面向大气颗粒物分级监测的空气微流控器件与系统集成技术研究

The frequent haze caused people to suffer from serious atmospheric particles, and the size-selective monitoring of atmospheric particulates has become a key technology for the cause of haze and prevention and control of the haze. In order to meet the application requirements of high precisionsize-selective monitoring for atmospheric particles, some key scientific problems, such as the establishment of the multi-stage separation model of air microfluidic chip and high sensitive quality testing technology based on FBAR, will be solved in this project. Multistage separation air microfluidic chip will be developed and a highly sensitive FBAR sensor based on AlN piezoelectric material will be fabricated and a multi-stage monitoring system integrated with air microfluidic chip and FBAR sensor for micro atmospheric particles will be developed. The system is able to realize high efficiency and multilevel separation of atmospheric particles and high precision on-line monitoring of the mass concentration of particles at all levels. The system has at least 2 levels of separation ability, and the classification efficiency of particles is not less than 90%, and the sensitivity of the system is not less than 1 ug/m3. This technique can be used for automatic fine size-selection of particles and continuous simultaneous concentration monitoring, which provides a scientific basis for the study of haze formation and control.

雾霾频发，正使人们遭受到严重的大气颗粒物危害，大气颗粒物分级监测已成为雾霾成因研究及治理防控的关键技术。本项目针对大气颗粒物高精度分级监测的应用需求，拟解决空气微流控多级分离模型构建及高灵敏FBAR质量检测技术等关键科学问题。研究多级分离空气微流控器件；研究基于AlN压电材料的高灵敏FBAR传感器；研究空气微流控器件与FBAR系统集成技术，并研制出微型化大气颗粒物多级监测系统。实现大气颗粒物高效多级分离及各级颗粒物质量浓度高精度在线监测，分离能力达到2级及以上水平，粒径分级效率≥90%，检测灵敏度达1μg/m3，可为雾霾机理研究及防治提供科学依据。

目前，重点关注的大气颗粒物是PM10和PM2.5，为实现两种截止直径颗粒物的高效分离，基于空气动力学理论，开展了虚拟冲击器的分析与设计。根据Marple理论，建立了颗粒物的截止直径表达式。据此，可实现对虚拟冲击器的初步设计。为进一步探究影响虚拟冲击器分离效率和粒壁损失两大重要性能的因素，采用数值分析的方法，重点分析了器件的结构类型、主/次流通通道宽度、倾斜角度、入口流量、喷嘴长度、流通通道长度及环境温度等影响。分析结果表明：影响器件两大性能的关键因素有主/次流通通道宽度S/M、倾斜角度φ、入口流量Q。根据上述结论，可用以指导虚拟冲击器的详细设计工作。为实现对分离后颗粒物浓度的有效检测，采用微型加热器提供的热泳力，使得颗粒物尽可能沉积到薄膜体声波谐振器（FBAR）的表面。通过对常见的两种类型加热器性能分析，确定了选用可获得更好加热效果的S型结构微型加热器。进而，对具有不同线宽、不同导体长度的微型加热器进行仿真分析发现，随着加热电阻阻值的减小，微型加热器的加热性能增强。根据Sauerbrey理论，开展了FBAR的设计研究，明确了FBAR的设计要点。根据上述分析结果，完成了二级微流控器件的结构设计及优化。最后，根据设计完成的二级微流控器件，对其进行详细的制备工艺研究。重点对虚拟冲击器及微型加热器的制备进行了较为详细的研究，并进行了器件装配。利用电子扫描电子显微镜对制备的虚拟冲击器流道进行了观测，确定了制备工艺的可行性。利用标准颗粒物质，对研制的二级微流控器件开展分离试验研究。结果表明，二级微流控器件可实现对PM10和PM2.5颗粒物的有效分离。从而，验证了前期理论分析及数值分析结果的有效性。