He Jiayang, Novosselov Igor V
University of Washington, Mechanical Engineering, Box 352600, Seattle, WA 98195.
Aerosol Sci Technol. 2017;51(9):1016-1026. doi: 10.1080/02786826.2017.1329515. Epub 2017 May 24.
Aerosol sampling and identification is vital for the assessment and control of particulate matter pollution, airborne pathogens, allergens, and toxins and their effect on air quality, human health, and climate change. In-situ analysis of chemical and biological airborne components of aerosols on a conventional filter is challenging due to dilute samples in a large collection region. We present the design and evaluation of a micro-well (µ-well) aerosol collector for the assessment of airborne particulate matter (PM) in the 0.5-3 micron size range. The design minimizes particle collection areas allowing for in-situ optical analysis and provides an increased limit of detection for liquid-based assays due to the high concentrations of analytes in the elution/analysis volume. The design of the collector is guided by computational fluid dynamics (CFD) modeling; it combines an aerodynamic concentrator inlet that focuses the aspirated aerosol into a narrow beam and a µ-well collector that limits the particle collection area to the µ-well volume. The optimization of the collector geometry and the operational conditions result in high concentrations of collected PM in the submillimeter region inside the µ-well. Collection efficiency experiments are performed in the aerosol chamber using fluorescent polystyrene microspheres to determine the performance of the collector as a function of particle size and sampling flow rate. The collector has the maximum collection efficiency of about 75% for 1 micron particles for the flow rate of 1 slpm. Particles bigger than 1 micron have lower collection efficiencies because of particle bounce and particle loss in the aerodynamic focusing inlet. Collected samples can be eluted from the device using standard pipettes, with an elution volume of 10-20 microliters. The transparent collection substrate and the distinct collection region, independent of particle size, allows for in-situ optical analysis of the collected PM.
气溶胶采样和识别对于评估和控制颗粒物污染、空气传播病原体、过敏原和毒素及其对空气质量、人类健康和气候变化的影响至关重要。由于在大收集区域中样品稀释，在传统滤膜上对气溶胶的化学和生物空气传播成分进行原位分析具有挑战性。我们展示了一种用于评估0.5 - 3微米尺寸范围内空气传播颗粒物（PM）的微孔（µ孔）气溶胶收集器的设计和评估。该设计将颗粒收集区域最小化，允许进行原位光学分析，并且由于洗脱/分析体积中分析物浓度高，提高了基于液体的检测限。收集器的设计由计算流体动力学（CFD）建模指导；它结合了一个空气动力学浓缩器入口，将吸入的气溶胶聚焦成窄束，以及一个µ孔收集器，将颗粒收集区域限制在µ孔体积内。收集器几何形状和操作条件的优化导致µ孔内亚毫米区域中收集的PM浓度很高。使用荧光聚苯乙烯微球在气溶胶室中进行收集效率实验，以确定收集器作为颗粒大小和采样流速函数的性能。对于1 slpm的流速，收集器对1微米颗粒的最大收集效率约为75%。大于1微米的颗粒由于颗粒反弹和在空气动力学聚焦入口中的颗粒损失而具有较低的收集效率。可以使用标准移液器从设备中洗脱收集的样品，洗脱体积为10 - 20微升。透明的收集基板和独立于颗粒大小的独特收集区域允许对收集的PM进行原位光学分析。
