Publication Date

5-2012

Advisor(s) - Committee Chair

Vladimir Dobrokhotov, Director, Alex Barzilov, Keith Andrew

Degree Program

Department of Physics and Astronomy

Degree Type

Master of Science

Abstract

The detection of low level concentrations of particles in a gaseous environment is of importance to many fields, especially Homeland Security. The ability to identify ppb concentrations of explosives and their degradation products can aid in the detection of improvised explosive devices (IEDs), ammunition dumps, or hidden explosives. One method of accomplishing this task is through the use of an array of chemiresistors in an electronic nose device. For this study, chemiresistors were constructed using 3-D silica nanospring mats with a contiguous film of ZnO nanocrystals and ZnO nanocrystals decorated by metallic nanoparticles. Samples with an average grain size of 15nm were found to be the most responsive and upon exposure to a gas flow of 20% O2 and 80% N2 with ~200 ppm of acetone and an operational temperature of 400 oC produced a relative change in conductance by a factor of 400. The addition of metal nanoparticles onto the surface of the ZnO nanocrystals produced a relative change in conductance by a factor of 1100. Under optimum conditions, sensing elements of this design exhibited well-defined spikes in conductance upon exposure to explosive vapors (TNT, TATP) at the ppb levels. The use of a pattern recognition system allowed discrimination between three analyte chemicals.

Disciplines

Physics

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