Smart semiliquid metal fibers with designed mechanical properties for room temperature stimulus response and liquid welding

Fiber-shaped electronics have attracted broad interests due to the surging demand for wearable devices in recent years. It is highly desired if we can design fiber or textile electronics that can respond to room temperature stimulus and be welded. In this work, we developed an efficient and scalable way to fabricate semiliquid metal coated conductive and weldable fibers in large quantity with various designed mechanical properties. The conductive fibers called Cu-Ga-In/fibers consist of natural and synthetic fiber cores, adhesive polymethacrylates coating and semiliquid metal (Cu-Ga-In) coating. Combining the unique mechanical properties of different fiber cores and high conductivity of Cu-Ga-In coating, conductive fibers with large tensile strength, knittability and strong stretchability are fabricated as high strength conductor, heater, and stretchable wire. Besides, Cu-Ga-In coating can realize liquid welding, response to room temperature stimulus and offer unique property of soft-stiffness switching. Finally, we demonstrated the applications of the Cu-Ga-In/fibers as 3D circuits and liquid bridges to reduce the resistance variation caused by the fiber stretching.