Thin and Flexible Liquid Metal Wires Encapsulated by Thermal Contraction Tubes

Abstract A flexible, conductive wire with a liquid metal core is ideal for wearable devices and smart textiles. Current methods encapsulate liquid metal in hollow fiber tubes, but these lack insulation, have complex fabrication, and unstable reshaping. Here, a simpler approach is proposed using polyethylene (PE) thermal contraction tubes for easy handling and stable reshaping. Liquid metal is filled into the tubes before heat treatment, where they deform into thin wires. A reel motor ensures uniform stretching, allowing precise control over diameter and length. The resulting wires achieve a core diameter as small as ≈132 µm, matching advanced technologies, while the thick tube walls provide excellent insulation. The wires can partially recover their original length through heat‐induced rebounding, enabling repeated stretching and reshaping – ideal for high‐flexibility applications like smart wearables. Their use is demonstrated in NFC, smart gloves, pressure sensors, and proximity sensors, showcasing potential for flexible electronics. This method combines simplicity, insulation, and reshaping stability, offering broad applications in wearable technology.