Gas-permeable and anti-freezing organohydrogel epidermal electrodes for long-term health monitoring

The development of adaptable hydrogel bioelectronics capable of sustaining long-term, continuous operation is essential for advancing early disease diagnosis and enabling personalized healthcare solutions. However, challenges such as hydrogel dehydration, poor temperature adaptability, and weak mechanical strength hinder the engineering of ultrathin, gas-permeable organohydrogel epidermal electrodes for long-term use in complex environments. Here, we report an ultrathin, robust, gas-permeable, and freeze-resistant organohydrogel epidermal electrode for high-quality electrophysiological monitoring. The 17 µm-thick reinforced structure is readily achieved by dipping coating polyurethane nanomeshes into a high-temperature (55 ℃–75 ℃) gelatin-deep eutectic solvent solution and gelling at room temperature. The introduction of deep eutectic solvents significantly enhances the anti-freezing and anti-drying properties of the organohydrogel. The resulting organohydrogels exhibit superior mechanical robustness (1000 cycles at 100% strain), excellent adhesion performance (135.9 μJ·cm⁻²), high gas permeance (2.1 × 10⁻² cm³·cm⁻²·s⁻¹·cmHg⁻¹), great water vapor transmission rate (1130.5 g·m⁻²·day⁻¹), exceptional anti-freezing (−25 ℃), and anti-drying (98.6% weight retention after 7 days) properties. Herein, we validate the utility of these gas-permeable organohydrogel epidermal electronics for continuous, high-precision bio-signal acquisition, ensuring robust performance even within dynamic ambulatory settings.