Robotic eel loaded with living sensors might hunt down pollution in the water
The robotics researchers at Switzerland's École Polytechnique Fédérale de Lausanne (EPFL) have produced some truly impressive (and creepy) animal-inspired droids over the years. Following in the footsteps of the team's robotic turtles, grasshoppers and crocodiles comes the Envirobot, a robotic eel built to snake through contaminated water to find the source of pollution.
Envirobot can be controlled remotely or swim on its own, measures 1.5 meters long (5 ft) and is made up of individual modules that each house a small electric motor. These motors are what changes the robot's curvature, enabling it to snake smoothly through the water without stirring up mud or annoying aquatic life.
Meanwhile, some of these modules contain sensors to measure things like conductivity and temperature, while others contain chambers designed to fill up with water. Those that fill up with water also house bacteria, small crustaceans and fish cells, which work as biological sensors.
By watching how these organisms respond to the water as it enters the chamber, the operators can get a read on what kind of pollutants are in the water and its toxicity in general. For now, the team has only tried this out in the lab, where it says it was shown to be highly effective.
"For example, we developed bacteria that generate light when exposed to very low concentrations of mercury," says Jan Roelof van der Meer, Project Coordinator and Head of the Department of Fundamental Microbiology at the University of Lausanne. "We can detect those changes using luminometers and then transmit the data in the form of electrical signals."
Another example of these biological sensors involves the use of Daphnia, which are tiny crustaceans less than 5 mm (0.20 in) whose movement is affected by water toxicity. Two of Envirobot's modules contain the Daphnia, one in clean water and one in water taken in while it swims around. By tracking the movement of the creatures in each tank, the team can gain an indication of the water's toxicity.
Envirobot has been trialed in Lake Geneva, where one recent exercise was designed to test its ability to track changes in water conductivity. The team did this by pumping salt into a specific area close to the shore and setting Envirobot free, where it successfully mapped the variations in conductivity resulting from the salt and created a temperature map of the area.
That is as far as the team has got for now, with further tests involving the biological sensors and real contaminants still a little ways off. But eventually, it imagines the Envirobot either following a preprogrammed path or following the direction of increasing water toxicity to autonomously zero in on the source of pollution.
"We obviously can't contaminate a lake like we do the test water in our lab," says van der Meer. "For now, we will continue using salt as the contaminant until the robot can easily find the source of the contamination. Then we will add biological sensors to the robot and carry out tests with toxic compounds."
You can hear from van der Meer and see Envirobot in action in the video below.