Tiny, self-assembling robots can swim and clamp onto particles and then release them when subjected to the right magnetic fields.

These mini robotic doughnuts spontaneously form from metal particles floating between a layer of oil and water, and could potentially be used to manipulate chemical reactions, deliver medical treatments in the body or clean surfaces.

“It’s really counter intuitive,” said physicist Igor Aranson, co-author of a study in Nature Materials, August 7. “There is nothing fancy about magnetic particles, you can just buy them. But if you pour them on the surface of a liquid, you can form robots which can do something useful.”(…)

Read the rest of this article by Danielle Venton on Wired.com: http://www.wired.com/wiredscience/2011/08/self-assembling-robots/