Ultrasensitive, flexible, and low-cost nanoporous piezoresistive composites for tactile pressure sensing

Abstract

Highly sensitive flexible tactile sensors are of continuing interest for various applications including wearable devices, human–machine interface systems, and internet of things. Current technologies for high sensitivity piezoresistive sensors rely on costly materials and/or fabrication methods such as graphene-based and micro-structured composites limiting accessibility and scalability. Here, we report a facile sacrificial casting–etching method to synthesize nanoporous carbon nanotube/polymer composites for ultra-sensitive and low-cost piezoresistive pressure sensors. Our synthesis method overcomes the limitations of the traditional solution-dip-coating method for adhering nanoscale conductive materials to the nanoscale porous surface. Importantly, we show ultra-high sensitivity with a strain gauge factor over 300, which is ∼50 times higher than that of traditional CNT-based piezoresistive sensors and ∼10 times higher than that of most of the graphene-based ones. For practical tactile sensing applications, we demonstrate that the sensors can detect both gentle pressures (1 Pa–1 kPa) and low pressures (1 kPa–25 kPa) with a fraction of the cost. Our nanoporous polymer composite could contribute to expanding the scope of using nanocomposites for applications including subtle locomotion sensing, interactive human–machine interface systems, and internet of things from its easy tunability for sensing diverse range of tactile signals.