Dynamic Liquid Metal–Microfiber Interlocking Enables Highly Conductive and Strain‐insensitive Metastructured Fibers for Wearable Electronics

Abstract Stretchable fibers with high conductivity are vital components for smart textiles and wearable electronics. However, embedding solid conductive materials in polymers significantly reduces conductive pathways when stretched, causing a sharp drop in conductivity. Here, a stretchable metastructured fiber with dynamic liquid metal–microfiber interlocking interface is reported to realize highly conductive yet ultrastable conductance. The Cu‐EGaIn mixture is partially embedded within the porous microfiber mat, thereby enabling its roll‐up into a spiral‐layered metastructured fiber with self‐compensating conductive pathways. The metastructured fiber shows outstanding performance, including high conductivity of 1.5 × 10⁶ S m⁻¹, large stretchability up to 629%, and ultrastable conductance with only 16% relative resistance change at 100% strain, which far surpasses the theoretical value. Moreover, these fibers have served as versatile platforms for wearable temperature‐visualizing electrothermal fiber heaters and fully stretchable smart sensing‐display fabrics. This dynamic solid–liquid interfacial interlocking strategy is promising for stretchable electronics.