Thermoplastic Polyurethane/Carbon Nanotube Composites for Stretchable Flexible Pressure Sensors

Developing conductive polymer composites (CPCs) with high stretchability and high resistance response is a challenge in the field of flexible sensing. In this study, porous CPCs with a microdome array on the surface are prepared based on thermoplastic polyurethane (TPU) and carbon nanotubes (CNTs). TPU/CNT composites are designed to be strain sensors and pressure sensors capable of monitoring external strain and pressure stimuli. Due to the excellent electrical properties of carbon nanotubes, the synergistic effect of composite surface microstructure, and an internal porous structure, the sensor has greatly improved the detection range and sensitivity of traditional sensors. The sensing properties of CPC materials in terms of strain and pressure monitoring are perfectly balanced. The detection ranges of the strain sensor and pressure sensor are 0–160% and 0–55 kPa, respectively, and the highest sensitivity is gauge factor (GF) = 12.88 (90–160%) and sensitivity S = 0.08 (0–6.5 kPa), respectively. Based on the reversible change of the CNT conductive network under tensile/compression loading, the sensor has excellent stability and durability during cyclic loading. In addition, the TPU/CNT composite sensors can monitor human movements, bending of composite components, and pressure positions, showing great application prospects in electronic skin, wearable smart devices, and human–computer interaction.