| Abstract
| - In this paper, we report on the preparation of novel cross-reactive optical microsensors for high-speed detection oflow-level explosives and explosives-like vapors. Poroussilica microspheres with an incorporated environmentallysensitive fluorescent dye are employed in high-densitysensor arrays to monitor fluorescence changes duringnitroaromatic compound (NAC) vapor exposure. Theporous silica-based sensor materials have good adsorption characteristics, high surface areas, and surfacefunctionality to help maximize analyte−dye interactions.These interactions occur immediately upon vapor exposure, i.e., in less than 200 ms and are monitored with ahigh-speed charge-coupled device camera to producecharacteristic and reproducible vapor response profilesfor individual sensors within an array. Employing thousands of identical microsensors permits sensor responsesto be combined, which significantly reduces sensor noiseand enhances detection limits. Normalized responseprofiles for 1,3-dinitrobenzene (1,3-DNB) are independent of analyte concentration, analyte exposure time, orsensor age for an array of one sensor type. Explosives-like NACs such as 2,4-dinitrotoluene and DNB aredetected at low part-per-billion levels in seconds. Sensor−analyte profiles of some sensor types are more sensitiveto low-level NAC vapor even when in a higher organicvapor background. We show that single-element arrayspermit the detection of low-level nitroaromatic compoundvapors because of sensor-to-sensor reproducibility andsignal averaging.
|
