Discontinuous Hydrogel/Thermoplastic Polyurethane Nanofiber Composite Sensors for Human Motion Monitoring

Abstract

Flexible strain sensors are essential components of wearable electronic devices for health monitoring and human-computer interaction. Achieving a wide detection range, high cyclic stability, and high sensitivity at low strains remains a significant challenge. In this study, a discontinuous integration strategy was developed to construct composite sensing systems that combine tunneling and bridging effects by integrating a hydrogel with thermoplastic polyurethane (TPU) nanofiber membranes modified with a silver nanoparticles/carbon black (AgNPs/CB) conductive network. The tunneling effect in exposed regions enables a high-sensitivity response at low strain, while the bridging effect in covered regions broadens the detection range at medium-high strain. Experimental results show that the prepared sensing systems have a high sensitivity of 22.13 in the low-strain zone (0–30%), a minimum detection strain of 0.1% under static tensile testing conditions, a wider detection range of 70%, a shorter lag time of 4.6 ms, and excellent cycle stability over 1000 cycles. Furthermore, they can accurately detect multiscale deformation signals, from weak pulse vibrations to large-amplitude joint movements. This approach offers a strategy for developing high-performance flexible strain sensors.