3D printed electret as self-powered wearable sensor and futuristic implementation for on-spot bone injury

Abstract

The importance of wearable pressure sensors extends to the progress of modern society and personal healthcare. The utility of currently available self-powered sensors is restricted in complex areas due to their limited geometrical configurations. In this study, an electret composed of polylactic acid (PLA) has been developed by 3D printing technology, where the pressure sensors with the desired complicated structure are possible to design. We demonstrate that the 3D-printed electret-based pressure sensor (3D-EPS) exhibits outstanding sensitivity (∼178 mV/kPa) with ultrafast response time (6 ms). It enables the capture of the biomechanical signals from different parts of bone-joint motions, which could be utterly suitable for monitoring injury recovery. We show that if the electret structure is printed as a shoe sole shape, then it generates 65 V of open circuit voltage and 12 μA of short circuit current during the human running action, indicating to use as an effective wearable energy harvester. It is also capable of detecting different motion and foot pressure distributions, which makes it a potential candidate as a wearable biomedical sensor. To demonstrate its futuristic potential applications in patient-specific bone damage recovery monitoring, the feasibilities of electrets with commonly desired structures have been shown to print.