生物气溶胶会引起一系列身体不良反应，有些菌种甚至还会腐蚀设备，为了保证人员财产安全，监测环境中的生物气溶胶是必要的。监测包括采样和检测两个步骤，为了与现代医学检测手段集成，必须将气溶胶颗粒收集到微量液体中；同时为了适应各种监测环境，检测手段必须满足现场快速检测的要求。本文中对气溶胶采样和检测技术进行分别研究：1、将微流控技术和静电采样结合，开发能够富集气溶胶颗粒到微量液体中并实现液体样品稳定输运的生物气溶胶采样器；2、研究均相团聚检测方法，开发基于微流控芯片的团聚检测系统。论文首先设计了集成荷电腔、半圆柱静电沉积区和微流控采样芯片的生物气溶胶静电采样器。理论分析了气溶胶颗粒在荷电腔的荷电过程并计算了其荷电量，结合静电沉积区的电场和流场仿真结果得到了颗粒在静电沉积区的运动轨迹和静电沉积区的收集效率。针对气溶胶颗粒收集到液体中并稳定输运的要求，设计了半开放微管道，对影响管道中液体输运性能的参数进行了分析。对静电采样器进行了性能测试。SU8疏水栅网可承受1900 Pa的背压而保持液体不溢出，半开放微管道容积28 μL，最大许可流速200 mm/s，能实现液体样品的稳定输运。采样器物理收集效率测试中测试的最大流量为13.2 L/min，对于粒径0.3 μm- 5 μm颗粒的物理有效收集效率约为40%。采样器对枯草芽孢杆菌的生物收集效率约为16%，虽然收集效率略低，但是可以实现样品的自动化稳定输运，方便与后续检测模块集成。研究了团聚检测方法。理论分析了团聚反应的过程，得出利用磁场操控磁珠运动可以促进团聚反应。仿真分析了团聚微球的散射特性，得出可以利用前向散射光区分团聚微球和单球。设计制作了面向团聚检测的无鞘液流式芯片，开发了基于选择性成像的前向散射光收集系统。利用表面修饰链霉亲和素的磁珠和生物素修饰的牛血清白蛋白(BSA)作为免疫反应的模型，实验研究了团聚反应检测方法。首先用商品化流式细胞仪检测团聚反应，结果显示单球所占比例可以表示样品中抗原浓度。然后用无鞘液流式芯片检测团聚反应，得到单球占比与样品中BSA浓度的关系，检测限1.5 pM。设计制作了团聚反应和检测一体化的微流控芯片和检测系统，研究了芯片上团聚检测的流程及实验参数，在微流控芯片上实现了进样、反应和检测的全自动化操作，检测限2.5 pM，总耗时11 min。
Exposure to bioaerosols are associated with a wide range of adverse health effects, and some species of microorganisms are able to provoke corrosion of instruments. To protect personnel and equipment, the monitoring of bioaerosols is necessary in both the occupational and residential environments. The monitoring processes include bioaerosol sampling and detection. On one hand, aerosol-to-hydrosol samplers are preferred for easy conjunction with the modern analytical methods. On the other hand, the detection methods had better meet the needs of point-of-care testing (POCT) to be appropriate for various testing environments. This dissertation introduces an integrated microfluidic electrostatic sampler for bioaerosol, and a method and system of homogeneous agglutination assay.In this dissertation, a bioaerosol sampler, consisting of a unipolar cylindric charging chamber, a half cylinder precipitation chamber and a collection microfluidic chip, is designed. The collection chip is composed a peristaltic micropump and a half-open microchannel which is covered by SU8 hydrophobic mesh. The charging and precipitation processes of bioaerosol particles in the sampler are analyzed. The number of elementary charges carried by bioaerosol particles, the precipitation trajectories of bioaerosol particles, and the collection efficiencies of the precipitation chamber are estimated. The half-open microchannel is designed for collecting biomass in air into liquid and at the same time implementing stable water transportation. The factors affecting the stability of water transportation in the half-open microchannel are investigated by theoretical calculations.The performance of the electrostatic sampler is tested. The maximum allowable pressure of the SU8 hydrophobic mesh is as high as 1900 Pa. The volume of the half-open microchannel is 28 μL and the maximum allowable velocity in the microchannel is higher than 200 mm/s which is well above the normal operating speed of sample delivery. The collection efficiencies of airborne particles and bio-particles are investigated for the sampler. The tested maximum sampling flow rate is 13.2 L/ min and the corresponding maximum physical effective collection efficiency is about 40% for particles with diameter in 0.5 μm - 5 μm. The collection efficiencies of bio-particles are about 16% with aerosolized Bacillus subtilis. Considering its integrated function of charging and automatic liquid sample delivery, the electrostatic sampler is a bioaerosol sampling system ready for integration with subsequent automated detection equipment.The kinetics of immunoagglutination is studied. Controlled manipulation of the magnetic beads is able to prompt the agglutination of beads, improving the reaction efficiency. The scattering properties of the agglutinated beads are simulated. The simulation results show that the forward scattered light can be used to distinguish aggregates from monomers. The sheathless microfluidic chip is fabricated and the optical detecting system is constructed. A microfluidic chip-based sheathless flow cytometer for agglutination assay is designed and a microscope objective is used for the selective collection of scattered light to reduce signal variance.Streptavidin-coated magnetic beads and biotinylated bovine serum albumin (BSA) are used as a model system to verify the method of immunoagglutination assay. Firstly, the commercial flow cytometer Calibur is used to detect agglutination reaction products. The detection results show that forward scattered light is a better signal for discriminating aggregates from monomers compared with side scattered light, and the proportion of monomers can be used to represent the concentration of antigens in sample. Then, the agglutination reaction products are detected using sheathless microfluidic chip, and the relationship between the proportion of monomers and the concentration of BSA is obtained, too. The detection limit for BSA is 1.5 pM using sheathless microfluidic chip.A microfluidic chip integrating agglutination reaction module and detection module is designed and fabricated, and the detection system is constructed. The agglutination assay in chip format is investigated and the operation process is optimized. The whole process of agglutination assay, including sample introduction, agglutination reaction and agglutination detection is implemented automatically. The total assay time is 11 min and a detection limit of 2.5 pM is achieved in the microfluidic chip.
