Highly Sensitive Flexible Capacitive Pressure Sensor with Porous Hierarchical Structure Realized by a Microwave Curing Method

Abstract

The introduction of porous hierarchical microstructures effectively improves the sensitivity of flexible pressure sensors. However, it is difficult to achieve porous hierarchical microstructures for pressure sensors through inexpensive, efficient, and simple preparation methods. Herein, a hemispherical array with porous hierarchical microstructure is prepared on polydimethylsiloxane substrate using a simple one‐step microwave curing process with glucose as porogen. Furthermore, the flexible electrode based on the polydimethylsiloxane substrate is combined with an ionic liquid polymeric gel membrane to obtain a flexible capacitive pressure sensor. Thanks to the deformability of porous hierarchical microstructure and the double‐dielectric layer effect of ionic liquid polymeric gel membrane, the sensor displays an ultrahigh sensitivity of 131.21 kPa −1 within 0–1 kPa. Meanwhile, the sensor has short response time, excellent dynamic loading stability, as well as excellent long‐term stability (>3000 cycles). In application testing, the sensor effectively monitors various physiological activities like pulse, breathe, speech, and swallowing, demonstrating its good prospects in the field of health electronics. Most importantly, the proposed microwave curing method can realize the preparation of porous hierarchical structure on flexible substrate through a one‐step process, which offers a fresh way for the economical, green, and efficient preparation of high‐sensitivity capacitive pressure sensors.