Abstract
To solve the challenge of extracting nano- to micrometer-sized atmospheric particles from a mixed sample, we developed an electrostatic sieve system, the Fine Sieving of Collected Atmospheric Particles using Oil Electrophoresis (iSCAPE), based on the application of an electrostatic field to a non-conductive mineral oil. Using atmospheric samples, which were collected from different cities, in addition to soil and road dust samples, we tested this system under different conditions and found that the “iSCAPE’d” particles moved rapidly at varying velocities and in two opposite directions. The diverse origins of the sample—ambient air, soil, or road dust—exhibited specific charged properties, and clearly affected the electrical mobility, as demonstrated by the graphs, of the particles following the “iSCAPEing,” which lasted from seconds to minutes. We also observed an increased abundance of particles in specific mobility ranges. Furthermore, according to our adenosine triphosphate (ATP) monitoring results, the iSCAPE is capable of separating bacterial particles by size and electrical mobility. The experimental data suggests that the iSCAPE relies heavily on the electrostatic field strength, mineral oil viscosity, and run time. In theory, this method can extract any targets from a complex sample, thus creating many research opportunities in environmental, biomedical, and life sciences.
Highlights
Air pollution, especially particulate matter (PM), has become one of the most important environmental problems in the world
The differences observed for different cities via the iSCAPE were likely due to the different components such as bacteria and metals, and the size distributions of their PM (Li et al, 2018; Yue et al, 2018; Li et al, 2019)
About 21% was located within 1 cm range from the feed point. These data suggest that the iSCAPE system can be used to separate bacterial particles, and a higher fraction of them were shown carrying negative charges
Summary
Especially particulate matter (PM), has become one of the most important environmental problems in the world. There are some commercially available instruments for studying differently sized atmospheric particles (Agranovski et al, 2003; Yao and Mainelis, 2006a), but some of them do not automatically provide samples for post-analysis. Differential mobility analyzer (DMA) with up to 192 size channels is otherwise used to study size distributions of nanoscale particles (1 nm–1 μm) (Hewitt, 1957; Knutson and Whitby, 1975). Use of such an equipment is often restrictive due to its availability and post-analysis difficulties. Separation and classification of atmospheric particles using currently available methods are often prohibitive in terms with their sizes and species, especially for post-analysis, and equipment cost
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