Integrated core-shell structured polyimide thermoelectric fiber with latent light-driven damage detection and self-driven temperature sensing performance

The rapid advancement of flexible electronics imposes escalating demands on high-performance thermoelectric materials, particularly in extreme environments such as fire rescue operations, where mechanical stability and multifunctionality must be synergistically integrated. This study, developed a polyimide (PI)-based core sheath thermoelectric fiber (PT-SCF) with adjustable pore networks using non-solvent induced phase separation assisted coaxial wet spinning technique. The fiber sheath layer uses PI as the substrate, and polyvinyl alcohol (PVA) as the pore regulator agent to regulate the pore size (∼1.77–3.23 µm), while the introduction of 2D MXene nanosheets endowed the fiber with the ability of temperature sensing (maximum output voltage of 7.9 mV). The fiber core layer combines thermoplastic polyurethane (TPU) and ultraviolet (UV) photosensitive materials (UVs) to achieve fiber damage detection through a UV light-driven mechanism. The optimized PT-SCF has excellent mechanical properties (4.1 MPa, (R-R 0 )/R 0  < 10 %) and flame retardancy (LOI≈37.4 %). Its thermoelectric conversion efficiency is outstanding, with a linear positive correlation between output voltage and temperature (R 2  = 0.99). In addition, the PT-SCF realizes fast high-temperature warning in 1.6 s. Its integration with a multi-level temperature threshold high-temperature warning system highlights its potential for applications in smart fire-fighting systems and wearable electronic devices. This work presents a novel approach for designing and developing multifunctional thermoelectric fibers tailored to various harsh environments.