyte. Alternatively, the second active region includes a second redox mediator that is the same as the first redox mediator. In certain embodiments, the second active region comprises a second polymer, a second redox mediator that is different from the first redox mediator and is covalently bound to the second polymer, and at least one enzyme that is covalently bound to the second polymer and is responsive to the second analyte. In certain embodiments, the at least one enzyme responsive to the second analyte may comprise an enzyme system comprising a plurality of enzymes having a common response to the second analyte. The second redox mediator in the second active region is not necessarily capable of promoting electron transfer at low potential, although it may. In some embodiments, a second portion of the mass transfer limiting film may cover the second active region. Alternatively or additionally, the second mass transfer limiting film may cover the second active region or the second mass transfer limiting film may cover the second active region and the first active region. In certain embodiments, the second mass transfer limiting film comprises a different polymer than the first mass transfer limiting film. In certain embodiments, the second mass transfer limiting film comprises the same polymer as the first mass transfer limiting film, but comprises a different cross-linking agent.

In certain embodiments, the analyte responsive active area of the present disclosure can include a ratio of enzyme to redox mediator of about 100:1 to about 1:100, such as about 95:1 to about 1:95, about 90:1 to about 1:90, about 85:1 to about 1:85, about 80:1 to about 1:80, about 75:1 to about 1:75, about 60:1 to about 1:60, about 55:1 to about 1:55, about 50:1 to about 1:50, about 45:1 to about 1:45, about 40:1 to about 1:40, about 35:1 to about 1:35, about 30:1 to about 1:30, about 25:1 to about 1:25, about 20:1 to about 1:20, about 15:1 to about 1:15, about 10:1 to about 1:10, about 9:1 to about 1:9, about 8:1 to about 1:8, about 7:1 to about 1:7, about 6:1 to about 1:5, about 1:1 to about 1:2, about 1:1:3, about 1:1 to about 1:2, about 1:3:2, or about 1:2:3:1. In certain embodiments, the analyte responsive active area can comprise a ratio of enzyme to redox mediator of about 10:1 to about 1:10. In certain embodiments, the analyte responsive active area can comprise a ratio of enzyme to redox mediator of about 9:1 to about 1:9. In certain embodiments, the analyte responsive active area can comprise a ratio of enzyme to redox mediator of about 8:1 to about 1:8. In certain embodiments, the analyte responsive active area can comprise a ratio of enzyme to redox mediator of about 7:1 to about 1:7. In certain embodiments, the analyte responsive active area can comprise a ratio of enzyme to redox mediator of about 6:1 to about 1:6. In certain embodiments, the analyte responsive active area can comprise a ratio of enzyme to redox mediator of about 5:1 to about 1:5. In certain embodiments, the analyte responsive active area can comprise a ratio of enzyme to redox mediator of about 4:1 to about 1:4. In certain embodiments, the analyte responsive active area can comprise a ratio of enzyme to redox mediator of about 3:1 to about 1:3. In certain embodiments, the analyte responsive active area can comprise a ratio of enzyme of about 2:1 to about 1:2. In certain embodiments, the analyte responsive active area can include a ratio of enzyme to redox mediator of about 1:1.

In certain embodiments, the analyte responsive active area can include from about 10% to about 50% by weight of a redox mediator, such as from about 15% to about 45%, from about 20% to about 40%, from about 20% to about 35%, or from about 20% to about 30% of a redox mediator. In certain embodiments, the analyte responsive active area can comprise from about 5% to about 35% by weight of the redox mediator. In certain embodiments, the analyte responsive active area can comprise from about 10% to about 35% by weight of the redox mediator. In certain embodiments, the analyte responsive active area can comprise from about 10% to about 30% by weight of the redox mediator. In certain embodiments, the analyte responsive active area can comprise from about 15% to about 35% by weight of the redox mediator.

3. Polymer backbone

In certain embodiments, the one or more active sites for facilitating analyte detection may include a polymer to which the redox mediators of the present disclosure are covalently bonded. Any suitable polymer backbone may be present in the active region to facilitate detection of the analyte by covalent bonding of the redox mediator and the enzyme. Non-limiting examples of suitable polymers within the active region include polyvinylpyridines, such as poly (4-vinylpyridine) and/or poly (2-vinylpyridine), and polyvinylimidazoles, such as poly (N-vinylimidazole) and poly (1-vinylimidazole), or copolymers thereof, such as those in which quaternized pyridine groups act as attachment points for redox mediators or enzymes. Exemplary copolymers that may be suitable for inclusion in the active region include those containing monomer units such as styrene, acrylamide, methacrylamide or acrylonitrile. In certain embodiments, the polymer is a copolymer of vinylpyridine and styrene. In certain embodiments, the polymer that may be present in the active region comprises polyurethane or a copolymer thereof, and/or polyvinylpyrrolidone. Other non-limiting examples of polymers that may be present in the active region include those described in U.S. patent 6,605,200, which is incorporated herein by reference in its entirety, such as poly (acrylic acid), styrene/maleic anhydride copolymers, methyl vinyl ether/maleic anhydride copolymers (GANTREZ polymers), poly (vinylbenzyl chloride), poly (allylamine), polylysine, poly (4-vinylpyridine) quaternized with carboxypentyl, and poly (sodium 4-styrenesulfonate). In certain embodiments, polymers that may be present in the active region include those described in U.S. Pat. nos. 8,444,834, 8,268,143 and 6,605,201, the disclosures of which are incorporated herein by reference in their entirety. In certain embodiments, the polymers within each active region may be the same or different.

In certain embodiments, the polymer is a polyvinylpyridine-based polymer. In certain embodiments, the polymer is polyvinylpyridine or polyvinylimidazole. In certain embodiments, the polymer is a copolymer of vinylpyridine and styrene or a copolymer of polyvinylpyridine and polystyrene sulfonate.

In certain embodiments, the polymers disclosed herein are covalently bonded to the redox mediators, for example, by the linking groups (R ₂ And/or R' ₂ )。

4. Enzymes

The sensors of the present disclosure include one or more enzymes, e.g., one or more enzymes covalently bonded to a polymer, for detecting one or more analytes. Suitable enzymes for use in the sensors of the present disclosure include, but are not limited to, enzymes for detecting glutamate, glucose, ketone, lactate, oxygen, hemoglobin A1C, albumin, alcohol, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, hematin nitrogen, calcium, carbon dioxide, chloride, creatinine, hematocrit, aspartate, asparagine, magnesium, oxygen, pH, phosphorus, potassium, sodium, total protein, and uric acid. In certain embodiments, the active region of the analyte sensors disclosed herein can include enzymes for detecting glucose, lactate, ketone, creatinine, alcohols (e.g., ethanol), and the like. In certain embodiments, the one or more enzymes covalently bound to the polymer may include a plurality of enzymes, such as an enzyme system, that have a common response to the analyte, such as at a low potential.

In certain embodiments, the active region may further comprise a redox mediator of the present disclosure. For example, and without limitation, an active region for detecting an analyte (e.g., glutamic acid, glucose, ketone, lactic acid, oxygen, hemoglobin A1C, albumin, alcohol, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, hematin nitrogen, calcium, carbon dioxide, chloride, creatinine, hematocrit, aspartic acid, asparagine, magnesium, oxygen, pH, phosphorus, potassium, sodium, total protein, or uric acid) includes a redox mediator comprising a structure of any one of formulas I-LV. In certain embodiments, the active region for detecting an analyte (e.g., glutamic acid, glucose, ketone, lactic acid, oxygen, hemoglobin A1C, albumin, alcohol, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, hematin nitrogen, calcium, carbon dioxide, chloride, creatinine, hematocrit, aspartic acid, asparagine, magnesium, oxygen, pH, phosphorus, potassium, sodium, total protein, or uric acid) includes a redox mediator comprising any of the structures of formula XLI-LV.

In certain embodiments, the sensors of the present disclosure may include one or more enzymes useful for detecting glucose, e.g., in a first active region. For example, but not by way of limitation, the sensor may include a glucose responsive enzyme, such as glucose oxidase or glucose dehydrogenase. In certain embodiments, the glucose responsive zone may include a glucose oxidase. In certain embodiments, the glucose responsive zone can include a glucose dehydrogenase. In certain embodiments, the glucose-responsive zone can further comprise a redox mediator of the present disclosure.

In certain particular embodiments, the sensors of the present disclosure may include one or more enzymes useful for detecting creatinine. For example, and without limitation, the sensor may include an amidohydrolase, a creatine amidino hydrolase, and/or a sarcosine oxidase. In certain embodiments, the creatinine responsive region may further comprise a redox mediator of the present disclosure.

In certain particular embodiments, the sensors of the present disclosure may include one or more enzymes that may be used to detect lactic acid. For example, but not by way of limitation, the sensor may include lactate oxidase and/or lactate dehydrogenase. In certain embodiments, the lactic acid responsive zone may further comprise a redox mediator of the present disclosure.

In certain particular embodiments, the sensors of the present disclosure may include one or more enzymes useful for detecting ketones, for example in a first active region or a second active region. As mentioned previously, ketones are typically present in low biological abundance and may benefit from low potential detection in accordance with the disclosure herein. Referring now to FIGS. 24A-24C, specific enzyme systems that may be used to detect ketones will be described in more detail. In the depicted enzymatic reaction, beta-hydroxybutyric acid is used as a substitute for ketone formed in vivo. As shown in fig. 22A, a pair of synergistic enzymes useful for detecting ketones according to the disclosure herein are beta-hydroxybutyrate dehydrogenase (HBDH) and diaphorase, which can be deposited in a ketone responsive active region on at least one working electrode surface, as further described herein. When the ketone responsive active region contains the pair of synergistic enzymes, the beta-hydroxybutyrate dehydrogenase enzyme may convert beta-hydroxybutyrate and Nicotinamide Adenine Dinucleotide (NAD) ⁺ ) Converted to acetoacetate and reduced Nicotinamide Adenine Dinucleotide (NADH), respectively. Enzyme cofactor NAD ⁺ And NADH helps to promote the synergistic enzymatic reactions disclosed herein. NADH can then be reduced under the mediation of diaphorase, and the electrons transferred during this process provide the basis for ketone detection at the working electrode. Thus, there is a 1:1 molar correspondence between the number of electrons transferred to the working electrode and the converted β -hydroxybutyrate, providing a basis for ketone detection and quantification based on current measurements at the working electrode. The transfer of electrons generated by NADH reduction to the working electrode can be performed by a redox mediator capable of facilitating operation at low potential. In some embodimentsWherein the redox mediator comprises a structure of any of formulas I-LV. In certain embodiments, albumin may be present as a stabilizer with the pair of synergistic enzymes.

In certain specific embodiments, the beta-hydroxybutyrate dehydrogenase and diaphorase may be covalently bound to a polymer within the ketone responsive active region of the analyte sensor. NAD (NAD) ⁺ Can be covalently bonded to the polymer. In certain embodiments, when NAD ⁺ Without covalent bonding, it may be physically retained within the ketone responsive active region. Membranes covering ketone responsive active regions can help to bind NAD ⁺ Remain in the ketone responsive active region while still allowing the ketone to diffuse sufficiently inward to allow detection thereof.

