Highly Stretchable, Resistance‐Stable, Conductive Liquid Metal Core‐Sheath Fibers Enable Ultrastable and Supersensitive Physiological Monitoring

Abstract Stretchable fiber conductors hold immense potential for revolutionizing wearable electronics, but most reported materials show a decline in conductivity after large strains, significantly hindering their widespread application. In this study, a new strategy for preparing high‐performance stretchable conductive core‐sheath fibers is proposed using a coaxial wet spinning technique. The inherent superior properties of both styrene‐butadiene‐styrene (SBS) and liquid metal (LM), along with their synergic interactions, provide robust support for the exceptional tensile characteristics (1860.32% and 27.58 MPa) and distinctive electrical properties (4.14 × 10 4 S m −1 ) demonstrated by the composite SBS/LM fiber (SLMF). Notably, SLMF retained remarkable resistance stability (variation rate of only 105.31% under 800% tensile deformation) even under repeated strain, washing, and exposure to various extreme environments such as acids, bases, and high temperatures. Moreover, due to the unique grooved structure on the fiber surface, SLMF generates a high voltage output, maintaining ultrastable electrical output after prolonged exposure to high‐frequency mechanical impacts. Furthermore, the integration of SLMF into stretchable triboelectric sensors paves the way for hypersensitive joint movement sensing and respiratory status monitoring. Consequently, this discovery offers invaluable insights and guidance for the fabrication and advancement of conductive fibers for skin‐interfaced wearable electronics.