Date of Award

Fall 1992

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)


Electrical and Computer Engineering

First Advisor

Josse, Fabien

Second Advisor

Schneider, Susan C.

Third Advisor

Shana, Zack A.


Recently, attention has been focused on investigating rapid, sensitive acoustic wave sensors which are capable of performing in liquid environments for chemical or biosensor applications. In this work, an effective computation method is developed to simulate the effects of various acoustic waves at the interface between various piezoelectric materials and various viscoelastic conductive fluid media. (The appropriate boundary conditions at the interfaces are presented. The solutions for the acoustic wave interaction between the piezoelectric crystal and a viscoelastic fluid medium are discussed for special cases. The computational results can be used to search for the appropriate materials and their orientations with the most sensitive mode as sensing element for designing new acoustic wave devices in liquid environments. The piezoelectric materials that are studied in this work include ZX-LiNbO3, STcut X-propagating quartz, Y-126° LiTaO3 and ST-90° quartz. The acoustic waves which have been studied in different environments and conditions are shear horizontal (SH) acoustic surface wave (SAW), leaky SAW, surface skimming bulk wave (SSBW) and plate modes. The effects of fluid properties such as conductivity, viscosity, and dielectric constant on the wave propagation (related to device frequency shift and/or energy loss) are simulated to determine the characteristics of sensor devices. The effects of liquid shear relaxation time and dielectric relaxation time are taken into account for relatively high viscosity and conductivity, respectively. The results of the simulation compare well with existing experimental data. The computation method are developed in this work can be used effectively in the design and analysis of liquid-phase acoustic wave devices for chemical and/or biosensor applications.



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