New Harvard's RoboBee micro-robot flies, dives, swims, and explodes out the of water

We’ve seen RoboBees that can fly, stick to walls, and dive into water. Now, Inspired by insects, researchers at the Wyss Institute and Harvard SEAS have developed a hybrid robot that can fly, dive into water, swim, propel itself back out of water, and safely land.

New, hybrid RoboBee can fly, dive into water, swim, propel itself back out of water, and safely land. The RoboBee is retrofitted with four buoyant and a central gas collection chamber. Once the RoboBee swims to the surface, an electrolytic plate in the chamber converts water into oxyhydrogen, a combustible gas fuel. Image courtesy of Wyss Institute at Harvard University

This latest-generation RoboBee, which is 1,000 times lighter than any previous aerial-to-aquatic robot, could be used for numerous applications, from search-and-rescue operations to environmental monitoring and biological studies.

The research is described in Science Robotics. It was led by a team of scientists from the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS).

“This is the first microrobot capable of repeatedly moving in and through complex environments,” says Yufeng Chen, Ph.D., currently a Postdoctoral Fellow at the Wyss Institute who was a graduate student in the Microrobotics Lab at SEAS when the research was conducted and is the first author of the paper. “We designed new mechanisms that allow the vehicle to directly transition from water to air, something that is beyond what nature can achieve in the insect world.”

Once the robot swims to the surface of the water, surrounding water is collected in a buoyancy chamber. Within the chamber, an electrolytic plate produced oxyhydrogen. This gives the robot extra buoyancy, which enables it to push its wings out of the water. The water surface tension keeps the robot upright as the wings start to flap. A sparker then ignites the combustible oxyhydrogen, giving the robot a boost, allowing it to jump off the water surface. Hybrid aerial-aquatic robots could be used for environmental explorations and search and rescue missions.

Another question is design a millimeter-sized robot that moves in and out of water has numerous challenges. First, water is 1,000 times denser than air, so the robot’s wing flapping speed will vary widely between the two mediums. If the flapping frequency is too low, the RoboBee can’t fly. If it’s too high, the wing will snap off in the water.

By combining theoretical modeling and experimental data, the researchers found the Goldilocks combination of wing size and flapping rate, scaling the design to allow the bee to operate repeatedly in both air and water. Using this multimodal locomotive strategy, the robot to flaps its wings at 220 to 300 hertz in air and nine to 13 hertz in water.