Imagine a swarm of microrobots—tiny devices a few hair widths across—swimming through your blood vessels and repairing damage, or zipping around in computer chips as a security lock, or quickly knitting together heart tissue. Researchers at the University of California, Berkeley, Dartmouth College, and Duke University have shown how to use a single electrical signal to command a group of microrobots to self-assemble into  larger structures. The researchers hope to use this method to build biological tissues. But for microrobots to do anything like that, researchers must first figure out a good way to control them.

"When things are very small, they tend to stick together," says Jason Gorman, a robotics researcher in the Intelligent Systems Division at NIST who co-organizes an annual microrobotics competition that draws groups from around the world. "A lot of the locomotion methods that have been developed are focused on overcoming or leveraging this adhesion."