Plantar pressure-measuring device powered by flexible all-solid-state battery

Abstract

Flexible or stretchable devices have been attracting attention because of the increase in popularity of internet-of-things devices and wearables. Because lithium-ion secondary batteries have rigid bulk shapes and therefore affect bodily motion, their use in such devices is problematic. Demand for plantar pressure-measuring devices has increased because impairment of ambulation leads not only to accidental falls by elderly people but also to arthritic disorders such as backaches induced by hallux valgus, calluses, and ingrown nails. Because the design of such a small, lightweight device with a medium-capacity lithium-ion battery is impossible, the collection of sufficient data has been impossible. We designed a novel all-solid-state battery produced with a solid-state electrolyte. The battery discharged even when folded, cut, or pushed. This 440 mAh battery could be used to improve overall usability of a prototype of an insole device that would consist of pressure sensors, a wireless communication device, and the battery.