Wearable, ultrathin and breathable tactile sensors with an integrated all-nanofiber network structure for highly sensitive and reliable motion monitoring

Wearable tactile sensors are under high pursuit in healthcare monitoring. However, most of previous sensors were assembled by non-binding multilayers and built on airtight substrates, hindering the wearability with comfort. Herein, we develop an ultrathin and breathable tactile sensor based on an integrated all-nanofiber network via a facile electrospinning and spray-drying technique. The sensor is constructed by directly ink-patterning of conductive Co3O4/PEDOT:PSS/AgNW electrodes on both sides of one single ionic IL/TPU fabric electrolyte mat, the overall thickness of which is only 40 µm for a conformal attachment on any curved surface. The highly porous nanofiber network endows the sensor with both high air and moisture permeabilities, ensuring an excellent comfortability for a long-time wearing. Due to the pseudocapacitive sensing mechanism and nanofiber-based microstrucutre, the sensor exhibits ultrahigh sensitivity of 79.5 kPa−1, fast response time of 40 ms, and a wide detection range of 38 kPa. Reliability tests show that the sesnor is capable of outputting stable and repeatable sensing signals for over 10,000 loading/unloading cycles of 5 kPa on testing machine and for over 5,000 s of continuous motion detection of foot stamping and elbow bending. Monitoring of arm swinging and elbow bending by sensor units and recognition of hand gesture by sensor array are also demonstrated towards practical wearable sensing applications.