Accession Number : ADA141537

Title :   Mechanism of Operation and Design Considerations for Surface Acoustic Wave Device Vapor Sensors.

Descriptive Note : Progress rept. Oct 82-Oct 83,


Personal Author(s) : Wohltjen,H

PDF Url : ADA141537

Report Date : 23 Apr 1984

Pagination or Media Count : 45

Abstract : Surface acoustic wave (SAW) devices offer many attractive features for application as vapor phase chemical microsensors. This paper describes the characteristics of SAW devices and techniques by which they can be employed as vapor sensors. The perturbation of SAW amplitude and velocity by polymeric coating films was investigated both theoretically and experimentally. High sensitivity can be achieved when the device is used as the resonating element in a delay line oscillator circuit. A simple equation has been developed from theoretical considerations which offers reasonably accurate quantitative predictions of SAW Device frequency shifts when subjected to a given mass loading. In this mode the SAW device behaves in a fashion very similar to conventional bulk wave quartz crystal microbalance except that the sensitivity can be several orders of magnitude higher and the device size can be several orders of magnitude smaller. Detection of mass changes of less than 1 femtogram by a SAW device having a surface area of 0.0001 square cm. is theoretically possible.

Descriptors :   *Surface acoustic wave devices, *Thin films, *Gas detectors, Oscillators, Polymeric films

Subject Categories : Physical Chemistry
      Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE