Rapid bioaerosol detection by measuring circular intensity differential scattering (CIDS) from single flowing through particle

Abstract

We present an advanced optical method to measure the phase function of circular intensity differential scattering (CIDS), i.e., the normalized Mueller matrix element -S14/S11, from individual single flowing through aerosol particles. Here, a 32-anode photomultiplier tube and its associated electronics, combined with an elliptical reflector, were used to record the scattering phase functions, when a particle were illuminated by a left-handed and a right-handed circular polarization laser beam around the focus of the reflector successively. The new design does not need lock-in amplifier, polarization modulator, and rotating goniometer as the traditional setup. It can reach a particle detection ability with a maximum rate of 50,000 particle/sec. CIDS phase functions from tryptophan particles, polystyrene latex microspheres, aggregates of Escherichia coli, Bacillus subtilis spores, Yersinia rohdei, and bacteriophage MS2 were measured, the results showed that this method has the ability to rapidly discriminate between single bioaerosol and non-bioaerosol particles.