A microvehicle with iron wheels (gold) and a polymer chassis (red). (Credit: Alcântara et al. Nature Communications 2020)

Using a new manufacturing technique, scientists have built microrobots out of metal and plastic, in which these two materials are interlocked as closely as links in a chain. The high-precision 3D printing technique produces complex objects on the micron level, a technique known as 3D lithography. The scientists produced a kind of mold or template for their micromachines. These templates have narrow grooves that serve as a negative and can be filled with the chosen materials. They filled some of the grooves with metal and others with polymers before ultimately dissolving the template away with solvents.

As a proof of principle, the scientists created various miniscule vehicles with plastic chassis and magnetic metal wheels powered by means of a rotating magnetic field. Some of the vehicles can be propelled across a glass surface, while others — depending on the polymer used — can float in liquid or on a liquid surface. They plan to refine their two-component micromachines and experiment with other materials. In addition, they will attempt to create more complex shapes and machines, including some that can fold and unfold themselves.

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