US scientists build robot that can walk on water

A team led by a US university professor has built a tiny robot that can walk on water, much like the insects known as water skimmers.

It could be called a mechanical miracle -- a robot that walks on water.

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With inspiration from nature and some help from research at the Massachusetts Institute of Technology, a team led by Carnegie Mellon engineering professor Metin Sitti built a tiny robot that can walk on water, much like the insects known as water skimmers or Jesus bugs.

It's only a prototype, but some researchers imagine the water-skimming robot could have many uses. With a chemical sensor, it could monitor water supplies for 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.

Producing it was "the final challenge of microrobotics," said Sitti, who runs Carnegie Mellon's NanoRobotics Lab. "It needs to be so light and so compact."

Sitti's robot is little more than a half-inch boxy body made from carbon fibres and eight, 5-centimetre steel-wire legs coated with a water-repelling plastic (technically making it a water spider).

It doesn't have a brain, any sensors or a battery. Its "muscles" are three flat-plate piezoelectric actuators -- pieces of metal that bend when electricity runs through them. Wires run from the actuators to a power supply.