This Fish Turns Plastic Into Power

An invention born from a contest at England's University of Surrey might be swimming us closer to cleaner oceans. Researchers have created a robotic fish that doesn’t just collect plastic pollution; it feeds on it.

This “robo-fish,” designed to fight the growing crisis of microplastic contamination, uses a microbial fuel cell that digests plastic particles and turns them into energy.

In other words, the more plastic it eats, the more energy it has to keep swimming, making it one of the world’s first self-sustaining robots built for the environment.

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The project began as part of the Natural Robots Contest at the University of Surrey, which invited participants to design bio-inspired machines that could help the planet. The winning design came from undergraduate chemistry student Eleanor Mackintosh, whose vision of a fish-shaped robot named “Gillbert” captured the judges’ attention.

From Mackintosh’s concept, university engineers brought Gillbert to life, transforming it into a foot-long, tail-flapping robot that swims like a salmon and filters the water as it goes.

As it glides through oceans, rivers or lakes, the robo-fish keeps its mouth open to pull in water. Inside, a fine mesh captures microplastic particles as small as two millimeters while pushing clean water back out through gill-like flaps. The robot even glows in the dark, a feature that helps researchers keep track of its movement and progress.

Small onboard sensors track light levels and water quality, offering valuable environmental data along the way.

And get this: The fish's open-source design is free to download and printable with a 3D printer, which means anyone, anywhere can build their own robo-fish and join the cleanup effort.

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The environmental potential here is enormous, experts say. Microplastics (tiny fragments formed when larger plastics break down) are now found everywhere: in the food we eat and the water we drink, ultimately making their way into our bloodstream.

These particles can damage cells, disrupt hormones and spread toxic chemicals throughout the food chain. According to Dr. Robert Siddall, roboticist and creator of the contest, the robo-fish could become a vital tool in understanding and controlling this invisible pollution.

“We don’t know where the vast majority of plastic dumped into our waterways ends up,” Siddall explained. “We hope this robo-fish and its future descendants are the first steps in the right direction to helping us find and eventually control this plastic pollution problem.”

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The original robo-fish was operated remotely, but future versions could swim autonomously, capture even smaller particles and cover greater distances.

At a time when millions of tons of plastic enter our oceans every year, this innovation blends environmental science, robotics and creativity in a way that feels both hopeful and practical. The robo-fish isn’t just cleaning the water; it’s showing how nature-inspired technology could help heal the damage we’ve caused, one bite of plastic at a time.

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