Self-Powered Piezoelectric Wearable Sensor With Motion Recognition Capability

This article presents a self-powered piezoelectric wearable sensor (PWS) with motion recognition capability to harvest stepping energy during human movement by placing it in the sole. In this device, two modules are designed to achieve different functions. The piezoelectric sensing module consists of rectangular piezoelectric sheets combined with the connector. Monitoring of motion is achieved by the longitudinal displacement stretching of four rectangular piezoelectric sheets. The power generation module is composed of circular piezoelectric sheets and contact elements, and the circular piezoelectric sheets are directly excited by the designed contact blocks to maximize the voltage output of the device. After the experimental test, it was found that when the prototype is at the installation angle of 45° and the contact block is the surface contact, the output performance and sensing performance of the prototype are the best. The maximum output power of the prototype is 264.1 mW, and it has high sensitivity as a sensor. With the help of the MATLAB neural network module combined with the output signal of the piezoelectric module, the function of motion recognition is realized, and the accuracy is 87.5%, providing innovative ideas for the development of wearable devices in the field of motion recognition.