Development of a microsampler suitable for aerial collection of aerosol particles

A microsampler for collecting aerosol particles on an unmanned aerial system (UAS) was designed and evaluated in the laboratory for dry (no condensed water) and wet (foggy, misty, or rainy) air conditions. This microsampler was produced using a customized impactor design to minimize size, weight, and power requirements uniquely suitable for aerial applications, also maximize the collection efficiency above a specific cut-off size in a short time and concentrate particles for future automated analysis using microfluidics. The computational fluid dynamics (CFD) results suggested a design that provided a higher sampling efficiency with minimal inlet loss. The microsampler was experimentally evaluated using fluorescent polystyrene latex (PSL) particles at four nominal sizes. The experimental results at the four PSL particle sizes agree reasonably well with the collection efficiencies predicted by CFD. We found no effect of humidity on the collection efficiency of the microsampler under conditions at 80% relative humidity. However, when condensed water exists, significant biases on the collection efficiencies were found suggesting that this microsampler should not be used under conditions where there is condensed water in the atmosphere, e.g., foggy, misty, and rainy conditions.