Coating of multi-wall carbon nanotubes (MWCNTs) on three-dimensional, bicomponent nonwovens as wearable and high-performance piezoresistive sensors

Wearable piezoresistive sensors have attracted increasing attention because of their important applications in wearable electronics, smart textiles and human-machine interaction. However, existing piezoresistive sensors still suffer from problems including expensive starting materials, weak bonding fastness between conductive substances and substrates, limited sensing range and poor comfort. Herein, we report a three-dimensional (3D) piezoresistive sensor based on a nonwoven substrate composed of highly crimped bicomponent fibers. The unique core-sheath structure of these fibers in combination with a thermally-assisted coating method ensures the swift and tight adhesion of multi-walled carbon nanotubes (MWCNTs) on fiber surface, and thus making the nonwoven conductive. With the multi-layered fibrous structure, the resultant sensor exhibits good flexibility, high sensitivity (5.57% and 0.113% kPa(-1) in the range of 0-7 and 30-131.32 kPa, respectively), broad dynamic sensing range (0-131.32 kPa), fast response/relaxation (105/156 ms), as well excellent breathability and longterm reliability. Versatility of this sensor is proved by real-time detection of both small and large human motions (such as pulse, speech recognition and joint motion). A sensor network containing 16 sensors is further developed to precisely map and recognize the position, shape and local distribution of pressure. Moreover, the sensor is fabricated by using affordable materials and scalable methods. Taken together, we believe this work may open up a new perspective for the design of high-performance wearable piezoresistive sensors.