Intelligent conductive hydrogels for wearable motion monitoring and stress-driven switching between electromagnetic shielding and conversion

Wearable electronics stimulate substantial demands for flexible hydrogels with exceptional softness and biocompatibility, but remain challenging to achieve multifunctional integration and intelligent function switching. In this study, conductive hydrogels enabling wearable sensing and switchable electromagnetic protection have been designed by incorporating LM and FeNi 3 @carbon nanotubes into the polyvinyl alcohol matrix. Benefitted from the cross-linked conductive networks induced by cyclic freezing-thawing, the hydrogel exhibits excellent flexibility, durability, and stability for real-time human motion monitoring and efficient electromagnetic interference (EMI) shielding. Stretching stress triggers an intelligent function switching from EMI shielding to wave absorption due to optimized impedance matching and enhanced attenuation, giving rise to a broadband electromagnetic absorption of 4.8 GHz. Space electromagnetic field and radar cross-section simulations unravel multiscale electromagnetic interactions, demonstrating the static shielding characteristic and stress-driven enhanced absorption. This work not only provides a novel strategy for the intelligent switchable electromagnetic compatible materials, but also advances insights into multifunctional wearable electronics for extended design in intelligent actuation, human-machine interaction, and healthcare.