Bioinspired Robojelly fuelled by hydrogen

American researchers have created a robotic jellyfish, named Robojelly, which not only exhibits characteristics ideal to use in underwater search and rescue operations, but could, theoretically at least, never run out of energy thanks to it being fuelled by hydrogen.
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From WP

Scientists funded by the U.S. Navy have developed a robot “jellyfish” — a foot-long submarine that runs on seawater and could be used on spy missions.

Researchers at The University of Texas at Dallas and Virginia Tech created the submarine drone, dubbed “Robojelly,” which is powered by hydrogen and oxygen in the water through which it sails.

The scientists, funded by the Office of Naval Research, reported their findings this week in the academic IOP Publishing's journal Smart Materials and Structures.

“We’ve created an underwater robot that doesn’t need batteries or electricity,” said Dr. Yonas Tadesse, assistant professor of mechanical engineering at the University of Texas and lead author of the study.
“The only waste released as it travels is more water.”
Engineers and scientists working for the military have increasingly turned to the animal kingdom, especially simple creatures like jellyfish or insects, for inspiration when creating new technology.

Scientists at the Defense Advanced Research Projects Agency, for example, are working on ways to create insect cyborgs, by incorporating mechanical elements into larvae and then using them to control the fully grown insect when it emerges.

The Robojelly consists of two fist-sized bell-like structures made of silicone that fold and unfold like an umbrella. Connecting the umbrella are artificial muscles created with nanotechnology that contract to move the vehicle.

“It could stay underwater and refuel itself while it is performing surveillance,” Dr. Tadesse said.