Revolutionary Sensor Mimics Shark Detection Ability

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A “quantum material” that mimics a shark’s ability to detect the minute electric fields of small prey has been tested. with potential applications from defense to marine biology. Such a sensor technology might be used to monitor the movement of ships for military and commercial maritime applications.

The material performed well in ocean-like conditions, maintaining its functional stability without corroding after being immersed in saltwater, a prerequisite for ocean sensing. Surprisingly, it also functions well in the cold, ambient temperatures typical of seawater, said Shriram Ramanathan, a Purdue professor of materials engineering, who led the research to develop the sensor. The Purdue portion of the research was funded by the U.S. Army Research Office, Air Force Office of Scientific Research and the National Science Foundation.

The new sensor was inspired by an organ near a shark’s mouth called the ampullae of Lorenzini, which is capable of detecting small electric fields from prey animals. The organ contains a jelly that conducts ions from seawater to a specialized membrane located at the bottom of the ampulla. Sensing cells in the membrane allow the shark to detect bioelectric fields emitted by prey fish.

The new sensor is made of a material called samarium nickelate, which is a quantum material, meaning its performance taps into quantum mechanical interactions, according to purdue.edu.

Because this material can conduct protons very fast, the researchers wondered whether they might develop a sensor that mimics the shark’s organ.

The researchers showed 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. They found that the detection distance of the device was similar to what has been reported for electroreceptors in sharks.

The quantum effect causes the material to undergo a dramatic “phase change” from a conductor to an insulator, which allows it to act as a sensitive detector. The material also exchanges mass with the environment, as protons from the water move into the material and then return to the water, going back and forth.

The material also changes optical properties, becoming more transparent as it becomes more insulating.