Spectral characterization of biological aerosol particles using two-wavelength excited laser-induced fluorescence and elastic scattering measurements

Sivaprakasam, Vasanthi; Lin, Horn-Bond; Huston, Alan L.; Eversole, Jay D.

doi:10.1364/oe.19.006191

Cited by 74 publications

(60 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Gain voltages applied differently to PMT2 and PMT3 could also impact differences in relative intensity observed. Lastly, it has been proposed that the rapid sequence of Xe1 and Xe2 excitation could lead to quenching of fluorescence from the first excitation flash, leading to overall reduced fluorescence in the FL3 channel (Sivaprakasam et al, 2011). These factors may similarly affect all WIBS instruments and should be kept in mind when comparing results here with other UV-LIF instrument types.…”

Section: Broad Separation Of Particle Typesmentioning

confidence: 96%

Systematic characterization and fluorescence threshold strategies for the wideband integrated bioaerosol sensor (WIBS) using size-resolved biological and interfering particles

et al. 2017

View full text Add to dashboard Cite

Abstract. Atmospheric particles of biological origin, also referred to as bioaerosols or primary biological aerosol particles (PBAP), are important to various human health and environmental systems. There has been a recent steep increase in the frequency of published studies utilizing commercial instrumentation based on ultraviolet laser/light-induced fluorescence (UV-LIF), such as the WIBS (wideband integrated bioaerosol sensor) or UV-APS (ultraviolet aerodynamic particle sizer), for bioaerosol detection both outdoors and in the built environment. Significant work over several decades supported the development of the general technologies, but efforts to systematically characterize the operation of new commercial sensors have remained lacking. Specifically, there have been gaps in the understanding of how different classes of biological and non-biological particles can influence the detection ability of LIF instrumentation. Here we present a systematic characterization of the WIBS-4A instrument using 69 types of aerosol materials, including a representative list of pollen, fungal spores, and bacteria as well as the most important groups of non-biological materials reported to exhibit interfering fluorescent properties. Broad separation can be seen between the biological and non-biological particles directly using the five WIBS output parameters and by taking advantage of the particle classification analysis introduced by Perring et al. (2015). We highlight the importance that particle size plays on observed fluorescence properties and thus in the Perring-style particle classification. We also discuss several particle analysis strategies, including the commonly used fluorescence threshold defined as the mean instrument background (forced trigger; FT) plus 3 standard deviations (σ ) of the measurement. Changing the particle fluorescence threshold was shown to have a significant impact on fluorescence fraction and particle type classification. We conclude that raising the fluorescence threshold from FT + 3σ to FT + 9σ does little to reduce the relative fraction of biological material considered fluorescent but can significantly reduce the interference from mineral dust and other non-biological aerosols. We discuss examples of highly fluorescent interfering particles, such as brown carbon, diesel soot, and cotton fibers, and how these may impact WIBS analysis and data interpretation in various indoor and outdoor environments. The performance of the particle asymmetry factor (AF) reported by the instrument was assessed across particle types as a function of particle size, and comments on the reliability of this parameter are given. A comprehensive online supplement is provided, which includes size distributions broken down by fluorescent particle type for all 69 aerosol materials and comparing threshold strategies. Lastly, the study was designed to propose analysis strategies that may be useful to the broader community of UV-LIF instrumentation users in order to promote deeper discussions about how best to continue i...

show abstract

Section: Broad Separation Of Particle Typesmentioning

confidence: 96%

Systematic characterization and fluorescence threshold strategies for the wideband integrated bioaerosol sensor (WIBS) using size-resolved biological and interfering particles

et al. 2017

View full text Add to dashboard Cite

show abstract

“…material (Hill et al, 2001;Huffman et al, 2010;Kaye et al, 2005;Pöhlker et al, 2012;Sivaprakasam et al, 2004Sivaprakasam et al, , 2011Pan et al, 2007Pan et al, , 2012Pinnick et al, 2013).…”

