Chemical Sensors Employed in Electronic Noses: A Review

Electronic noses utilizes an array of chemical sensors of different specificities which responds to the volatile organic compounds present in the gases. The use of electronic chemical sensors in an array design with coupled signal conditioning and appropriate pattern recognition system is capable of identifying complex odours.Such an artificial gas sensing system is called 'electronic nose'. The requirement for the sensors in a electronic nose is that they have a partial sensitivity, i.e. that they can respond broadly to a range or class of gases rather than to a specific one. However, The electronic nose will categorize many odours that contain many chemical components. Different types of gas sensors in the sensor array includes metal oxide semiconductors,optical and amperometric gas sensor, surface acoustic sensors,piezoelectric gas sensors. In this review paper,we discuss the operating principle of each chemical sensor type and its use in electronic nose system.