Each of these robots measures just 2 x 1.8 x 0.8 millimeters. For comparison, a typical adult carpenter ant can measure anywhere from 6 to 20mm in length. These robots are so small that you’d have trouble even seeing one. That, of course, presents many unique challenges. They can’t have legs actuated by motors, like a conventional robot — there isn’t even room for a battery. Instead, the robots move using small vibrations. The specially-designed legs of the robots translate those vibrations into forward locomotion.
The robots are fabricated using two-photon polymerization lithography (TPP) 3D printing. The design looks simple: it’s just a body with either four or six legs. But the robots are carefully-designed to respond to specific vibration frequencies. With no electric parts, they can be moved using vibrations from an external source. Or, a tiny piezoelectric actuator backpack can create its own vibrations using an external power source. In both cases, the robots can be tuned to respond to different frequencies, so many robots can work simultaneously. Two can be put together so that they can turn by sending vibrations to one instead of the other. The team hopes that this design can be made even smaller, and eventually even work inside the human body.