A prototype instrument was developed to measure geometric surface area (GSA) concentrations and mass or volume concentrations for agglomerated or aggregated particles at a time resolution of 1 s. It couples a diffusion charger with two sets of electrostatic precipitators and electrometers to monitor two current signals synchronously. In this way, we refined the measurements with a weighted-sum method. Initially, we tested the ability to distinguish different particle morphologies. Subsequently, theoretical volume and GSA measurements of single agglomerates and aggregates were performed to calibrate the instrumental sensitivity for particle sizes. Experimental results with polydisperse silver particles indicated that a diffusion charger coupled with a differential mobility analyzer and a condensation particle counter could identify particle shapes having different fractal dimensions. Above all, the instrument could be used to measure GSA, volume, or mass concentrations of both agglomerates and aggregates in real time. A favorable comparison with results obtained with a scanning mobility particle sizer suggested great potential for commercial applications.
Bibliographical noteFunding Information:
The authors also gratefully acknowledge financial assistance from the China Scholarship Council and the National Science Foundation of China (Grant 51676059). The authors thank the following member companies of the Center for Filtration Research for their support: 3M Corporation, A.O. Smith Company, Applied Materials, Inc., BASF Corporation, Boeing Company, Corning Co., China Yancheng Environmental Protection Science and Technology City, Cummins Filtration Inc., Donaldson Company, Inc., Entegris, Inc., Ford Motor Company, Guangxi Wat Yuan Filtration System Co., Ltd, MSP Corporation; Samsung Electronics Co., Ltd., Xinxiang Shengda Filtration Technology Co., Ltd., TSI Inc., W. L. Gore & Associates, Inc., and Shigematsu Works Co., Ltd. The authors likewise thank the Center?s affiliate member, the National Institute for Occupational Safety and Health (NIOSH).
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- Jason Olfert