Cornell University's laser-activated robot is smaller than a paramecium

They could one day crawl through our bloodstreams.

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Cornell University

Semiconductors aren’t the only silicon technology racing to outpace Moore’s Law. Researchers from Cornell University unveiled an entire robot that is teensy enough to fit most anywhere in the human body — yes, even in there — and inexpensive enough to produce on a mass scale.

The walking robots are the creation of Cornell physics professor Itai Cohen, professor of physical science Paul McEuen, and assistant professor at the University of Pennsylvania, Marc Miskin. This is not Cohen’s first microscopic rodeo, mind you. This work builds off of his previous efforts on origami-inspired, shape-shifting, micro-machines and manages to overcome a significant hurdle that’s been plaguing the field: the lack of a “micrometre-scale actuator system that seamlessly integrates with semiconductor processing and responds to standard electronic control signals,” according to the team’s study published Wednesday in Nature.

The robots themselves are only 5 microns thick, 40 microns wide and between 40 and 70 microns long, depending on the design. The brain and body consist of a silicon photovoltaic circuit while the legs are made from a quartet of electrochemical actuators.

“In the context of the robot’s brains, there’s a sense in which we’re just taking existing semiconductor technology and making it small and releasable,” McEuen told Cornell News. “But the legs did not exist before. There were no small, electrically activatable actuators that you could use. So we had to invent those and then combine them with the electronics.”

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Cornell University

The legs are layered from atom-thick strips of platinum with a titanium “cap” covering one end. When the platinum is exposed to an electric charge, negatively charged ions from the surrounding chemical solution absorb onto the platinum surface to neutralize the charge. That absorption causes the platinum leg to bend, though it’s thin enough to not break under the stress of repeated bendings. To encourage the robot to actually move, the team blasts the photovoltaics in its body with laser pulses. Each set of pulses targets a separate circuit which in turn controls a separate set of legs.

“While these robots are primitive in their function – they’re not very fast, they don’t have a lot of computational capability – the innovations that we made to make them compatible with standard microchip fabrication open the door to making these microscopic robots smart, fast and mass producible,” Cohen noted. “This is really just the first shot across the bow that, hey, we can do electronic integration on a tiny robot.”

And since they’re built using the same production method that semiconductors do, they can be mass produced the same way semiconductors are. In parallel and to the tune of roughly 1 million robots per 4-inch silicon wafer. The team envisions a day when swarms of these robots will swim through your bodily fluids, clearing plaques, repairing blood vessels, even probing into your grey matter.

“Controlling a tiny robot is maybe as close as you can come to shrinking yourself down. I think machines like these are going to take us into all kinds of amazing worlds that are too small to see,” Miskin concluded.

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