Vapor Sensing by Means of a ZnO-on-Si Surface Acoustic Wave Resonator

S. J. Martin, K. S. Schweizer, S. S. Schwartz, R. L. Gunshor

Research output: Contribution to journalConference articlepeer-review


Surface Acoustic Wave (SAW) devices can function as sensitive detectors of vapors. The high surface acoustic energy density of the device makes it extremely sensitive to the presence of molecules adsorbed from the gas phase. Mass loading by the adsor-bate is the primary mechanism for the surface wave velocity perturbation. If the device is used as the frequency control element of an oscillator, perturbations in wave velocity on the order of 10 parts per billion may be resolved by means of a frequency counter. ZnO-on-Si SAW resonators have been examined as vapor sensors. The piezoelectric ZnO layer permits transduction between electrical and acoustic energies, as well as endowing the surface with particular adsorptive properties. These devices exhibit Q-values up to 12,000 at a resonant frequency of 109 MHZ. The resonant frequency of the device shifts upon exposure to a vapor-air mixture, with a transient response which is distinct for each of the organic vapors tested. Due to the permeability of the polycrystalline ZnO layer, the instantaneous reversibility of the resonant frequency shift is found to depend on the type of adsorbed molecule.

Original languageEnglish (US)
Article number1535231
Pages (from-to)207-212
Number of pages6
JournalProceedings - IEEE Ultrasonics Symposium
StatePublished - 1984
Externally publishedYes
Event1984 IEEE Ultrasonics Symposium, IUS 1984 - Dallas, United States
Duration: Nov 14 1984Nov 16 1984

ASJC Scopus subject areas

  • Acoustics and Ultrasonics


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