Nature's answer to flexible electronics: Polysaccharide-based hydrogel sensors

Polysaccharide hydrogel based flexible sensors exhibit significant promise for human health monitoring, leveraging their exceptional biocompatibility, biodegradability, and tunable surface chemistry. To date, research on polysaccharide hydrogels in flexible electronic sensing has achieved substantial progress. However, a systematic structure-property relationship linking fabrication strategies, network structure, hydrogel properties, and sensing performances remains unestablished. Herein, this review critically examines: (i) Design principles and performance-enhancement strategies for conductive polysaccharide-based hydrogels; (ii) Interaction mechanisms between polysaccharide functional groups and composite constituents within hydrogels, emphasizing the pivotal role of dynamically bonded networks in modulating key properties; (iii) Operational mechanisms of polysaccharide hydrogel sensors; (iv) Their application advances in monitoring strain/pressure, temperature, humidity, and bio-signals. We further discuss future development trajectories and persistent challenges. This work might establish an integrated composition-structure-property-performance design framework, thereby accelerating the development of high-performance, multifunctional, green, and sustainable sensing platforms.