Aerosol Flow Rate Research Articles

Optimization of an air-liquid interface exposure system for assessing toxicity of airborne nanoparticles.

The use of refined toxicological methods is currently needed for characterizing the risks of airborne nanoparticles (NPs) to human health. To mimic pulmonary exposure, we have developed an air–liquid interface (ALI) exposure system for direct deposition of airborne NPs on to lung cell cultures. Compared to traditional submerged systems, this allows more realistic exposure conditions for characterizing toxicological effects induced by airborne NPs. The purpose of this study was to investigate how the deposition of silver NPs (AgNPs) is affected by different conditions of the ALI system. Additionally, the viability and metabolic activity of A549 cells was studied following AgNP exposure. Particle deposition increased markedly with increasing aerosol flow rate and electrostatic field strength. The highest amount of deposited particles (2.2 μg cm–2) at cell‐free conditions following 2 h exposure was observed for the highest flow rate (390 ml min–1) and the strongest electrostatic field (±2 kV). This was estimated corresponding to deposition efficiency of 94%. Cell viability was not affected after 2 h exposure to clean air in the ALI system. Cells exposed to AgNPs (0.45 and 0.74 μg cm–2) showed significantly (P < 0.05) reduced metabolic activities (64 and 46%, respectively). Our study shows that the ALI exposure system can be used for generating conditions that were more realistic for in vitro exposures, which enables improved mechanistic and toxicological studies of NPs in contact with human lung cells.Copyright © 2016 The Authors Journal of Applied Toxicology Published by John Wiley & Sons Ltd.

Experimental evaluation of miniature plate DMAs (mini-plate DMAs) for future ultrafine particle (UFP) sensor network

ABSTRACTTwo iPhone-sized differential mobility analyzers (DMAs) in the parallel-plate configuration (i.e., mini-plate DMAs) were designed and their performance was calibrated in this study in order to gain the instructive knowledge for the future mini-plate DMA design and to have a well-calibrated mini-plate DMA for the ultrafine particle (UFP) sensor network. The performance of mini-plate DMAs was calibrated using the tandem DMA (TDMA) technique. The experimental transfer functions of prototypes at different particle sizes and under various combinational conditions of aerosol and sheath flow rates were derived from the TDMA data. It is concluded that mini-plate DMAs performed reasonably well for UFP sizing. It was also found that the sizing resolution of mini-plate DMAs is closer to the aerosol-to-sheath flow rate ratio when the percentage of aerosol slit opening in length was increased (relative to the width of aerosol classification zone). A new concept of “effective sheath flow rate” was introduced to...

Performance evaluation of a miniature plate Electrostatic Aerosol Analyzer (mini-plate EAA)

To enable the tempo-spatial distribution monitoring/measurement of ultrafine particles, a cost-effective and miniature plate Electrostatic Aerosol Analyzer (mini-plate EAA) has been designed and characterized in this study for the use in electrical-mobility-based aerosol sizers. The prototype consists of two metal plates, installed in parallel in an insulation block, to establish the zone for particle classification. To minimize the effect of side wall in the classification zone, the length of aerosol entrance slit opening is half of the width of the classification zone. The performance of the mini-plate EAA, i.e., its transmission efficiency and transfer function, were experimentally evaluated for particles with the sizes ranging from 20 to 120nm. It is shown that the transmission efficiency of singly charged particles was nearly 100% in the sizes larger than 60nm and was dependent on the aerosol-to-sheath flow rate ratio for particles with the sizes less than 60nm when operated at the total flow rate of 3.0lpm. The particle penetration curves as a function of applied voltages were obtained for various combinations of aerosol and sheath flow rates. A modified 2-D model was further proposed to better calculate the cutoff voltage at the 50% penetration. The experimental transfer functions of the mini-plate EAA under the conditions of various aerosol-to-sheath flow rate ratios and at 3.0lpm sheath flow were given in this study.

