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 composition 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 three time constants for the slope. The leading edge of the response is analysed for the sensors with the aim of characterising the target smell using a set of time constants instead of the equilibrium response signal. The sets are applied for the characterisation of the volatile substances emitted from the model solutions based on glucose and glycine in which Maillardʹs browning reaction took place. In the sets, the collection of the time constants is shown being characteristic of the odour produced by the target solutions. Based on the sets, volatile compounds could be recognised in the aroma.