Hierarchically engineered Janus fiber-hydrogel architecture: An ultrathin biomimetic skin for multiple-response sensing

Hydrogels served as core materials for wearable sensors in recent years, yet their practical application was constrained by water-loss-induced instability, suboptimal mechanical properties, and insufficient functionality in complex scenarios. To overcome these challenges, this study innovatively engineered a Janus fiber scaffold-based composite hydrogel biomimetic skin with a triple humidity-responsive mechanism, achieving substantial breakthroughs in performance optimization and multifunctional integration. HSBS leveraged triple humidity response mechanisms: chitosan-gelatin buffering, Janus scaffolds' unidirectional conduction, and LiCl deliquescence, achieving high hygroscopic sensitivity across 30–90 % RH. Concurrently, the HSBS exhibited wide temperature adaptability from −20 °C to 50 °C, exceptional strain-sensing stability, and mechanical durability, with a water retention rate of 76 % at room temperature and a tensile strength of 3.09 MPa. It could also precisely detect variations in skin temperature and humidity, as well as fluctuations in physiological signals. Endowed with a triple humidity-responsive mechanism as its core advantage, this novel biomimetic skin was poised to significantly expand the application frontier of wearable sensors in domains such as healthcare monitoring and sports science.