Magnetically Controllable Liquid Metal Marbles

Gallium-based liquid metal alloys (LMAs) are extensively studied and used recently due to their excellent fluidity, high conductivity, and low evaporation pressure. Nonwettable and nonsticky liquid metal marbles (LMMs) are also developed to address the stickiness issue of oxidized LMAs in air. Current LMMs, however, lack acceptable controllability, shape stability, and robustness, greatly limiting their practical application. Here, a magnetically controllable liquid metal marble (MCLMM) that is noncorrosive and nonsticky, and exhibits good elasticity and mechanical robustness, is presented. The as-obtained MCLMM consists of a soft liquid metal core coated with a mixture of ferronickel (FN) and polyethylene (PE) microparticles. This combined structure shows excellent magnetic controllability, good elasticity, and favorable mechanical robustness, as demonstrated by contact angle measurements, rolling angle measurements, corrosive testing, magnetically actuated locomotion, and impact and bounce tests. The MCLMM also possesses satisfying stability in air and stability against temperature changing. In addition, its capabilities are demonstrated as a robotic motor, controllable obstacle cleaner, and a flexible switch for circuits, which shows the potential for MCLMM applications in robotic locomotion and manipulation, electronic circuits, and beyond.