It's about the size of a bumblebee, and weighs just 190 milligrams (a bit more than a toothpick). It’s powered by an infrared laser aimed at that tiny little photovoltaic cell, which can harvest the 250 mW required to get the robot airborne. In the video, the laser doesn’t track the robot, so as soon as the solar cell moves out of the beam, it loses power and the robot stops flying.
(Don't swat RoboFly!)
The biggest hurdle for making cordless tiny robots was figuring out how to store the power that keeps them aloft. Flapping takes a lot of energy, so the equipment needed to hold enough power on minuscule devices would be so big that there would be no point in having such a tiny bot at all.
So the RoboFly traded a cable for a laser beam. Laser power constantly feeds energy to the robot from far away, so there’s no wire and no bulky battery.
RoboFly’s back has a solar cell that, when hit with a laser, converts light to electricity. Then, a circuit amps the power up to 240 volts — enough for flight. That same circuit also holds a basic computer called a microcontroller. This command center sends the voltage out in waves that stimulate different flapping speeds. Together, the solar cell, circuit, and metal fly body weigh about as much as a toothpick.