Researchers at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS) have built an insect-size robot that is capable of flying and swimming.

SEAS experts have successfully demonstrated the tiny robot. The engineers presented their research in a recent paper at the International Conference on Intelligent Robots and Systems in Germany.

A major challenge for the researchers was the fact that aerial vehicles need large airfoils such as wings to generate lift. Underwater, however, vehicles need as small a surface area as possible to reduce drag. Puffins, which use similar flapping motions in the air and underwater, provided inspiration for Harvard’s experts, according to SEAS.

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“Through various theoretical, computational and experimental studies, we found that the mechanics of flapping propulsion are actually very similar in air and in water,” said Kevin Chen, a graduate student in the Harvard Microrobotics Lab at SEAS, in a statement. “In both cases, the wing is moving back and forth. The only difference is the speed at which the wing flaps.”

The Harvard RoboBee is described as being smaller than a paperclip, but can fly and hover thanks to its tiny wings. The microbot’s wings beat 120 times per second, according to SEAS.

The tiny size of the RoboBee, however, makes it difficult for the robot to break the surface tension of water. To overcome this problem the robot hovers over the water at an angle, and then briefly switches off its wings before crashing into the water and sinking.

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To cope with the density of the water, RoboBee’s wings flap just 9 times per second underwater.  

At this stage, though, RoboBee is unable to generate enough lift to propel itself from water to air.