Bio-Based Hydrogel Transducer for Measuring Human Motion with Stable Adhesion and Ultrahigh Toughness

Adaptability could meet basic technological application requirements. Therefore, a hydrogel-based transducer with durable adhesion, ultrahigh toughness, and super resilience was highly demanded. Here, a skin-like hydrogel transducer was successfully prepared through introducing carboxymethyl chitosan and sodium caseinate into a polyacrylamide hydrogel system. In addition, the polyacrylamide-sodium casein-carboxymethyl chitosan (PAAM-SC-CC) hydrogel has strong mechanical properties and excellent mechanical flexibility, largely due to the adequate energy dissipation mechanism. Surprisingly, the PAAM-SC-CC hydrogel exhibited stable and reproducible adhesion to various solid substrates and the human skin. Due to abundant free ions driven from sodium caseinate, the PAAM-SC-CC hydrogel could maintain stable and sensitive ionic conductivity without adding additional fillers. Experiments have proved that it can be applied to the field of human motion monitoring with complex signals. Therefore, the PAAM-SC-CC hydrogel sensor could monitor human movement in different strain ranges, including throat movement and joint extension. Such a flexible hydrogel-based transducer with various properties is conceivable to broaden the application field of bioelectrodes, human machines, personalized medical health fields, etc.