Structurally programmable biomimetic helical fibers for hazard sensing and adaptive thermal management.

The development of fiber systems that integrate ultrahigh stretchability, stable electrical conductivity and multifunctional responsiveness remains a central challenge in wearable electronics. Herein, two types of silver nanoparticles/polyurethane (AgNPs/PU) -based ultrastretchable helical fibers are engineered via non-isometric coaxial wet spinning, nanocoating deposition and reverse-twist structural regulation. The resulting fibers feature topologically defined helical architectures, while a polyvinylpyrrolidone (PVP) -assisted strategy enables the robust immobilization of AgNPs, thereby establishing a reliable and durable conductive network. Benefiting from this structural design, the fibers exhibit exceptional mechanical compliance, including ultrahigh elongation at break, rapid elastic recovery and stable electrical performance under large deformation. Notably, the conductive pathways remain continuous during stretching, leading to strain-insensitive Joule heating behavior and excellent long-term durability. Functionally, the conventional helical fibers display high sensitivity to large strain, mechanical impact and solvent stimuli, enabling multimodal sensing capabilities. Additionally, the tubular helical fibers exhibit strain-triggered adaptive thermal regulation under low mechanical input. This work establishes a topology-guided design strategy that couples structural evolution with functional performance, offering a versatile platform for next-generation intelligent textiles operating under complex and dynamic conditions.