Surface Acoustic Wave Gas Sensor

Application ID: 2129

A surface acoustic wave (SAW) is an acoustic wave propagating along the surface of a solid material. Its amplitude decays rapidly, often exponentially, through the depth of the material.

SAWs are utilized in many kinds of electronic components, including filters, oscillators, and sensors. SAW devices typically apply electrodes to a piezoelectric material to convert an electric signal into a SAW, and then back again. The SAW response provides the information that the device is used to collect.

This model investigates the resonance frequencies of a SAW gas sensor. The sensor consists of an interdigitated transducer etched onto a piezoelectric substrate, covered with a thin film. The mass of the film increases as its material selectively adsorbs a chemical substance from the air. This causes a shift in resonance to a slightly lower frequency and thus information about the amount of species in the air.

This model example illustrates applications of this type that would nominally be built using the following products: