Researchers at the University of Pennsylvania have developed microscopic robots that could enable scientific exploration at a microscopic level. These new robots are too small to be seen with the naked eye: about 5 microns thick, 40 microns wide and ranging from 40 to 70 microns in length. While there is nothing new about microscopic robots, what makes this innovation different is that they are capable of moving by themselves. This has been achieved by developing a new type of actuator from an extremely thin layer of platinum on each of the robots four legs. These are connected to solar cells that bend the robots’ legs in response to laser light. Although these robots are only capable of movement at the moment and have a sluggish top speed of 30 microns per second, this has provided an important proof of concept that it is possible to mass produce microrobots with onboard electronics. They are small enough to be injected through hypodermic needle and are made from biocompatible materials, so there is potential for them to roam inside the human body.