Sub-400 nanometer-thick skin and environment adaptable organohydrogel nanofilm epidermal electrode

Hydrogels are crucial for soft bioelectronics in long-term health monitoring; however, reconciling skin comfort with environmental resilience remains a major challenge. We present a 392 nm-thick organohydrogel nanofilm electrode that mimics skin deformation, offers high gas/water vapor/sweat permeability and heat transfer, and remains functional under various extreme conditions. The electrode comprises a genipin-crosslinked gelatin matrix, reinforced by polyurethane nanomeshes and plasticized with a glycerol/sodium chloride/tannic acid electrolyte. It achieves ultralow flexural rigidity (8.7 × 10^-11 nN·m), high stretchability (166.3% strain), toughness (3.0 MJ m^-3), adhesion (365.8 µJ cm^-2), and durability (1000 cycles at 100% strain). Solvent replacement strategies suppress ice formation and evaporation, preserving its physical and electrical performance under extreme conditions (-80-150 °C, 2% relative humidity, vacuum) and 200-day ambient storage. The organohydrogel nanofilm electrodes record stable electrocardiograms for 9 consecutive days with superior resistance to motion and sweat artifacts, offering a resilient platform for skin-integrated bioelectronics.