Coordination/salting-out synergistic construction of multifunctional PVA/chitosan conductive organohydrogel as strain and bioelectrical sensors

The salting-out action and the cation-induced-crosslinking reaction have been reported separately for the preparation of conductive hydrogels, but there are few studies on the synergistic effect of these two interactions. Also, how to construct flexible strain sensors with more functions is rarely reported by introducing multiple ions through the simple immersion method based on the synergistic action of two kinds of ions. Herein, a polyvinyl alcohol (PVA)/O-carboxymethyl chitosan (O-CMCS)-based composite conductive organohydrogel POAPZ was designed and fabricated by replacing pure water solvent with nano-silver particles (AgNPs) solution, followed by the immersion treatment in the PDO (1, 3-propylene glycol)-ZnSO4 (zinc sulfate) blended solution. Due to the synergistic effect of crosslinking coordination, salting out and hydrogen bonding, the electromechanical properties and sensing behavior of the resulting organohydrogel POAPZ were almost unchanged at room temperature and long-term storage conditions. The flexible electronic device, constructed by this organohydrogel, exhibited considerable anti-freezing, moisturizing, antibacterial, conductive (1.4 S/m) and mechanical properties (fracture stress of 2.2 MPa), and could be used as strain sensor to monitor human movement at room or low temperatures, including large-scale and subtle body movements and bioelectrical signals, which is a long-term wearable sports health monitoring system. In summary, this work successfully constructed an organic flexible electronic device POAPZ with the advantage of remaining good mechanical durability and applicability under harsh environmental conditions, and the fabrication strategy used provides a new idea for the construction of conductive hydrogel via ion immersion procedure.