Protein-assisted freeze-tolerant hydrogel with switchable performance toward customizable flexible sensor

[Display omitted] •Antifreeze proteins endowed hydrogel with excellent adhesion and good stretchability.•Switching of outstanding adhesion and high strength was achieved by tuning network.•Antifreeze proteins imparted anti-freezing ability to hydrogel at low temperature.•Biocompatible hydrogel served as customizable sensor for monitoring human motions. The design of a hydrogel material with cold-adaptation and switchable properties is incredibly significant for developing flexible electronics to accommodate diverse application requirements. Herein, an anti-freezing and biocompatible hydrogel sensor with adjustable performance was constructed by incorporating natural fish antifreeze proteins into a hydrogel system consisting of chemical crosslinking poly(acrylamide/sodium methacrylate) and physical crosslinking polyvinyl alcohol. The biocompatible hydrogels with conductivity and shape-adaptability demonstrated tunable features between extraordinary self-adhesion and robust mechanical strength for adapting personalized application requirements. Meanwhile, breaking through the conventional anti-icing strategy, the ice crystals inhibition ability of antifreeze proteins endowed hydrogels with an anti-freezing performance at low-temperature conditions. Additionally, the hydrogels exhibited fast and extremely sensitive responsiveness to mechanical deformation, together with insignificant asynchronism of input/output signals. As a result, the hydrogel sensors could attach directly to human skin for perceiving various body motions and physiological movements, with the advantages of perfect accuracy and reproducibility. Besides, the sensors were competent for capturing unpredictable animal behavior in real-time. The property-tunable design strategy and fish-inspired anti-icing method fuel an exciting new direction for wearable devices for serving in diverse fields.