Robotic Eel Tracks Down Pollution in Lakes

©. Alain Herzog / 2017 EPFL

Researchers at École Polytechnique Fédérale de Lausanne (EPFL) have developed a robotic eel that can efficiently scan a source of water for pollution and wirelessly deliver the data it gathers in real time. The robotic eel mimics its namesake by swimming through the water with a similar locomotion to find and follow signs of pollution.

Water quality samples are typically taken by hand on a regular schedule, but the process is slow and only represents the quality of the water at the spots where it was sampled. The a team of robotic eels could more regularly take measurements and cover the expanse of a body of water.

“There are many advantages to using swimming robots. 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,” said Auke Ijspeert, Head of EPFL's Biorobotics Laboratory.

The robotic eel is outfitted with sensors that make it able to test the water for changes in conductivity and temperature as well as signs of toxins. The robot is made of several modules, each containing a small electric motor and different sensors. The modular design allows researchers to add or take from its length and change the robot's make up as needed for each task.

The robot features traditional sensors measuring temperature and conductivity, but there are also biological ones comprised of bacteria, crustaceans and fish cells that detect the presence of toxins. The researchers observe any changes to the organisms when placed in the water. For instance, the bacteria will luminesce when exposed to even very low concentrations of mercury. Luminometers measure the light given off by the bacteria and that information is transmitted to a central hub for analysis.

The tiny Daphnia crustaceans are observed in clean water compared to the water sample and any changes in movement are used to detect pollutants. The fish cells are grown directly on electrodes and then exposed to the water. If toxins are present, the cells move apart and the flow of electricity is interrupted.

For now the team is concentrating on lab tests of the biological sensors, but soon they'll start taking the robot out to real bodies of water to see what it can do. In a real world application, the robot could detect pollution and then swim towards the source, moving in the direction of greater concentrations. That would allow scientists to not only detect pollution in the water, but find the source and work to contain it.

You can watch a video about the robotic eel below.