Self-Healing Hydrogels for Flexible Underwater Motion Sensing and Rapid Information Transmission

To realize underwater environment applications of conductive hydrogels, comprehensive performance metrics including mechanical properties, adhesive capability, high-sensitivity sensing, and durability must be considered. Herein, we developed a composite hydrogel (Gelatin/PAA/PDA@Ag/HTAB) through facile thermal polymerization, incorporating hydrophobic interactions, electrostatic forces, and cation-π multivalent interactions. The hydrogel exhibited excellent multifunctional characteristics, including low tensile and compressive moduli (0.12-0.24 kPa), remarkable fracture elongation (1605.57%), and good self-healing efficiency (90%). Using molecular dynamics simulations, we pioneered the simulation of the adhesion behavior between the hydrogel and various substrates in air and underwater environments. Combined with experimental results, this collectively demonstrated that the hydrogel exhibited robust adhesion to diverse substrates. Notably, the Gelatin/PAA/PDA@Ag/HTAB_7.5 hydrogel sensor demonstrated good sensitivity in detecting underwater human motions and enabled rapid underwater signal transmission through leveraging of mobile phone T9 input methodology and CNN model. These advancements suggested that the designed hydrogel could be used as a promising candidate for next-generation underwater wearable sensors, offering broad application prospects in diverse underwater monitoring systems.