Robotic cockroach walks on - and beneath - water

According to the group from the university’s School of Engineering and Applied Sciences (SEAS), robots able to traverse complex terrains in this way hold promise for applications in environmental monitoring and the exploration of confined spaces.

The so-called Harvard Ambulatory Microbot (HAMR) uses multifunctional foot pads that rely on surface tension and surface tension induced buoyancy when it needs to swim, but can also apply a voltage to break the water surface when it 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.

According to a paper in Nature moving on the surface of water allows a microbot to evade submerged obstacles and reduces drag. The device uses four pairs of asymmetric flaps and custom designed swimming gait to paddle on the water surface.