<i>In Situ</i> Fabrication of PEDOT:PSS on the Surface of Antiswelling Gel for Amphibious Multifunctional Sensors

Underwater sensors play a crucial role in marine exploration, resource development, environmental monitoring, and national defense security. Gel sensors, with their flexibility, biomimetic properties, and environmental friendliness, are indispensable in marine precision detection and biointeraction scenarios. However, the tendency of hydrogels to swell and leak ions in aquatic environments limits their application in underwater sensing. Against this backdrop, this paper proposes a gel preparation strategy that induces hydrophobic chain aggregation to achieve gel swelling resistance, followed by in situ growth of conductive polymers on the gel surface to achieve high-sensitivity response. The prepared gel sensor exhibits excellent swelling resistance (swelling rate of 5.73%), good mechanical properties (tensile strain of 1484.81%), and high sensitivity (GF = 3.21). As a multifunctional gel sensor suitable for both aquatic and terrestrial environments, it also exhibits an ultrawide operating range and linearity (0 to 500% strain range) to ensure reliable detection under high-strain conditions. Additionally, it exhibits excellent fatigue resistance (1000 cycles at 70% strain) and rapid response/recovery times (0.43 s/0.36 s in tensile state and 0.34 s/0.41 s in compressive state). Therefore, with these outstanding performance characteristics, the designed multifunctional gel sensor, when combined with deep learning algorithms, can not only be used for human motion detection, information encryption transmission, and speed recognition scenarios, but also can be used underwater to construct an independent detection system that integrates data sensing, collection, and transmission to achieve human motion perception. Consequently, the designed amphibious gel sensor not only enables daily human motion monitoring but also has significant application value in underwater rescue and marine ecological monitoring.