Programmable Digital Liquid Metal Droplets in Reconfigurable Magnetic Fields.

Gallium-based liquid metals exhibit excellent locomotion and deformation capabilities under external stimuli and has potential in developing intelligent robots. Programing the locomotion and morphology of the Liquid metal (LM) to endow it with functionalities and intelligence as robots is charming but remains challenging. In this study, we develop a programmable digital LM (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 a magnetic field are due to the interplay of surface tension and magnetic forces. Furthermore, we present a functional cooperative droplet robot by equipping the MLM droplets with three-dimensionally printed microtool modules. We show that both the position and orientation of a rod-shaped object can be precisely manipulated by the cooperation of 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 programing a group of MLM droplets to accomplish a digital display task. We believe that 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, multifunctionalities, and intelligence.