Micro-robots pick up a glass bead

Physicists at the US Department of Energy’s (DOE) Argonne National Lab, have coaxed “micro-robots” to do their bidding. The robots, just half a millimeter wide, are composed of microparticles. Confined between two liquids, they assemble themselves into star shapes when an alternating magnetic field is applied.
The scientists Alexey Snezhko and Igor Aronson can control the robots’ movement and even make them pick up, transport and put down other non-magnetic particles – potentially enabling fabrication of precisely designed functional materials in ways not currently possible.
HOW THEY DID IT
This was made possible by suspending the tiny ferromagnetic particles between two layers of immiscible, or non-mixing, fluids. Without a magnetic field, the particles drift aimlessly or clamp together. But when an alternating magnetic field is applied perpendicular to the liquid surface, they self-assemble into spiky circular shapes that the scientists nicknamed “asters”, after the flower.