The microscopic robots consist of a simple circuit made from silicon photovoltaics – essentially the torso and brain – and four electrochemical actuators that function as legs. When laser light is shined on the photovoltaics, the robots walk. (Image: Cornell University)

A Cornell University team has created microscopic robots that incorporate semiconductor components, allowing them to be controlled – and made to walk – with standard electronic signals. The robots are about 5 microns thick, 40 microns wide, and range from 40 to 70 microns in length.

Each consists of a simple circuit and four electrochemical actuators that function as legs. Since there were no small, electrically activatable actuators that could be used, the team had to invent them and then combine them with the electronics. The robots are controlled 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.