for National Geographic News
Researchers have built one of the world's smallest controllable robotsa machine tinier than the period that ends this sentence.
The miniscule device is as narrow as a human hair. Its inventors note that some 200 of them could line up across the top of an M&M candy.
A lab headed by Bruce Donald, a computer science professor at Dartmouth College in Hanover, New Hampshire, designed the robot. It was unveiled earlier this month at the 12th International Symposium of Robotics Research in San Francisco.
The machine can be steered anywhere on a specially designed surface. It moves with a wormlike crawl and turns by dragging a silicon "foot" around which it can pivot.
"Machines this small tend to stick to everything they touch, the way the sand sticks to your feet after a day at the beach," said Craig McGray, who earned a Ph.D. in computer science working on the robot.
"So we built these microrobots without any wheels or hinged joints, which must slide smoothly on their bearings. Instead these robots move by bending their bodies like caterpillars."
Small But Fast
A special floor provides a power signal to the robot anywhere on its surface, like a bumper car at an amusement park. Embedded in that power signal are instructions that the robot interprets, determining whether to go forward or to turn.
The machine can take thousands of "steps" per second, though each step is a tiny 10 nanometers (a nanometer is one billionth of a meter). It is tireless and, for its size, amazingly fast.
In half an hour, the robot can cover a foot (a third of a meter) in some 35 million steps. For a human, a proportionately similar stroll would lead half way around the world.
"Cleary it's a really neat thing to have done," said Kristofer Pister, a professor in the University of California at Berkeley's Robotics and Intelligent Machines Laboratory.
"There is a whole community of researchers that has been trying to get things to move around at the sub-millimeter scale, and [the robot's designers] have succeeded in one aspect of that far better than anyone else has."
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