DETECTION OF ODORANTS USING AN ARRAY OF PIEZOELECTRIC-CRYSTALS AND NEURAL-NETWORK PATTERN-RECOGNITION

AT-cut quartz crystals were applied as chemical vapour sensors. The responses of such crystals operating at 9 MHz and coated with phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, phosphatidylserine and lipid A were determined for amyl acetate, acetoin, menthone and other organic vapours which showed different affinities for each lipid. The identification of odorants depending on the species of lipid used for coating is discussed in terms of the normalized resonant frequency shift pattern. Using a number of different lipid-coated quartz crystals, odorants could be identified by a neural-network pattern recognition with a back-propagation algorithm.