Bioluminescent Explosive Detector.

The utilization of the bioluminescence concept for the detection of buried military explosives was advanced closer to realistic field application. The sensitivities of the biosensors were enhanced by mutagenesis, optimization of biosensor environment, and nutritional evaluations. An estimate of current sensorequipment sensitivity ranges below 30 ppb to pure TNT at saturated vapor pressure, 20 C. Based on experimental data, it was shown that the biosensors do possess some degree of specificity, especially with the TNT detection signals. Some of the common impurities found in TNT i.e., DNT and Composition B which elicited sensor responses resembling explosive detection curves are not expected to be found in the normal environment. Potential interferents such as nitrogen dioxide, sulfur dioxide, human effluents, etc., did not cause false positive reactions. A dual-channel photosensing unit was developed and fabricated to facilitate the acquisition of more detailed information on biosensor performance. Circuitry was developed which increased system signal-to-noise ratio and sensor pattern reproducibility. System detection capability was extended to accept dimmer sensor luminosities.