Miniaturized, Lightweight, Cost-effective and Fast Response Particle Classifier

Abstract

<p>Aerosol particles properties depend strongly on their particle size and they have significant effects on both, human health and environment. Nanometer sized particles possess special electrical, optical, and/or magnetic properties. This is one of the reasons which started the interest towards studying aerosol particles in the nanometer size range (Chen and Pui, 1995). The most efficient tool for determining the size of aerosol particle in the sub-micrometer and nanometer range is the differential mobility analyzer (DMA). This popular tool has two coaxial cylindrical electrodes between of them a potential difference is applied and forces the charged polydisperse aerosol to migrate from one electrode to another. Only those particles which have an electrical mobility in a narrow range, the will pass through the classifier (Stolzenburg, 1988).   Classifying aerosols according to their electrical mobility dates back to the first half of the 20<sup>th</sup> century and from that time plethora different DMAs have been build and their performances have been tested according to their transfer function and size resolution. One major limitation of classical DMAs is the time it takes to scan over the entire size range to get the size distribution of the aerosol. This is especially leading to the loss of information if the aerosol is changing its size and/or concentration rapidly. This happens for instance during new particle formation events, or also when the measurement takes place on fast moving platforms, such as cars, or airplanes.</p><p>The present work evaluates the performance of two different, newly developed DMA types, that aim towards overcoming this limitation. This is done by replacing the classic design of a single monodisperse outlet DMA to a multiple monodisperse outlet DMA. In our case the DMAs have three monodisperse outlets and are 3D-printed (namely, the 3MO-DMA) (Chen et al., 2007; Giamarelou et al., 2012; Barmpounis et al., 2016; Bezantakos et al., 2016). The 3MO-DMA is not only a fast response instrument able to sizing three different sizes ranges at the same time but also is a cost-effective and lightweight instrument suitable to get measurements not only ground based but also on Unmanned Aerial Vehicles or balloons.</p>