Metal oxide sensor arrays for detection of explosives at sub-parts-per million concentration levels by the differential electronic nose

The study presents an application of the differential electronic nose to the estimation and recognition of the TNT, PETN and RDX in the complex environments under their storage. Generally there are two separate problems in the field of recognition of explosives: first – detection of the trace concentration of explosives by analytical methods (gas chromatography, ion mobility spectrometry, neutron activation analysis) and the second – the estimation of the state of explosives during their time storages in the military objects. In the second problem the concentration of a vapor of explosives is at level of sub-parts-per million where chemosensors technique is fully applicable. This paper is concerned with the second type problem. It defines the recognition criteria providing stable and robust basis for the recognition of different explosive materials. The important part of this procedure performs the 2-dimensional convolution of the differential signals formed on the basis of two sensor arrays used in the construction of the differential nose. The experimental results of the recognition of TNT, PETN and RDX have confirmed the excellent recognition ability of the developed system.