Stretchable Semi-Interpenetrating Carboxymethyl Guar Gum-Based Composite Hydrogel for Moisture-Proof Wearable Strain Sensor

Wearable strain sensors of conductive hydrogels have very broad application prospects in electronic skins and human–machine interfaces. However, conductive hydrogels suffer from unstable signal transmission due to environmental humidity and inherent shortcomings of their materials. Herein, we introduce a novel moisture-proof conductive hydrogel with high toughness (2.89 MJ m–3), mechanical strength (1.00 MPa), and high moisture-proof sensing performance by using dopamine-functionalized gold nanoparticles as conductive fillers into carboxymethyl guar gum and acrylamide. Moreover, the hydrogel can realize real-time monitoring of major and subtle human movements with good sensitivity and repeatability. In addition, the hydrogel-assembled strain sensor exhibits stable sensing signals after being left for 1 h, and the relative resistance change rate under different strains (25–300%) shows no obvious noise signal up to 99% relative humidity. Notably, the wearable strain sensing is suitable for wearable sensor devices with high relative humidity.