3D printed micro-cyclones with improved geometries for low-cost aerosol size separation

This is the authors' abstract. We don't add key points for this paper.

The impact of suspended particles on health, climate, and industrial applications is highly size-dependent. Thus, regulations are typically based on particles with diameters below a specific size, such as particulate matter less than 2.5 μm (PM2.5). For over a century, cyclones have been employed to isolate particles below a certain diameter by removing large particles from a gas stream, but cyclones are typically relatively large, heavy, and expensive to fabricate compared to objects made with low-cost 3-dimensional (3D) printers. Herein, we present one-piece 3D-printed micro-cyclones (PM2.5 and PM1) to isolate particles smaller than a specific diameter. The collection efficiencies and 50% cut-off diameters (d50) of multiple cyclones were evaluated with both monodisperse and polydisperse standards ranging from 0.1 to 3 μm, as well as ambient aerosol. By altering the inlet orientation relative to the micro-cyclone centerline (orthogonal, 50% offset, and fully offset), we show that shifting the inlet radially outward increased the steepness of the transmission curve resulting in a sharper cut-point. The d50 also decreased below the designed for diameter, (PM1 = 1.4, 1.0, and 0.9 μm; PM2.5 = 3.2, 2.0, 1.9 μm), which was attributed to imperfect models, internal surface roughness, and print errors versus machining. These single piece, 3D-printed cyclones provide a cheaper (< $1), faster, and more accessible approach to manufacture micro-cyclones for use in a range of aerosol applications.