Other suitable chemistries for enzymatically detecting ketones are shown in FIGS. 24B and 24C. In both cases, there is also a 1:1 molar correspondence between the number of electrons transferred to the working electrode and the amount of beta-hydroxybutyric acid converted, thus providing the basis for ketone detection.

As shown in FIG. 22B, beta-hydroxybutyrate dehydrogenase (HBDH) can convert beta-hydroxybutyrate and NAD ⁺ Converted to acetoacetate and NADH, respectively. Instead of the electron transfer to the working electrode being accomplished by diaphorase (see fig. 22A) and a suitable redox mediator, the reduced form of NADH oxidase (NADHOx (red)) undergoes a reaction to form the corresponding oxidized form (NADHOx (Ox)). Then, NADHOx (red) can be regenerated by reaction with molecular oxygen to produce superoxide, which can then be converted to hydrogen peroxide under the mediation of superoxide dismutase (SOD). The hydrogen peroxide may then undergo reduction at the working electrode to provide a signal that may be correlated to the amount of ketone initially present. According to various embodiments, SOD may be covalently bonded to a polymer in the ketone responsive active area. As with the enzyme system shown in FIG. 22A, the β -hydroxybutyrate dehydrogenase and NADH oxidase may be covalently bonded to a polymer in the ketone responsive active region. In certain embodiments, NAD may be covalently bound to a polymer in the ketone responsive active region. In certain other embodiments, NAD can be present without covalent bonding to polymers in the ketone responsive active region At the point. If NAD ⁺ Non-covalent bonding, it may physically remain in the ketone responsive active region, where the membrane polymer facilitates NAD ⁺ Remain within the ketone responsive active region. In certain embodiments, SOD is not included in the enzyme system used to detect ketones. For example, and without limitation, an enzyme system for use in the analyte sensors of the present disclosure is provided in International patent application No. PCT/US21/62968, the contents of which are incorporated herein by reference in their entirety.

As shown in FIG. 22C, another enzymatic detection chemistry for ketones can utilize beta-hydroxybutyrate dehydrogenase (HBDH) to convert beta-hydroxybutyrate and NAD ⁺ Converted to acetoacetate and NADH, respectively. In this case, the electron transfer cycle is completed by oxidation of poly-1, 10-phenanthroline-5, 6-dione at the working electrode to reform NAD. The poly-1, 10-phenanthroline-5, 6-dione may be covalently bonded to a polymer within the ketone responsive active region or remain in or near the active region. As with the enzyme system shown in fig. 22A, the β -hydroxybutyrate dehydrogenase may be covalently bonded to a polymer in the ketone responsive active region and the NAD may be covalently bonded to a polymer in the ketone responsive active region or remain in or near the ketone responsive region. Inclusion of albumin in the active region may provide a surprising response stability improvement. Suitable membrane polymers can promote NAD ⁺ Remain within the ketone responsive active region.

In certain embodiments, an analyte sensor disclosed herein can include an active site that includes one or more enzymes for detecting an analyte, such as one or more enzymes for use in detecting glucose. In certain embodiments, the analyte sensors disclosed herein can include an active site that includes one or more enzymes for detecting an analyte, such as one or more enzymes for use in detecting a ketone. Alternatively, the analyte sensors disclosed herein may include two or more active sites, each active site containing one or more enzymes. For example, but not limiting of, the analyte sensors of the present disclosure may include: a first active region comprising a first enzyme (or enzyme system) for use in detecting a first analyte (e.g., glucose) and a second active site comprising a second enzyme (or second enzyme system) for detecting a second analyte (e.g., ketone).

In certain embodiments, when more than one active region is present in the sensor, the enzymes may be the same or different. For example, and without limitation, when the sensor includes a first active region and a second active region, the enzyme in the first active region and the enzyme in the second active region may be the same. In certain other embodiments, when the sensor includes a first active region and a second active region, the one or more enzymes of the first active region and the one or more enzymes of the second active region may be different. For example, and without limitation, the second active region may be configured to detect glucose in combination with a different analyte detectable in the first active region, e.g., at a low potential. Thus, in certain embodiments, the second enzyme may be glucose oxidase.

In certain embodiments, the first analyte is glucose, detectable by an enzyme system comprising glucose oxidase (e.g., glucose oxidase or glucose oxidase and diaphorase), and the second analyte is a ketone, detectable by an enzyme system described herein (e.g., β -hydroxybutyrate dehydrogenase and diaphorase). Alternatively, the first analyte is a ketone, detectable by the enzyme systems described herein (e.g., β -hydroxybutyrate dehydrogenase and diaphorase), and the second analyte is glucose, detectable by a glucose responsive enzyme, such as a glucose oxidase (e.g., glucose oxidase or glucose oxidase and diaphorase).

In certain embodiments, the analyte responsive active areas of the present disclosure can include from about 10% to about 80% (e.g., from about 15% to about 75%, from about 20% to about 70%, from about 25% to about 65%, from about 30% to about 60%, or from about 20% to about 50%) by weight of one or more enzymes disclosed herein. In certain embodiments, the analyte responsive active area can comprise from about 20% to about 70% by weight of one or more enzymes disclosed herein. In certain embodiments, the analyte responsive active area can comprise from about 30% to about 60% by weight of one or more enzymes disclosed herein. In certain embodiments, the analyte responsive active area can comprise from about 30% to about 50% by weight of one or more enzymes disclosed herein. In certain embodiments, the analyte responsive active area can comprise from about 20% to about 50% by weight of one or more enzymes disclosed herein. In certain embodiments, the analyte responsive active area can comprise from about 20% to about 40% by weight of one or more enzymes disclosed herein.

In certain embodiments, the analyte responsive active area can further comprise a stabilizer, e.g., for stabilizing one or more enzymes. For example, but not by way of limitation, the stabilizing agent may be albumin, such as serum albumin. Non-limiting examples of serum albumin include bovine serum albumin and human serum albumin. In certain embodiments, the stabilizing agent is human serum albumin. In certain embodiments, the stabilizing agent is bovine serum albumin. In certain embodiments, the analyte responsive active areas of the present disclosure can include a ratio of stabilizing agent (e.g., serum albumin) to one or more enzymes present in the active area of about 100:1 to about 1:100, such as about 95:1 to about 1:95, about 90:1 to about 1:90, about 85:1 to about 1:85, about 80:1 to about 1:80, about 75:1 to about 1:75, about 60:1 to about 1:60, about 55:1 to about 1:55, about 50:1 to about 1:50, about 45:1 to about 1:45, about 40:1 to about 1:40, about 35:1 to about 1:35, about 30:1 to about 1:30, about 25:1 to about 1:25, about 20:1 to about 1:20, about 15:1 to about 1:15, about 10:1 to about 10, about 9:1 to about 1:9, about 8:1 to about 1:8, about 7:1 to about 1:1, about 6:1 to about 1:1, about 1:4:1 to about 1:1, about 3:1 or about 1:1 to about 2:1. In certain embodiments, the analyte responsive active area can include a ratio of stabilizing agent to one or more enzymes present in the active area of about 50:1 to about 1:50. In certain embodiments, the analyte responsive active area can include a ratio of stabilizing agent to one or more enzymes present in the active area of about 10:1 to about 1:10. In certain embodiments, the analyte responsive active area can include a ratio of stabilizing agent to one or more enzymes present in the active area of about 7:1 to about 1:7. In certain embodiments, the analyte responsive active area can include a ratio of stabilizing agent to one or more enzymes present in the active area of about 6:1 to about 1:6. In certain embodiments, the analyte responsive active area can include a ratio of stabilizing agent to one or more enzymes present in the active area of about 5:1 to about 1:5. In certain embodiments, the analyte responsive active area can include a ratio of stabilizing agent to one or more enzymes present in the active area of about 4:1 to about 1:4. In certain embodiments, the analyte responsive active area can include a ratio of stabilizing agent to one or more enzymes present in the active area of about 3:1 to about 1:3. In certain embodiments, the analyte responsive active area can include a ratio of stabilizing agent to one or more enzymes present in the active area of about 2:1 to about 1:2. In certain embodiments, the analyte responsive active area can include a ratio of stabilizing agent to one or more enzymes present in the active area of about 1:1. In certain embodiments, the analyte responsive active area can include from about 5% to about 50% (e.g., from about 10% to about 50%, from about 15% to about 45%, from about 20% to about 40%, from about 20% to about 35%, or from about 20% to about 30%) by weight of a stabilizing agent. In certain embodiments, the analyte responsive active area can include from about 5% to about 40% by weight of a stabilizing agent. In certain embodiments, the analyte responsive active area can include from about 5% to about 35% by weight of a stabilizing agent. In certain embodiments, the analyte responsive active area can include from about 5% to about 30% by weight of a stabilizing agent. In certain embodiments, the analyte responsive active area can include from about 10% to about 30% by weight of a stabilizing agent. In certain embodiments, the analyte responsive active area can include from about 15% to about 35% by weight of a stabilizing agent.

In certain embodiments, the analyte responsive active area (e.g., analyte responsive active area) can further comprise a cofactor or coenzyme for one or more enzymes present in the analyte responsive active area. In certain embodiments, the cofactor is Nicotinamide Adenine Dinucleotide (NAD) or Nicotinamide Adenine Dinucleotide Phosphate (NADP) (collectively referred to herein as "NAD (P)"). In certain embodiments, the coenzyme is FAD. In certain embodiments, the analyte responsive active area can include a cofactor to enzyme ratio of about 40:1 to about 1:40, for example about 35:1 to about 1:35, about 30:1 to about 1:30, about 25:1 to about 1:25, about 20:1 to about 1:20, about 15:1 to about 1:15, about 10:1 to about 1:10, about 9:1 to about 1:9, about 8:1 to about 1:8, about 7:1 to about 1:7, about 6:1 to about 1:6, about 5:1 to about 1:5, about 4:1 to about 1:4, about 3:1 to about 1:3, about 2:1 to about 1:2, or about 1:1. In certain embodiments, the analyte responsive active area can include a cofactor to enzyme ratio of about 5:1 to about 1:5. In certain embodiments, the analyte responsive active area can include a cofactor to enzyme ratio of about 4:1 to about 1:4. In certain embodiments, the analyte responsive active area can include a cofactor to enzyme ratio of about 3:1 to about 1:3. In certain embodiments, the analyte responsive active area can include a cofactor to enzyme ratio of about 2:1 to about 1:2. In certain embodiments, the analyte responsive active area can include a cofactor to enzyme ratio of about 1:1. In certain embodiments, the analyte responsive active area can comprise from about 10% to about 50% cofactor by weight, such as from about 15% to about 45% by weight, from about 20% to about 40% by weight, from about 20% to about 35% by weight, or from about 20% to about 30% by weight. In certain embodiments, the analyte responsive active area can comprise from about 20% to about 40% cofactor by weight. In certain embodiments, the analyte responsive active area can comprise from about 20% to about 30% cofactor by weight. In certain embodiments, the analyte responsive active area can comprise from about 15% to about 35% cofactor by weight. In certain embodiments, a cofactor (e.g., NAD (P)) may be physically retained within the analyte responsive active region. For example, and without limitation, a membrane covering the analyte responsive active area may help retain the cofactor in the analyte responsive active area while still allowing the analyte to diffuse sufficiently inward to allow detection thereof.

