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Airborne particles are separated according to their electrical mobilities using a microfabricated corona ionizer and separator electrodes. Oleic acid particles with sizes ranging from 30 to 300 nm are used to characterize the device. They are generated using a TSI 3075 constant output atomizer. These particles are electrically charged by a microfabricated corona ionizer, and the resultant particle electrical mobility is a function of the size of the particle. A varying dc potential difference of 0-2 kV across the separator electrodes selects charged particles of various electrical mobilities. These separated particles are subsequently counted using a TSI 3025A Condensation Particle Counter. The device demonstrated its ability to separate particles between 50 and 130 nm into five distinct size bins. The operational flow rate is 0.5 L/min, and the micropin-between-planes corona ionizer operates at 1.3 kV with 7 [mu]A. The theoretical and experimental electrical mobilities of the particles are compared. [2008-0091] Index Terms--Aerosol instrumentation, corona ionizer, particle electrical mobility, particle separation.

A microfabricated corona ionizer is developed for miniaturized air particle monitoring instruments. Peek's breakdown criterion and Warburg's Law are used to calculate the required electrode geometries. Single mask electroplating is employed as the microfabrication technique. Devices with discharge pin radius of 20 [micro]m and interelectrode spacing of 1.4, 1.8, 2.0, and 2.2 mm are fabricated and tested. The inception voltages in the range from 1.4 to 2 kV are achieved without substrate breakdown. It consumes relatively low power at 150 mW or less. Corona charging currents of more than 50 [micro]A were achieved before streamers break down. The experimental results also demonstrated the nondependency of the inception voltage on the pin's radius of curvature so long as it is significantly smaller than the interelectrode spacing. There is only one value of inception voltage for each given interelectrode spacing ( 1.4 to 2.2 ram) with the pin's radius of curvature ranging from 10 to 200 [micro]m. This implies that strict dimensional control is not required in the microfabrication process in order to ensure the same inception voltage for each device. [2007-0152] Index Terms--Avalanche, corona, discharge, electroplating, inception, ionizer, microfabricated, plasma, streamer.

ABSTRACT Particle number distributions were measured simultaneously upwind and downwind of a suburban-agricultural freeway to determine relationships with traffic and meteorological parameters. Average traffic volumes were 6330 vehicles/hr with 10% [...]

Light detection and ranging (lidar) has been proven to be a potentially effective means of measuring PM10 emissions from agricultural nonpoint sources. Lidar enables the description and modelling of plume dynamics, measurement of average wind speed and direction, quantitative sampling of dust missed by point sampling arrays and the generation of temporal and spatial information on nonpoint source emission variability.

Sandy aquifers, which are important sources of groundwater, may be exposed to anthropogenic contamination. Cost-effective remediation of such contaminated water resources requires an understanding of the kinetic processes in the contamination by hydrophobic organic compounds (HOCs) of the aquifers. The research examined the retarded diffusion in the coatings, which may control the sorption rate of HOCs, of three quartzitic aquifer sands.

We have demonstrated the sensing of airborne nanoparticles using a miniaturized Whipple double condenser (MWDC). Each condenser (17 mm long, 2.2 mm wide, and 1 mm tall) was fabricated using photolithography and copper electroplating. The MWDC was theoretically shown to function within the laminar flow regime and capable of detecting 10- and 20-nm particles at a flow rate of 0.3 LPM. Monodispersed isopropyl alcohol and oleic acid airborne nanoparticles (10 and 20 nm) were generated using a TSI Model 9302 Single Jet Atomizer and TSI 3080 Electrostatic Classifier, and were electrically charged with 85Kr isotope. The calculated and experimental particle pass through ratio (PPR) agreed reasonably well. Using a Keithley 616 electrometer, similar threshold condenser voltage (maximum second condenser current) was observed in both experimental PPR as well as the second condenser current versus condenser voltage plot. The MWDC also displayed characteristic Whipple curves in its experimental I/V versus \textkc plots. These data demonstrate the feasibility of the microfabricated double condenser design as the basis of a miniaturized nanoparticle sizing and counting device. [ABSTRACT FROM PUBLISHER]

A microfabricated electrostatic precipitator successfully demonstrated its airborne liquid phase particles precipitation functionality. The particles used in the experiments were polydispersed liquid phase oleic acid particles with sizes ranging from 30 nm to 300 nm. Two configurations with electrode gaps of 1.8 mm and 2.0 mm were tested at 2.2 kV and 2.6 kV, respectively. During the test, the microfabricated electrostatic precipitator was inserted into a flow chamber with an aerosol stream containing oleic acid particles. Particle precipitation is demonstrated via both visual observation and the measurement of the corona current during aerosol exposure. The corona current for the 2.0 mm electrode gap configuration was decreased by approximately 50% and the circuit resistivity is increased by the corresponding magnitude as the oleic acid particles precipitated during a 60 s exposure. The recovery of corona current is observed when the aerosol source is turned off. Wicking of precipitated oleic acid away from the collection grid to its anchoring feature is observed. The analytical and experimental corona current versus time elapsed during the aerosol exposure are calculated and compared. The discrepancy between the analytical and experimental corona currents is consistent with the observed wicking effect and variation in percent coverage on the collector grid by precipitating particles. \hfill[2013\--0016] [ABSTRACT FROM AUTHOR]

Airborne particles are separated according to their electrical mobilities using a microfabricated corona ionizer and separator electrodes. Oleic acid particles with sizes ranging from 30 to 300 nm are used to characterize the device. They are generated using a TSI 3075 constant output atomizer. These particles are electrically charged by a microfabricated corona ionizer, and the resultant particle electrical mobility is a function of the size of the particle. A varying dc potential difference of 0-2 kV across the separator electrodes selects charged particles of various electrical mobilities. These separated particles are subsequently counted using a TSI 3025A Condensation Particle Counter. The device demonstrated its ability to separate particles between 50 and 130 am into five distinct size bins. The operational flow rate is 0.5 L/min, and the micropin-between-planes corona ionizer operates at 1.3 kV with 7μA. The theoretical and experimental electrical mobilities of the particles are compared. [ABSTRACT FROM AUTHOR]

A microfabricated corona ionizer is developed for miniaturized air particle monitoring instruments. Peek's breakdown criterion and Warburg's Law are used to calculate the required electrode geometries. Single mask electroplating is employed as the microfabrication technique. Devices with discharge pin radius of 20 µm and interelectrode spacing of 1.4, 1.8, 2.0, and 2.2 mm are fabricated and tested. The inception voltages in the range from 1.4 to 2 kV are achieved without substrate breakdown. It consumes relatively low power at 150 mW or less. Corona charging currents of more than 50 µA were achieved before streamers break down. The experimental results also demonstrated the nondependency of the inception voltage on the pin's radius of curvature so long as it is significantly smaller than the interelectrode spacing. There is only one value of inception voltage for each given interelectrode spacing (1.4 to 2.2 mm) with the pin's radius of curvature ranging from 10 to 200 µm. This implies that strict dimensional control is not required in the microfabrication process in order to ensure the same inception voltage for each device. [ABSTRACT FROM AUTHOR]