Stable Liquid-Metal-Based Magnetic Droplet Robot Enabled by ATRP-Grafted PMMA on Cobalt Ferrite Particles

Liquid-metal-based magnetic droplet robot attract considerable attentions due to their noncontact operation, rapid response, strong maneuverability, and deformability. However, prolonged use leads to gradual alloying between the liquid-metal and magnetic particles, which causes a progressive decline in magnetic performance until complete loss. In this work, we report a strategy to address both the alloying and interfacial nonwettability between the liquid-metal and magnetic particles via a poly-(methyl methacrylate) (PMMA) layer onto the magnetic particles via atom transfer radical polymerization (ATRP). Subsequently, liquid-metal-based magnetic droplet robot was constructed to perform rapid locomotion and targeted cargo transport in complex environments under actuation of external magnetic field. Finally, liquid-metal-based magnetic droplet robot can achieve reversible circuit switching or long-term repair of damaged circuits. This work presents a new methodology for fabricating liquid-metal-magnetic particle composites. The resultant droplet robot exhibit outstanding performance, thereby holding significant promise for future use in biomedical, electronic, and related fields.