Modulus-Mediated Random Rough Surface: A New Strategy for Fibrous Membrane Pressure Sensor Sensitivity Enhancement

Electrospun fiber membranes have emerged as promising candidates for wearable flexible pressure sensors, owing to their excellent flexibility and compressibility. However, the internal pores between fibers hinder the rapid contact of conductive fillers, ultimately leading to low sensitivities. To address this issue, we propose a modulus-mediated strategy to obtain a randomly distributed rough surface by using a carbon nanotube-decorated polyacrylonitrile/carboxymethyl cellulose (CNTs-PAN/CMC) composite fibrous membrane sensor. Our strategy focuses on adjusting the stiffness and deformability of the PAN/CMC fiber membrane, thereby achieving a balanced stiffness and robustness substrate and, hence, a random rough surface after loading with CNT aggregates. It is worth noting that the CNT aggregates not only provide a conductive network but also facilitate surface protrusions and grooves in the sensing layer, resulting in multiple deformations and the rapid contact of conductive fillers under external pressure. The optimized CNTs-PAN/CMC pressure sensor exhibits a high sensitivity of 123 kPa –1, a fast response (200 ms), a low detection limit of 2.5 Pa, and excellent durability. Consequently, this sensor shows excellent capability for monitoring a wide range of human motions, including wrist, elbow, and knee bending as well as mouse clicks. It also demonstrates the ability to distinguish different English letters written directly on its surface. This study demonstrates a powerful strategy to enhance the sensing performance of fibrous membranes, which can be adapted to various flexible sensors.