Performance study of a miniature quadru-inlet cyclone

A miniature cyclone with four inlets was designed and experimentally calibrated in this study as a size-selective inlet for compact/miniature sensors monitoring ultrafine particles (UFPs). The development of compact/miniature UFP sensors stemmed from the concern for adverse health effects resulting from ultrafine particles, reported by recent epidemiological studies. The performance of these sensors was often interfered by the presence of large particles in sampling stream. Miniature cyclones with multiple inlets can also minimize the potential issue of directional aerosol sampling, encountered in single-inlet cyclones. The pressure drop and particle cut-off performance of this quadru-inlet cyclone were experimentally characterized at various aerosol flowrates. Compared with mini-cyclones developed by Hsiao, Chen, and Son (2009) it is found that the prototype has smaller cutoff particle size and lower pressure drop when operated at the same aerosol flowrate. The linear relationship between the dimensionless cutoff particle size (i.e.,C0.5d50DC) and the annular flow Reynolds number (Reann), reported for single-inlet cyclones, was also observed for the studied quadru-inlet cyclone. Semi-empirical models were further proposed to calculate the pressure drop and cutoff particle sizes of mini-cyclones with only one-, two- and four inlets opened. The proposed models may serve as the guideline for the future design of mini- cyclones with multiple inlets.

Development of a single cyclone separator with three stages for size-selective sampling of particles

In this study, a single cyclone separator composed of three cylinders of different diameters and one vortex finder was developed for size-selective sampling of particles. This cyclone separator had three particle traps, that is, dust bins, each of which was connected to each of the cylinders. A single cyclone separator with three stages was designed and manufactured. The numerically predicted sampling fractions agreed well with the experimental data. From both numerical and experimental results, three distinct sampling fraction curves with different geometric mean diameters (GMD) appeared and the size-selective sampling of particles was possible using the single cyclone separator with three stages. Then, the flow rate of aerosol introduced to the cyclone separator was varied to change the GMD of particles collected on the bottom of each particle trap.

Surfactant Driven Post-Deposition Spreading of Aerosols on Complex Aqueous Subphases. 1: High Deposition Flux Representative of Aerosol Delivery to Large Airways.

Aerosol drug delivery is a viable option for treating diseased airways, but airway obstructions associated with diseases such as cystic fibrosis cause non-uniform drug distribution and limit efficacy. Marangoni stresses produced by surfactant addition to aerosol formulations may enhance delivery uniformity by post-deposition spreading of medications over the airway surface, improving access to poorly ventilated regions. We examine the roles of different variables affecting the maximum post-deposition spreading of a dye (drug mimic). Entangled aqueous solutions of either poly(acrylamide) (PA) or porcine gastric mucin (PGM) serve as airway surface liquid (ASL) mimicking subphases for in vitro models of aerosol deposition. Measured aerosol deposition fluxes indicate that the experimental delivery conditions are representative of aerosol delivery to the conducting airways. Post-deposition spreading beyond the locale of direct aerosol deposition is tracked by fluorescence microscopy. Aqueous aerosols formulated with either nonionic surfactant (tyloxapol) or fluorosurfactant (FS-3100) are compared with surfactant-free control aerosols. Significant enhancement of post-deposition spreading is observed with surfactant solutions relative to surfactant-free control solutions, provided the surfactant solution surface tension is less than that of the subphase. Amongst the variables considered--surfactant concentration, aerosol flow-rate, total deposited volume, time of delivery, and total deposited surfactant mass--surfactant mass is the primary predictor of maximum spread distance. This dependence is also observed for solutions deposited as a single, microliter-scale drop with a volume comparable to the total volume of deposited aerosol. Marangoni stress-assisted spreading after surfactant-laden aerosol deposition at high fluxes on a complex fluid subphase is capable of driving aerosol contents over significantly greater distances compared to surfactant-free controls. Total delivered surfactant mass is the primary determinant of the extent of spreading, suggesting a great potential to extend the reach of aerosolized medication in partially obstructed airways via a purely physical mechanism.

Aerosol Charge Fractions Downstream of Six Bipolar Chargers: Effects of Ion Source, Source Activity, and Flowrate

Bipolar diffusion charging is used routinely in aerosol electrical mobility size distribution measurements. In this study, aerosol charge fractions produced by six bipolar chargers (neutralizers) were measured using a tandem differential mobility analyzer system. Factors that were studied include the type of ion source (210Po, 85Kr, 241Am, and soft X-ray), source activity, charger design, and aerosol flowrate. It was found that all six types of neutralizers achieve stationary state charge distributions when the source activity is sufficiently high. For 210Po neutralizers with an initial radioactivity of 18.5 MBq (0.5 mCi), stationary state charge distributions are achieved when the source is less than 3.25 years old (residual activity no less than 0.0527 MBq). Stationary state was achieved for 85Kr neutralizers having residual radioactivity greater than 70 MBq. Source activities of 241Am and soft X-ray neutralizers are discussed. Aerosol charge fractions for six neutralizers remain reasonably invariant over a wide range of flowrates. The positive charge fractions achieved by the soft X-ray neutralizer are higher than those by the other five neutralizers using radioactive sources while negative charge fractions for all neutralizers studied are all in a similar range. This study also raises questions about bipolar charging fractions used for data inversion in some scanning mobility particle spectrometer (SMPS) systems, and underscores the need to better understand bipolar charging to achieve more accurate measurements of particle size distributions.Copyright 2014 American Association for Aerosol Research

