High‐Conductivity, Self‐Healing, and Adhesive Ionic Hydrogels for Health Monitoring and Human‐Machine Interactions Under Extreme Cold Conditions

Abstract Ionic conductive hydrogels (ICHs) are emerging as key materials for advanced human‐machine interactions and health monitoring systems due to their unique combination of flexibility, biocompatibility, and electrical conductivity. However, a major challenge remains in developing ICHs that simultaneously exhibit high ionic conductivity, self‐healing, and strong adhesion, particularly under extreme low‐temperature conditions. In this study, a novel ICH composed of sulfobetaine methacrylate, methacrylic acid, TEMPO‐oxidized cellulose nanofibers, sodium alginate, and lithium chloride is presented. The hydrogel is designed with a hydrogen‐bonded and chemically crosslinked network, achieving excellent conductivity (0.49 ± 0.05 S m −1 ), adhesion (36.73 ± 2.28 kPa), and self‐healing capacity even at −80 °C. Furthermore, the ICHs maintain functionality for over 45 days, showcasing outstanding anti‐freezing properties. This material demonstrates significant potential for non‐invasive, continuous health monitoring, adhering conformally to the skin without signal crosstalk, and enabling real‐time, high‐fidelity signal transmission in human‐machine interactions under cryogenic conditions. These ICHs offer transformative potential for the next generation of multimodal sensors, broadening application possibilities in harsh environments, including extreme weather and outer space.