Explosives Detection in Residential Building Ventilation Systems

One approach to locating illicit bomb factories in Iraq and Afghanistan is analytical monitoring within the ventilation systems of suspect residential buildings. We are proposing a multiple sensor analyzer that sequentially interrogates individual vents or ducts in such buildings and produces fingerprints characteristic of present target substances. The basic premise of this proposal is to locate sensor probes in key ducts or vents and connect them with fiber cabling to a spectral analyzer located in the attic or roof of the building. This setup would monitor a number of different locations within the building with emission of a wireless alarm report to a regional Tactical Operations Center from all online sensors every 10 to 15 minutes. We will achieve reproducible and selective detection of explosives using novel self-assembled structures that create an inherently uniform pattern, leading to rapid, reproducible manufacturing. The specific instrument we propose to analyze the sensors is a field portable spectrograph, with accompanying fiber optic probes, coupled to an accessory containing the sensing elements. Phase I work will focus on the demonstration of reproducible detection of airborne explosives using the sensors in the presence of potentially confusing interfering substances. The Phase II program will focus on quantifying the extent of fouling of the sensors due to long-term exposure to building air, developing a fieldable self-contained and powered instrument including multiplexed probes and wireless communication, and testing the sensors in mock ventilation systems.