US engineers create injectable walking robot bugs

The microscopic robots, which are each just 70 microns long, were produced using a multistep nanofabrication technique that turns a 4-inch specialised silicon wafer into a million microscopic robots in just weeks.

"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," explained Marc Miskin, assistant professor at the University of Pennsylvania, who developed the techniques whilst a post-doc at Cornell University with his colleagues professors Itai Cohen and Paul McEuen and researcher Alejandro Cortese.

The robots' bodies are formed from a superthin rectangular skeleton of glass topped with a thin layer of silicon into which the researchers etch its electronics control components and either two or four silicon solar cells.

Each of a robot's four legs is formed from a bilayer of platinum and titanium (or alternately, graphene). The platinum is applied using atomic layer deposition and the platinum-titanium layer is then cut into each robot's four 100-atom-thick legs. "The legs are super strong," he said. "Each robot carries a body that's 1,000 times thicker and weighs roughly 8,000 times more than each leg."