Ion gradient induced self-powered flexible pressure sensor

Various self-powered flexible pressure sensors (including piezoelectric, triboelectric and electrochemical types) have attracted great attentions and made significant progresses, but they also have some shortcomings, such as the inability to detect static pressure (piezoelectric and triboelectric types) and performance degradation (electrochemical type). Inspired by the ion gradient power generation mechanism, we propose a self-powered flexible pressure sensor based on pressure regulated ion gradient coupled with piezoresistive effect. The proposed pressure sensor is mainly composed of high humidity region (LiCl-filter paper (FP)) and low humidity region (carbon nanotubes-FP). The results show that the sensor can directly output current signal with a wide pressure range (0.1–100 kPa). Based on the output voltage and current signals and the morphology characterization, the power generation and pressure sensing mechanisms of the sensor are clarified using the ion gradient and piezoresistive effects. In addition, the sensor can be used to identify different respiratory states in combination with machine learning. This work provides a new strategy for constructing self-powered pressure sensor based on pressure regulated ion gradient strategy coupled with piezoresistive effect.