An organic/inorganic coating strategy that greatly enhanced sensing performances and reliability of all-fabric piezoresistive sensors

Abstract

Flexible pressure sensors are indispensable in wearable electronics, human–machine interfaces and medical wisdom. Despite notable progress achieved in improving the sensitivity and the sensing range of piezoresistive sensors, long-term reliability of these sensors is easily interfered by weak binding fastness of conductive substances on substrates and environmental factors (such as humidity change, sweating, sunlight exposure and corrosive chemicals). Herein, a highly reliable piezoresistive sensor was developed based on a three-dimensional nonwoven coated with an organic/inorganic mixture. The addition of thermoplastic polyurethane into the coating mixture achieved firm immobilization of multi-walled carbon nanotubes and perfluorodecyltrichlorosilane on fiber surfaces. Subsequent sandwiching of the coated nonwoven in between a fabric interdigital electrode and a spunbond nonwoven endowed the resultant all-fabric piezoresistive sensor with a broad sensing range (0–118 kPa), high sensitivity (10.03 kPa⁻¹), fast response/relaxation time (135/100 ms) and excellent reproducibility (≥2000 cycles), thus making it ideal to be used for real-time monitoring of human motions (including breath, pulse and joint bending). The sensor also showed good anti-fouling properties and high endurance against harsh environments (humidity change, sweating, sunlight exposure and corrosive chemicals), and its versatile application was demonstrated in wireless monitoring and spatial pressure recognition. Moreover, our sensor was fabricated using cost-effective materials and scalable approaches, making us believe in its great practical significance for commercialization.