Researchers make a million tiny robots
Nanofabbed bots are small enough to be delivered via syringe, raising all sorts of fantastic voyage possibilities. Nick Carne reports.
How do you build a very big army of very small robots? Start with a 10-centimetre silicon wafer.
That’s what engineers from the University of Pennsylvania in the US did to create a million of them in just a few weeks using nanofabrication techniques borrowed from the semiconductor industry.
Each robot is wirelessly powered, able to walk and survive harsh environments, and tiny enough to be injected through an ordinary hypodermic needle, which opens up all manner of possibilities.
"When I was a kid, I remember looking in a microscope and seeing all this crazy stuff going on. Now we're building stuff that's active at that size; we don't just have to watch this world, you can actually play in it,” says research leader Marc Miskin.
The smarts are in the robots’ legs, which are formed from a bilayer of platinum and titanium. When a laser light shines on their solar panels, the platinum expands but the titanium remains rigid, causing the legs to bend.
The robot's gait is generated because each solar cell causes the alternate contraction or relaxing of the front or back legs.
The legs are just 100 atoms thick, but they’re strong. "Each robot carries a body that's 1000 times thicker and weighs roughly 8000 times more than each leg," says Miskin.
The solar panels (two or four per unit) and the electronics control components are etched into a layer of silicon that sits on top of the robot’s rectangular glass skeleton.
Miskin presented the work to date at this week’s meeting of the American Physical Society in Boston.
Already he and colleagues at Pennsylvania and at Cornell University, also in the US, are working on ever smarter versions of the robots with on-board sensors, clocks and controllers.
In particular, they are looking at new energy sources, including ultrasound and magnetic fields, that would give the robots greater range and ultimately allow them to work in the human body, delivering drugs or mapping the brain.
"We found out you can inject them using a syringe and they survive,” Miskin says. “They're still intact and functional, which is pretty cool.”