A multi-functional flexible piezoresistive sensor based on sericin-functionalized CNTs decorated carbon foams for wearable thermal-therapy devices

With the rapid development of science and technology, multifunctional wearable devices have become a major trend in medical field. There is an urgent need to fabricate multifunctional materials with thermal insulation, mechanical flexibility, piezoresistance, and adjustable heating behavior to cope with the thermal management and health monitoring of human body in the harsh environment. To address this issue, three-dimensional melamine-based carbon foams (CMF) have been developed, with sericin-functionalized carbon nanotubes (CNTs) and in situ-grown carbon nanofibers (CNFs) in the CMF skeleton. The strategy of hierarchical porous micro-nanostructure enhanced the synergistic effect between CNTs and CNFs, resulting in exceptional resilience at 0–80 % compressive strain and cyclic stability at 20 % strain. Such carbon foam composites demonstrated excellent piezoresistive sensing performance, wide pressure range (0–20 kPa), high sensitivity (S = 0.11 kPa−1), and quick response (response/recovery time of 150/120 ms). They also showed good thermal insulation and Joule heating properties, particularly in presenting strain-dependent Joule heating mode at low voltage. Such amazing characteristics provide inspiration for temperature regulation of flexible, energy-efficient heating devices, and make them promising for smart sportswear, human-machine interfaces, and wearable medical devices.