Metal-loaded polymer films for chemical sensing of ES&H-related pollutants
This report summarizes the results of a Laboratory Directed Research and Development (LDRD) effort to study and model surface acoustic wave (SAW) devices for environmental applications. The response of polymer-coated SAW devices to temperature changes and polymer vapor absorption is examined. A perturbational approach is used to relate velocity and attenuation responses to film translational and strain modes generated by the SAW. Two distinct regimes of film behavior arise, causing different SAW responses. For glassy films, displacement is nearly uniform across the film thickness, varying only in the direction of propagation. A model developed to predict velocity and attenuation in this regime, reduces to the familiar Tiersten (Wohltjen) equation for purely elastic films. For elastomeric (rubbery) films, inertial effects cause a phase lag to occur across the film for shear displacements. A model to account for these cross-film displacement gradients predicts a characteristic resonant response when the film phase shift reaches np/2, where n is an odd integer. These model predictions are compared with measured responses from polyisobutylene-coated SAW devices as temperature is varied and during exposure to high vapor concentrations.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Environment, Safety, and Health, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 459905
- Report Number(s):
- SAND--97-0619; ON: DE97004160
- Country of Publication:
- United States
- Language:
- English
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