Abstract: The Nebulized Airborne Biohazard Stage Alert (NABSA) is a method utilizing an optical particle counter in conjunction with a fluorometer as triggers to detect and assess potential biohazard threats infused into surrounding air. In the first stage an optical particle counter is constantly passing sampled air in front of an energy source, in turn scattering light. This scattered light is evaluated to establish if the particles are above one micrometer in concentrations, and thus potentially an aerosolized threat. Such detection triggers the secondary stage in which the sample particles are tested for viability via processing through a dye with fluorescent properties affected when bonded with an entity universally found in all biological substances and a UV light source. The detection of concentrations of oversized, viable particles triggers the third stage to compare a sample of the particles to known biowarfare agents to delineate the specific agent species.

Abstract: The Nebulized Airborne Biohazard Stage Alert (NABSA) is a method utilizing an optical particle counter in conjunction with a fluorometer as triggers to detect and assess potential biohazard threats infused into surrounding air. In the first stage an optical particle counter is constantly passing sampled air in front of an energy source, in turn scattering light. This scattered light is evaluated to establish if the particles are above one micrometer in concentrations, and thus potentially an aerosolized threat. Such detection triggers the secondary stage in which the sample particles are tested for viability via processing through a dye with fluorescent properties affected when bonded with an entity universally found in all biological substances and a UV light source. The detection of concentrations of oversized, viable particles triggers the third stage to compare a sample of the particles to known biowarfare agents to delineate the specific agent species.

Abstract: A light scattering photometer signal-enhancement systems includes an adaptive sample and subtract circuit controlled by a computer or microcontroller (MCU). The MCU controls the gain of a programmable-gain amplifier (PGA) cascade that is used to amplify the raw photometer signal. In order to maintain the DC accuracy, the DC offset contained in the raw signal from the photometer is estimated by an algorithmic within the MCU and then subtracted from the raw signal before allowing it to be amplified by the PGA cascade. In addition to DC estimation and adaptive cancellation, the MCU applies a digital filtering scheme to compensate irrelevant frequency bands in the amplified signal and offers user determined averaging functions for additional signal conditioning. Moreover, hardware filters are used to prevent signal aliasing by the analog to digital converters (ADC) and a 60 Hz notch filter suppresses general electrical noise.