July 27, 2011 at 2:33 PM ET
It weighs about as much as about 390 water striders, but this leggy robot can skitter across water just like the real deal.
Scientists built the robot after studying the way real water striders scuttled across the surface of water. Some years ago, a different group of researchers zoomed in on the water strider legs and found that they had leg hairs that trapped air, forming tiny air cushions. Together with the legs' waxiness, this feature makes the water strider legs behave more oars when they hit the surface of the water, keeping the bug afloat.
The design of the tiny robot and its legs is similar. The legs of the robots have air-trapping nanostructures made of copper, giving the 'bot limbs some extra lift in water. Xinbin Zhang, who published a paper describing the walking waterproof wonder in the journal Applied Materials and Interfaces, wrote that "the robot stands effortlessly on its slim supporting legs."
The water-walking robot is powered by a motor worn on its "body," which is wired to an external control board. Ten "walking" legs support the robot, and the two other legs are connected to motors on its body. When either one of the two motors was turned off, the robot turned to the left or right.
The current model doesn't quite match the insects in agility, but Zhang and his colleagues write that better skating versions of this waterproof robot could find application as water pollution surveyors and monitors.