Real-Time FET-Based Biosensor Using the Wet Cyclone Air Sampler

Traditionally, microbial pollution of the environment has been associated with missions from operations in agricultural farms, poultry processing plants, landfills, and waste processing facilities. With the advent of biotechnology, new sources of bio-aerosol pollution have been generated from the utilization of genetically-engineered microbial strains in producing pharmaceuticals, enzymes, and food substitutes. Thus, detection of airborne pollution particles such as pathogenic, allergenic, and microorganisms is crucial to ensure a sanitary work environment. In this study, a cyclone bio-aerosol sampler is designed based on the Stokes number and Reynolds number to collect and concentrate bio-aerosol particles in a liquid. In addition, computational fluid dynamics (CFD) techniques are used to study the performance of an bio-aerosol sampling cyclone that continuously collects particles onto a flowing liquid film. At an aerosol sampling flow rate of 1000 L/min and a continuous liquid outflow rate of 1 mL/min, Cutpoint particle size is about 1 μm aerodynamic diameter. The sampler was connected to the FET-based biosensor using fluid channel in order to design real-time detection system (fig. 1). To evaluate the real-time detection system, protein particles were injected in the chamber of 1 m3 and collected in a liquid that are passed through the wet cyclone. The collected concentrate was delivered to the FET-based biosensor causing antigen-antibody reaction with protein through the fluid channel. Then the electrical signals were detected between the two materials using Semiconductor Parameter Analyzer (SPA).

Numerical Investigation of Sheath and Aerosol Flows in the Flow Combination Section of a Baron Fiber Classifier.

The Baron fiber classifier is an instrument used to separate fibers by length. The flow combination section (FCS) of this instrument is an upstream annular region, where an aerosol of uncharged fibers is introduced along with two sheath flows; length separation occurs by dielectrophoresis downstream in the flow classification section. In its current implementation at NIOSH, the instrument is capable of processing only very small quantities of fibers. In order to prepare large quantities of length-separated fibers for toxicological studies, the throughput of the instrument needs to be increased, and hence, higher aerosol flow rates need to be considered. However, higher aerosol flow rates may give rise to flow separation or vortex formation in the FCS, arising from the sudden expansion of the aerosol at the inlet nozzle. The goal of the present investigation is to understand the interaction of the sheath and aerosol flows inside the FCS, using computational fluid dynamics (CFD), and to identify possible limits to increasing aerosol flow rates. Numerical solutions are obtained using an axisymmetric model of the FCS, and solving the Navier-Stokes equations governing these flows; in this study, the aerosol flow is treated purely aerodynamically. Results of computations are presented for four different flow rates. The geometry of the converging outer cylinder, along with the two sheath flows, is effective in preventing vortex formation in the FCS for aerosol-to-sheath flow inlet velocity ratios below ~ 50. For higher aerosol flow rates, recirculation is observed in both inner and outer sheaths. Results for velocity, streamlines, and shear stress are presented.

Inkjet Aerosol Generator as Monodisperse Particle Number Standard

The AIST-inkjet aerosol generator (IAG) can generate highly monodisperse solid or liquid aerosol particles in the particle diameter range from 0.3 to 20 μm at precisely known particle generation rates. The device has been developed for evaluating the counting efficiencies of optical and condensation particle counters. Particle generation efficiency of the IAG is defined as the number of aerosol particles generated by one voltage pulse sent to an inkjet head. The 95% confidence interval of the efficiency were 0.998 ± 0.006 within the 0.4 to 10 μm particle diameter range. The efficiencies remained close to unity when the droplet generation rates were within 20–500 s−1 and 100–900 s−1 using ultrapure-water and isopropyl alcohol (IPA) as the solvent of the inkjet solution, respectively. The operating aerosol flowrate range of the IAG is currently 0.5 and 1.0 L/min. The coefficients of variations (C.V.) of the size distributions were 2 to 3% indicating the generated particles were highly monodisperse. The generated particle sizes were defined as the volume equivalent diameter, Dve. The uncertainty analysis on the factors affecting Dve indicated that 95% confidence interval of the Dve is expected to be ±5%. The uncertainty of Dve was entirely caused by the uncertainty of the average mass of a droplet. The reproducibility of particle sizes within 0.5 to 10 μm was evaluated using an aerodynamic particle sizer. The C.V. of the measured particle sizes were less than 6% and 4% when NaCl particles and ionic liquid droplets were generated, respectively.Copyright 2014 American Association for Aerosol Research

