Nature 570, 491–495 (2019)

Tiny robots that mimic the flying abilities of insects could be more nimble and manoeuvrable than other flying machines, such as fixed-wing drones, allowing them to navigate intricate spaces. However, these flapping-wing vehicles typically need to be attached to off-board power supplies and signal generators in order to fly. Noah Jafferis and colleagues at Harvard University have now developed an untethered, insect-sized robot called RoboBee X­-Wing.

Credit: Noah T. Jafferis and E. Farrell Helbling, Harvard Microrobotics Laboratory

RoboBee has four wings that are driven by piezoelectric actuators and a span of only 3.5 centimetres. To power the vehicle, solar cells are incorporated above the wings. The low voltages (around 5 V) generated by the solar cells are then converted to the high-voltage (around 200 V), time-varying signals needed to drive the vehicle by power electronics incorporated below the wings. The complete integrated system is around five centimetres long and weighs just 259 milligrams.

With a light source of approximately three suns, the robot is capable of flying for only around half a second, before moving out of the illuminated area. However, the researchers also note that RoboBee could incorporate an extra payload of around 70 milligrams, which could be used to carry a larger power supply such as a bigger solar cell array or a battery.