Researchers at the Bristol Robotics Laboratory in the United Kingdom have developed an aquatic robot that generates the electricity it needs to power itself by "eating" microscopic microbes ever present in water. The dirtier the water, the more power it produces.

The swimming robot named "Row-bot" uses microbes as fuel for its Microbial Fuel Cell (MFC) that generate electricity. The MFC is located in Row-bot's "stomach," which has a "mouth" that opens to swallow water. Row-bot moves forward using two paddles attached to its sides.

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Microbes emit electrons as a by-product of eating even smaller organisms. Row-bot takes advantage of this natural function to generate power by harvesting these electrons.

Each time Row-bot opens its mouth, it swims forward by 10 strokes at a speed of one stroke per second. As it moves forward, the machine channels water into the MFC in its stomach and digests the water for three minutes.

Row-bot expels the water out its back side as it swims forward again. It then repeats this cycle.

Row-bot stores the energy generated by the MFC in a capacitor. Over one cycle (opening its mouth, swimming and then closing its mouth), it only uses 1.8 joules.

That's 20 centimeters of motion with about 1 joule of energy leftover that could be used to power sensors or laser turrets or something.

As long as Row-bot swims, the MFC makes it "energetically autonomous."

Bristol researchers said Row-bot's MFCs work in all kinds of water. This includes fresh water in rivers and lakes, seawater and even waste water. As an added benefit, Row-bots clean the water as they swim along it eating microbes along the way.

Row-bot's prototype is a testbed for integration of the MFC with actuators to see how well it works.

Researchers said there's a lot more optimization required, like reducing body drag and finding the most efficient combination of materials to use for the paddles. They also believe multiple MFCs could be configured in series to generate more power.

They feel Row-bot could be developed for applications such as remote sensing and environmental monitoring and clean-up.

TagsRow-bot, Bristol Robotics Laboratory, Microbes, water, swims