Polyacrylamide/carboxymethyl chitosan double-network hydrogels with high conductivity and mechanical toughness for flexible sensors

Conductive hydrogels are ideal candidate materials for flexible sensors, but the integration of satisfactory mechanical performances with high conductivity to meet the requirements for practical applications remains a challenge. Herein, a tough ionically conductive polyacrylamide (PAAm)/carboxymethyl chitosan (CMCs) double-network (DN) hydrogel is fabricated via in situ polymerization of acrylamide in CMCs aqueous solution, followed by ferric chloride (FeCl3) solution immersing. The PAAm/CMCs-Fe3+ DN hydrogel demonstrates satisfactory mechanical properties, including sufficient tensile strength (similar to 440 kPa), prominent stretchability (similar to 715%), high toughness (similar to 1658 kJ m(-3)), and excellent fatigue resistance, as well as superb conductivity up to 3.1 S m(-1). Moreover, the ionically conductive DN hydrogel-based sensors exhibit high sensitivity in a broad strain window (0%-700%) and can accurately, and repeatedly monitor the motions of body joints, such as finger and wrist, exhibiting great potential in applications of flexible sensors.