Design and feasibility evaluation of a single-pump cascade micro virtual impactor for simultaneous classification of PM2.5 and PM1.0

초록

The prevalence of respiratory diseases and health risks associated with fine particulate matter has been increasing, creating a demand for ultra-compact, low-power devices capable of simultaneously classifying and detecting PM2.5 and PM1.0 particles in real time. This study developed a single-pump cascade micro virtual impactor (SPC-μVI) with a serial dual-stage structure, in which a single pump precisely controls the major and minor flows of both stages to classify PM2.5 and PM1.0 particles simultaneously. In each stage, thermophoretic effects in the major flow were used to deposit particles on a SAW sensor for potential real-time detection. Numerical simulations indicated cutoff sizes of 2.35 μm and 1.15 μm for the first and second stages, respectively, showing good agreement with the targets of 2.5 μm and 1.0 μm. High classification accuracy was demonstrated under low-flow conditions, as reflected by sharpness values of 1.38 and 1.60. Experiments with KCl aerosols confirmed that particles smaller than 2.5 μm and 1.0 μm were captured in the first and second stages, respectively, in qualitative agreement with the simulations. At low Reynolds numbers of 300–500, the staggered sensor configuration mitigated stage-to-stage particle loss caused by deposition on the first-stage SAW sensor. This study demonstrates the feasibility of dual-cutoff separation with integrated sensing using a single-pump structure under a low-flow rate of 50 mL/min. Compared with high-flow, high-velocity systems, conditions that may be more favorable for bioaerosol sampling could be achieved. Therefore, the SPC-μVI shows feasibility for integration into portable devices with potential for future real-time air-quality monitoring.

키워드