Mechanically robust and highly conductive polyacrylamide/carboxymethyl chitosan organohydrogels via synergistic physical interactions for flexible sensing

Conductive hydrogels have revolutionized wearable electronics due to their biocompatibility and tunable properties. However, it remains a great challenge for hydrogel-based sensors to maintain both conductivity and mechanical integrity in harsh environments. Synergistic dynamic interactions provide a promising strategy to address this issue. Herein, we report a tough and conductive organohydrogel that can be readily prepared by immersing a dried polyacrylamide/carboxymethyl chitosan matrix in an ethylene glycol/water mixture containing tannic acid and calcium chloride. Multiple dynamic hydrogen bonds and metal coordination interactions were formed within the organohydrogel network, synergistically reinforcing the structure and leading to a tensile strength of 2.69 MPa, a breaking strain of 1292 %, and a toughness of 14.21 MJ/m 3 . Incorporating calcium chloride and ethylene glycol into the gel system imparted multifunctionality, such as high conductivity (1.16 S/m), strong anti-freezing capability, and long-term water retention. Benefiting from their low modulus and high conductivity, the organohydrogels were well-suited for flexible strain sensors. The resulting sensors exhibited high sensitivity with a gauge factor of 1.92, a wide sensing range, and good linearity, thereby enabling precise monitoring of diverse human motions. These results demonstrate the great potential of the organohydrogels in the field of flexible electronic devices even under extreme environments.