A self-powered piezoelectret sensor based on foamed plastic garbage for monitoring human motions

Constructing piezoelectret based on foamed plastic garbage is an advisable strategy for obtaining self-powered flexible electromechanical sensors with good performances. Herein, a self-powered piezoelectret sensor with basic material of low density polyethylene (LDPE) foamed plastic garbage is proposed, with characteristics of easy fabrication, excellent flexibility, and high equivalent piezoelectric coefficient d33 value up to ∼ 1,100 pC/N. The output stability is verified by continuously stimulating a sensor for ∼ 180,000 cycles under low and high applied pressure, and the variations of peak outputs are less than 5.5%. Applications for measuring low- and high-pressure signals from human body are achieved. Assembled with a wristband, a sensor is demonstrated for detecting the human pulse waves. Moreover, real time human sitting information is wirelessly monitored with a smart chair based on 4 pixels sensors array.