Mussel-adhesive chemistry inspired conductive hydrogel with self-adhesion, biocompatibility, self-recovery and fatigue-resistance performances as flexible sensing electronics

Conductive hydrogels are ideal candidates for wearable strain sensors due to their intrinsic stretchability and conductivity. However, it's still a challenge to fabricate a conductive hydrogel with a combination performance of high mechanical strength, self-adhesion, sensitivity, self-recovery capability, fatigue-resistant ability and biocompatibility. Herein, a dual-network hydrogel (TG/P-LP) composed of 2,2,6,6-tetra-methylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOCNs) supported graphene (GN), Laponite-oxidized polydopamine (LP) and polyacrylic acid-co-poly acrylamide (P) hydrogel matrix was synthesized via a facile in-situ radical polymerization process. The optimized biocompatible TG/P-LP hydrogel exhibits a high mechanical strength, self-adhesive performance, intrinsic self-recovery capability (95.7 % in 60 min) and anti-fatigue property. The hydrogel-based strain sensor exhibits a wide strain range (0 ∼ 600 %) and a high sensitivity (GF = 12). This work designs a novel hydrogel-based sensor with excellent mechanical properties, long-term fatigue resistance, high strain sensitivity and wearability, demonstrating enormous potential in the applications of human motion detection and human–machine interaction.