Effect of a Horizontal Inlet on the Collection Efficiency of a Rectangular-Slit-Nozzle Impactor

A horizontal inlet was employed to improve the collection efficiency of a rectangular-slit-nozzle impactor. A numerical and experimental study of the collection efficiency of rectangular-slit-nozzle impactors, with either typical inlets or horizontal inlets, was conducted. In the comparison of typical inlet impactors and horizontal-inlet impactors, parameters such as the nozzle width, impaction plate width, nozzle-to-plate distance, and aerosol flow rate were held constant, and only the inlet shape was changed. A parametric study was conducted to examine the effects of the horizontal inlet dimensions on the collection efficiency of rectangular-slit-nozzle impactors. It was found that a horizontal inlet could reduce the square root of the Stokes number corresponding to the cutoff size from 0.77 to 0.60, compared with a typical inlet.Copyright 2014 American Association for Aerosol Research

Effects of synthesis conditions on the physical and electrochemical properties of Li1.2Mn0.54Ni0.13Co0.13O2 prepared by spray pyrolysis

Layered Li1.2Mn0.54Ni0.13Co0.13O2 materials were synthesized via spray pyrolysis. Synthesis conditions were varied in order to understand their effect on the electrochemical properties of the material. Three process parameters were evaluated: aerosol flow rate, reactor wall temperature and precursor concentration. Electrochemical results show excellent batch-to-batch reproducibility and no non-uniformities, as measured by energy dispersive X-ray spectroscopy (EDX). Phase purity is maintained for all the samples as measured by powder X-ray diffraction (XRD). The primary particle size has the most significant effect on the electrochemical performance of the materials with smaller primary particles promoting electrochemical activation and increasing capacity. Discharge capacities exceeding 200 mAh g−1 after 100 cycles at C/3 rate (where 1C = 200 mAh g−1) are consistently obtained over a wide range of operating conditions. Spray pyrolysis is shown to be a promising, robust synthesis technique for the production of Li1.2Mn0.54Ni0.13Co0.13O2 material, delivering excellent electrochemical performance within a wide range of process conditions.

Assessment of a Cylindrical and a Rectangular Plate Differential Mobility Analyzer for Size Fractionation of Nanoparticles at High-Aerosol Flow Rates

An existing differential mobility analyzer (DMA) of cylindrical electrodes and a novel DMA of rectangular plate electrodes are demonstrated for size fractionation of nanoparticles at high-aerosol flow rates in this work. The two DMAs are capable of delivering monodisperse size selected nanoparticles (SMPS σg < 1.1) at gas flow rates ranging from 200 slm to 500 slm. At an aerosol flow rate of 200 slm, the maximum attainable particle mean size is of about 20 nm for the cylindrical DMA and of nearly 50 nm for the rectangular plate DMA. The number concentration of the monodisperse nanoparticles delivered by the high-flow DMAs spans from 104 cm−3 to 106 cm−3 depending upon the particle mean size and particle size dispersion. Copyright 2014 American Association for Aerosol Research

Characterization of a Vortex Shaking Method for Aerosolizing Fibers.

Generation of well-dispersed, well-characterized fibers is important in toxicology studies. A vortex-tube shaking method is investigated using glass fibers to characterize the generated aerosol. Controlling parameters that were studied included initial batch amounts of glass fibers, preparation of the powder (e.g., preshaking), humidity, and airflow rate. Total fiber number concentrations and aerodynamic size distributions were typically measured. The aerosol concentration is only stable for short times (t < 10 min) and then falls precipitously, with concomitant changes in the aerosol aerodynamic size distribution; the plateau concentration and its duration both increase with batch size. Preshaking enhances the initial aerosol concentration and enables the aerosolization of longer fibers. Higher humidity strongly affects the particle size distribution and the number concentration, resulting in a smaller modal diameter and a higher number concentration. Running the vortex shaker at higher flow rates (Q > 0.3 lpm), yields an aerosol with a particle size distribution representative of the batch powder; running the vortex shaker at a lower aerosol flow rate (Q ~ 0.1 lpm) only aerosolizes the shorter fibers. These results have implications for the use of the vortex shaker as a standard aerosol generator.

