High-performance wearable flexible strain sensors based on an AgNWs/rGO/TPU electrospun nanofiber film for monitoring human activities

Abstract Wearable flexible strain sensors have attracted considerable attention in recent years, while it is still a significant challenge to fabricate wearable flexible strain sensors with high sensitivity and wide sensing range simultaneously. In this work, a high-performance wearable flexible strain sensor based on a thermoplastic polyurethane electrospun nanofibers (TPUNFs) film embedded with a silver nanowires/reduced graphene oxide (AgNWs/rGO) composite conductive material was fabricated via a simple drop-coating technique. The effect of the amount of AgNWs/rGO composite conductive material on the strain sensing range of the AgNWs/rGO/TPUNFs film flexible strain sensor was investigated, the strain sensing range of AgNWs/rGO/TPUNFs film flexible strain sensor was compared with that of the AgNWs/TPUNFs and GO/TPUNFs film flexible strain sensor, and the strain sensing properties of the AgNWs/rGO/TPUNFs film flexible strain sensor were measured. The results showed that the AgNWs/rGO/TPUNFs film flexible strain sensor with high sensitivity and wide sensing range simultaneously was achieved by compounding AgNWs and the reduced graphene oxide (rGO) conductive material. The strain sensing range of the AgNWs/rGO/TPUNFs film flexible strain sensor could be improved by increasing the amount of the AgNWs/rGO composite conductive material, and it was obviously better than that of AgNWs/TPUNFs and the rGO/TPUNFs film flexible strain sensor. The obtained AgNWs/rGO/TPUNFs film flexible strain sensor possessed high sensitivity (the gauge factor could reach a maximum of 2513.23.) as well as a wide sensing range (∼187%). Furthermore, the obtained AgNWs/rGO/TPUNFs film flexible strain sensor had a fast response/recovery time (200 ms/300 ms) and good cycling stability (∼3,000 cycles). Benefitting from the outstanding strain sensing performance, the AgNWs/rGO/TPUNFs film flexible strain sensor could detect large human motions such as finger, wrist, and knee bending as well as expression, which demonstrates great potential applications in wearable devices.