These bots were made for walkin’

Cosmos Magazine


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A Cornell University collaboration is trying to up the ante on walking robots by developing some you can control with standard electronic signals.

They’re tiny (the kind that scientists hope will one day be able to travel through human tissue), but large enough to include semiconductor components.

The key is the development of a new class of micrometre-scale actuator – a component that makes robots move – that is compatible with existing silicon electronics.

And that, Itai Cohen and colleagues suggest in a paper in the journal Nature, could provide a template for building even more complex versions that use silicon-based intelligence and can be mass produced.

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

The bots are five microns thick (a micron is one-millionth of a metre), 40 wide and 40-70 long. Each consists of a simple circuit made from silicon photovoltaics – which essentially functions as the torso and brain – and four electrochemical actuators that function as legs.

You control them by flashing laser pulses at different photovoltaics, each of which charges up a separate set of legs. By toggling the laser back and forth between the front and back photovoltaics, the robot walks.

The researchers say they are strong and robust for their size – surviving highly acidic environments and temperature variations of more than 200 degrees Kelvin – and can be injected through hypodermic needles.

They also use very little power and, because they are made with standard lithographic processes, can be fabricated in parallel. About a million fit on a 10-centimetre silicon wafer.

It has to be acknowledged that they currently have limited function; they are slower than other swimming robots, they do not sense their environments, and they lack integrated control.

However, Cohen and colleagues say they are exploring ways to soup them up with more complicated electronics and onboard computation.

A microscopic robot walking in a circle. Its locomotion can be changed by altering the pattern of the rigid panels. Here the back legs are rotated slightly relative to the body during fabrication. Credit: Marc Miskin

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