Abstract: Biopolymer-based temperature-sensing fibers are increasingly employed to realize the eco-friendly concept of wearable electronics. However, keeping their long-term development remains challenging due to limited mechanical robustness and poor environmental tolerance. Herein, a bionic autonomous self-healing thermoelectric (TE) aerogel fiber with visual damage warning function (STDF) inspired by biological skin was prepared via a coaxial wet spinning strategy, which yielded a core-shell heterogeneous structure with a protective sheath with an intrinsic self-healing ability and a temperature-sensing core layer. The core layer of STDF, composed of flexible thermoplastic polyurethane embedded with rigid Ti₃C₂T_x MXene, effectively minimizes disruptions in continuous conductive pathways during repeated extreme bending. Featuring a synergistic network of reversible hydrogen bonds and dynamic Schiff-base linkages constructed among oxidized alginate, sericin, and tannic acid, the fractured STDF aerogel fiber exhibits exceptional water-responsive self-healing efficiency (97.51 % stress recovery). Moreover, the visual damage location in STDF fiber is enabled through a coloration reaction at the damaged interface between the Fe²⁺ ions and 1,10-phenanthroline incorporated into the core and sheath layers, respectively. Furthermore, the resultant STDF demonstrates a wide-range temperature-sensing performance at 100-500 °C and an ultrasensitive alarm response time (within 2 s) when encountering fires. This work sheds new light on the design of bionic temperature sensing fibers with environment-adaptive self-healing and damage warning abilities for improved reliability and durability in real-world wearable application scenarios.

Key words: Thermoelectric aerogel fiber, Coaxial wet spinning, Damage detection and warning, Self-healing, Multiple reversible bonds, Wearable temperature sensing