Thermosetting Continuous Coaxial Spinning of PDMS/Liquid Metal Core–Sheath Fibers: Enabling Dual-Function Force-Electro-Thermochromic Sensing and Magnetically Actuated

Smart multifunctional fibers are essential for advanced wearables, but current technologies struggle to integrate sensing, visualization, and actuation in single fiber. In this study, we successfully fabricated color-hanging fibers with a pigment-containing polydimethylsiloxane (PDMS) sheath and a liquid metal (LM) core using a thermosetting continuous coaxial spinning technique. Fabrication employed a custom-designed coaxial spinneret coupled with a 135 °C silicone oil thermal curing bath, enabling simultaneous fiber formation and PDMS cross-linking. The incorporation of thermochromic microcapsules into the silicone shell enabled reversible color transitions. When subjected to force deformation (uniaxial stretching or local compression), the deformation of the LM core will cause a change in resistance, generating joule heat to activate the thermochromic response, and a grid-like sensing array was designed to achieve multimodal coupling of force, electricity, heat, and color. The fibers exhibited excellent performance in human joint motion monitoring and integration into smart textiles, offering both sensing functionality and visual temperature feedback. Moreover, under the influence of a magnetic field, the fibers demonstrated controllable bending behavior driven by a Lorentz force, realizing a mechanical actuation function based on energy conversion. This method establishes a new paradigm for multifunctional fiber manufacturing.