Anti-swellable, stretchable, self-healable, shape-memory and supramolecular conductive TA-based hydrogels for amphibious motion sensors

Conductive hydrogel endures as an ideal candidate for flexible electronic devices. However, conventional conductive hydrogels cannot incorporate superior sensitivity under low deformation, biocompatibility and underwater sensing into one system, which widely obstructs their applications in an aqueous environment. Herein, we designed a supramolecular conductive poly(vinyl alcohol) (PVA) and tannic acid (TA) based PVA/TA hydrogel. Due to the effective hydrogen bonding between PVA and TA, the hydrogel possesses some unique properties, including anti-swelling, stretching, self-healing and shape-memory. The PVA/TA supramolecular hydrogel demonstrates an excellent electrical performance where the conductivity and gauge factor (GF) is obtained at 5.5 × 10-4 S/cm and 1.3 in dry and 5.0 × 10-4 S/cm and 1.2 in wet conditions, respectively. The multifunctional hydrogel manifests excellent mechanical properties, where the maximum tensile strength of the hydrogels is 700 kPa at an elongation of 4700 %. Additionally, the hydrogel possesses excellent shape-memory and self-healable properties. Moreover, the hydrogel depicts outstanding biocompatibility, anti-swellable properties and exerts long-term stability underwater to detect human motions. Based on excellent anti-swelling and stability, high electrical conductivity and extraordinary stretching capability, the hydrogels may consider as promising candidates for applications in amphibious motion sensors.