Electrostatic Evaluation of a Unipolar Diffusion and Field Charger of Aerosol Particles by a Corona Discharge

This article presents a unipolar diffusion and field charger by corona discharge is presented and electrostatically evaluated for charging aerosol particles. The electrostatic characteristics of the charger were investigated with an electrometer by measuring the ion number concentrations corresponding to the discharge and charging currents. The discharge and charging currents, and ion number concentration in the discharge and charging zones of the charger, increased with corona voltage. The magnitudes of the ion number concentration for positive and negative coronas in the discharge zone ranged from 1.34 × 1013 to 1.84 × 1015 ions/m3 and 7.34 × 1013 to 2.64 × 1015 ions/m3, respectively. For the charging zone, the ion number concentrations for positive and negative coronas ranged from 2.95 × 1013 to 1.52 × 1014 ions/m3 and 2.06 × 1013 to 1.47 × 1014 ions/m3, respectively. To predict the behavior of the electric field strength and lines in the discharge and charging zones of the charger, the electric field strength and distribution of the charger in the discharge and charging zones were calculated by a commercial computational fluid dynamics software package. Numerical calculation results of electric field distribution and lines through the inner electrode showed good agreement with experimental results. Also, the mean charge per particle for particle diameters were in the range of 0.01 to 50 µm for various operating conditions of the charger was theoretically evaluated. For both diffusion and field charging, lower aerosol flow rate and higher corona voltage resulted in an increase in the mean charge per particle within the charger. This simple charger proved to be particularly useful in diffusion and field charging of aerosol particles in particulate matter detector instruments for measuring PM10 and PM2.5 concentration.

A tool for uniform coating of 300-mm wafers with nanoparticles

We report a laminar flow thermophoretic aerosol deposition tool suitable for depositing nanoparticles on flat substrates such as silicon wafers up to 300 mm in diameter. The essential features were found to be a high aerosol flow rate, an inlet designed to minimize flow separation (a hyperbolic design in this case), and heating the aerosol inlet gas flow. A high flow rate reduces the residence time, thereby limiting particle agglomeration. The hyperbolic design of the aerosol inlet nozzle maintains the dynamic pressure that is needed to prevent flow recirculation, and is robust up to flow rates of 15 SLM without flow separation. Finally, heating the inlet gas flow ensures uniform particle deposition over the entire surface of the substrate. Particle deposition is quite uniform in both radial and azimuthal directions, with less than ±5.5 % variation of particle density on a 150-mm wafer, as characterized using non-contact AFM imaging. Computational fluid dynamics simulations predict that similar uniformity can be attained on larger (300 mm diameter) wafers.

Effects of breathing frequency and flow rate on the total inward leakage of an elastomeric half-mask donned on an advanced manikin headform.

The objective of this study was to investigate the effects of breathing frequency and flow rate on the total inward leakage (TIL) of an elastomeric half-mask donned on an advanced manikin headform and challenged with combustion aerosols. An elastomeric half-mask respirator equipped with P100 filters was donned on an advanced manikin headform covered with life-like soft skin and challenged with aerosols originated by burning three materials: wood, paper, and plastic (polyethylene). TIL was determined as the ratio of aerosol concentrations inside (C in) and outside (C out) of the respirator (C in/C out) measured with a nanoparticle spectrometer operating in the particle size range of 20-200nm. The testing was performed under three cyclic breathing flows [mean inspiratory flow (MIF) of 30, 55, and 85 l/min] and five breathing frequencies (10, 15, 20, 25, and 30 breaths/min). A completely randomized factorial study design was chosen with four replicates for each combination of breathing flow rate and frequency. Particle size, MIF, and combustion material had significant (P < 0.001) effects on TIL regardless of breathing frequency. Increasing breathing flow decreased TIL. Testing with plastic aerosol produced higher mean TIL values than wood and paper aerosols. The effect of the breathing frequency was complex. When analyzed using all combustion aerosols and MIFs (pooled data), breathing frequency did not significantly (P = 0.08) affect TIL. However, once the data were stratified according to combustion aerosol and MIF, the effect of breathing frequency became significant (P < 0.05) for all MIFs challenged with wood and paper combustion aerosols, and for MIF = 30 l/min only when challenged with plastic combustion aerosol. The effect of breathing frequency on TIL is less significant than the effects of combustion aerosol and breathing flow rate for the tested elastomeric half-mask respirator. The greatest TIL occurred when challenged with plastic aerosol at 30 l/min and at a breathing frequency of 30 breaths/min.

