基于微混合器的重金属离子微全分析系统芯片研究

发布时间：2018-01-20 23:04

本文关键词： 微全分析系统芯片混沌微混合器多层芯片键合重金属检测　出处：《哈尔滨工业大学》2015年博士论文　论文类型：学位论文

【摘要】：基于微电子机械系统(Micro Electro Mechanical System,MEMS)技术的微全分析系统(Micro total analysis systems,μTAS)是微电子、电化学、及分析化学等多学科交叉结合的产物,由于具有广阔的应用前景而成为研究的热点。然而目前用于水质重金属污染检测的μTAS芯片还存在预处理效率低、多层芯片键合难等问题,导致其集成程度并不高,无法满足便携化和实时化检测需求。本文提出了三维马蹄混沌混合器结构,以改善预处理效率;以微混合器为核心,结合固相萃取及安培检测技术,设计了集成化的重金属μTAS芯片;提出了基于聚甲基丙烯酸甲酯(PolymethylMethacrylate,PMMA)材料的新颖键合方法,以实现带有功能模块的多层复杂μTAS芯片的组装;基于以上设计和装配工艺,制备了重金属μTAS芯片,并采用多种检测方法对芯片的性能进行了验证。提出了三维马蹄变换模型,通过“垂直折叠”使二维马蹄变换后“溢出”的流体再次回到系统内部,不仅减少了变换过程中的流体损失,而且流动方向的多次改变使得混合器内的流动情况更加复杂。以流体动力学方程和多组分物质扩散方程为基础,建立了微尺度下的流体混合模型,研究了混沌混合器的性能,结果表明变换后混沌流对混合的促进作用更为显著。当Re=10时经优化设计后的三维马蹄微混合器在12mm的混合距离内即可接近均匀混合(σ0.05),与“挤回式”马蹄混合器(Re=10,σ0.2)相比混合效果得到了明显改善。以微混合器为核心,设计了新颖的重金属μTAS芯片集成结构。利用三维马蹄混合器对试样进行预处理,以满足固相萃取柱的选择性吸附条件;设计一体化的填充式柱床结构,结合改性吸附剂实现对重金属离子的分离富集;在流经式检测池结构的基础上设计了带有内充液池的Ag/Ag Cl参比电极,保证重金属安培检测的稳定性。芯片由4层基片组成,整体尺寸为70mm×40mm×14mm,除压力进样装置和电化学工作站外,整个检测过程无需借助其他外部设备,使μTAS芯片的集成化程度得到了显著提高。为实现基于PMMA材料的多层复杂结构μTAS芯片的装配,提出了有机溶剂混溶浸泡键合法。把三氯甲烷与无水乙醇按照一定比例混合,通过调节溶液组成和浸泡时间等参数控制材料形变量,在保证微结构形貌的前提下实现了芯片的封合。当浸泡键合条件为:V三氯甲烷:V乙醇=1:10、t=10 min、T=40°C时,键合强度达到了267.5N/cm~2而形变量只有7.26%。为解决带有功能模块的μTAS芯片的装配,提出了有机溶剂熏蒸键合法。利用聚酰亚胺和硅胶作为掩膜,保护功能模块中易受有机蒸汽破坏的部分,当使用三氯甲烷作为熏蒸溶剂、熏蒸温度为65°C、熏蒸时间为40s时,键合强度为61N/cm~2,形变量为9.5%。使用以上装配方法,分别制作了用于试样预处理的微混合器芯片、用于重金属离子分离的固相萃取芯片和用于重金属离子检测的安培传感器芯片,并采用多种测试方法对上述芯片的性能进行了评价。以此为依据确定了μTAS芯片的工作条件。最后以Hg~（2+）溶液和Pb~（2+）、Cr~（3+）混合溶液作为模拟试样,对μTAS芯片进行了整体性能测试。芯片对Hg~（2+）离子的检出限为20μg/L,(n=5,标准差3%);当有高浓度干扰离子时(Cr~（3+）=1.0×10-6 mol/L),芯片仍可实现对浓度为1mg/L的Pb~（2+）离子准确检出,两项指标均满足我国现行污水综合排放标准(GB8978-1996)中对金属汞(50μg/L)和金属铅(1mg/L)的检测要求。
[Abstract]:Based on micro electro mechanical system (Micro Electro Mechanical System, MEMS) micro total analysis system technology (Micro total analysis systems, TAS) is the product of microelectronics, electrochemistry, chemical analysis and interdisciplinary combination, because of its wide application and become a research hotspot. However, for TAS chip detection of heavy metal pollution there are water pretreatment efficiency is low, multilayer chip bonding and other difficult issues, the integration degree is not high, can not meet the demand of portable and real-time detection. This paper proposes a three-dimensional horseshoe mixed structure chaotic mixer, in order to improve the efficiency of pretreatment; micro mixer as the core, combined with solid phase extraction and amperometric detection technology. The design of the heavy metal TAS chip integrated; based on poly (PolymethylMethacrylate, PMMA) for new key materials, in order to achieve a power Multi module complex assembly TAS chip; the design and assembly process based on TAS chip, heavy metals were prepared, and using a variety of detection methods on the performance of the chip is verified. The 3D horseshoe model, through the "vertical folding" to transform two-dimensional horseshoe fluid "overflow" again within the system, not only reduces the loss of fluid in the process of transformation, and the flow direction of the flow in the mixer makes many changes more complex. As the fluid dynamics equations and multicomponent diffusion equation as the foundation, established a mixed fluid model in micro scale, the research results