Engineers at the University of California, Berkeley, have developed the world’s smallest wireless flying robot, weighing only 21 milligrams and measuring less than one centimeter in diameter. This insect-inspired device can hover, change direction, and target small objects. UC Berkeley's Liwei Lin, Distinguished Professor of Mechanical Engineering, noted that "bees exhibit remarkable aeronautical abilities, such as navigation, hovering and pollination, that artificial flying robots of similar scale fail to do."

The new robot is described in a paper published on March 28 in Science Advances. It was created to mimic the flight behavior of insects like bumblebees. The team used an external magnetic field to power and control the device, as integrating a power source and electronics into such a small device presented challenges. The robot's propeller, outfitted with small magnets, spins under a magnetic field, generating enough lift for flight control through modulation of the field's strength.

The next largest robot with such capabilities measures 2.8 cm in diameter, significantly larger than this latest development. Fanping Sui, co-first author and recent UC Berkeley Ph.D. graduate, explained that "tiny flying robots are useful for exploring small cavities and other complicated environments." Sui noted potential applications in artificial pollination or inspecting confined spaces.

Currently, the robot can only achieve passive flight and lacks onboard sensors for real-time trajectory adjustments. Wei Yue, another co-author from UC Berkeley, expressed plans for future enhancements: "In the future, we will try to add active control, which would allow us to change the robot’s attitude and position in real time."

The robot requires a strong magnetic field from an electromagnetic coil; however, further miniaturization could enable control using weaker fields, like radio waves. Yue is also working on swarming robots inspired by ants, which could perform collaborative tasks, including medical procedures. "I’m working with 5-millimeter-scale robots that can crawl, roll and spin, and they can also work together to form chains and arrays, or do even harder tasks," Yue said.

The team also includes Kamyar Behrouzi, Yuan Gao, and Mark Mueller from UC Berkeley. Funding for this research was provided by the Berkeley Sensor and Actuator Center.