Flexible Tactile Sensing Microfibers Based On Liquid Metals

High-performance and intelligent fibers are indispensable parts of wearable electronics in the future. This work mainly demonstrates the preparation of flexible intelligent liquid metal (LM) fibers with three core-sheath structures. An ultra-thin (10-50 μm), conductive, and highly flexible LM was deposited on the fiber core [carbon/polyethylene terephthalate (C/PET)--150-500 μm] along the fiber direction and then deposited on a polymer-protective layer [polyvinyl alcohol/epoxy resin (PVA/EP)--10 μm]. Four kinds of LM intelligent fibers were manufactured, including the C-LM-PVA fiber, C-LM-EP fiber, PET-LM-PVA fiber, and PET-LM-EP fiber. These LM intelligent fibers (diameter, 150-600 μm) were demonstrated with a high conductivity of 7.839 × 10⁴ S·m^-1. The changes in resistance in different torsion directions were measured, and these smart LM fibers could also be used as electrical heaters or thermoelectric generators, which released heat (36-36.9 °C/1-1.5 V) into the environment. Then, these multifunctional LM fibers were applied as high-performance strain sensors and bending sensors. These flexible LM conductive fibers could be successfully utilized in intelligent wearable fabrics and were expected to be widely utilized in artificial muscle and sensor fields.