In certain embodiments, the one or more enzymes of the analyte responsive active region can be covalently bound to a polymer present in the active region, such as the polymer backbone described in section 3. In certain embodiments, when an enzyme system having multiple enzymes is present in a given active region, all of the multiple enzymes may be covalently bonded to the polymer. In certain other embodiments, only a portion of the plurality of enzymes is covalently bonded to the polymer. For example, and without limitation, one or more enzymes of the enzyme system may be covalently bonded to the polymer, and at least one enzyme may be non-covalently associated with the polymer such that the non-covalently bonded enzyme is physically retained in the polymer. In certain embodiments, a membrane covering the analyte responsive active area can help retain one or more enzymes within the analyte responsive active area while still allowing the analyte to diffuse sufficiently inward to allow detection thereof. Suitable membrane polymers for covering the analyte responsive active area are further discussed herein.

In certain embodiments, when a stabilizer is present in the active region, one or more enzymes within the region may be covalently bonded to the stabilizer. For example, and without limitation, one or more enzymes may be covalently bonded to a stabilizer, such as albumin, present in the active region.

In certain specific embodiments, covalent bonding of one or more enzymes and/or redox mediators to polymers and/or stabilizers in a given active region may be performed by cross-linking introduced by a suitable cross-linking agent. In certain embodiments, crosslinking of the polymer and/or stabilizer with one or more enzymes and/or redox mediators may reduce the occurrence of delamination of the enzyme composition from the electrode. Suitable crosslinking agents may include one or more crosslinkable functional groups such as, but not limited to, vinyl, alkoxy, acetoxy, alkenyloxy, oxime, amino, hydroxyl, cyano, halogen, acrylate, epoxy, and isocyanate groups. In certain embodiments, the crosslinking agent includes one or more, two or more, three or more, or four or more epoxy groups. For example, and without limitation, cross-linking agents for use in the present disclosure may include mono-, di-, tri-, and tetra-oxiranes. In certain embodiments, the cross-linking agent used to react with the free amino groups in the enzyme (e.g., with the free side chain amine in lysine) may include cross-linking agents such as, for example, polyethylene glycol dibutyl ether, polypropylene glycol dimethyl ether, polyimide Alkyl glycol allyl methyl ether, polyethylene glycol diglycidyl ether (PEGDGE) or other polyepoxides, cyanuric chloride, N-hydroxysuccinimide, imidoester (imidoester), epichlorohydrin or derived variants thereof. In certain embodiments, the crosslinking agent is PEGDGE, e.g., having an average molecular weight (M) of about 200 to 1,000 (e.g., about 400) _n ). In certain embodiments, the crosslinking agent is PEGDGE 400. In certain embodiments, the cross-linking agent may be glutaraldehyde. In certain embodiments, the crosslinking of the enzyme to the polymer is generally intermolecular. In certain embodiments, the crosslinking of the enzyme with the polymer is generally intramolecular.

In certain embodiments, the analyte responsive active area can include a ratio of cross-linking agent to one or more enzymes of the active area of about 100:1 to about 1:100. In certain embodiments, the analyte responsive active area can include a ratio of cross-linking agent to one or more enzymes of the active area of about 40:1 to about 1:40, such as about 35:1 to about 1:35, about 30:1 to about 1:30, about 25:1 to about 1:25, about 20:1 to about 1:20, about 15:1 to about 1:15, about 10:1 to about 1:10, about 9:1 to about 1:9, about 8:1 to about 1:8, about 7:1 to about 1:7, about 6:1 to about 1:6, about 5:1 to about 1:5, about 4:1 to about 1:4, about 3:1 to about 1:3, about 2:1 to about 1:2, or about 1:1. In certain embodiments, the analyte responsive active area can include a ratio of cross-linking agent to one or more enzymes of the active area of about 5:1 to about 1:5. In certain embodiments, the analyte responsive active area can include a ratio of cross-linking agent to one or more enzymes of the active area of about 4:1 to about 1:4. In certain embodiments, the analyte responsive active area can include a ratio of cross-linking agent to one or more enzymes of the active area of about 3:1 to about 1:3. In certain embodiments, the analyte responsive active area can include a ratio of cross-linking agent to one or more enzymes of the active area of about 2:1 to about 1:2. In certain embodiments, the analyte responsive active area can include a ratio of cross-linker to one or more enzymes of the active area of about 1:1. In certain embodiments, the analyte responsive active area can include from about 5% to about 50% (e.g., from about 5% to about 45%, from about 5% to about 40%, from about 5% to about 35%, from about 10% to about 30%, or from about 10% to about 25%) by weight of the cross-linking agent. In certain embodiments, the analyte responsive active area can include from about 5% to about 35% by weight of a cross-linking agent. In certain embodiments, the analyte responsive active area can include from about 10% to about 30% by weight of a cross-linking agent. In certain embodiments, the analyte responsive active area can include from about 10% to about 25% by weight of a cross-linking agent.

In certain embodiments, the active regions of the present disclosure may have a thickness of about 0.1 μm to about 100 μm, for example about 1 μm to about 90 μm, about 1 μm to about 80 μm, about 1 μm to about 70 μm, about 1 μm to about 60 μm, about 1 μm to about 50 μm, about 1 μm to about 40 μm, about 1 μm to about 30 μm, about 1 μm to about 20 μm, about 0.5 μm to about 10 μm, about 1 μm to about 5 μm, or about 0.1 μm to about 5 μm. In certain embodiments, a series of droplets may be applied on top of each other to achieve a desired thickness of the active region without significantly increasing the diameter of the applied droplets (i.e., maintaining their desired diameter or range).

5. Mass transfer limiting membrane

In certain embodiments, the analyte sensors disclosed herein further comprise an analyte-permeable mass transport limiting membrane that covers at least one active region, such as the first active region. In certain embodiments, when there are multiple active regions, the mass transfer limiting film may cover each active region. Alternatively, the first film covers one of the active areas and the second film covers the second active area. In certain embodiments, the first film covers one of the active areas and the second film covers the first active area and the second active area.

In certain embodiments, a membrane covering the analyte responsive active area may be used as a mass transfer limiting membrane and/or to improve biocompatibility. The mass transfer limiting membrane may act as a diffusion limiting barrier to reduce the mass transfer rate of the analyte. For example, and without limitation, limiting the entry of an analyte (e.g., glucose or ketone) into an analyte responsive active area using a mass transfer limiting membrane can help avoid overloading (saturation) of the sensor, thereby improving detection performance and accuracy.

In certain embodiments, the mass transfer limiting membrane may be homogeneous and may be monocomponent (contain a single membrane polymer). Alternatively, the mass transfer limiting film may be multicomponent (contain two or more different film polymers). In certain embodiments, the multicomponent film may be present as a bilayer film or as a homogeneous mixture of two or more film polymers. The homogeneous mixture may be deposited by combining two or more film polymers in a solution and then depositing the solution on the working electrode (e.g., dip coating).

In certain embodiments, the mass transfer limiting film may comprise two or more layers, such as a bilayer or trilayer film. In certain embodiments, each layer may comprise a different polymer or different concentrations or thicknesses of the same polymer. In certain embodiments, the first analyte responsive active area can be covered by a multilayer film (e.g., a bilayer film), while the second analyte responsive active area can be covered by a monolayer film. In certain embodiments, the first analyte responsive active area can be covered by a multilayer film (e.g., a bilayer film), and the second analyte responsive active area can be covered by a multilayer film (e.g., a bilayer film). In certain embodiments, the first analyte responsive active area can be covered by a single layer membrane and the second analyte responsive active area can be covered by a multi-layer membrane (e.g., a double layer membrane). In certain embodiments, the first analyte responsive active area may be covered by a single layer membrane and the second analyte responsive active area may be covered by a single layer membrane.

In certain embodiments, the mass transfer limiting membrane may comprise a polymer comprising heterocyclic nitrogen groups. In certain embodiments, the mass transfer limiting film may comprise a polyvinyl pyridine-based polymer. Non-limiting examples of polyvinyl pyridine-based polymers are disclosed in U.S. patent publication No. 2003/0042137 (e.g., formula 2 b), the contents of which are incorporated herein by reference in their entirety. In certain embodiments, the polyvinyl pyridine-based polymer has a molecular weight of about 50Da to about 500 kDa.

In certain embodiments, the mass transfer limiting membrane may comprise a polyvinylpyridine (e.g., poly (4-vinylpyridine) or poly (4-vinylpyridine)), polyvinylimidazole, polyvinylpyridine copolymers (e.g., copolymers of vinylpyridine and styrene), polyacrylates, polyurethanes, polyether urethanes, silicones, polytetrafluoroethylene, polyethylene-co-tetrafluoroethylene, polyolefins, polyesters, polycarbonates, biostable polytetrafluoroethylene, homopolymers, copolymers or terpolymers of polyurethane, polypropylene, polyvinylchloride, polyvinylidene fluoride, polybutylene terephthalate, polymethyl methacrylate, polyether ether ketone, cellulosic polymers, polysulfones, and block copolymers thereof, including, for example, diblock, triblock, alternating, random and graft copolymers or chemically-related materials, and the like.

In certain embodiments, a film (e.g., a one-component film) for use in the present disclosure may include a polyvinylpyridine (e.g., poly (4-vinylpyridine) and/or poly (2-vinylpyridine)). In certain embodiments, a film (e.g., a one-component film) for use in the present disclosure may comprise poly (4-vinylpyridine). In certain embodiments, a film (e.g., a one-component film) for use in the present disclosure may include a copolymer of vinylpyridine and styrene. In certain embodiments, the film may comprise a polyvinylpyridine-co-styrene copolymer. For example, and without limitation, a polyvinylpyridine-co-styrene copolymer for use in the present disclosure may include a polyvinylpyridine-co-styrene copolymer in which a portion of the pyridine nitrogen atoms are functionalized with non-crosslinked polyethylene glycol tails and a portion of the pyridine nitrogen atoms are functionalized with alkylsulfonic acid (e.g., propylsulfonic acid) groups. In certain embodiments, the derivatized polyvinylpyridine-co-styrene copolymer used as the film polymer may be a 10Q5 polymer described in U.S. patent No. 8,761,857, the disclosure of which is incorporated herein by reference in its entirety.

Suitable copolymers of vinylpyridine and styrene may have a styrene content ranging from about 0.01 to about 50 mole percent, or from about 0.05 to about 45 mole percent, or from about 0.1 to about 40 mole percent, or from about 0.5 to about 35 mole percent, or from about 1 to about 30 mole percent, or from about 2 to about 25 mole percent, or from about 5 to about 20 mole percent. The substituted styrenes may be used similarly and in similar amounts. Suitable copolymers of vinylpyridine and styrene can have a molecular weight of 5kDa or greater, or about 10kDa or greater, or about 15kDa or greater, or about 20kDa or greater, or about 25kDa or greater, or about 30kDa or greater, or about 40kDa or greater, or about 50kDa or greater, or about 75kDa or greater, or about 90kDa or greater, or about 100kDa or greater. In a non-limiting example, suitable copolymers of vinylpyridine and styrene can have a molecular weight in the range of about 5kDa to about 150kDa, or about 10kDa to about 125kDa, or about 15kDa to about 100kDa, or about 20kDa to about 80kDa, or about 25kDa to about 75kDa, or about 30kDa to about 60kDa.

