Improving the Selectivity of Semiconductor Gas Sensors Using the Pulse Adsorption Mode

A procedure is proposed for improving the selectivity of semiconductor gas sensors by the pulsed supply of the test gas mixture, with the use of transient spectroscopy for the separation and assessment of component contributions to the response of an electrical conductivity detector. The experimental verification of the procedure showed that the selective determination of several compounds and their mixtures can be performed using the same SnO₂ detector. The simulation of the detector response as the sum of simplest relaxations revealed three types of surface sites on SnO₂ films, with energy levels of 0.97, 1.38, and 1.50 eV. This means that the number of gas components that can be selectively determined with a single detector is limited to three.