Dual-Network PVA-PNIPAM Hydrogel for Decoupled Strain-Temperature Sensing and Intelligent Motion Recognition.

Multifunctional hydrogel-based sensors capable of integrating mechanical adaptability, stable conductivity, and multimodal responsiveness are highly desirable for wearable electronics and intelligent human-machine interfaces. However, achieving synergistic optimization of multi-stimuli responsiveness and stable signal transduction remains challenging. Herein, a multifunctional conductive hydrogel based on a poly(vinyl alcohol)-poly(N-isopropylacrylamide) (PVA-PNIPAM) dual-network structure was developed through synergistic chemical and physical crosslinking for multimodal flexible sensing. The hydrogel exhibited excellent stretchability (fracture strain >300%), stable ionic conductivity (0.252 S·m-1), and highly linear strain-sensing performance (GF = 0.352, R2 = 0.993). Benefiting from the thermoresponsive phase transition of the PNIPAM network, the hydrogel showed stable and reversible temperature responsiveness over 30-70 °C with partial strain-temperature decoupling capability. In addition, the hydrogel enabled real-time monitoring of multiple human motions and achieved high-accuracy motion recognition approaching 100% when combined with machine-learning-assisted analysis. This work establishes an integrated multimodal sensing platform spanning material design, signal transduction, and intelligent recognition, providing a versatile strategy for wearable electronics and intelligent sensing systems.