Biological skin-inspired damage warning and self-healing thermoelectric aerogel fiber via coaxial wet spinning for wearable temperature sensing

• Bionic autonomous self-healing thermoelectric fiber with damage warning (STDF) was developed • Dual reversible bonds enabled STDF to have 97.51% interfacial self-healing recovery • Visual damage warning of STDF was achieved via the chelation of Phen by Fe 2+ • STDF provided an ultrasensitive high-temperature alarm (within 2 s) from 100 to 500°C 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 Ti 3 C 2 T 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 Fe 2+ 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.