Trace Detection of Explosives Using Metal Oxide Catalysts

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There is a growing need for a continuous monitoring system that can detect explosives at trace levels in the vapor phase. Triacetone triperoxide (TATP) is a common explosive used by terrorists in improvised explosive devices (IED's) that still goes largely undetected in many densely-populated venues. No electronic trace detection system currently exists, which is capable of continuously monitoring TATP or its precursors. However, we have demonstrated that a thermodynamic sensor employing low mass microheaters and metal oxide catalysts can detect TATP and 2, 4-DNT at the ppb level. The improved selectivity and sensitivity of these low-mass sensors enabled us to investigate the mechanism and pathway responsible for the detection of explosives. We now believe that the sensor response relies on specific oxidation-reduction reactions taking place on the surface of the metal oxide catalyst. These surface reactions are specific to the explosive molecule of interest, catalyst (metal oxide), and the oxidation states of the catalyst. Experiments employing SnO, Cu2O, and ZnO as catalysts were performed to establish a mechanism responsible for the detection of various explosives at trace levels using our thermodynamic sensor. The responses of our trace detection system to TATP and 2, 4-DNT at trace levels will be presented as well as the proposed detection mechanism.

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IEEE Sensors Journal