Section: N H Robinson Et Al: Cluster Analysis Of Wibs Datamentioning

confidence: 99%

Cluster analysis of WIBS single-particle bioaerosol data

et al. 2013

View full text Add to dashboard Cite

?? Author(s) 2013. This work is distributed under the Creative Commons Attribution 3.0 LicenseHierarchical agglomerative cluster analysis was performed on single-particle multi-spatial data sets comprising optical diameter, asymmetry and three different ???uorescence measurements, gathered using two dual Wideband Integrated Bioaerosol Sensors (WIBSs). The technique is demonstrated on measurements of various ???uorescent and non-???uorescent polystyrene latex spheres (PSL) before being applied to two separate contemporaneous ambient WIBSdata sets recorded in a forest site in Colorado, USA, as part of the BEACHON-RoMBAS project. Cluster analysis results between both data sets are consistent. Clusters are tentatively interpreted by comparison of concentration time series and cluster average measurement values to the published literature (of which there is a paucity) to represent the following: non-???uorescent accumulation mode aerosol; bacterial agglomerates; and fungal spores. To our knowledge, this is the ???rst time cluster analysis has been applied to long-term online primary biological aerosol particle (PBAP) measurements. The novel application of this clustering technique provides a means for routinely reducing WIBS data to discrete concentration time series which are more easily interpretable, without the need for any a priori assumptions concerning the expected aerosol types. It can reduce the level of subjectivity compared to the more standard analysis approaches, which are typically performed by simple inspection of various ensemble data products. It also has the advantage of potentially resolving less populous or subtly different particle types. This technique is likely to become more robust in the future as ???uorescence-based aerosol instrumentation measurement precision, dynamic range and the number of available metrics are improved

show abstract

“…The relation between elastic scatter intensity and particle size is highly dependent on specific optical design. For the collection optics used here, particle size dependence for different particle materials is discussed in greater detail comparing Mie theory calculations to measured values in Table 3 of Sivaprakasam et al (2011). To illustrate the principle of operation, data is shown in Figure 2 for mono-dispersed 1.5 μm silica particles (top left), 1, 2, 3, and 5 μm poly styrene latex (PSL) spheres (Thermo Scientific Inc., Palo Alto, CA, USA) (top right), bacterial spores, Bacillus atrophaeus, ssp.…”

Section: Aerosol Resultsmentioning

confidence: 99%

A Novel Polarized Elastic Scatter Detection Method of Aerosol Particle Velocimetry with Reduced Errors Due to Coincidence and Phantom Particles

Sivaprakasam

Huston

Schultz

et al. 2012

Aerosol Science and Technology

Self Cite

View full text Add to dashboard Cite

This article describes a novel polarized elastic scattering method to measure flow velocities of aerosol particles. Velocities of individual aerosol particles of mixed size, and composition have been determined from time differences between scattered light pulses as they move between two parallel laser beams separated by a fixed distance, known as a time-of-flight method. By using two orthogonally polarized laser beams, the detected light pulses can be assigned to each beam by simultaneously determining their respective depolarization ratio. This implementation of time-of-flight velocimetry provides a mechanically robust distance between the two beams, which reduces error in the measurement and improves both its precision and accuracy, but more importantly, the use of the polarization features of the scattered light reduces errors due to particle coincidence and phantom particles caused by confusion of start and stop timing pulses. This approach was developed and demonstrated in an application to provide effective timing for subsequent selective actions on individual particles downstream such as: further diagnostic measurement, electrical charging and capture. These downstream actions require accurately predicted individual particle trajectories.

show abstract

Spectral characterization of biological aerosol particles using two-wavelength excited laser-induced fluorescence and elastic scattering measurements

Cited by 74 publications

References 17 publications

Systematic characterization and fluorescence threshold strategies for the wideband integrated bioaerosol sensor (WIBS) using size-resolved biological and interfering particles

Systematic characterization and fluorescence threshold strategies for the wideband integrated bioaerosol sensor (WIBS) using size-resolved biological and interfering particles

Cluster analysis of WIBS single-particle bioaerosol data

A Novel Polarized Elastic Scatter Detection Method of Aerosol Particle Velocimetry with Reduced Errors Due to Coincidence and Phantom Particles

Contact Info

Product

Resources

About