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Microbots made to turn as they swim

Diode, powered by an AC electric field, propelling back and forth on water by electronically modifying the applied AC field.

Scientists have figured out a way to remotely steer teeny, tiny robots that swim under their own power when placed in a fluctuating electric field — a breakthrough on the path to eventually using such machines for tasks such as delivering drugs and vaccines inside our bodies.

The millimeter-sized robots are essentially miniature diodes — electronic components that allow current to flow in one direction. To make them self propel, researchers apply an alternating electric field.

"They rectify the AC field and this makes them propel on water," Rachita Sharma, a graduate student in the department of chemical and biomolecular engineering at North Carolina State University, explained to me today.


Now, she and colleagues have been able to control the direction of these self-propelling diodes by introducing a DC component to the AC field. They believe the DC component leads to redistribution of the ions near the diode surface, which exerts a torque that causes the change in direction "making them shuttle forward and backwards on water," Sharma told me.

In order for the microbots to start delivering drugs in our bodies or seek out toxins will require even greater control of the microbots so that they can turn at any angle. They also need to be smaller and biocompatible. "So, a lot of additional work," Sharma said.

The research will be presented March 25 at a meeting of the American Physical Society. You can read the abstract here

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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).