Engineering versatile chitosan hydrogel sensor for satisfying complex and harsh demands

The chitosan-based hydrogel sensor with successful integration of robust mechanical performances, simultaneously anti-freezing/drying environments and excellent biocompatibility still remains challenged. To overcome this challenge, here, a superhydrogen-bond networks (SHBNs) strategy was presented to assemble a novel chitosan-based hydrogel sensor CS/PVA/GL (chitosan/polyvinyl alcohol/glycerol) which exhibits excellent mechanical performances (e. g. load capacity of 60 kg) and 99 % cell viability. Moreover, the hydrogel has exceptional anti-freezing capacity with -100 °C glass transition temperature. Even after going through freezing at -75 °C, it still displays good flexibility, conductivity and mechanical performances. Interestingly, after 60 days of dryness, it still possesses very good flexibility. Importantly, its anti-freezing capacity is nearly close to that before being dried, and the mechanical properties are higher than those before being dried, indicating its excellent anti-drying capacity. With these prominent advantages, after being assembled into a hydrogel sensor, it can monitor human action signals, and be used as bionic skin to write the words "engineer" and "function" on the screen of a mobile phone. The engineering concept developed in this work can provide a valuable insight into constructing high-performance chitosan-based hydrogel sensors which can satisfy real-time tasks regardless of in extremely low temperature and long-term open environments.