Myelin\nSheath-Inspired Hydrogel Electrode for Artificial\nSkin and Physiological Monitoring

Significant\nadvancements in hydrogel-based epidermal electrodes\nhave been made in recent years. However, inherent limitations, such\nas adaptability, adhesion, and conductivity, have presented challenges,\nthereby limiting the sensitivity, signal-to-noise ratio (SNR), and\nstability of the physiological-electrode interface. In this study,\nwe propose the concept of myelin sheath-inspired hydrogel epidermal\nelectronics by incorporating numerous interpenetrating core–sheath-structured\nconductive nanofibers within a physically cross-linked polyelectrolyte\nnetwork. Poly(3,4-ethylenedioxythiophene)-coated sulfonated cellulose\nnanofibers (PEDOT:SCNFs) are synthesized through a simple solvent-catalyzed\nsulfonation process, followed by oxidative self-polymerization and\nionic liquid (IL) shielding steps, achieving a low electrochemical\nimpedance of 42 Ω. The physical associations within the composite\nhydrogel network include complexation, electrostatic forces, hydrogen\nbonding, π–π stacking, hydrophobic interaction,\nand weak entanglements. These properties confer the hydrogel with\nhigh stretchability (770%), superconformability, self-adhesion (28\nkPa on pigskin), and self-healing capabilities. By simulating the\nsaltatory propagation effect of the nodes of Ranvier in the nervous\nsystem, the biomimetic hydrogel establishes high-fidelity epidermal\nelectronic interfaces, offering benefits such as low interfacial contact\nimpedance, significantly increased SNR (30 dB), as well as large-scale\nsensor array integration. The advanced biomimetic hydrogel holds tremendous\npotential for applications in electronic skin (e-skin), human-machine\ninterfaces (HMIs), and healthcare assessment devices.