Demonstrating Kirigami Haptic Swatches for Cut-and-Fold Haptic Feedback Mechanisms

Origami is the art of making 2D/3D shapes by folding paper, and kirigami is an extended method of origami by allowing cuts in addition to folds. In HCI, origami has recently been applied to 4D printing [1], where a 2D sheet is transformed into 3D structure driven by stimuli (e.g., heat). Although 4D printing utilizes the benefits of rapid fabrication and smaller volume enabled by 2D shape, we further leveraged the force-displacement curve of origami in shape transition.

HCI community has long been exploring paper electronics including both hand-made [9] and printed methods [4]. Thanks to the compatibility of materials, Kirigami Haptic Swatches can be easily combined with paper electronics, since both of them are implemented on paper substrate.

In Pushables [5], Klamka et al. proposed a DIY approach to prototype membrane buttons with clicking effects, by embossing the plastic into a dome shape. Despite its simplicity, however, tunability of the haptic properties was not discussed, which makes it hard to customize buttons depending on users’ needs. Groeger et al. [2] have recently proposed the method to prototype 3D objects with haptic feedback, but it is based on electro-tactile sensation and cannot render kinesthetic motion of physical buttons.

In order to allow users to explore different haptic properties, we used four primitive structures of RES, SFWB, SFWB+RES, and cylindrical origami. Each primitive corresponds with linear, bistable, snap-through, and angular motion of the button, respectively. The schematic structure, photos in motion, and the typical force-displacement curve of each structure are shown in Figure 1. Users first decide which primitive structure to adopt depending on their needs.

After choosing the primitive, users then go to the step of the simulation. We implemented a graphical simulation tool with Glasshopper on Rhinoceros 3D, as shown in Figure 2. When users input the parameters specific to each primitive, the software automatically calculates and generates the 3D structure and the force needed to push the structure. Using these graphical and numerical results, users can iterate the design process in a trial-and-error way. Once users are satisfied with the results, the software outputs the 2D cut and crease pattern (in .dxf format) that can fold into the designated 3D structure.

Next, users cut the sheet material according to the given 2D pattern. As a sheet materials, we used white PET film (Takeo 4783347, thickness: 230 μm) for RES and SFWB and Tant paper (Takeo 473439, thickness: 180 μm) for cylindrical origami. To cut the materials, we used the laser cutter (Universal Laser Systems PLS6.150D), the cutting plotter (MIMAKI CFL-605RT), or just scissors. After cut, users fold the pattern by hand and complete the assembly process.

Here we exemplify the applications of Kirigami Haptic Swatches in Figure 3. Figure 3 a shows a custom keyboard with RES buttons combined with inkjet-printed touch sensors [4]. Thanks to the easy fabrication of both paper circuit and kirigami keyboards, users can change the keys’ mechanical property and distribution on demand. Figure 3 b demonstrates that the proximity sensor under the cylindrical origami can detect and visualize the angular motion of the object. Figure 3 c is a multi-sensory toy. This toy aims to stimulate children's sense by different mechanical feelings and different sounds of buttons in motion. Figure 3 d is a task checklist with bistable clicking haptics. In this application, the designer assigned a stronger pushing force to a more important task. Finally, Figure 3 e shows a therapeutic phone accessory. This is the tool to help those who are addicted to smartphones stay away from the screen. Users can select their preferred touch sensation among the primitives and simply attach the button to the backside of the smartphone.