Sweat-activated conductive hydrogel nanomesh for breathable, long-term electrophysiological monitoring and human-centric interfaces

Developing breathable and reusable ultrathin bioelectrodes is crucial for continuous electrophysiological monitoring. Thin, dry electrodes suit long-term use but lose hydrogel advantages like near-zero half-cell potential (HCP) and adhesion, critical for detecting weak physiological signals. Polymer nanomesh-reinforced breathable hydrogel electrodes offer interfacial improvement and last ∼10 days, yet performance degrades after extended time. This study introduces a "spinning-crosslinking-soaking" (SCS) technique to produce ultrathin (∼6 μm), self-standing conductive hydrogel nanomesh (CHN) electrodes with sweat-activated ionic conductivity and adhesion, enabling dynamic, long-term reuse. The versatility of the SCS technique was demonstrated by fabricating three types of biocompatible CHN electrodes, all exhibiting low skin impedance, negligible HCP, gas/moisture permeability, and skin-like mechanics. Paired with a miniature flexible circuit, the system exhibits high-fidelity electrophysiological monitoring and can be sweat reactivated for over 100 days without skin irritation. This innovation offers a significant advancement in long-term breathable bioelectrodes, facilitating health monitoring and seamless human-centric interactions.