Design Considerations and Performance Evaluation of a Compact Aerosol Particle Mass Analyzer

A compact aerosol particle mass analyzer (APM) of which the size of the classifier was significantly reduced than that of the first commercial model (Kanomax Model 3600) was developed. Firstly, requirements for desired performance in classifying particle mass were set forth. Secondly, a theoretical framework for the design parameters of an APM that satisfies the requirements was formulated. Thirdly, the design parameters were determined that satisfies the requirements while reducing the instrument size. The requirements include the condition that the classification range covers from 0.001 to 1000 fg (approximately 12 to 1200 nm in size for spherical particles having the density of 1 g/cm3), and the condition that both the classification resolution and particle penetration in this mass range are higher than certain specified values. A prototype having the design parameters determined according to this theoretical framework was constructed, and its performance was evaluated experimentally. The external dimensions of the electrodes of the compact APM are approximately 140 mm in length and 60 mm in diameter. It was confirmed that the performance of the compact APM operated at the aerosol flow rate of 0.3 L/min was comparable to that of the Model 3600 APM operated at 1 L/min. Because of the reduced size and of the resultant improved portability, it is expected that the compact APM is readily applicable to field measurements. Copyright 2013 American Association for Aerosol Research

Calibration of the passive cavity aerosol spectrometer probe for airborne determination of the size distribution

Abstract. This work describes calibration methods for the particle sizing and particle concentration systems of the passive cavity aerosol spectrometer probe (PCASP). Laboratory calibrations conducted over six years, in support of the deployment of a PCASP on a cloud physics research aircraft, are analyzed. Instead of using the many calibration sizes recommended by the PCASP manufacturer, a relationship between particle diameter and scattered light intensity is established using three sizes of mobility-selected polystyrene latex particles, one for each amplifier gain stage. In addition, studies of two factors influencing the PCASP's determination of the particle size distribution – amplifier baseline and particle shape – are conducted. It is shown that the PCASP-derived size distribution is sensitive to adjustments of the sizing system's baseline voltage, and that for aggregates of spheres, a PCASP-derived particle size and a sphere-equivalent particle size agree within uncertainty dictated by the PCASP's sizing resolution. Robust determinations of aerosol concentration, and size distribution, also require calibration of the PCASP's aerosol flowrate sensor. Sensor calibrations, calibration drift, and the sensor's non-linear response are documented.

Deposition of Charged Aerosol Particles on a Substrate by Collimating Through an Electric Field Assisted Coaxial Flow Nozzle

Electroaerodynamic (EAD) jet printing, where aerodynamic force is coupled with electrostatic force in order to obtain a wide range of controlled pattern sizes, is introduced. Charged and sheathed aerosol particles yield a high deposition rate even at low velocity owing to the force of their electrostatic attraction to the substrate. In this study, two coaxial nozzles (inner diameters of 6 mm and 100 μm) were designed and tested theoretically and experimentally in order to observe the effects of electrostatic force, particle size, and air flow rate on particle trajectory and dot pattern size. A higher sheath air flow rate (higher Stokes number) caused the aerosol jet stream to be focused. For Stokes numbers higher than 1, the effect of applied voltage on pattern size was less than that of the sheath air flow rate. However, for Stokes number lower than 1, the pattern size was affected by both the applied voltage and the sheath air flow rate. After incorporating all data, the diameter of the particle deposition area (Wp) was expressed as a function of nozzle diameter (W), sheath air flow rate (Qsheath), aerosol flow rate (Qaerosol), Stokes number (Stk), and Electrostatic number (Es). Three different equations were obtained for Stk < 1, for 1 ≤ Stk < 5, and for Stk ≥ 5, respectively. These equations would be used to predict pattern width for given conditions of aerosol and sheath flow rates, particle size, electric field, and nozzle size. Copyright 2013 American Association for Aerosol Research