Sub-400 nanometer-thick skin and environment adaptable organohydrogel nanofilm epidermal electrode
Zonglei Wang, Yuli Wang, Jiawei Yang, Pengcheng Zhou, Wenqing Yan, Shihong Lin, Yujie Zhang, Qing‐Yuan Sun, Yumiao Xu, Zichong Ji, Mingzhe Wang, Zongman Zhang, Junhong Yi, Junhong Yi, Xuezhong He, Lulu Sun, Sunghoon Lee, Tomoyuki Yokota, Hossam Haick, Takao Someya, Yan Wang, Yan Wang, Yan Wang
Abstract
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. Hydrogels can be integrated into skin bioelectronics, though balancing stability, mechanical properties, and breathability remains challenging. Here the authors design a crosslinked organohydrogel using a solvent replacement strategy integrated into on-skin sensors.