Flexible and highly sensitive three-axis pressure sensors based on carbon nanotube/polydimethylsiloxane composite pyramid arrays

Abstract The development of flexible and sensitive three-axis pressure sensors is of great interest for various wearable applications, such as electronic skin, soft robotics, and health monitoring. This study aims to propose a highly sensitive and flexible pressure sensor that can measure three-axis pressure based on conductive microstructured carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS) elastomer with a simple and large-scale fabrication method that uses a polymer wet etching process. The randomly exposed CNTs on the surface using PDMS wet etching improve the sensitivity of the pressure sensors. The fabricated sensors exhibit a high sensitivity of 1.39 kPa−1 for a pressure range of 250 Pa, excellent limit of detection capability of 1.26 Pa, fast response time of within 52 ms, and high reliability of over 10,000 times of pressure loading/unloading. As an application, the pressure sensors are demonstrated using electronic skin on human fingers for the detection of the pressure levels and pattern recognition of distributed pressure. Moreover, to measure the three-axis pressure, pressurization tests are conducted using artificial fingers, demonstrating that the fabricated sensor can successfully measure the pressures applied along the three axes.