Sodium alginate-based eutectogel fibers with high-speed ion channels with extreme environmental resilience and...

Hydrogel fibers have attracted considerable attention in sports science and healthcare for their merits on natural flexibility and favourable conductivity. However, creating hydrogel fiber sensors with flexibility at cryogenic temperatures and high-resolution responses to various environmental stimuli is still a tough problem. In this study, the fibers were fabricated using sodium alginate as the matrix and gelatin as the reinforcing phase, while deep eutectic solvent (DES) was chosen as the conductive phase. The eutectogel fiber sensors capable of real-time detection of multiple environmental signals were obtained through a strategy of wet spinning combined with solvent exchange. The tubular fiber structure provides more binding sites for DES molecules, improving flexibility and electrical conductivity. The presence of numerous strong and dense hydrogen bond chains within DES prevents them from freezing at temperatures as low as -70 °C. The sensors accurately monitored subtle strains (0.1%) and minute external humidity variations while simultaneously tracking human joint motion and respiratory activity. The fibers demonstrated excellent tensile strength (2.9 MPa), high electrical conductivity (1.44 mS·cm^-1), dehydration resistance and potential for large-scale production. This work presents a promising platform to the actualization of advanced motion monitoring and the next-generation wearable sensing applications.