AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Development of a Geometrical Surface Area Monitor for Nanoparticles: Experiments and Models
LEO N.Y. CAO, Jing Wang, Heinz Fissan, David Y. H. Pui, University of Minnesota
Abstract Number: 248 Working Group: Instrumentation and Methods
Abstract Compared to particle size, number, or mass concentration, geometric surface area (GSA) correlates better to catalytic activity, drug delivery, particle reactivity, and human health for ultrafine particles. However, there is no cheap, portable instrument which can measure it.
We are developing a portable instrument to deliver GSA for arbitrarily shaped particles in the range of 25 to 400 nm in real time by unipolar charging method.
A unipolar diffusion charger is used to charges particles and an electrometer measures the final electrical current generated by the collection of those charged particles. Between them, a custom-built electrostatic precipitator (ESP) is used to control the penetration of charged particles by applying different voltage such that the final current is proportional to GSA. A CFD simulation of the penetration of charged particles through the ESP was conducted via Fluent.
We found the measured current is proportional to the diameter to the power of 2.03 and 1.98 (or effectively GSA) for monodisperse particles from 25 to 100 nm and from 100 to 400 nm for ESP applied voltages of 0.15 and 1 kV, respectively. Numerical simulations show similar penetration results for the ESP compared to experimental data.
For particles in the range of 25 to 400 nm, current results validate our proposed design for an instrument to measure GSA for spherical particles. Future work will focus on extending the instrument’s capability towards arbitrarily shaped nanoparticles.