High-Performance Flexible Porous Composites Based on Bioinspired Gradient Design for Wide-Range Pressure Monitoring

Porous conductive composites have proven to be a promising material for flexible sensors. However, highly deformable porous pressure sensors typically produce high sensitivity only in narrow pressure ranges. Inspired by the structure of human skeletal gradients and the dispersed morphology of inorganic substances, a multilayered thermoplastic polyurethane (TPU)/epoxy resin (EP)/ carbon nanotubes (CNTs)/ silver nanoparticles (AgNPs) flexible pressure sensor has been designed based on the gradient distribution of gradient pores and conductive fillers. The gradient pore structure allows the material to deform continuously from low to high pressure. The combination of small pores/low conductivity and large pores/high conductivity allows the creation of multiple forms of contact resistance and conductive pathways, further increasing the sensitivity of the sensors over the entire pressure range. The gradient porous flexible pressure sensors have a wide sensing range (0 ∼ 500 kPa), high sensitivity of 1.17 kPa−1 (0 ∼ 47 kPa), fast response time (198 ms) and excellent dynamic stability (>4000). In addition, the sensor enables monitoring of plantar pressure, weight/position detection and bicycle speed, showing great potential in the areas of wearable devices and intelligent human-computer interaction. This work will pave the way for the development of advanced flexible sensors.