Simulation of NO2 Gas Sensor Based on Multistrip Couplers Surface Acoustic Wave Devices

The Surface Acoustic Wave (SAW) gas sensor for nitrogen dioxide (NO
2
) detection utilizing the Multistrip coupler (MSC) is numerically investigated. A model for SAW-MSC based on LiNbO3 as a piezoelectric substrate and employing the copper phthalocyanine (CuPc) as a sensing layer for the NO
2
gas sensor is explored. The sensor signal originates from surface conductivity changes induced by the adsorbed NO
2
. This variation in conductivity leads to a changing coupling efficiency of the multistrip coupler and, thus, to variations in the insertion loss (IL) of the device under the adsorption influence of the NO
2
gas concentration. The number of electrodes has been optimized. Then, the impact of the NO
2
gas concentration, up to 3000 ppb, on the change in the velocity is explored. The results reveal an almost linear behavior of the IL versus the gas concentration. The obtained results are found to agree well with the previous experimental results.