Scientists at the University of Texas at Dallas and Virginia Tech have built a jellyfish-inspired robot that can refuel itself, offering the possibility of perpetual ocean surveillance.

Like Slugbot, a robot designed to be able to hunt garden slugs and devour them for fuel, Robojelly, as the machine is called, is self-sustaining. It extracts hydrogen and oxygen gases from the sea to keep itself running.

"We've created an underwater robot that doesn't need batteries or electricity," Yonas Tadesse, assistant professor of mechanical engineering at UT Dallas, told the UT Dallas news service. "The only waste released as it travels is more water."

The robot offers one way around a problem that continues to vex researchers developing autonomous machines: operational limitations imposed by the need for frequent refueling. Scientists at Sandia National Laboratories and Northrop Grumman last year concluded that nuclear power would extend the capabilities of aerial drones but couldn't be implemented due to political considerations. The U.S. government presumably would rather avoid the political outrage that would follow from a downed nuclear drone.

A self-sustaining surveillance bot that doesn't involve hazardous materials and doesn't pollute would be much more politically palatable, not to mention operationally useful.

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Robojelly looks as if it could be related to a novelty umbrella hat, except that it has two hemispherical canopies, stacked one on top of another (the video embedded below depicts an earlier single-canopy version). These bell-like structures are made of silicone and are connected to artificial muscles that contract when heated. The contractions, like those in a real jellyfish, propel the device.

The muscles are made of a nickel-titanium alloy encased in carbon nanotubes, coated in platinum, and housed in a casing. The chemical reaction arising from contact between the mixture of hydrogen and oxygen and the platinum generates heat, which causes the artificial muscles to contract and move the silicone canopies while expelling water.

Tadesse says the next step in the project is to revise the device's legs so it can move in different directions. Right now, Robojelly's fixed supports allow it to move in only one direction.

Robojelly was funded by the Office of Naval Research, which has an obvious interest in monitoring the seas. In addition to scanning the waves, Tadesse suggests the device could be used to check the water for pollutants.

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