论文总字数：27461字

摘 要

电导率是表征溶液特性的重要指标，在生物制药、化学工程、环境监测、微电子行业等领域有着广泛的应用。而石英晶体微天平（quartz crystal microbalance，QCM）可对溶液的电导率的改变做出应答，输出频率响应。且石英晶体微天平结构简单、灵敏度高、可实时监测等优点，所以本文研究设计了基于横向场激励（Lateral field excitation，LFE）的石英晶体微天平监测电导率的变化。

本文介绍了QCM的基本工作原理，还通过石英晶体的等效电路对QCM进行了分析。同时介绍了QCM的两种激励模式，指出了LFE模式在研究电导率方面的优势。在进行了充分的理论分析之后，提出了基于LFE模式的高频QCM传感器，且通过双通道设计消除粘密度对频率响应的影响，并且设计研制了两种不同的浮动电极。与流通池，流动注射技术相结合，组成了高灵敏度的测试系统。最后选用不同浓度的NaCl溶液对QCM进行测试实验，实验表明随着NaCl溶液浓度的增加，QCM的谐振频率逐渐降低，最后会出现饱和状态。但在低电导率溶液中，环形电极的频率变化速率比矩形电极大，这说明环形电极的QCM在低电导率的液体环境下对电导率感应更灵敏，而当电导率高于一定值时，矩形电极对电导率感应更加灵敏。

关键词：电导率，QCM，LFE，双通道

Abstract

Electrical conductivity is an important indicator of the characteristics of solutions. It has been widely applied in biopharmaceutical, chemical engineering, environmental monitoring, microelectronics and other fields. The quartz crystal microbalance (QCM) can respond to the change of the conductivity of the solution, and output the frequency response. Moreover, the quartz crystal microbalance has the advantages of simple structure, high sensitivity and real-time monitoring, so this paper studied and designed the quartz crystal microbalance based on the transverse field excitation (Lateral field excitation, LFE) to monitor the change of electrical conductivity.

This paper introduces the basic working principle of QCM, and analyzes the QCM through the equivalent circuit of quartz crystal. At the same time, the two incentive modes of QCM are introduced, and the advantages of LFE mode in studying electrical conductivity are pointed out. After a full theoretical analysis, a high frequency QCM sensor based on LFE mode is proposed, and the effect of the viscous density on the frequency response is eliminated through a dual channel design, and two different floating electrodes are designed and developed. Combined with flow cell and flow injection technology, a high sensitivity test system is formed. At last, QCM was tested with different concentration of NaCl solution. The experiment showed that the resonance frequency of QCM gradually decreased with the increase of NaCl solution concentration, and the saturation state would appear at last. But in the low conductivity solution, the frequency change rate of the ring electrode is larger than that of the rectangular electrode, which indicates that the QCM of the ring electrode is more sensitive to the conductivity in the low conductivity liquid environment, and the rectangular electrode is more sensitive to the conductivity when the electrical conductivity is higher than the certain value.

KEY WORDS: electrical conductivity, QCM, LFE, Double channel

目 录

摘要 I

Abstract II

第一章 绪论 1

1.1 研究背景和意义 1

1.2 研究现状 2

1.2.1 国外研究现状 2

1.2.2 国内研究现状 3

1.3 论文研究内容 3

第二章 QCM理论分析 5

2.1 石英晶体特性分析 5

2.1.1 压电效应 5

2.1.2 石英晶体切型选择 6

2.2 QCM的工作原理 7

2.2.1 Sauerbrey 公式 7

2.2.2 石英晶体的等效电路模型 8

2.2.3 LFE-QCM的工作原理 10

第三章 QCM芯片的设计 12

3.1 激励电极设计 12

3.2 浮动电极设计 13

3.3 双通道设计 15

第四章 QCM测试系统设计 17

4.1 流通池结构介绍 17

4.2 流动注射系统 19

4.3 阻抗分析仪 20

第五章 实验检测及分析 21

5.1 实验设计 21

5.1.1 实验材料选择 21

5.1.2 实验步骤 21

5.2 数据分析 22

5.2.1 环形电极液体电导率测试 22

5.2.2 矩形电极液体电导率测试 26

第六章 总结 29

致谢 30

参考文献 31

绪论

研究背景和意义

石英晶体微天平是基于石英晶体压电效应的一种谐振式质量型传感器，它将石英晶体表面的极小质量的变化转换为可测量的谐振频率的变化，测量精度可达纳克级。

长期以来，对于QCM方面的研究，局限于基于质量效应的测量原理，且多采用厚度场激励（Thickness field excitation，TFE）模式的石英晶体谐振器，这只是针对机械量的负载效应。而在液相环境中，QCM的谐振频率的变化不仅决定于石英晶体表面的质量负载的改变，而且还受其表面液体的物理化学性质参量的影响，所以对于液相中的电特性检测，基于质量效应的TFE传感器无法感知被测液体电学信息。

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