Researchers at the University of Pennsylvania have developed wireless bug-shaped microrobots using nanofabrication techniques. They are able to produce a million of the devices from a 4-inch silicon wafer. The microrobots can “walk,” survive in harsh environments, and can function even after passing through a hypodermic syringe, suggesting that they may have potential as injectable drug-delivery devices.
The microrobots are powered using on-board silicon solar cells and are only 70 microns long, the width of a thin human hair. Consisting of a glass skeleton coated with a thin silicon layer, the devices contain electronics control components that the researchers etch in place, and titanium/platinum bilayers form the legs of the robots. Each leg is just 100 atoms thick.
“The really high-level explanation of how we make them is we’re taking technology developed by the semiconductor industry and using it to make tiny robots,” said Marc Miskin, a researcher involved in the study.
To actuate the robots, the researchers shine a laser on them, which creates power through the on-board solar cells. This results in the platinum layer expanding, which causes the legs to bend. Different solar cells power the front and back legs, meaning that they can bend in sequence to create movement. “The legs are super strong,” said Miskin. “Each robot carries a body that’s 1,000 times thicker and weighs roughly 8,000 times more than each leg.”
The current devices represent a proof-of-concept, but the researchers hope to create more sophisticated versions of the robots with on-board sensors and controllers.