A low-cost multichannel aerosol fluorescence sensor for networked deployment

Abstract

We describe a low-cost prototype bio-aerosol fluorescence sensor designed for unattended deployment in medium to large area networks. The sensor uses two compact xenon flash units to excite fluorescence in an aerosol sample volume drawn continuously from the ambient environment. In operation, the xenons are pulsed alternately at 300ms intervals whilst absorption filters restrict their radiation output to UV bands ~260-290nm and ~340-380nm respectively, optimal for exciting the biological fluorophores tryptophan and NADH. Fluorescence from all particles instantaneously present within a sensing volume is measured using two miniature photomultiplier detectors optically filtered to detect radiation in the bands ~320-600nm and ~410-600nm. The second of these bands covers the principal emission from NADH, whilst the difference between the first and second detector channels yields fluorescence in the 320-410nm band, covering much of the tryptophan emission. Whilst each sensor is clearly limited in specificity, the low sensor cost (<$5k) offers potential for the deployment in large networks that would be prohibitively expensive using particle fluorescence sensors based on currently available UV lasers. Preliminary details are also given of a variant of the sensor, currently under development, in which xenon illumination is used to acquire single particle fluorescence data at rates of up to 200 particles per second.

On-line monitoring of airborne bioaerosols released from a composting/green waste site

“…For this purpose instrumentation such as the Wideband Integrated Bioaerosol Sensor (WIBS) series has been developed (Hairston et al, 1997;Kaye et al, 2005Kaye et al, , 2004Kaye et al, 2007). Its LIF methodology depends upon the fact that many structural components and secondary metabolites of PBAP such as tryptophan, tyrosine and NAD(P)H fluoresce (Roshchina et al, 2004(Roshchina et al, , 1995(Roshchina et al, , 1998Roshchina, 2003;Pöhlker et al, 2013).…”

Optimization of a UV light-emitting diode based fluorescence-phase sensor

“…3b). 5,8,9,14,[16][17][18] Since the peaks observed in the B. globigii spectra can be shifted in respect of those observed in unbound fluorophores due to an inhomogeneous environment, it is difficult to unambiguously assign the blue-green emission to particular autofluorphores. Nevertheless, the most probable assignment is that the blue band in B. globigii is mainly due to DPA and NADH, whereas the green band is due to flavins.…”

“…[8][9][10] However, there exists no viable concept of a bioparticle fluorescence sensor, which employs an additional detection channel for the characterization of fluorescence decay time. A straightforward introduction of such a channel can result in a significant increase in the sensor price.…”

Optics of Biological Particles

“…Researchers at the University of Hertfordshire and Defence Science and Technology Laboratory in the UK examined the use of xenon discharge tubes in a prototype bio-aerosol monitoring system, WIBS1 (Kaye et al, 2004). WIBS1 was developed with the self-imposed constraint of using only low-cost COTS (commercial off-the-shelf) components.…”