A MONOLITHIC SPIRAL COIL ACOUSTIC TRANSDUCTION SENSOR FOR CHEMICAL AND BIOLOGICAL ANALYTES

A MONOLITHIC SPIRAL COIL ACOUSTIC TRANSDUCTION SENSOR FOR CHEMICAL AND BIOLOGICAL ANALYTES

By Donald McCann

Thesis Advisor: Dr. John Vetelino

A Lay Abstract of the Thesis Presented

in Partial Fulfillment of the Requirements for the

Degree of Doctor of Philosophy

 (in Electrical & Computer Engineering)

May, 2010

Piezoelectric materials are unique in that mechanical stresses may be excited electrically and vice-versa.  This unique property allows one to realize a sensor which can be used to sense a wide range of chemical and biological entities.  When piezoelectric materials are used as a sensor, metal is deposited on one face of the piezoelectric material.  The metal is excited electrically which cause mechanical stresses and therefore acoustic waves to appear in the material.  The resonant frequency of the acoustic waves inside the sensor are monitored and these changes provide information about chemical or biological agents that may be present.  The actual sensor developed in this work consists of a piezoelectric quartz sensor in which acoustic waves are excited by a spiral coil antenna.  This sensor configuration is known as a Monolithic Spiral Coil Acoustic Transduction (MSCAT) device.  The main advantage of this technique is that the MSCAT is capable of operating at high frequencies which can lead to increased sensor sensitivity.  In this work the antenna configurations have been experimentally and theoretically examined. 

In order to demonstrate the real-world applicability of the MSCAT, it was also tested for use as a biological and chemical sensor. The biological sensing application chosen was E. coli O157:H7, the most dangerous strain of E. coli.  The chemical analyte was saxitoxin, the most dangerous neurotoxin resulting from red tide outbreaks.  In both cases the MSCAT was found to be superior to other sensor platforms.