In certain embodiments, the membrane comprises a polyurethane membrane comprising hydrophilic and hydrophobic regions. In certain embodiments, the hydrophobic polymer component is a polyurethane, polyurethane urea, or poly (ether-urethane-urea). In certain embodiments, the polyurethane is a polymer produced by the condensation reaction of a diisocyanate and a difunctional hydroxyl containing material. In certain embodiments, the polyurethaneurea is a polymer produced by a condensation reaction of a diisocyanate and a difunctional amine-containing material. In certain embodiments, the diisocyanate for use herein includes aliphatic diisocyanates (e.g., containing about 4 to about 8 methylene units), or diisocyanates containing cycloaliphatic moieties. Other non-limiting examples of polymers that can be used to form the membrane of the sensor of the present disclosure include vinyl polymers, polyethers, polyesters, polyamides, inorganic polymers (e.g., polysiloxanes and polycarbosiloxanes), natural polymers (e.g., cellulose and protein based materials), and blends (e.g., blends or layered structures) or combinations thereof. In certain embodiments, the hydrophilic polymer component is polyethylene oxide and/or polyethylene glycol. In certain embodiments, the hydrophilic polymer component is a polyurethane copolymer. For example, and without limitation, a hydrophobic-hydrophilic copolymer component for use in the present disclosure is a polyurethane polymer comprising about 10% to about 50% (e.g., about 20%) of a hydrophilic polyethylene oxide.

In certain embodiments, the membrane comprises a silicone polymer/hydrophobic-hydrophilic polymer blend. In certain embodiments, the hydrophobic-hydrophilic polymer used in the blend may be any suitable hydrophobic-hydrophilic polymer, such as, but not limited to, polyvinylpyrrolidone, polyhydroxyethyl methacrylate, polyvinyl alcohol, polyacrylic acid, polyethers (e.g., polyethylene glycol or polypropylene oxide) and copolymers thereof, including, for example, diblock, triblock, alternating, random, comb, star, dendritic, and graft copolymers. In certain embodiments, the hydrophobic-hydrophilic polymer is a copolymer of polyethylene oxide (PEO) and polypropylene oxide (PPO). Non-limiting examples of PEO and PPO copolymers include PEO-PPO diblock copolymers, PPO-PEO-PPO triblock copolymers, PEO-PPO-PEO triblock copolymers, alternating block copolymers of PEO-PPO, random copolymers of ethylene oxide and propylene oxide, and blends thereof. In certain embodiments, the copolymer may be substituted with a hydroxy substituent.

In certain embodiments, a hydrophilic or hydrophobic modifier may be used to "fine tune" the permeability of the resulting membrane to the target analyte. In certain embodiments, hydrophilic modifiers (e.g., poly (ethylene glycol)), hydroxyl or polyhydroxy modifiers, and the like, as well as any combination thereof, may be used to enhance the biocompatibility of the polymer or resulting film.

In certain embodiments, the mass transfer limiting membrane may comprise a membrane polymer, such as a polyvinylpyridine or polyvinylimidazole homopolymer or copolymer, which may be further crosslinked with a suitable crosslinking agent. In certain particular embodiments, the film polymer may comprise a copolymer of vinylpyridine and styrene, for example, further crosslinked with a suitable crosslinking agent.

In certain embodiments, the mass transfer limiting membrane may comprise a membrane polymer crosslinked with a crosslinking agent as disclosed herein and in section 4 above. In certain embodiments where there are two mass transfer limiting films (e.g., a first mass transfer limiting film and a second mass transfer limiting film), each film may be crosslinked with a different crosslinking agent. For example, and without limitation, the cross-linking agent may create a membrane that is more restrictive to the diffusion of certain compounds (e.g., analytes within the membrane), or a membrane that is less restrictive to the diffusion of certain compounds (e.g., by affecting the size of pores within the membrane).

In certain embodiments, the cross-linking agent for use in the present disclosure may include polyepoxides, carbodiimides, cyanuric chloride, triglycidyl (Gly 3), N-hydroxysuccinimide, imidoesters, epichlorohydrin, or derivative variants thereof. In certain embodiments, the film polymer covering one or more active regions may be crosslinked with a branching crosslinking agent, which may, for example, reduce the amount of extractables available from the mass transfer limiting film. Non-limiting examples of branched crosslinkers include branched glycidyl ether crosslinkers, including for example branched glycidyl ether crosslinkers containing two or three or more crosslinkable groups. In certain embodiments, the branched crosslinking agent may include two or more crosslinkable groups, such as polyethylene glycol diglycidyl ether. In certain embodiments, the branched crosslinking agent may include three or more crosslinkable groups, such as polyethylene glycol tetraglycidyl ether. In certain embodiments, the mass transfer limiting film may comprise a polyvinylpyridine or a copolymer of vinylpyridine and styrene crosslinked with a branched glycidyl ether crosslinking agent comprising two or three crosslinkable groups (e.g., polyethylene glycol tetraglycidyl ether or polyethylene glycol diglycidyl ether). In certain embodiments, the epoxide groups of the polyepoxide (e.g., polyethylene glycol tetraglycidyl ether or polyethylene glycol diglycidyl ether) can form covalent bonds with pyridine or imidazole through epoxy ring opening, resulting in hydroxyalkyl groups bridging the crosslinker body to the heterocycle of the film polymer.

In certain embodiments, the crosslinker is polyethylene glycol diglycidyl ether (PEGDGE). In certain embodiments, PEGDGE used to facilitate crosslinking (e.g., intermolecular crosslinking) between two or more membrane polymer backbones can exhibit a wide range of suitable molecular weights. In certain embodiments, the molecular weight of PEGDGE may range from about 100g/mol to about 5,000 g/mol. The number of ethylene glycol repeat units in each arm of PEGDGE may be the same or different and may generally vary within the range of a given sample to provide an average molecular weight. In some embodiments, for the presentThe PEGDGE disclosed has an average molecular weight (M) of about 200 to 1,000 (e.g., about 400) _n ). In certain embodiments, the crosslinking agent is PEGDGE 400.

In certain embodiments, the crosslinking may be intermolecular. Polyethylene glycol tetraglycidyl ethers used to facilitate crosslinking (e.g., intermolecular crosslinking) between two or more film polymer backbones can exhibit a wide range of suitable molecular weights. Up to four polymer backbones can be crosslinked with a single molecule of polyethylene glycol tetraglycidyl ether crosslinker. In certain particular embodiments, the molecular weight of the polyethylene glycol tetraglycidyl ether can range from about 1,000g/mol to about 5,000 g/mol. The number of ethylene glycol repeat units in each arm of the polyethylene glycol tetraglycidyl ether may be the same or different and may generally vary within a range within a given sample to provide an average molecular weight. The structure of the polyethylene glycol tetraglycidyl ether prior to crosslinking can be represented by the following formula LVI:

Wherein n1, n2, n3 and n4 are each integers greater than or equal to 0. In certain embodiments, each of n1, n2, n3, and n4 is 1 or greater, and n1, n2, n3, and n4 may be the same or different. The sum of n1, n2, n3 and n4 may be selected so that the molecular weight of the polyethylene glycol tetraglycidyl ether falls within the above range. In other words, to produce polyethylene glycol tetraglycidyl ethers having a molecular weight in the above range, the sum of n1, n2, n3 and n4 may be in the range of about 14 to about 110, or about 15 to about 104, including any subrange between these values, wherein n1, n2, n3 and n4 independently may be any integer greater than or equal to 0 or greater than or equal to 1.

As used herein, crosslink density refers to the number of membrane polymer side chains having a crosslinker attached thereto. Film polymers crosslinked with branched glycidyl ethers (e.g., polyethylene glycol tetraglycidyl ether or similar polyethylene oxide crosslinkers having three or more crosslinkable groups) can have crosslink densities that vary over a wide range. In a specific example, the fraction of side chains that may have a crosslinker attached thereto may be about 0.1% or greater of available heterocycles in the membrane polymer, or about 0.2% or greater of available heterocycles in the membrane polymer, or about 0.3% or greater of available heterocycles in the membrane polymer, or about 0.4% or greater of available heterocycles in the membrane polymer, or about 0.5% or greater of available heterocycles in the membrane polymer, or about 0.6% or greater of available heterocycles in the membrane polymer, or about 0.7% or greater of available heterocycles in the membrane polymer, or about 0.8% or greater of available heterocycles in the membrane polymer, or about 1.0% or greater of available heterocycles in the membrane polymer, or about 1.2% or greater of available heterocycles in the membrane polymer, or about 1.4% or greater of available heterocycles in the membrane polymer, about 0.6% or greater than about 0.5% or greater of available heterocycles in the membrane polymer, about 0.7% or greater of available heterocycles in the membrane polymer, about 0.8% or greater than about 0.9% or greater of available heterocycles in the membrane polymer, or about 1.2% or greater than about 1% or greater than about 0.5% or greater than available heterocycles in the membrane polymer, about 1.0.0% or greater than about 0.8% or greater than available heterocycles in the membrane polymer, or about 7.0% or greater of the available heterocycles in the film polymer, or about 7.5% or greater of the available heterocycles in the film polymer, or about 8.0% or greater of the available heterocycles in the film polymer, or about 8.5% or greater of the available heterocycles in the film polymer, or about 9.0% or greater of the available heterocycles in the film polymer, or about 9.5% or greater of the available heterocycles in the film polymer, or about 10% or greater of the available heterocycles in the film polymer. In certain embodiments, the crosslinker may be added to about 1% to about 20% of the available heterocycles in the film polymer, or about 2% to about 10% of the available heterocycles in the film polymer, or about 3% to about 8% of the available heterocycles in the film polymer, or about 4% to about 9% of the available heterocycles in the film polymer, or about 5% to about 12% of the available heterocycles in the film polymer.

Suitable membrane polymers may further comprise one or more polyether arms (side chains) bonded to the nitrogen atom of the pyridine or imidazole monomer unit. Any of the film polymers disclosed herein can further comprise one or more polyether arms. Polyether arms differ from crosslinking groups formed from polyethylene glycol tetraglycidyl ether or similar crosslinking agents in that the polyether arms do not extend between separate polymer chains or terminate within molecules within a single polymer chain. Thus, the polyether arms are separate and distinct from the crosslinking groups formed by the crosslinking agent. The polyether arms may include polyethylene oxide (PEO) blocks and polypropylene oxide (PPO) blocks, in particular polyether arms having a polypropylene oxide block interposed between two polyethylene oxide blocks. The bonding of the polyether arms to the nitrogen atoms of the heterocycle may occur through any reactive functional group capable of forming a bond with the nitrogen atoms of the heterocycle in the film polymer. The linkage of the polyether arm to the nitrogen atom of the heterocycle may be alkyl, hydroxy functionalized alkyl or carbonyl. The polyether arms may also contain amine groups remote from the heterocyclic nitrogen atom or in other specific cases be free of amine groups.

