Flexible Strain Sensors with Enhanced Sensing Performance Prepared from Biaxially Stretched Carbon Nanotube/Thermoplastic Polyurethane Nanocomposites

Conductive polymer composites (CPCs) with good flexibility and electrical properties have attracted extensive concern for application in high-performance strain sensors. Here, a strain sensor with high performance was produced using biaxially stretched carbon nanotubes (CNTs)/thermoplastic polyurethane (TPU) nanocomposites. The results show that the biaxial stretching process enhanced the uniform dispersion and planar orientation of the CNTs, which improved the crystallinity of materials and the sensing property of the sensors. The optimal stretching ratios (SRs) of nanocomposites were also investigated. The 2.0 wt % CNT/TPU-1.5 strain sensor with a SR of 1.5 showed high sensitivity with a maximum gauge factor (GF) value of 16908.8, large detectable strain range (0–375%), and good cyclic stability (1000 cycles) and exhibited an application prospect in wearable devices.