A linear and large-range pressure sensor based on hierarchical structural SnO2@carbon nanotubes/polyurethane sponge

Abstract

Flexible pressure sensors arouse an extensive interest in health monitoring, human-computer interaction, and wearable electronic devices. However, the preparation of pressure sensors with high sensitivity, high linearity, and wide working range continues to be challenging. In this study, a SnO2@carbon nanotubes/polyurethane (SnO2@CNT/PU) sponge pressure sensor was presented with high sensitivity in a wide linear pressure range. SnO2 was attached to CNT/PU sponge, which allowed the pressure sensor to obtain low initial current, thus increasing the sensitivity of the pressure sensor. The applied compressive strain was linearly related to the resistance since the nodes of CNT/PU sponge porous skeleton change synchronously during contact. SnO2@CNT/PU sponge pressure sensor shows a wide pressure range (3 Pa–30 kPa), while maintaining high sensitivity (53.4 kPa−1), and excellent linearity (R2 = 0.996). Furthermore, the sensor exhibited stable cycle performance (1500 cycles), fast response time (23 ms), as well as low detection limit (3 Pa). More importantly, the pressure sensor is capable of accurately detecting the human body's physiological signals, and shows promising application for health monitoring.