The polyether arms of the film polymer may include at least one polyethylene oxide block and at least one polypropylene oxide block, thereby providing at least a diblock arrangement of polyethylene oxide and polypropylene oxide monomer units bonded to the heterocyclic nitrogen atoms through the spacer. The polyethylene oxide blocks or polypropylene oxide blocks may be bonded to the spacer. In other certain embodiments, the polyether arm may include ase:Sub>A spacer, ase:Sub>A first polyethylene oxide block, ase:Sub>A polypropylene oxide block, and ase:Sub>A second polyethylene oxide block in that order (i.e., ase:Sub>A-B-ase:Sub>A repeating pattern) or ase:Sub>A spacer, ase:Sub>A first polypropylene oxide block, ase:Sub>A polyethylene oxide block, and ase:Sub>A second polypropylene oxide block in that order (i.e., B-ase:Sub>A-B repeating pattern). The amine groups can be between the polyethylene oxide blocks and the polypropylene oxide blocks in the amine-containing polyether arms.

In certain embodiments, the polyether arms in the film polymers described herein can have a structure generally defined by the following formula LVII-LX:

wherein PE represents a polyethylene oxide block, PP represents a polypropylene oxide block, A is an amine group, and J is a spacer group. The spacer group J may be bonded to a heterocycle of the membrane polymer. Suitable spacer groups J may include, but are not limited to, alkyl, hydroxy-functionalized alkyl, carbonyl, carboxylate, carboxamide, and the like. The variables q, r, s and t are positive integers defining the number of monomer units in each block and the number of block repetitions, provided that in a diblock arrangement the variable t may be 0 and the variable s may be 1. In certain embodiments, the variable q is an integer ranging from about 2 to about 50 or from about 6 to about 20, the variable r is an integer ranging from about 2 to about 60 or from about 10 to about 40, and the variable t is an integer ranging from about 2 to about 50 or from about 10 to about 30. In certain other embodiments, the variable s is an integer ranging from 1 to about 20 or from 1 to about 10. In certain particular embodiments, the variable s is equal to 1.

In certain particular embodiments of the present disclosure, amine-free polyether arms having a triblock arrangement of polyethylene oxide, polypropylene oxide, and polyethylene oxide (corresponding to formula LVII) arms may have a structure defined by formula LXI:

Where R is an alkyl group (such as, but not limited to, methyl), the variable w is 0 or 1, the variable x is an integer ranging from about 4 to about 24 or from about 6 to about 20, the variable y is an integer ranging from about 8 to about 60 or from about 10 to about 40, and the variable z is an integer ranging from about 6 to about 36 or from about 10 to about 30. In more specific embodiments, the variable x may range from about 8 to about 16 or about 9 to about 12, the variable y may range from about 10 to about 32, or about 16 to about 30, or about 12 to about 20, and the variable z may range from about 10 to about 20, or about 14 to about 18. In certain embodiments, the variable x may be less than the variable z such that the second polyethylene oxide block is longer (greater) than the first polyethylene oxide block. If the variable w is 0, the amine-free polyether arm is directly bonded to the membrane polymer through a two carbon alkyl group, although longer alkyl groups are also contemplated by the present disclosure.

In certain particular embodiments of the present disclosure, polyether arms having a triblock arrangement of polyethylene oxide, polypropylene oxide, and polyethylene oxide (corresponding to formula LIX) and having amine groups between the polyethylene oxide blocks and polypropylene oxide blocks may have a structure defined by formula LXIII:

wherein w, x, y, z and R are as defined above for formula LXI. If the variable w is 0, the polyether arm is directly bonded to the membrane polymer through a two carbon alkyl group, although longer alkyl groups are also contemplated by the present disclosure.

The polyether arms described herein may be bonded to the heterocyclic nitrogen atom through a reactive functional group in the polyether arm precursor. Suitable reactive functional groups may include, for example, halogens or epoxides. For example, epoxides result in the formation of a hydroxyalkyl spacer that connects the polyether arm to the heterocyclic nitrogen atom of the membrane polymer, as exemplified in formulas LXI and LXII above (n=1 in formulas LXI and LXII). In contrast, halogen-functionalized polyether arm precursors may yield alkyl spacers (n=0 in formulas LXI and LXII), where suitable alkyl groups may be straight or branched C ₂ -C ₂₀ An alkyl group.

In certain embodiments, sulfonate (sulfonate) -containing arms can be attached as side chains to at least a portion of the film polymers disclosed herein. The sulfonate-containing arms can be present in any suitable ratio in combination with the polyether arms and/or the crosslinking agent. Any of the film polymers disclosed herein can include a higher amount of polyether arms or crosslinking groups than sulfonate containing arms. Sulfonate containing arms can be attached to the membrane polymer through alkyl groups. According to various embodiments, the alkyl group may contain from 1 to about 6 carbon atoms, or from 2 to about 4 carbon atoms. Suitable reagents for incorporating sulfonate-containing arms into the membrane polymers disclosed herein may include halosulfonic acid compounds, such as chloromethylsulfonic acid, bromoethane sulfonic acid, and the like, or cyclic sulfonates (sultones).

Polydimethylsiloxane (PDMS) may be incorporated into any of the mass transfer limiting films disclosed herein.

Accordingly, at least some of the analyte sensors described herein can include a sensor tail including at least a first working electrode, a first active region disposed on a surface of the first working electrode, and a first analyte-permeable mass transport limiting membrane covering at least the first active region. The first active region includes a first polymer and at least one enzyme covalently bonded to the first polymer and responsive to a first analyte. In certain embodiments, the mass transfer limiting membrane comprises a membrane polymer crosslinked with a branched glycidyl ether crosslinking agent (e.g., polyethylene glycol diglycidyl ether or polyethylene glycol tetraglycidyl ether) comprising two or more or three or more crosslinkable groups.

In certain embodiments, when a first active region and a second active region configured for determining different analytes are disposed on separate working electrodes, the mass transfer limiting membrane may have different permeability values for the first analyte and the second analyte. While the film thickness and/or the size of the active region at each working electrode may be varied to balance the sensitivity for each analyte, such an approach can significantly complicate the manufacture of analyte sensors. As an alternative, the mass transfer limiting membrane covering at least one active region may comprise a mixture of the first membrane polymer and the second membrane polymer or a bilayer of the first membrane polymer and the second membrane polymer. The homogeneous membrane may cover the uncovered active area with a mixture or bilayer, wherein the homogeneous membrane comprises only one of the first membrane polymer or the second membrane polymer. Advantageously, the architecture of the analyte sensor disclosed herein readily enables a continuous membrane having a homogeneous membrane portion to be disposed over a first active area of the analyte sensor and a multicomponent membrane portion to be disposed over a second active area of the analyte sensor, thereby homogenizing the permeability values for each analyte to provide improved sensitivity and detection accuracy at the same time. In certain embodiments, continuous film deposition may be performed by a sequential dip coating operation.

Typically, the thickness of the film is controlled by the concentration of the film solution, the number of droplets of film solution applied, the number of times the sensor is immersed or sprayed with the film solution, the volume of film solution sprayed onto the sensor, and the like, as well as any combination of these factors. In certain embodiments, the films described herein can have a thickness ranging from about 0.1 micrometers (μm) to about 1,000 μm, such as from about 1 μm to about 500 μm, from about 10 μm to about 100 μm, or from about 10 μm to about 100 μm. In certain embodiments, the sensor may be immersed more than once in the membrane solution. For example, and without limitation, the sensor (or working electrode) of the present disclosure may be immersed in a film solution at least two times, at least three times, at least four times, or at least five times to obtain a desired film thickness.

6. Interference domain

In certain embodiments, the sensor (e.g., sensor tail) of the present disclosure may further comprise an interference domain. In certain embodiments, the interfering domain may comprise a polymer domain that restricts the flow of one or more interfering streams to, for example, the surface of the working electrode. In certain embodiments, the interfering domain may act as a molecular sieve, allowing the analyte and other substances to be measured by the working electrode to pass through while preventing other substances (e.g., interferents) from passing through. In certain embodiments, the interferents affect the signal obtained at the working electrode. Non-limiting examples of interferents include acetaminophen, ascorbate (ascorbate), ascorbic acid, bilirubin, cholesterol, creatinine, dopamine, ephedrine, ibuprofen, levodopa, methyldopa, salicylate (salicyclic), tetracycline, tolasulfuron, triglycerides, urea and uric acid.

In certain embodiments, the interference domain is located between the working electrode and the one or more active regions. In certain embodiments, non-limiting examples of polymers that can be used for the interfering domain include polyurethanes, polymers having ionic side groups, and polymers having controlled pore sizes. In certain embodiments, the interfering domain is formed from one or more cellulose derivatives. Non-limiting examples of cellulose derivatives include polymers such as cellulose acetate, cellulose acetate butyrate, 2-hydroxyethyl cellulose, cellulose acetate phthalate (cellulose acetate phthalate), cellulose acetate propionate, cellulose acetate trimellitate, and the like.

In certain embodiments, the interfering domain is part of the mass transfer limiting membrane and not a separate membrane. In certain embodiments, the interference domain is located between the one or more active regions and the mass transfer limiting membrane.

In certain embodiments, the interfering domain comprises a hydrophobic membrane that is non-swellable and limits diffusion of high molecular weight species. For example, and without limitation, the interfering domain may be permeable to relatively low molecular weight substances, such as hydrogen peroxide, while restricting passage of higher molecular weight substances, such as ketones, glucose, acetaminophen, and/or ascorbic acid.

In certain embodiments, the interfering domain may be deposited directly onto the working electrode, for example onto the surface of the permeable working electrode. In certain embodiments, the interfering domain has a thickness, e.g., a dry thickness, in the range of about 0.1 μm to about 1,000 μm, e.g., about 1 μm to about 500 μm, about 10 μm to about 100 μm, or about 10 μm to about 100 μm. In certain embodiments, the interference domain may have a thickness of about 0.1 μm to about 10 μm, such as about 0.5 μm to about 10 μm, about 1 μm to about 5 μm, or about 0.1 μm to 5 μm. In certain embodiments, the sensor may be immersed more than once in the interference domain solution. For example, and without limitation, the sensor (or working electrode) of the present disclosure may be immersed in the interference domain solution at least two times, at least three times, at least four times, or at least five times to obtain a desired interference domain thickness.

III methods of use

The present disclosure further provides methods of using the analyte sensors and redox mediators disclosed herein. In certain embodiments, the present disclosure provides methods for detecting an analyte. For example, and without limitation, the present disclosure provides methods for detecting one or more analytes (including glutamic acid, glucose, ketone, lactic acid, oxygen, hemoglobin A1C, albumin, alcohol, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, hematin nitrogen, calcium, carbon dioxide, chloride, creatinine, hematocrit, aspartic acid, asparagine, magnesium, oxygen, pH, phosphorus, potassium, sodium, total protein, or uric acid).

In certain embodiments, the analyte is glucose, ketone, lactic acid, alcohol, and/or creatinine. In certain embodiments, the present disclosure provides methods for detecting, for example, glucose as a first analyte. In certain embodiments, the present disclosure provides methods for detecting one or more ketones. In certain embodiments, the present disclosure provides methods for detecting glucose and ketones.

In certain embodiments, the present disclosure provides methods for detecting an analyte in a subject in need thereof. In certain embodiments, the subject has a disease or disorder associated with an analyte disorder.

In certain embodiments, the subject is in need of monitoring glucose levels. For example, but not by way of limitation, a subject in need thereof is a subject at risk for or already suffering from diabetes. Alternatively, the glucose level of the subject may be monitored for health. The health data may generally comprise any type of data related to the health of a person, such as their weight, heart rate, blood pressure, blood glucose levels, etc. In certain embodiments, the glucose level of the subject may be monitored for weight management to obtain better sleep and/or to help the subject feel better and think more clearly.

