Development, Characterization, and Application of a Versatile Single Particle Detection Apparatus for Time-Integrated and Time-Resolved Fluorescence Measurements—Part II: Experimental Evaluation

Abstract

This paper describes the experimental realization and characterization of a versatile single particle detection apparatus. The system utilizes a novel particle beam inlet that can serve as either an on-line particle concentrator (i.e., all diameters confined in a narrow beam) or as a segregator (i.e., selected diameters confined in a narrow beam) and can be operated in a high-speed mode as well as in a low-speed mode, thus allowing different interaction times between the particles and the laser beam. An aerodynamic sizing technique has been incorporated into the system to provide rapid, real-time, and high-resolution sizing. Parameters such as transmission efficiency and size-segregation efficiency have been measured. The performance of the instrument has been demonstrated by on-line detection of spectrally resolved and time resolved fluorescence detection from airborne dyedoped particles and aerosolized endogenous fluorophores found in biological agents.

Development of a High-Pressure Aerodynamic Lens for Focusing Large Particles (4–10 μm) into the Aerosol Time-of-Flight Mass Spectrometer

“…Since empirical measurements were not measured above ∼3 μm, it is unclear if these model discrepancies exist for their lens. Wu et al (2009a) feature an adjustable lens operating at 1000 Pa (7.5 torr) capable of being tuned to meet specific transmission requirements. Modeled transmission efficiencies could be tuned to achieve ∼100% transmission efficiency for particle sizes between 0.5-10 μm.…”

“…The critical orifice diameter was essential to particle transmission. Increasing the critical orifice to 400 μm, as was used by Wu et al (2009a), is expected to improve transmission for large particle sizes.…”

“…The majority of DEVELOPMENT OF A HIGH-PRESSURE AERODYNAMIC LENS 949 aerodynamic lens systems were designed to focus particles with diameters <1 μm (Liu et al 1995a,b;Schreiner et al 1998;Zhang et al 2002;Su et al 2004;Zhang et al 2004;Wang et al 2005a; Lee et al 2008Lee et al , 2009, while relatively few lens systems are capable of focusing particles >1 μm (Schreiner et al 1999;Fergenson et al 2004;Deng et al 2008;Wu et al 2009b;Lee et al 2013;Williams et al 2013). Significant efforts have been made to simulate transmission of larger particles (Schreiner et al 1999;Liu et al 2007;Deng et al 2008;Wu et al 2009b;Lee et al 2013;Williams et al 2013); however, there are few reported empirical measurements showing significant transmission of particles >3 μm (Schreiner et al 1999;Deng et al 2008;Wu et al 2009a;Williams et al 2013).…”

Development, Characterization, and Application of a Versatile Single Particle Detection Apparatus for Time-Integrated and Time-Resolved Fluorescence Measurements—Part I: Theoretical Considerations

“…The technical and analytical characterization of this apparatus is described in detail in a companion paper [20].…”