The fifth sense-on the scent of the electronic nose

The author describes how electronic sensors for scent and odours work. Gases produce changes in the properties of an array of sensors, resulting in electrical signals, which are then amplified, linearised for gas concentration and digitised before being fed into a pattern-recognition system. The gas sensitive layer is tin oxide with catalytic additives for detection of particular gases. The author discusses how different sensors combined with pattern recognition techniques, can discriminate between different odours. The different types of sensor and their application to gas testing systems are also discussed.<
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