The researchers remotely controlled swimming magnetic particles to form assembly lines that pick up and move other objects -- even objects much bigger and heavier than they are.
Such self-assembling micro-machines, which measure half a millimeter wide, could enable precise and delicate work that has not been previously possible.
Though this work is in the research phase, it could have multiple implications. The mini-robots could manipulate chemical reactions, transport medical treatments to specific places in the body, remove particles for further study or clean surfaces.
At first, when sandwiched between layers of water and oil, ferromagnetic particles will float aimlessly. But when the researchers placed an alternating magnetic field perpendicularly to the liquid, the particles formed circular shapes that the scientists called asters, a similarly shaped flower.
When a second magnetic field is applied parallel to the liquid, the asters begin swimming. Then the researchers can remotely control the asters' motion by changing the magnetic field. In a press release, Argonne Labs scientist Alexey Snezhko said,
"We can make them open their jaws and close them. This gives us the opportunity to use these creatures as mini-robots performing useful tasks. You can move them around and pick up and drop objects."
As you can see in the video below, one aster curls up and carries a small glass bead, which is four times its weight.
In this video, four asters grouped together act like a mini-vacuum cleaner, collecting free-floating particles.