Rapid optical detection and classification of microbes in suspicious powders

This paper describes a rapid, reagentless, standoff method of detection and classification of bulk and trace suspicious substances on natural surfaces using solar-blind deep UV excitation and detection. Detection is typically accomplished in less one second. The detection method is solar blind and can be employed at standoff distances up to 5 m or more without interference from natural or man-made light sources. By this method, unknown suspicious powders, that potentially contain biological hazards, are automatically triaged using a four-step sequential iteration of Principal Component Analysis methods using pre-determined eigenvector sets to: 1) detect and differentiate whether a sample is bio or non-bio; 2) whether the detected bio is microbial, protein, or plant; 3) if microbial, whether the sample is a bacterial cell or spore, yeast, fungi, or fungal spore; and 4) to provide some higher level of cellular differentiability. The same method is also applicable to a wide range of chemical agents and explosives materials. The method and related instruments employ sample excitation at 248.6 nm and detection over a spectral range from 250 nm to below 350 nm, a spectral region blind to solar and most man-made light sources. Detection and classification is accomplished in less a few seconds. Sample detection and classification rates can be over 20 per second. Fully integrated and self-contained hand-held instruments are presently under development with an overall weight less than about 8 lbs, including a battery for over 8 hours of typical use. The standoff detection range is nominally 5 cm to 5 m.