High Performance Flexible Strain Sensors Based On Silver Nanowires/thermoplastic Polyurethane Composites for Wearable Devices

Flexible strain sensors have attracted numerous attentions due to their application in wearable devices. However, it is still a significant challenge to fabricate flexible strain sensors with both wide sensing range and high sensitivity simultaneously. In this article, this challenge had been addressed by using ultralong silver nanowires (AgNWs) to composite with stretchable thermoplastic polyurethane (TPU). Benefitted by the ultralong AgNWs, stretchable TPU and the hydrogen bond interaction between TPU and PVP on the surface of the ultralong AgNWs, the AgNWs/TPU composite flexible strain sensor with wide sensing range and high sensitivity simultaneously was achieved. The obtained AgNWs/TPU composite flexible strain sensor possessed wide sensing range above 250% with high gauge factor (GF) of 329.43 and excellent stability. The sensing range and GF of the obtained AgNWs/TPU composite flexible strain sensor were higher than those of other similar flexible strain sensor reported in the literature. The response and recovery times were about 100 and 300 ms, respectively. The AgNWs/TPU composite flexible strain sensor could be used to detect human motions such as finger, wrist, elbow, and knee bending as well as facial expressions and micro-acoustic vibrations. The AgNWs/TPU composite flexible strain sensor demonstrates excellent potential for applications in wearable device.