In certain embodiments, the subject in need of monitoring ketone levels is a subject on a ketogenic diet. In certain embodiments, the present disclosure provides methods for detecting ketone levels in a subject in a ketosis state or detecting ketone levels in a subject to maintain a ketosis state. In certain embodiments, the analyte sensors of the present disclosure can be used to ensure that a subject adheres to a ketogenic diet. For example, and without limitation, the analyte sensors of the present disclosure may be used to measure the level of ketone in a sample to inform a subject to adjust or alter their diet to maintain ketosis. In certain embodiments, the present disclosure provides methods for detecting ketone levels in a subject at risk of developing ketoacidosis. In certain embodiments, the present disclosure provides methods for detecting ketone levels in a subject at risk of developing diabetic ketoacidosis. In certain embodiments, the sensors of the present disclosure may be used to monitor and/or prevent diabetic ketoacidosis. For example, and without limitation, the sensors of the present disclosure include a sensing chemistry for detecting ketone and glucose to monitor and/or prevent diabetic ketoacidosis in a subject (e.g., a subject with diabetes). Alternatively or additionally, the sensors of the present disclosure may be used in conjunction with glucose sensors (or glucose responsive active areas) to monitor and/or prevent diabetic ketoacidosis. In certain embodiments, the sensors of the present disclosure may be used with applications for monitoring ketone levels in a subject (e.g., for monitoring compliance with a ketogenic diet, for maintaining ketosis status, and/or for monitoring and/or preventing diabetic ketoacidosis). In certain embodiments, a ketogenic diet may be beneficial in promoting weight loss and helping epileptic individuals manage their condition.

In certain embodiments, the subject is in need of monitoring lactic acid levels. In certain embodiments, the subject in need of monitoring lactate levels is an athlete, such as a professional athlete. In certain embodiments, monitoring lactic acid levels during an exercise regimen may be used as a performance indicator. In certain embodiments, monitoring lactic acid levels may be used to diagnose, monitor, and/or evaluate various forms of sepsis and/or related infections. For example, and without limitation, determining the concentration of lactic acid according to the present disclosure may allow for more effective monitoring, assessment, and/or management of sepsis and/or infection. Alternatively, the analyte sensors of the present disclosure can be used to monitor subjects (e.g., patients in hospitals) who are at risk of sepsis and/or infection, but who are not currently exhibiting signs of any condition.

In certain embodiments, the methods of the present disclosure comprise: (i) Providing an analyte sensor, the analyte sensor comprising: a sensor tail including at least a first working electrode; a first active region disposed on a surface of the first working electrode and responsive to a first analyte, e.g., at a low potential, the first active region comprising a first polymer, a first redox mediator covalently bound to the first polymer, and at least one enzyme covalently bound to the first polymer and responsive to the first analyte, wherein the redox mediator comprises any of the structures of formulas I-LV, e.g., has a structure represented by formula XLI-LV; and a first analyte-permeable mass transport limiting membrane covering at least the first active region; (ii) Applying an electrical potential, such as a low electrical potential, to the first working electrode; (iii) Obtaining a first signal at or above the redox potential of the first active region, the first signal being proportional to the concentration of the first analyte in the fluid contacting the first active region; and (iv) correlating the first signal to the concentration of the first analyte in the fluid.

In certain embodiments, the methods of the present disclosure may comprise: (i) Exposing the analyte sensor to a fluid comprising a first analyte; wherein the analyte sensor comprises: a sensor tail including at least a first working electrode; a first active region disposed on a surface of the first working electrode and responsive to a first analyte, e.g., at a low potential, the first active region comprising a first polymer, a first redox mediator covalently bound to the first polymer, and at least one enzyme covalently bound to the first polymer and responsive to the first analyte; wherein the first redox mediator comprises any of the structures of formulas I-LV, e.g., has a structure represented by the formula XLI-LV; and a first analyte-permeable mass transport limiting membrane covering at least the first active region; (ii) Applying an electrical potential, such as a low electrical potential, to the first working electrode; (iii) Obtaining a first signal at or above the redox potential of the first active region, the first signal being proportional to the concentration of the first analyte in the fluid; and (iv) correlating the first signal to the concentration of the first analyte in the fluid.

In certain embodiments, the at least one enzyme that is responsive to the first analyte comprises an enzyme system comprising a plurality of enzymes that are commonly responsive to the first analyte. In certain embodiments, the first analyte comprises one or more ketones. In certain embodiments, the first analyte is glucose.

In certain embodiments, an analyte sensor for use in the disclosed methods may further comprise a second working electrode; and a second active region disposed on a surface of the second working electrode and responsive to a second analyte different from the first analyte, the second active region comprising a second polymer, a second redox mediator different from the first redox mediator covalently bound to the second polymer, and at least one enzyme covalently bound to the second polymer and responsive to the second analyte; wherein a second portion of the mass transfer limiting membrane covers the second active region. In certain embodiments, the at least one enzyme responsive to the second analyte comprises an enzyme system comprising a plurality of enzymes having a common response to the second analyte. In certain embodiments, the second analyte comprises glucose.

In certain embodiments, the mass transfer limiting membrane of the analyte sensor comprises a membrane polymer crosslinked with a branched crosslinking agent comprising three or more crosslinkable groups. In certain embodiments, the membrane polymer comprises polyvinylpyridine or polyvinylimidazole. In certain embodiments, the film polymer comprises a copolymer of vinylpyridine and styrene. In certain embodiments, the branched crosslinking agent comprises polyethylene glycol diglycidyl ether or polyethylene glycol tetraglycidyl ether.

Exemplary embodiment

A. In certain non-limiting embodiments, the presently disclosed subject matter provides an analyte sensor comprising:

(i) A sensor tail including at least a first working electrode;

(ii) A first active region disposed on a surface of the first working electrode and responsive to a first analyte, wherein the first active region comprises a redox mediator and at least one enzyme responsive to the first analyte;

wherein the first redox mediator comprises at least one tridentate ligand selected from the group consisting of formulas I-XXI,

wherein R is ₁ And R is ₃ Independently selected from H, alkoxy, alkyl, alkylamide, alkylamino, or a linking group,

wherein R is ₂ Selected from H, an electron donating group, or a linking group capable of bonding a redox mediator to the first polymer; and

(iii) A first analyte-permeable mass transfer limiting membrane covering at least the first active region.

The analyte sensor of a.a., wherein the first active region further comprises a first polymer.

Analyte sensor of a2.a1, wherein a redox mediator is covalently bound to a first polymer, e.g. via R ₂ Is a linking group of (a).

An analyte sensor of a3.A1 or A2, wherein at least one enzyme responsive to a first analyte is covalently bound to a first polymer.

The analyte sensor of any one of a4 a1-A3, wherein the linking group is capable of binding a redox mediator to the first polymer.

The analyte sensor of any one of A-A4, wherein R ₁ And/or R ₃ Is an alkyl group.

A6.A5 analyte sensor wherein the alkyl group is selected from the group consisting of methyl, ethyl, C ₁ -C ₁₂ Straight chain alkyl groups and branched chain alkyl groups.

The analyte sensor of any one of A-A4, wherein R ₁ And/or R ₃ Is a polyether group.

The analyte sensor of any one of A-A4, wherein R ₁ And/or R ₃ Is an alkoxy group such as methoxy or ethoxy.

The analyte sensor of any one of A-A8, wherein the first redox mediator comprises two tridentate ligands selected from the group consisting of formulas I-XXI.

The analyte sensor of any one of A-A9, wherein the first redox mediator comprises two tridentate ligands selected from the group consisting of formulas I-XXI in a complex with a metal (e.g., a coordination complex).

An analyte sensor of a11.a10, wherein the metal is osmium.

The analyte sensor of any one of A-A11, wherein the tridentate ligand is selected from the group consisting of formulas XXII-XL.

The analyte sensor of any one of A-A12, wherein the first active region comprises about 10% to about 80% by weight of a first redox mediator.

The analyte sensor of any one of A-A13, wherein the first active region comprises an enzyme system comprising a plurality of enzymes having a common response to a first analyte (e.g., glucose oxidase).

The analyte sensor of any one of A-A14, wherein the first analyte comprises glucose.

The analyte sensor of any one of A-A15, wherein the first active region further comprises a stabilizing agent.

The analyte sensor of any one of A-A16, wherein the first active region further comprises a cross-linking agent.

The analyte sensor of any one of A-A17, wherein the first active region further comprises a cofactor.

The analyte sensor of any one of A-A18, wherein the mass transfer limiting membrane comprises a polyvinylpyridine-based polymer, polyvinylimidazole, polyacrylate, polyurethane, polyether urethane, silicone, or a combination thereof.

An analyte sensor of a20.a19, wherein the mass transfer limiting membrane comprises polyvinylpyridine or polyvinylimidazole.

An analyte sensor of a21.a19, wherein the mass transfer limiting membrane comprises a polyvinylpyridine-based polymer.

An analyte sensor of a22.a19, wherein the membrane polymer comprises a copolymer of vinylpyridine and styrene.

The analyte sensor of any one of A-A22, further comprising:

(iv) A second working electrode; and

(v) A second active region disposed on a surface of the second working electrode and responsive to a second analyte different from the first analyte, wherein the second active region comprises at least one enzyme responsive to the second analyte.

An analyte sensor of a24.a23, wherein a second portion of the mass transfer limiting membrane covers the second active region.

The analyte sensor of a25.a23, further comprising a second mass transfer limiting membrane covering the second active region, or further comprising a second mass transfer limiting membrane covering the second active region and the first active region.

The analyte sensor of any one of a23-a25, wherein the second active region further comprises a second redox mediator.

The analyte sensor of any one of a23-a26, wherein the second analyte is a ketone.

The analyte sensor of any one of A-A27, wherein the analyte sensor is configured to detect a first analyte and/or a second analyte in interstitial fluid from a subject.

The analyte sensor of any one of A-A28, wherein the analyte sensor is implanted in a subject having diabetes.

The analyte sensor of any one of A-A29, wherein the analyte sensor is implanted in a subject experiencing ketoacidosis or at risk of experiencing ketoacidosis.

The analyte sensor of any one of A-A28, wherein the analyte sensor is implanted in a subject undergoing a ketogenic diet.

The analyte sensor of any one of A-A31, wherein the analyte sensor is implanted in a subject in a ketosis state or in need of maintenance of a ketosis state.

The analyte sensor of any one of A-A28, wherein the analyte sensor is implanted in a subject in need of lactate monitoring.

B. In certain non-limiting embodiments, the presently disclosed subject matter provides an analyte sensor comprising:

(i) A sensor tail including at least a first working electrode;

(ii) A first active region disposed on a surface of the first working electrode and responsive to a first analyte, wherein the first active region comprises a first redox mediator and at least one enzyme responsive to the first analyte; and

(iii) A first analyte-permeable mass transport limiting membrane covering at least the first active region, wherein the first redox mediator has a structure selected from the group consisting of formulas I-XXI.

