A symbiotic skin hydrogel interface enabled by flexible hydrogel network with embedded enhancement structure.

Abstract

Wearable electrophysiological monitoring based on hydrogel electrodes is pivotal for decoding the body's "electrical language", yet fundamentally hampered by the unstable mechano-electrical interface between flexible electrodes and the skin caused by dehydration and poor breathability. Here, we demonstrate a symbiotic interface between an embedded-interfacial enhanced breathable conductive hydrogel network (BCHN) and skin for high-fidelity long-term electrophysiological monitoring. By embedding sodium chloride-containing polyvinyl alcohol hydrogel into an oxidized electrospun 3D porous polylactic acid skeleton, a BCHN with embedded enhanced interface featuring dense ion transport pathways and multiple water molecule-adsorbing sites is constructed. Upon application, the breathable (1.85 kg·m⁻²·day⁻¹, ~3× skin perspiration) flexible conductive hydrogel network with bending stiffness of ~10^-10N·m² seamlessly conforms to the microscopic landscape of the skin, forming a symbiotic BCHN-skin interface, which allows BCHN to "breathe" in harmony with the skin to preserve stable hydration and conductivity by dynamically balancing sweat capture, permeation, and evaporation, evidenced by a sustained 55 Ω impedance even at 20%RH. Integrated into a wearable monitoring system, the BCHN electrodes maintain high-quality signals (SNR > 25 dB) for over 30 days, thereby permitting the quantitative assessment and early warning of driver fatigue through long-term electroencephalography analysis.