<p>Foldable and wearable electronics are electronics which are often made on stretchable and highly deformable substrates and therefore can exhibit shapes and undergo deformations not seen with conventional electronics. These types of electronics have been developed intensively over the past decade because of their ability to improve our daily lives and their pertinent use for situations which require an optimization of storage space. The applications for foldable and wearable electronics are nearly limitless, but wearable energy harvesting, foldable solar cells, displays with sub-millimeter bending radii, inertial and pressure sensors, and chemical/biosensors name just a few of the current novelties. One sought-after characteristic of foldable electronics is a large packing ratio of the device. Much of the current work on foldable and wearable electronics focuses on the stretchable nature of the materials used, improvement in embedding conductive materials into soft substrates, and the development of a wide variety of sensors, with less of an emphasis on the exploration of folding mechanisms for foldable and wearable electronics (aside from demonstrations with origami and kirigami, which are often used to show intricate conductive structures).</p><p>Recently, our group demonstrated a novel folding method: ring origami. Rings of different shapes with tuned characteristics under buckling exhibited self-guided snap-folding and bistability, meaning that the rings could deform to stable states after the ring’s snapping point had been reached, regardless of the load applied during buckling. In this work, we utilize the concept of snap-folding ring origami and integrate it with electronic components to achieve bistable foldable and wearable electronics that can transform from tablet to wearable wrist device with huge packing. This is achieved with the fabrication of curved-rectangular metal rings onto which we attached a fabric with flexible circuitry. The conductive material used as the basis of our flexible circuit is liquid metal, which serves as the wires and connections between electrical components of the circuit. The fabric, liquid metal wires, and all components are coated by a thin layer of silicone elastomer which allows for reliable flexibility of the circuit. The circuit integrates an LED matrix display to allow for conveyance of information and interaction with the user through touch sensor switches, a heart rate module to track health information, and a speaker for enhanced user interaction. The snap-folding characteristic of our device allows for bistability via self-guided folding with high packing ratio and less strain on the film as compared to existing foldable devices and displays.</p>

Ring Origami for Foldable and Wearable Electronics

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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