Bio-inspired, super-stretchable and self-adhesive hybrid hydrogel with SC-PDA/GO-Ca²⁺/PAM framework for high precision wearable sensors

Flexible sensors which are highly stretchable, sensitive, and self-adhesive are critically required for wearable electronics, personalized healthcare monitoring and electronic skins. Conductive hydrogel-based sensors hold great promises for this purpose. However, it remains a critical challenge to integrate all the critical functions (e.g., remarkable stretchability, high sensitivity, and self-adhesiveness) into one hydrogel. Here, we propose a bio-inspired hybrid hydrogel framework with a hierarchical configuration that incorporates sodium casein, polydopamine, calcium chloride, and graphene oxide into a polyacrylamide hydrogel. Multiple interpenetrating network architectures and their strong interactions provide superior stretchability of 10,300%, high strain sensitivity with a gauge factor of 13.45 over a broad strain range, robust adhesiveness, fast responsiveness, and excellent reproducibility. This hydrogel-based wearable sensor demonstrates outstanding sensing performance in detecting, quantifying, and remotely monitoring human motions through integration into a cloud platform. A durable glove is further developed using the hybrid hydrogel for wirelessly controlling synchronized motions of a manipulator and accurately recognizing hand gestures. This hybrid hydrogel has shown wide-range applications in fields including wearable electronics, human–machine interfaces, and electronic skins.