ABSTRACT We present a new surface acoustic wave gas sensor utilizing a multistrip coupler on LiNbO3 and LiTaO3 substrates and using copper phtalocyanine as a sensor layer for NO2. The sensor signal originates from surface conductivity changes induced by the adsorbed NO2. This variation in conductivity leads to a changing coupling efficiency of the multistrip coupler and thus to variations in the insertion loss of the device. Rayleigh and shear wave devices with operating frequencies of 170 and 243 MHz have been tested. A sensitivity of better than 1 ppb NO2 in air was achieved.
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