Flexible capacitive pressure sensors with high sensitivity and durability via an electrohydrodynamic printing method

Abstract

Flexible pressure sensors with a wide detection range and high stability are essential to realize reliable tactile sensing. Although dielectric microstructures can endow capacitive pressure sensors with excellent sensing sensitivity, how to realize reliable micro-structured dielectric layers is still an important issue to be solved. This paper presents a method for fabricating polydimethylsiloxane/multi-walled carbon nanotube (PDMS/MWCNT) dielectric layers with oriented MWCNTs utilizing an electrohydrodynamic printing method, thereby achieving a wide detection range and good stability for flexible capacitive pressure sensors. The synergistic effect of MWCNT orientation and printed microstructure within the dielectric layer enables the sensor to exhibit excellent mechanical and sensing performance in the detection pressure range of 20 Pa–150 kPa. The sensor shows excellent linearity in the pressure range of 60 kPa with a sensitivity of 0.1821 kPa⁻¹. The sensor shows excellent sensing accuracy with a response time of about 120 ms under 10 kPa pressure, and its performance does not degrade after 2.5 h of continuous cyclic pressure loading/unloading, showing excellent sensing stability. Furthermore, the application demonstration of real-time monitoring of arterial pulse signals from different physiological parts of the human body and immediate transmission of encrypted information verifies the sensor's potential for use in wearable electronic devices.