AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Development of a Pulsed-Voltage Differential Mobility Analyzer for Measuring Shape Parameters for Non-Spherical Particles
MINGDONG LI, Rian You, George Mulholland, Michael Zachariah, University of Maryland
Abstract Number: 134 Working Group: Instrumentation and Methods
Abstract For a non-spherical particle, a DMA measurement in a static electric field can only be used to get an equivalent spherical diameter, but is not sufficient to obtain geometric shape information. The electrical mobility of nonspherical particles is dependent on the particle orientation. It was previously found that the orientation of such particles can be changed by varying the electric field strength. This method required changed the flow to change the peak voltage. Here we describe the operation of a pulsed differential mobility analyzer (PDMA) which enables one to change the peak E-field experienced by the particle, for an arbitrary period of time during the particle transit through the DMA. With this approach the particle can be partially oriented in the field thus changing its average mobility without changing the flow. By varying the peak voltage and frequency we show how one can obtain both the length and diameter of rods. Furthermore this approach can be used to separate spherical from non-spherical particles with the same average mobility.