“One e-nose just came back from six months in space, where it sniffed the air on the International Space Station every few seconds. Various gases that provide lighting and help cool the station, like mercury, freon and ammonia, can be harmful to astronauts' health, so NASA wants to monitor for leaks. The shoebox-sized e-nose has 32 sensors that can detect a wide variety of chemicals; in the latest experiment, it sniffed for 10 contaminants, said Amy Ryan, the project's principal investigator at NASA's Jet Propulsion Laboratory.
The e-nose consists of several polymers, which react differently to various substances. When exposed to a chemical, the polymers change size, which affects the resistance of an electrical current running through them. The changes become a pattern interpreted by a complex algorithm -- our brains use similar pattern-recognition to decipher smells. “
Below on electronic tongue from Washington Post
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