Date of Award

2017

Degree Type

Thesis

Degree Name

Master of Science in Chemical Engineering (MSChE)

Department

Chemical Engineering

First Advisor

Otto J. Gregory

Abstract

There is a growing need for a continuous monitoring system that can detect explosives in the vapor phase at trace levels. For example, triacetone triperoxide (TATP), an explosive commonly used by terrorists in improvised explosive devices (IEDs) is still going largely undetected in many densely populated venues. No electronic trace detection system currently exists that is capable of continuously monitoring TATP vapors or its precursors. Solid-state metal-oxide sensors have demonstrated the ability to successfully detect TATP. However, to improve sensor sensitivity, the large thermal mass associated with these solid-state sensors was dramatically reduced by replacing them with extremely low mass (25 μm diameter) coil microheaters. These coil microheaters have a thermal mass that is two orders of magnitude less than the solid-state sensors and resulted in much greater signal-to-noise ratios with excellent selectivity amongst metal-oxides. These sensors were able to detect TATP, 2,4-DNT and ammonium nitrate vapors at the 20 ppm level under varied conditions including sensor temperature, catalyst material used, inlet flow rate (sampling rate) and humidity.

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