Programmable Digital Liquid Metal Droplets in Reconfigurable Magnetic Fields.

Gallium based liquid metal (LM) exhibits excellent locomotion and deformation capabilities under external stimuli and have presented potentials in developing intelligent robots. Programming the locomotion and morphology of LM to endow it with functionalities and intelligence as robots is charming but remains challenging. In this study, we develop a programmable digital liquid metal (PDLM) control platform that can realize versatile locomotion and morphological manipulation of magnetic LM (MLM) droplets using arrays of electromagnets. We demonstrate on-demand transportation, deformation, breakup and merging of multiple MLM droplets simultaneously and precisely. We find that the intriguing behaviors of MLM under magnetic field is owning to the interplay of surface tension and magnet forces. Furthermore, we present a functional cooperative droplet robot by equipping the MLM droplets with 3D printed micro-tool modules. We show that both position and orientation of a rod-shaped object can be precisely manipulated by the cooperation the MLM droplet robots. More interestingly, we explore the capability of the MLM droplet robots for cooperatively handling a copper wire to connect and disconnect electronic circuits. Finally, we demonstrate that the PDLM control platform is capable of programming a group of MLM droplets to accomplish a digital display task. We believe the PDLM control system presents a promising potential in developing LM based reconfigurable circuits, digital display systems, and biomimetic soft robotic systems with high controllability, multi-functionalities and intelligence.