Design and Performance of a Low-Cost Micro-Channel Aerosol Collector

Aerosol sampling and identification is vital for assessment and control of particulate matter pollution, airborne pathogens, allergens and toxins, and their effect on air quality, human health, and climate change. Assays capable of accurate identification and quantification of chemical and biological airborne components of aerosol provide very limited sampling time resolution and relatively dilute samples. A low-cost micro-channel collector (mu CC) which offers fine temporal and spatial resolution, high collection efficiency, and delivers highly concentrated samples in very small liquid volumes was developed and tested. The design and optimization of this mu CC was guided by computational fluid dynamics (CFD) modeling. Collection efficiency tests of the sampler were performed in a well-mixed aerosol chamber using aerosolized fluorescent microspheres in the 0.5-6 mu m diameter range. Samples were collected in the mu CC and eluted into 100 mu L liquid aliquots; bulk fluorescence measurements were used to determine the performance of the collector. Typical collection efficiencies were above 50% for 0.5 mu m particles and 90% for particles larger than 1 mu m. The experimental results agreed with the CFD modeling for particles larger than 2 mu m, but smaller particles were captured more efficiently than predicted by the CFD modeling. Nondimensional analysis of capture efficiencies showed good agreement for a specific geometry but suggested that the effect of channel curvature needs to be further investigated.