EPFL’s robotic eel detects water pollutants

EPFL’s robotic eel detects water pollutants

EPFL envirobot, marine conservation with a difference

A research team from the École Polytechnique Fédérale de Lausanne (EPFL) has developed a 3D-printed robotic eel. It’s called Envirobot, and has been designed to swim through contaminated water to detect pollutants. 

It’s not unusual for scientists and engineers to look to the natural world for inspiration. There are few better examples of that than Swiss university EPFL‘s eel-inspired Envirobot. From a distance, you might think that Lake Geneva’s newest resident has escaped from a nearby zoo. But it’s actually a sophisticated robot capable of gathering a range of data from the water’s surface.

Water pollution detected

The ambitious amphibious project has been backed by the Swiss NanoTera Program. The end goal is to develop a swimming robot that autonomously detects the source of water pollution. Envirobot’s component parts are modular, designed to be switched in and out depending on the task at hand. It can be equipped with chemical, physical and biological sensors.

EPFL’s robot propels itself through the water like an eel and measures nearly 1.5 meters long. Its fluid movement has been designed to help it trace a path through water that won’t disturb the bed of a river or lake, or other aquatic life. Its sensors can measure a range of data points and send back information to a linked computer in real-time.

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Autonomous eel

Auke Ijspeert, Head of EPFL’s Biorobotics Laboratory, pointed out the benefits of using an eel-inspired robot, rather than conventional measuring systems that rely on a web of fixed sensors.

“There are many advantages to using swimming robots,” he said. “They can take measurements and send us data in real-time – much faster than if we had measurement stations set up around the lake. And compared with conventional propeller-driven underwater robots, they are less likely to get stuck in algae or branches as they move around. What’s more, they produce less of a wake, so they don’t disperse pollutants as much.”

“The Envirobot can follow a preprogrammed path, and has also the potential to make its own decisions and independently track down the source of pollution. That could be by, for example, steadily swimming in the direction of increasing toxicity.”

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Pushing the boundaries

In testing so far, Envirobot has been generating maps of water conductivity and temperature in a small section of Lake Geneva.

But the team from EPFL has been working alongside the University of Lausanne, the University of Applied Sciences and Arts of Western Switzerland and the Swiss Federal Institute of Aquatic Science and Technology to explore more potential applications for the technology.

While some of Envirobot’s modules contain conductivity and temperature sensors, others highlight a much more innovative approach to marine conservation research. Inside are tiny chambers that fill up with water as the robot moves along. Contained within the chambers are miniaturized biological sensors that are home to bacteria, small crustaceans or fish cells.

The sensors observe the reaction that these sensitive organisms have to the water, giving an indication of its toxicity and the type of pollutants present.

“We developed bacteria that generate light when exposed to very low concentrations of mercury. We can detect those changes using luminometers and then transmit the data in the form of electrical signals,” says Jan Roelof van der Meer, project coordinator and head of the Department of Fundamental Microbiology at the University of Lausanne.

Another biosensor relies on Daphnia, also known as water fleas. These tiny crustaceans are always on the move, but the extent of that movement is impacted by water toxicity. “By comparing changes in their movement relative to the control group, we can get an idea of how toxic the water is,” said van der Meer.