C. In certain non-limiting embodiments, the presently disclosed subject matter provides an analyte sensor comprising:

(i) A sensor tail including at least a first working electrode;

(ii) A first active region disposed on a surface of the first working electrode and having a response to a first analyte, wherein the first active region comprises a first redox mediator and at least one enzyme having a response to the first analyte;

wherein the first redox mediator has the structure:

wherein M is iron, ruthenium, osmium, cobalt, or vanadium;

wherein n is I, II, II, IV or V;

wherein R is ₁ 、R ₃ 、R’ ₁ And R'. ₃ Independently selected from H, alkylamide, alkylamino, alkoxy or alkyl;

wherein R is ₂ And R'. ₂ Independently selected from H, electron donating groups or linking groups; and

The analyte sensor of C1.B and C, wherein the first active region further comprises a first polymer.

The analyte sensor of c2.c1, wherein the first redox mediator is covalently bound to the first polymer.

An analyte sensor of C3.c1 or C2, wherein at least one enzyme responsive to a first analyte is covalently bound to a first polymer.

The analyte sensor of any one of C4, C1-C3, wherein the linking group is capable of binding the first redox mediator to the first polymer.

The analyte sensor of any one of C5-C4, wherein the first analyte is glucose.

The analyte sensor of any one of C-C4, wherein the first analyte is a ketone.

D. In certain non-limiting embodiments, the presently disclosed subject matter provides an analyte sensor comprising:

(i) A sensor tail including at least a first working electrode;

(ii) A first active region disposed on a surface of the first working electrode and having a response to a first analyte, wherein the first active region comprises a first polymer, a first redox mediator covalently bound to the first polymer, and at least one enzyme having a response to the first analyte covalently bound to the first polymer;

wherein the first redox mediator has the structure:

wherein M is iron, ruthenium, osmium, cobalt or vanadium;

wherein n is I, II, II, IV or V;

wherein R is ₂ And R'. ₂ Independently selected from H, electron donating groups or linking groups;

wherein the linking group covalently bonds the first redox mediator to the first polymer; and

The analyte sensor of any one of b-D, wherein the first active region comprises about 10% to about 80% by weight of the first redox mediator.

The analyte sensor of any one of claims b-D1, wherein at least one enzyme comprises an enzyme system comprising a plurality of enzymes having a common response to the first analyte.

The analyte sensor of any one of claims D3, b-D2, wherein the first analyte is glucose.

The analyte sensor of any one of claims D4, b-D3, wherein the first active region further comprises a stabilizing agent.

The analyte sensor of any one of claims b-D4, wherein the first active region further comprises a cross-linking agent.

The analyte sensor of any one of claims b-D5, wherein the first active region further comprises a cofactor.

The analyte sensor of any one of b-D6, wherein the mass transfer limiting membrane comprises a polyvinylpyridine-based polymer, polyvinylimidazole, polyacrylate, polyurethane, polyether urethane, silicone, or a combination thereof.

D8.d7 analyte sensor wherein the mass transfer limiting membrane comprises polyvinylpyridine or polyvinylimidazole.

D9.d7 analyte sensor wherein the mass transport limiting membrane comprises a polyvinylpyridine-based polymer.

D10.d7 analyte sensor wherein the membrane polymer comprises a copolymer of vinylpyridine and styrene.

The analyte sensor of any one of b-D10, further comprising:

(iv) A second working electrode; and

An analyte sensor of d12.d11, wherein the second portion of the mass transfer limiting membrane covers the second active region.

The analyte sensor of d13.d11 further comprising a second mass transfer limiting membrane covering the second active area, or further comprising a second mass transfer limiting membrane covering the second active area and the first active area.

The analyte sensor of any one of D14, D11-D13, wherein the second active region further comprises a second redox mediator.

The analyte sensor of any one of D11-D14, wherein the second analyte is a ketone.

The analyte sensor of any one of c-D15, wherein M is Os.

The analyte sensor of any one of c-D16, wherein the first redox mediator has the structure:

the analyte sensor of any one of c-D17, wherein the first redox mediator has the structure:

wherein n is II or III.

The analyte sensor of any one of c-D18, wherein the linking group comprises an amide bond.

The analyte sensor of any one of D-D19, further comprising:

(iv) A second working electrode; and

(v) A second active region disposed on a surface of the second working electrode and responsive to a second analyte different from the first analyte, wherein the second active region comprises a second polymer, a second redox mediator different from the first redox mediator covalently bound to the second polymer, and at least one enzyme responsive to the second analyte covalently bound to the second polymer;

wherein a second portion of the mass transfer limiting membrane covers the second active region.

An analyte sensor of d21.d20, wherein the at least one enzyme responsive to the second analyte comprises an enzyme system comprising a plurality of enzymes having a common response to the second analyte.

An analyte sensor of D22, D20 or D21, wherein the second analyte comprises one or more ketones.

The analyte sensor of any one of D-D22, wherein the first active region has a response to the first analyte at a potential that is above the redox potential of the first redox mediator and about-80 mV lower relative to the Ag/AgCl reference.

The analyte sensor of any one of D-D23, wherein the analyte sensor is configured to detect a first analyte and/or a second analyte in interstitial fluid from a subject.

The analyte sensor of any one of D-D24, wherein the analyte sensor is implanted in a subject with diabetes.

The analyte sensor of any one of D-D25, wherein the analyte sensor is implanted in a subject experiencing ketoacidosis or at risk of experiencing ketoacidosis.

The analyte sensor of any one of D-D24, wherein the analyte sensor is implanted in a subject on a ketogenic diet.

The analyte sensor of any one of D-D27, wherein the analyte sensor is implanted in a subject in a ketosis state or in need of maintenance of a ketosis state.

The analyte sensor of any one of D-D24, wherein the analyte sensor is implanted in a subject in need of lactate monitoring.

E. In certain non-limiting embodiments, the presently disclosed subject matter provides methods of detecting a first analyte using the analyte sensor of any one of a-D23.

The method of e1.E, wherein the first analyte is glucose.

The method of e2.E, wherein the first analyte is a ketone.

The method of e3.E, wherein the first analyte is lactic acid.

The method of e4.E, wherein the first analyte is an alcohol.

F. In certain non-limiting embodiments, the presently disclosed subject matter provides a method for detecting a first analyte, wherein the method comprises:

(i) Providing an analyte sensor, the analyte sensor comprising:

(a) A sensor tail including at least a first working electrode;

(b) A first active region disposed on a surface of the first working electrode and responsive to the first analyte, wherein the first active region comprises a first polymer, a first redox mediator covalently bound to the first polymer, and at least one enzyme responsive to the first analyte covalently bound to the first polymer;

wherein the first redox mediator has the structure:

wherein M is iron, ruthenium, osmium, cobalt, or vanadium;

wherein n is I, II, III, IV or V;

(c) A first analyte-permeable mass transport limiting membrane covering at least the first active region;

(ii) Applying an electrical potential to the first working electrode;

(iii) Obtaining a first signal at or above the redox potential of the first active region, the first signal being proportional to the concentration of the first analyte in the fluid contacting the first active region; and

(iv) The first signal is correlated to a concentration of a first analyte in the fluid.

A method of f1, wherein the first active region comprises from about 10% to about 80% by weight of the first redox mediator.

A method of F or F1, wherein at least one enzyme comprises an enzyme system comprising a plurality of enzymes having a common response to a first analyte.

The method of any one of F-F2, wherein the first analyte comprises glucose.

The method of any one of F-F3, wherein the first active region further comprises a stabilizer.

The method of any one of F-F4, wherein the first active region further comprises a cross-linking agent.

The method of any one of F-F5, wherein the first active region further comprises a cofactor.

The method of any one of F-F6, wherein the mass transfer limiting film comprises a polyvinylpyridine-based polymer, polyvinylimidazole, polyacrylate, polyurethane, polyether urethane, silicone, or a combination thereof.

The method of f8, f7, wherein the mass transfer limiting membrane comprises polyvinylpyridine or polyvinylimidazole.

The method of f9, f7, wherein the mass transfer limiting membrane comprises a polyvinyl pyridine based polymer.

The method of f10, f7, wherein the membrane polymer comprises a copolymer of vinylpyridine and styrene.

The method of any one of F-F10, further comprising:

(iv) A second working electrode; and

F12.f11, wherein the second portion of the mass transfer limiting membrane covers the second active region.

The method of f13, f11, further comprising a second mass transfer limiting film covering the second active region, or further comprising a second mass transfer limiting film covering the second active region and the first active region.

The method of any one of F11-F13, wherein the second active region further comprises a second redox mediator.

The method of any one of F11-F14, wherein the second analyte is a ketone.

The method of any one of F-F15, wherein the potential is higher than the redox potential of the first redox mediator and is about-80 mV lower relative to the Ag/AgCl reference.

The method of any one of F11-F16, wherein the second active region comprises a second polymer, a second redox mediator different from the first redox mediator covalently bound to the second polymer, and at least one enzyme responsive to the second analyte covalently bound to the second polymer.

The method of any one of F-F17, wherein the first redox mediator has the structure:

the method of any one of F-F19, wherein the first redox mediator has the structure:

wherein n is II or III.

Examples

The subject matter of the present disclosure will be better understood by reference to the following examples, which are provided as examples of the subject matter of the present disclosure, and not as limitations.

Example 1: synthesis of tridentate ligands. 2, 6-bis (N-methylimidazol-2-yl) -pyridine and 2, 6-bis (N-methylimidazol-2-yl) -4- (dimethylamino) -pyridine

This example provides an exemplary method for preparing a tridentate ligand of formula XXIII (compound (3 a)). The ligand may be prepared by the following three (3) steps:

scheme Ia

NaOMe/MeOH was added to a MeOH solution of 2, 6-pyridine-dinitrile (1 a) under nitrogen, and the mixture was stirred at room temperature for 4 hours. Subsequently, 2-dimethoxyethylamine and HOAc were added to the reaction mixture. Then, the reaction mixture was heated to 55 ℃ in an oil bath for 1 hour and cooled to room temperature. Then, meOH and 6N HCl (aq) were added sequentially to the reaction mixture. The reaction flask was fitted with a reflux condenser and the reaction mixture was refluxed overnight at 80 ℃. The reaction mixture was then cooled to room temperature and the solvent was removed by rotary evaporation. By EtOAc/H ₂ O working up (workup) separates intermediate (2 a).

The isolated intermediate (2 a) was dissolved in DMF under an argon atmosphere. The reaction mixture was then cooled in an ice bath and NaH was slowly added to the reaction mixture in three portions. After the addition of NaH, the reaction mixture was stirred in an ice bath for about 1 hour. Methyl p-toluenesulfonate (MPTS) was dissolved in DMF and added dropwise to the reaction mixture. The reaction mixture was stirred for 15 minutes and then quenched with NaH. By organic CH ₃ Cl/H ₂ O working up separates the product (3 a).

This example also provides an exemplary method for preparing a tridentate ligand of formula XXV (compound (4 b)). As shown in scheme Ib, starting from 4-chloropyridine-2, 6-carbonitrile (compound (1)), the ligand is synthesized in four (4) steps:

scheme Ib

NaOMe/MeOH was added to a solution of 4-chloropyridine-2, 6-dinitrile in MeOH under nitrogen and the mixture was stirred at room temperature for 4 hours. Subsequently, 2-dimethoxyethylamine and HOAc were added to the reaction mixture. The reaction mixture was then heated to 55 ℃ in an oil bath and maintainedFor 1 hour and cooled to room temperature. Then, meOH and 6N HCl (aq) were added sequentially to the reaction mixture. The reaction flask was fitted with a reflux condenser and the reaction mixture was refluxed overnight at 80 ℃. The reaction mixture was then cooled to room temperature and the solvent was removed by rotary evaporation. By EtOAc/H ₂ O working up separates intermediate (2 b).

