It could be called a mechanical miracle — a robot that walks on water. With inspiration from nature and some help from research at the Massachusetts Institute of Technology, a research team led by Carnegie Mellon engineering assistant professor Metin Sitti has built a tiny robot that can walk on water, much like insects known as water skimmers, water skaters, pond skaters or Jesus bugs.

Although it’s only a basic prototype, Sitti and other researchers imagine that his water-skimming robot could be used on any still water. With a chemical sensor, it could monitor water supplies for contamination or other toxins; with a camera it could be a spy or an explorer; with a net or a boom, it could skim contaminants off the top of water.

Sitti, who runs Carnegie Mellon’s NanoRobotics Lab, said he has long been fascinated by water striders and what it would take to build one.

“I think it is the final challenge of microrobotics if you can make this thing,” Sitti said. “It needs to be so light and so compact. Look how this animal stays on the water in that kind of miniature, very lightweight body.”

For their size — a half-inch on average — the insects can move. Water striders skim across the water as fast as a meter per second; the human equivalent of going 400 miles per hour. They’re also very mobile.

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