Detection and classification of bioaerosols using laser-induced fluorescence

This report describes the capability of a Laser Induced Fluorescence (LIF) system, which is currently under development at FOI, with the purpose of rapid detection of bioaerosols. The LIF technology is deemed as one of the strongest candidates to be able to fulfill the task of near real-time detection in order to detect and provide timely warning of possible dangerous bioaerosols. The system is a so-called point detector which continuously samples aerosol from the surrounding air after which the aerosol is fed into the measuring chamber as a particle beam. By using two lasers (404 nm and 263 nm) and several detector systems, the elastically scattered light and any laser induced fluorescence is collected from each of the micron-sized particles. Measurements were performed on pure bioaerosols as well as various interferents after which classification algorithms were designed to evaluate the system at the given conditions. The system was upgraded during 2015, which resulted in that additional parameters can now be measured and a more stable particle beam. These changes provided less variation in the data and it is expected that an alarm algorithm will produce lower false alarm rates.