Numerical and Experimental Analysis of the Response of a SAW Structure with WO3 Layers on Action of Carbon Monoxide

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.

Theoretical analysis of acoustoelectrical sensitivity in SAW gas sensors with single and bi-layer structures

“…It has been presented, that in such configurations there were new ranges for the acoustoelectric parameter , where the acoustoelectric sensitivity could be much higher than for a single sensor film structure [6]. Therefore the analysis of acoustoelectrical (AE) sensitivity is very necessary in order to achieve the best SAW sensor performance [7][8][9][10][11] …”

Review of Dissolved CO and H2 Measurement Methods for Syngas Fermentation

“…The CO sensing layer can be coated on the top of thin-film interdigital transducers or between the transducers at the same horizontal level [ 149 ]. The reported CO sensing coatings include ZnO [ 157 ], WO 3 [ 158 ], graphene nano-sheet [ 159 , 160 ], cobalt corroles [ 161 ], and polyaniline (PANI) [ 162 ]. However, most reports did not provide results on sensor selectivity to reducing gases, such as H 2 .…”

Numerical Analysis of the Steady State in SAW Sensor Structures with Selected Polymers for Detection of DMMP and CO

“…The main aim of the investigation was to study thin film interaction with target gases in the SAW detector based on a simple reaction-diffusion eq. [5][6][7][8][9][10][11]. Diffusion equations provide theoretical bases for the analysis of physical phenomena like heat transport or mass transport in porous, roughness substrates [5].…”

“…The channel with the detector layer generates as a result oscillations with a different frequency (usually lower) and is shifted in phase relative to the signal generated in the reference path (Figure 2a). The work focused on the electrical effect is a new contribution to the SAW gas detector technology [7].…”