Detection and identification of biological aerosols
The growing concentration of different types of aerosols in the atmosphere becomes more and more an important issue for the international community. Their influence on the climate change and air quality is still an open question for researches as for the people from other field of human activity. Moreover, some of aerosols (ex. pollens, spores) have huge impact on human health (ex. allergies) and need to be detected in real-time to warn the population.
In our group, we develop and test a new mobile aerosol detector that measures scattered light and emitted fluorescence of individual aerosols. The measurement is done in real-time, and as the result, the different species are identified and counted by the machine. This provides the real-time statistics on particle concentration.
The detector uses two crossed continuous wavelength lasers to detect the presence of single aerosol and to measure its size. Then a particle is detected, an UV light source receives a trigger signal and fires on the particle. UV light gets absorbed by fluorophore molecules inside the aerosols, and visible light is emitted. This light is a fluorescence signature of an individual aerosol. Given the aerosol size and fluorescent response, one can classify it into a corresponding group.
The actual detector can use two different UV source: for one-photon fluorescence – Xenon flash lamp with excitation band 245 nm to 280 nm; for multi-photon fluorescence – triggered amplified femtosecond laser pulses at 800 nm. First approach lets to keep the detector compact and cost-effective resulting in a close-to-market prototype. The second approach will let in the future to implement pump-probe method or more complex coherent control to increase the discrimination power of the detector.
1) Spectrally resolved detection of single aerosols with Xenon ash lamp, D. Kiselev et al. Review of Scientific Instruments, to be submitted in 2011.
2) Individual bioaerosol particle discrimination by multi-photon excited fluorescence, D. Kiselev, L. Bonacina, and J.-P. Wolf, Optics Express 19 (24), 24516-24521 (2011)
3) Single-particle fluorescence spectrometer for ambient aerosols, Pan, Y. L., J. Hartings, et al. Aerosol Science and Technology 37 (8): 628-639 (2003).
4) A puff of air sorts bioaerosols for pathogen identification, Pan, Y. L., V. E. Boutou, et al. Aerosol Science and Technology 38 (6): 598-602 (2004).