Time-dependent humidity calibration for drift corrections in electronic noses equipped with SnO2 gas sensors

Changes in the ambient humidity induce significant, long-termed variations both in conductance and in the calibration characteristics of SnO2 gas sensors for different reducing gases. These gas-dependent variations depend both on humidity changes (initial and final humidity) and on the time spent in each humidity. A previous knowledge of the conductance and calibration transients, together with a permanent information about humidity and about the time spent in each humidity, should result in significant improvements in the operation of electronic noses equipped with SnO2 gas sensors.