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One signal herds microbot swarm

Igor Paprotny / Thayer School of Engineering

Researchers have managed to control a swarm of microbots with a single signal. The breakthrough may eventually lead to robots that are able to build tissues inside the human body.

With the application of a single electrical signal, researchers can control swarms of tiny robots to assemble themselves into structures. 

"We are controlling these robots kind of like remote controlled cars," Igor Paprotny, a postdoctoral scientist at the University of California at Berkeley who is co-leading the research effort, told me Friday. 

Instead of one controller transmitting a signal to steer one car, the signal controls several cars at once, sending each in a slightly different direction. 

This is accomplished by building each microbot so that they behave in a different way when they get the signal. Paprotny said to think of the robots as individual pieces of a puzzle. When controlled by the global the signal, they come together to build and solve the puzzle.

Control breakthrough
The breakthrough in control of the tiny robots, each a few hair widths across, overcomes a problem of stickiness at small scale due to the same type of forces that allow geckos to scurry across the ceiling.

Researchers have previously controlled tiny machines with the use of magnetic fields, MIT's Technology Review reports, but the equipment is complex and robot control is difficult at best.

The idea of controlling microbots with an electrical signal was first presented in 2005 by team co-leader Bruce Donald, a professor of computer science and biochemistry at Duke University. 

Now, the team is able to control several microbots at once to perform a singular task.

The assembly breakthrough could eventually lead to applications such as sending swarms of robots into the body to build tissues, such as a new wall for a damaged capillary.

More complex robots could assemble themselves into tools to perform surgery or make images, Paprotny explained. 

Keeping it simple
To date, the team has created a set of four simple silicon robots which have been tweaked to move in slightly different ways on a surface. MIT's Technology Review describes them this way:

The robots contain an actuator called a scratch drive, which bends in response to voltage supplied through the electric array. When it releases tension, it goes forward, in a movement similar to an inchworm's. But the key to the robots' varying behavior is the arms extending from the actuators. ... To control a swarm, the team designed each robot with an arm that reacts differently during portions of the voltage signal.

"We keep the robots simple, but we can achieve this very rich behavior which allows us now to assemble these shapes," Paprotny told me.

The next step is to move from this substrate to a system that can function in a liquid environment, allowing the robots to move and assemble 3-D structures. This is needed for tissue assembly.

A collaborator, Ali Khademhosseini at Harvard Medical School, envisions the robots building tissue cells as they assemble themselves.

"The cells, once they're assembled, come off from the robots letting cells rearrange further to make things that are indistinguishable from natural tissue," he told MIT Technology Review.

"But right now," he added, "the challenge is we're still not very good at making each of these individual components."

More stories on tiny robots: 

John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).