10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
A Modified Real-Time Method to Measure Particle Geometric Surface Area with a Time Resolution of 1s
LIPENG SU, Qisheng Ou, Leo N.Y. Cao, David Y. H. Pui, University of Minnesota
Abstract Number: 877 Working Group: Instrumentation
Abstract This paper reports the improvement of a real-time method to measure geometric surface area (GSA) of nanoparticles with a higher precision and an improved time resolution of 1s. In this method, a unipolar diffusion charger was used, followed by two identical systems in parallel, both consisting of an ion trap and an electrometer. By applying different voltages on the two ion traps, charged particles with different electric mobility may penetrate through the corresponding ion trap, with the carried charges measured by the electrometer downstream. The two measured electric currents were combined in a biquadratic subtractive process to achieve linear correlation with GSA of nanoparticles precisely. To validate the newly developed method, laboratory tests and field measurements were carried out by combined measurement using above-mentioned system and a Scanning Mobility Particle Sizer (SMPS) simultaneously. Good agreements were found between the two sets of instruments, with the improved unipolar charging technique having better time resolution of 1s.