PREDICTION OF GAS SENSOR RESPONSE USING BASIC MOLECULAR-PARAMETERS

The response of a silicone oil used as a gas sensor coating to a selection of gases and vapours was investigated by measurement of the mass change, due to sorption at the oil/gas interface, using a piezoelectric quartz crystal microbalance. The sensors were exposed to each of 26 test analytes and the frequency shifts were used to calculate the partition coefficients and hence the Gibbs free energy of absorption. Molecular physico-chemical properties of the analyte vapours were calculated using semi-empirical molecular orbital and molecular mechanics methods and were related to the observed partitioning by pattern recognition methods. The key molecular parameters that influence the sensor response were extracted to build mathematical models for the quantitative prediction of a gas sensor response to a limited number of analytes. The approach shows how a model can be developed to describe the response of a gas sensor to an analyte based solely on its molecular descriptors.