Abstract
The paper presents the results of an analysis of gaseous sensors based on
a surface acoustic wave (SAW) by means of the equivalent model theory. The
applied theory analyzes the response of the SAW sensor in the steady state
affected by carbon monoxide (CO) in air. A thin layer of WO3 has been used
as a sensor layer. The acoustical replacing impedance of the sensor layer
was used, which takes into account the profile of the concentration of gas
molecules in the layer. Thanks to implementing the Ingebrigtsen equation,
the authors determined analytical expressions for the relative changes of
the velocity of the surface acoustic wave in the steady state. The results
of the analysis have shown that there is an optimum thickness of the layer
of CO sensor at which the acoustoelectric effect (manifested here as a
change in the acoustic wave velocity) is at its highest. The theoretical
results were verified and confirmed experimentally
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