Durable adhesion in flexible sensors via synergistic interactions in tannic acid/thiosemicarbazide-chitosan networks

Adhesive conductive hydrogels have a broad application prospect in the field of flexible sensors, but existing adhesive hydrogels often struggle to balance adhesion performance and mechanical strength, and their adhesion stability is poor, which limits their long-term applications. In this study, a dual-network-structured hydrogel with durability, conductivity, and adhesion was prepared using a photoinitiated polymerization process, and its potential application in flexible sensors was explored. The hydrogel is based on thiosemicarbazone-modified chitosan (CS-SCM) as the backbone, introducing a reducible group into the system, acrylic acid (AA), tannic acid (TA), and Fe3+ are incorporated, endowing the hydrogel with excellent electrical conductivity and adhesion durability through multiple hydrogen bonds, electrostatic interactions, and metal-phenol complexation effects. The experimental results show that the hydrogel is able to maintain stable and long-lasting adhesion on the surface of various substrates, and its adhesion to plank remains above 90 kPa after 5 days of storage and more than 20 kPa after 13 days, which is significantly better than traditional hydrogels. Moreover, the durable adhesion of this hydrogel is highly valuable for research and applications in flexible sensors, smart wearables, and bioelectronic devices.