Gallium-Based Liquid Metal Flexible Electronics Prepared by Solid–Liquid Phase Transition

A facile fabrication method of pure gallium-based flexible electronics has been developed by using the solid–liquid phase transition at ambient temperature, effectively broadening the application of traditional processing techniques in these stretchable devices. The key point of this work is to make ductile Ga-based liquid metal wires, which exhibit superior mechanical properties with a tensile strength of 30 MPa and a break strain higher than 10%. Their fracture mechanisms were successfully investigated with their fracture morphology and Schmid’s law. Some electronic devices were prepared by patterning Ga-based wires in the form of U-shape, S-shape, and spiral shapes, and tested to obtain the variation in their structural resistance with stretching. Finite element method (FEM) simulations with the COMSOL code and analytical predictions were also performed to elucidate their piezo-resistance effect, and a good agreement among these predictions were reached. The present fabrication technique is of high simplicity, high efficiency, high quality, mass production, and low cost in making high-resolution, highly conductive, and three-dimensional flexible electronic devices.