Date of Award
Summer 1991
Document Type
Thesis - Restricted
Degree Name
Master of Science (MS)
Department
Electrical and Computer Engineering
First Advisor
Josse, F.
Second Advisor
Jeutter, Dean C.
Third Advisor
Haworth, Daniel T.
Abstract
This thesis reports an experimental investigation of the use of acoustic plate mode (APM) devices as liquid phase-based sensors capable of measuring liquid conductivity, dielectric constant and/or chemical concentration. An APM delay line device on Z-cut X-propagating lithium niobate (ZX-LiNb03 ), a relatively strong piezoelectric coupling material, is utilized for the experimental measurements. The sensing acoustic wave is a slow shear wave with most of the energy confined to the horizontal particle displacement. Propagation measurement technique is utilized to monitor the sensor performance. Several experiments are performed with various dilute electrolytes and metal ion solutions. The electrolytes tested include potassium chloride (KCl), lithium chloride (LiCl) and potassium nitrate (KN03). The metal ion solutions tested include calcium chloride (CaC12), magnesium nitrate (Mg(N03 )2) and iron(III) nitrate (Fe(N03)3). A change in wave propagation characteristics in terms of frequency shift and loss due to a change in liquid conductivity and/ or concentration is observed. To study the effect of a change in liquid dielectric constant, some experiments are performed with non-aqueous solutions, where methanol is used as a solvent. The effect of higher operating frequency of the APM device on the sensor performance is studied by operating the APM delay line device at higher harmonics. An approximate theoretical solution has been used to describe the liquid/crystal interface problem and experimental data are compared with the theoretical results. The measured data show good agreement with the theoretical calculations. These results indicate that an APM delay line device on ZX-LiNb03 can be successfully utilized as a sensitive detector to perform microanalysis of dilute electrolytes and metal ion solutions. Such sensors show an increase in sensitivity at least two orders of magnitude greater than that of previously reported acoustic wave sensors.
Recommended Citation
Kelkar, Uday R., "Lithium Niobate Acoustic Plate Mode Device As Conductivity Detector for Chemical Liquids" (1991). Master's Theses (1922-2009) Access restricted to Marquette Campus. 4893.
https://epublications.marquette.edu/theses/4893