Then, intermediate (2 b) was dissolved in DMF and dimethylamine hydrochloride and DMF/K ₂ CO ₃ Added to the reaction mixture. The reaction mixture was placed in a pressure reaction at 110-120 ℃ for 5 days. After this time and after working up, intermediate (3 b) is isolated.

Methylation of intermediate (3 b) was performed similarly as described above. Specifically, naH (2.2 eq) in mineral oil was slowly added to a solution of compound (3 b) in DMF under argon, followed by methyl p-toluenesulfonate (MPTS, 2.2 eq). The reaction mixture was stirred in an ice bath for three days. The reaction mixture is then worked up to give the ligand (4 b).

Example 2: synthesis of tridentate 2, 6-bis (N-methylimidazol-2-yl) -pyridine ligands with ethylenediamine linking groups

This example provides an exemplary method for preparing a tridentate ligand of formula XXIV (compound (7)) starting from compound (5), as shown in scheme II:

scheme II

This example further provides an exemplary method for preparing a tridentate ligand of formula XXVIII (compound (11)) starting from compound (8), as shown in scheme III:

scheme III

To 4-chloro-2, 6-bis (1-methyl-1H-imidazol-2-yl) pyridine (8) was added a pure solution of 2- (methylamino) ethan-1-ol and the reaction mixture was heated in a pressure flask at 125℃for 48-72 hours. The resulting product (9) was methanesulfonylated using methanesulfonyl chloride and triethylamine. The methanesulfonylated intermediate (10) was then treated with methanol ammonia at a temperature of 65-70 ℃ in a pressure flask to obtain ligand (11) (2- ((2, 6-bis (1-methyl-1H-imidazol-2-yl) pyridin-4-yl) (methyl) amino) ethyl methanesulfonate) which was purified by column chromatography.

Example 3: synthesis of polymeric tridentate redox mediators

This example provides an exemplary method of generating an exemplary redox mediator of formula XLV (compound (7)) from tridentate ligands of formulas XXV and XXIV. As shown in scheme IV, ammonium hexachloroosmium ((NH) ₄ ) ₂ OsCl ₆ ) And compounds (4) and (6) (which are represented by the above compounds (4 a) and (7), respectively), to synthesize the compounds:

scheme IV

The compounds (4) and (6) are added to (NH) in sequence ₄ ) ₂ OsCl ₆ To achieve selectivity for the redox mediator of formula XLV. Preparative HPLC was performed to separate the redox mediator of formula XLV from a complex comprising two identical ligands.

NH of redox mediator (Compound (7)) through the linking group ₂ The groups are further covalently bonded to the polymer. Specifically, as shown in scheme V, the redox mediator (7) passes NH of the linking group ₂ The reaction of the groups with the COOH groups of poly (4-vinyl) pyridine (PVP-COOH) derivatized with bromohexanoic acid bonds to polyvinylpyridine (PVP), which forms an amide bond.

Scheme V

Example 4: analysis of redox mediators

This example provides cyclic voltammetry of an exemplary redox mediator. 23A, 24A, 25A, 26A, 27A, 28A, 29A and 31A provide chemical structures of exemplary redox mediators analyzed. 23B, 24B, 25B, 26B, 27B, 28B, 29B and 31B provide cyclic voltammograms of the redox mediators analyzed. Generally, cyclic voltammetry is performed as follows: unit (component): CH Instruments; working electrode: glass carbon; a counter electrode graphite; a reference electrode: ag/AgCl; scanning rate: 0.1V/s; the samples were dissolved in PBS buffer. FIG. 25B is run at a scan rate of 0.2V/s. Fig. 26B and 29B are crude mixtures which in each case contain the compound (heterocomplex), but also contain both homocomplexes. FIG. 31B shows a cyclic voltammogram of a complete sensor made with the complex of FIG. 31A.

Example 5: at low O ₂ Detection of glucose under conditions

The present embodiments provide assays configured for sensors that detect glucose and include the redox mediators of the present disclosure.

FIG. 32A shows a current versus time plot for a glucose sensor incorporating the redox mediator shown in FIG. 25A under low oxygen conditions. FIG. 32B shows a current-glucose plot for a glucose sensor incorporating the redox mediator shown in FIG. 25A under low oxygen conditions. The redox mediator of FIG. 25A is in free form and is not covalently bonded to the polymer.

FIG. 33A shows a current versus time plot for a glucose sensor incorporating the redox mediator shown in FIG. 31A under low oxygen conditions. FIG. 33B shows a current-glucose plot for a glucose sensor incorporating the redox mediator shown in FIG. 31A under low oxygen conditions. As shown in fig. 31A, the redox mediator is covalently bound to the polymer PVP.

In FIGS. 32A-B and 33A-B, sensors were constructed using a sensing layer containing 25A or 31A, respectively, of a redox mediator as the redox mediator component, the film layer was coated, and the test was performed in a PBS solution in a temperature-controlled beaker under low oxygen conditions. The stepwise increase in current in fig. 32A and 33A corresponds to the addition of glucose at controlled doses. The linearity of the glucose response can be evaluated in fig. 32B and 33B. The nonlinearity observed in fig. 32B may be due to unbound mediator, and no nonlinearity is observed in fig. 33B when the mediator is attached to the polymer.

Although the subject matter of the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosed subject matter. Furthermore, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, methods and processes described in the specification.

As one of ordinary skill in the art will readily appreciate from the presently disclosed subject matter, processes, machines, manufacture, compositions of matter, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the presently disclosed subject matter. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Various patents, patent applications, publications, product descriptions, and protocols are cited throughout this disclosure, and their applications are incorporated herein by reference in their entirety for all purposes.

Claims

1. An analyte sensor, comprising:

(i) A sensor tail including at least a first working electrode;

(ii) A first active region disposed on a surface of the first working electrode and responsive to a first analyte, wherein the first active region comprises a first polymer, a first redox mediator covalently bound to the first polymer, and at least one enzyme responsive to the first analyte covalently bound to the first polymer;

wherein the first redox mediator has the structure:

wherein M is iron, ruthenium, osmium, cobalt, or vanadium;

wherein n is I, II, II, IV or V;

(iii) The first analyte-permeable mass transfer limiting membrane covers at least the first active region.

2. The analyte sensor of claim 1, wherein the at least one enzyme comprises an enzyme system comprising a plurality of enzymes having a common response to the first analyte.

3. The analyte sensor of claim 2, wherein the first analyte comprises glucose.

4. The analyte sensor of any of claims 1-3, wherein the mass transfer limiting membrane comprises a membrane polymer crosslinked with a branched crosslinking agent comprising three or more crosslinkable groups.

5. The analyte sensor of claim 4, wherein the mass transfer limiting membrane comprises a polyvinylpyridine-based polymer, polyvinylimidazole, polyacrylate, polyurethane, polyether urethane, silicone, or a combination thereof.

6. The analyte sensor of any one of claims 1-5, wherein the first active region further comprises (i) a cofactor, (ii) a stabilizer, or (iii) a cofactor and a stabilizer.

7. The analyte sensor of claim 4, wherein the branched cross-linking agent comprises polyethylene glycol diglycidyl ether or polyethylene glycol tetraglycidyl ether.

8. The analyte sensor of any one of claims 1-7, wherein M is osmium.

9. The analyte sensor of any one of claims 1-8, wherein the first redox mediator has the structure:

10. The analyte sensor of any one of claims 1-9, wherein the first redox mediator has the structure:

wherein n is II or III.

11. The analyte sensor of any one of claims 1-10, wherein the linking group comprises an amide bond.

12. The analyte sensor of any one of claims 1-11, further comprising:

(iv) A second working electrode; and

13. The analyte sensor of claim 12 wherein the at least one enzyme responsive to the second analyte comprises an enzyme system comprising a plurality of enzymes having a common response to the second analyte.

14. The analyte sensor of claim 12 or 13, wherein the second analyte comprises one or more ketones.

15. The analyte sensor of any of claims 1-14, wherein the first active region is responsive to the first analyte at a potential that is about-80 mV higher than a redox potential of the first redox mediator and lower than an Ag/AgCl reference.

16. A method, comprising:

(i) Providing an analyte sensor, the analyte sensor comprising:

(a) A sensor tail including at least a first working electrode;

(b) A first active region disposed on a surface of the first working electrode and responsive to a first analyte, wherein the first active region comprises a first polymer, a first redox mediator covalently bound to the first polymer, and at least one enzyme responsive to the first analyte covalently bound to the first polymer;

wherein the first redox mediator has the structure:

wherein M is iron, ruthenium, osmium, cobalt, or vanadium;

wherein n is I, II, III, IV or V;

(c) A mass transfer limiting membrane permeable to the first analyte, the mass transfer limiting membrane covering at least the first active region;

(ii) Applying an electrical potential to the first working electrode;

(iii) Obtaining a first signal at or above the redox potential of the first active region, the first signal being proportional to the concentration of a first analyte in a fluid contacting the first active region; and

(iv) Correlating the first signal to a concentration of the first analyte in the fluid.

17. The method of claim 16, wherein the at least one enzyme comprises an enzyme system comprising a plurality of enzymes having a common response to the first analyte.

18. The method of claim 16 or 17, wherein the first analyte comprises glucose.

19. The method of any one of claims 16-18, wherein the mass transfer limiting film comprises a film polymer crosslinked with a branched crosslinking agent comprising three or more crosslinkable groups.

20. The method of claim 19, wherein the mass transfer limiting film comprises a polyvinyl pyridine-based polymer, polyvinyl imidazole, polyacrylate, polyurethane, polyether urethane, silicone, or a combination thereof.

21. The method of any one of claims 16-20, wherein the first active region further comprises (i) a cofactor, (ii) a stabilizer, or (iii) a cofactor and a stabilizer.

22. The method of claim 19, wherein the branched crosslinking agent comprises polyethylene glycol diglycidyl ether or polyethylene glycol tetraglycidyl ether.

23. The method of any one of claims 16-22, wherein the potential is higher than the redox potential of the first redox mediator and is about-80 mV lower relative to an Ag/AgCl reference.

24. The method of any one of claims 16-23, wherein the analyte sensor further comprises:

(d) A second working electrode; and

(e) A second active region disposed on a surface of the second working electrode and responsive to a second analyte different from the first analyte, wherein the second active region comprises a second polymer, a second redox mediator different from the first redox mediator covalently bound to the second polymer, and at least one enzyme responsive to the second analyte covalently bound to the second polymer;

25. The method of claim 24, wherein the at least one enzyme responsive to the second analyte comprises an enzyme system comprising a plurality of enzymes having a common response to the second analyte.

26. The method of claim 24 or 25, wherein the second analyte comprises one or more ketones.

27. The method of any one of claims 16-26, wherein the first redox mediator has the structure:

28. the method of any one of claims 16-27, wherein the first redox mediator has the structure:

wherein n is II or III.