Highly Sensitive and Flexible Capacitive Pressure Sensor Based on a Dual-Structured Nanofiber Membrane as the Dielectric for Attachable Wearable Electronics

Abstract

Wearable devices are an indispensable part of modern life, and flexible capacitive pressure sensors as their luminous subset have assumed a significant role in this day and age owing to ultralow power consumption. In recent years, a fierce debate as well as numerous studies have been conducted to improve the sensitivity of capacitive pressure sensors, but a vital challenge of the mass production of a highly sensitive sensor by a low-cost method still remains. In this paper, to meet industrial demands, we propose a simple method to fabricate sandwich-structured capacitive pressure sensors on an industrial scale and at low cost; as the electrospinning collector, stainless steel screens with regular patterns and structures were utilized to gain the dielectric with both external microstructure and internal pores (dual structure). The prepared pressure sensor is composed of a thermoplastic-urethane electrospun nanofiber film, as a dielectric, in the middle and two conductive woven fabrics on the upper and lower sides as electrodes. Benefiting from the prolific air in the dielectric layer, the designed sensor demonstrates outstanding sensing performance, such as high sensitivity (0.28 kPa–1) in the low-pressure region (0–2 kPa), fast response/relaxation time (65/78 ms), and high-grade durability (1000 cycles). Moreover, the produced pressure sensor is employed for not only detecting human limb movements and object grasping but also detecting pressure distribution in sensor array state, so demonstrating the application potential in attachable wearable electronics.