A unique, flexible, and porous pressure sensor with enhanced sensitivity and durability by synergy of surface microstructure and supercritical fluid foaming

Flexible thermoplastic polyurethane (TPU)/multi-walled carbon nanotube (MWCNT) nanocomposite piezoresistive sensor with microsphere surface and internal porous structure were prepared using a facile glass template method combining with supercritical carbon dioxide (Sc-CO2) foaming process. Effects of surface microstructure and cell structure on the piezoresistive sensing performance of TPU/MWCNT nanocomposite foam had been investigated in detail: the novel hybrid structure significantly improved the sensing performance with a fast response time (≤100 ms), a wide operating range (0 ∼ 80 kPa) and a stability of over 1000 cycles. In addition, the prepared piezoresistive sensor can be used to monitor a wide range of human physiological signals (facial activity, small arm muscle contraction and arterial pulse, etc.) due to its excellent integrated sensing performance. This work provides a route for the design of advanced piezoresistive sensors that show great potential for applications in human motion detection, artificial intelligence devices, and medical detection, etc.