Shark and diver

Shark-inspired electrical sensor functions in ocean-like conditions

Image credit: Dreamstime

Researchers at Purdue University, Indiana, have created a ‘quantum material’ sensor with the shark-like ability to sense minute electrical signals. Like its predatory inspiration, the device has been demonstrated to function in ocean-like conditions.

Sharks have the uncommon ability to detect prey from their tiny electrical signals: this is known as electroreception. This ability is mostly associated with aquatic and amphibious animals, although it has also been observed in cockroaches, platypuses and other creatures.

Sharks, which are the most electrically sensitive of animals, rely on an organ near their mouths – the ampullae of Lorenzini – to detect the bioelectrical signals of fish.

“This organ is able to interact with its environment by exchanging ions from seawater, imparting the so-called sixth sense to sharks,” said Dr Zhen Zhang, a Purdue University researcher and an author of the Nature report on the project.

While the sharks’ organs contain jelly which conducts seawater ions to a membrane containing sensitive cells, the sensor developed at Purdue University is based on a material called samarium nickelate. As a ‘quantum material’, its exotic electronic and magnetic properties tap into interactions on a tiny scale: the quantum scale.

A quantum effect that causes the material to switch rapidly from conductor to insulator inspired the Purdue researchers to create a sensitive detector which mimics a shark’s ampullae.

The researchers tested their shark-inspired material by submerging it in salt water at an ambient temperatures and acidities typical of the oceans where it could have potential applications. In these ocean-like conditions, the material was able to remain functional, and did not corrode.

“We have been working on this for a few years,” said Professor Shriram Ramanathan, a materials engineer at Purdue University. “We show that these sensors can detect electrical potentials well below one volt, on the order of millivolts, which is comparable to electric potentials emanated by marine organisms.”

“The material is very sensitive. We calculated the detection distance of our device and find a similar length scale to what has been reported for electroreceptors in sharks,” said Professor Ramanathan.

“It has potentially very broad interest in many disciplines.”

In the future, the researchers plan to test the devices in real oceans. The unique sensor could have applications in defence to track the motion of ships, in commercial maritime applications, as well as in marine biology, for which it could be used to detect and study organisms living in the largely unexplored oceans

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