Development and characterization of an electrostatic particle sampling system for the selective collection of trace explosives

Detection of trace explosives residues at people and cargo control points has become a key security challenge. A severe obstacle is that all commercial and military high explosives have low to extremely low vapor pressures which make them very hard to detect. With detectable vapors not being present, explosives detection needs to proceed through a series of sequential steps including particle collection, thermal vapor conversion and vapor detection. The present paper describes the design and test of an electrostatic particle precipitator which allows particle residue to be collected from the environment, the collected particle residue to be separated into high- and low-electron affinity fractions and the high-electron-affinity one to be concentrated onto a small-area collector surface for later vaporization. The selectivity of this particle collection and separation process is demonstrated and a full-chain demonstration of a DNT detection experiment is presented (DNT: di-nitro-toluene).