show that the performance of chaotic mixer, chaos transform the flow of mixed effect is more significant. When Re=10 by 3D horseshoe optimization design of the micro mixer can be mixed in the distance 12mm near uniform mixture (sigma 0.05), and "Push back" horseshoe mixer (Re=10, sigma 0.2) compared to the mixing effect has been improved. The micro mixer design as the core, the heavy metal TAS chip integrated with new structure. The samples were pretreated by using three-dimensional horseshoe mixer, to meet the selection of adsorption conditions of solid phase extraction column; column type filling structure the integrated design, combined with the modified adsorbent to achieve the separation of the enrichment of heavy metal ions; based on flow-through detection pool structure on the design of the pool with liquid filling within the Ag/Ag Cl reference electrode, ensure the stability of heavy metal. The chip amperometric detection consists of 4 layers of substrate, the overall size is 70mm * 40MM * 14mm. In addition to the pressure sampling device and electrochemical workstation, the whole testing process without the help of other external devices, the integration degree of TAS chip has been greatly improved. In order to realize the complex structure of multilayer PMMA material based on TAS Chip assembly, proposed miscible organic solvent immersion bonding. The chloroform and ethanol are mixed according to a certain proportion, by adjusting the composition of solution and soaking time parameters of material deformation control, in the premise of the micro structure and morphology of the chip to achieve sealing. When immersion bonding conditions are as follows: V chloroform: V =1:10 t=10 min, T=40 ethanol, C, the bonding strength reached 267.5N/cm~2 and 7.26%. as the only variable assembly to solve TAS chip with the function module, the organic solvent bonding method. Using the fumigation of polyimide and silica gel as a mask, vulnerable to destruction of organic vapor partial protection module, when using chloroform as solvent fumigation, fumigation temperature is 65 ~ C, fumigation time is 40s, the bonding strength is 61N/cm~2, the shape variables for 9.5%. using the above method of assembly, we fabricated the sample pretreatment for the micro Mixer chip, chip used for solid phase extraction and separation of heavy metal ions for amperometric detection of heavy metal ion sensor chip, and uses a variety of testing methods on the performance of the chip was evaluated. In order to determine the TAS chip working conditions as the basis. Finally, using Hg~ (2+) solution and Pb~ (2+), Cr~ (3+) mixed solution as simulated specimens of TAS chip for the overall performance test. The chip of Hg~ (2+) ion detection limit was 20 (g/L, n=5, standard deviation 3%); when there is a high concentration of interference ions (Cr~ (3+) =1.0 * 10-6 mol/L), the concentration of 1mg/L can be realized on chip Pb~ (2+) ion detection, two indicators are meet the integrated wastewater discharge standard of China (GB8978-1996) of mercury (50 g/L) and lead (1mg/L) detection requirements.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TN40;TH-39

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