Abstract: Properties of propagation modes for a layered {ZnO}/XZ {{LiNbO}$_3$} surface acoustic wave sensor have been investigated both theoretically and experimentally. By calculating the effective permittivity function, it was shown that after the {ZnO} deposition two distinct propagation modes have been generated: a Rayleigh and a shear horizontal. A layer of {InOx}, was deposited to provide a conductometric sensing mechanism to NO2. It was found that the sensor is at least one order of magnitude more sensitive when operating in Rayleigh mode than in the shear horizontal mode. This sensitivity was found to be in good agreement with calculations for low concentrations of NO2, however discrepancies were observed for higher concentrations.

Keywords: saw gas sensor; layered; conductometric; zno; inox; no2;; saw sensor

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