Metal-ion and cellulose nanofibers-reinforced polyacrylamide (PAM)/polyvinyl alcohol (PVA) conductive organohydrogels for flexible strain sensors

Conductive hydrogels are promising functional materials with numerous potential applications in flexible electronics. Nevertheless, developing conductive hydrogels with superior mechanical properties, high electrical conductivity, and robust environmental adaptability remains a significant challenge for flexible strain sensors. Here, a metal-ion and cellulose nanofibers (CNFs)-reinforced conductive hydrogel based on polyacrylamide (PAM)/polyvinyl alcohol (PVA) double network structure is synthesized via a facile one-pot polymerization followed by a solvent displacement strategy. Tannic acid (TA)-modified CNFs are strategically incorporated into PAM/PVA conductive hydrogel network structure, synergistically reinforced by dual metal ions (Na + /Fe 3+ ), to enhance mechanical and electrical properties simultaneously. The resulting conductive hydrogel exhibits an ultrahigh elongation at break (1440 %), a robust tensile strength (110 kPa), and a high conductivity (0.32 S/m). Furthermore, the organic solvents endow the conductive hydrogel with exceptional antifreezing and antidrying capabilities, ensuring the long-term stability under ambient conditions. In addition, the fabricated conductive hydrogel serves as a core strain-sensing element, demonstrating a good strain sensitivity with a gauge factor (GF) of 2.6 over a 0–250 % strain range, and can be used for human motion monitoring. This study presents a versatile strategy for fabricating conductive hydrogels with tunable properties for wearable electronics.