Specific set of the time constants for characterisation of organic volatile compounds in the output of metal oxide sensors

The time dependence of the resistance response to a steep change of gas com position in the atmosphere is investigated for the gas sensors based on tin oxide and indium oxide thin films. The dependence is assumed to pertain to the exponential decrease with thrice time constants for the slope. The lea ding edge of the response is analysed for the sensors with the aim of chara cterising the target smell using a set of time constants instead of the equ ilibrium response signal. The sets are applied for the characterisation of the volatile substances emitted from the model solutions based on glucose a nd glycine in which Maillard's browning reaction took place. In the sets, t he collection of the time constants is shown being characteristic of the od our produced by the target solutions. Based on the sets, volatile compounds could be recognised in the aroma. (C) 2000 Elsevier Science S.A. All right s reserved.