Detection of Chemical Liquid Hazards on Surfaces using Biomimetic Stand-off Sensing

Here we describe the performance of a recently developed infrared-based chemical sensor for detecting liquid chemical hazards on surfaces at stand-off distances. This sensor uses the signal acquired through three broadband infrared optical filters in the mid and long wave infrared ( MWIR & LWIR), as opposed to requiring a spectrally tuneable source (such as Quantum Cascade Laser systems) or an FTIR spectrometer, to discriminate between target chemicals and background interferents. Although this technique doesn't interrogate the full MWIR/LWIR spectrum, it's ideal for screening a pre-determined list of hazards as well as lowering system cost and complexity. The technique is the IR analogue of how the human eye discriminates between different colors, and utilizes modified International Commission on Illumination (CIE) chromaticity charts to illustrate chemical detection performance. We demonstrate that the sensor can correctly discriminate between the chemical warfare agents VX and T-mustard, as well as DEET (N, N-Diethyl-meta-toluamide) insect repellent deposited upon surfaces at a distance of 1.9 meters.