Harvard's new robotic cockroach can walk on water surface, survive underwater

Have you heard the commonly cited anecdote about how cockroaches can survive a nuclear explosion? Well, that’s not actually true , although their simple body design does equip them to withstand extreme levels of radiation. But other cool attributes of cockroaches have also fascinated humans for centuries, such as their ability to survive underwater for up to 30 minutes.

Now Harvard University’s new robotic cockroach can do even better. The Harvard’s Ambulatory Microrobot (HAMR) can walk on land, swim on the surface of water and even walk underwater for as long as necessary.

The HAMR paddles on the water surface using custom designed swimming gaits and four pairs of asymmetric flaps. Because of how the robot’s passive flaps interact with the surrounding water, the robot generates swimming gaits similar to that of a diving beetle, allowing the robot to effectively swim forward and turn left or right.

Here is the science HAMR employs to complete its task, as explained in the  The Harvard Gazette , “The HAMR uses multifunctional foot pads that rely on surface tension and surface tension induced buoyancy when HAMR needs to swim, but can also apply a voltage to break the water surface when HAMR needs to sink. This process is called electrowetting, which is the reduction of the contact angle between a material and the water surface under an applied voltage. This change of contact angle makes it easier for objects to break the water surface.”

The robot weighs a mere 1.65 gram and is extremely small in size. It can, however, carry 1.44 gram of additional payload without sinking.

“HAMR’s size is key to its performance,” Neel Doshi, graduate student and co-author of the paper, was quoted as saying. “If it were much bigger, it would be challenging to support the robot with surface tension and if it were much smaller, the robot might not be able to generate enough force to break it.”

In the future, researchers hope to further improve HAMR’s movement and find a way to return to land without a ramp, by using gecko-inspired adhesives or impulsive jumping mechanisms.