Electric Eel-Inspired Elastomer-Encapsulated Hydrogel Sensor with Superior Anti-Swelling, Self-Adhesion, and Electrical Stability for Diverse Underwater Applications.

Developing reliable underwater flexible sensing materials is a highly focused research topic, but challenges such as insufficient environmental stability and signal attenuation still remain. In this work, an electric eel-inspired encapsulation structure is proposed, consisting of a hydroxyl-rich conductive hydrogel (SNA) core and a hydrophobic insulating elastomer (HPC) shell, with encapsulation achieved through in situ polymerization by embedding wires. The SNA-HPC gel sensor demonstrates excellent signal stability (no signal attenuation during water entry and exit, over 3000 cycles of testing), ultra-high underwater sensitivity and conductivity (GF = 1.997, σ = 0.51), and outstanding self-adhesion (143.1 kPa in air/91.3 kPa underwater). Moreover, the interfacial bonding strength between SNA and HPC reaches 243.63 N m^-1. SNA-HPC is successfully applied in deep-learning-assisted swim posture recognition, Morse code-based underwater communication, and multi-scenario human-machine interaction through the SNA∗n-HPC matrix sensor. This work is expected to provide insights into the development of high-quality underwater wearable electronic devices and the multifunctionalization of underwater sensing.