QCM质量灵敏度的分析与验证
发布时间:2018-03-27 13:09
本文选题:QCM 切入点:质量灵敏度 出处:《电子科技大学》2017年硕士论文
【摘要】:QCM(Quartz Crystal Microbalance)是20世纪60年代出现的一种基于压电效应进行微质量测量的传感器装置,由于其测量精度可达纳克级,且结构简单、成本低、可实时监测,所以在生物医学、环境保护等领域应用广泛。然而实际应用中需要先拟合出质量与谐振频率偏移量的线性关系,然后才能投入使用,这限制了QCM的应用。另外,QCM表面电极对其受迫振动有影响,不同区域电极存在情况不同导致各区域在逆压电效应下引起的质点位移不同,因此QCM不同位置的质量灵敏度存在差异,所以QCM在应用中存在重复性低、测量误差大的问题,阻碍了QCM的推广应用。本文以石英晶体的压电特性和振动特性为基础,推导了QCM的质量灵敏度计算方式,并分析了影响QCM质量灵敏度的因素。本文的主要内容:1、从石英晶体的特性出发,介绍了石英晶体的压电效应、频率温度特性以及石英晶体谐振器的等效电路。2、在石英晶体压电方程和质点位移方程的基础上,分区域分析了石英晶体谐振器的受迫振动情况,得出QCM质量灵敏度的计算方法。通过Matlab仿真分析QCM的质量灵敏度分布,分析表明QCM电极中心的质量灵敏度最大,随着远离电极中心质量灵敏度呈指数级衰减。然后通过Matlab仿真分析电极厚度、电极尺寸、石英晶片厚度以及电极密度对质量灵敏度的影响,以便在设计时提供理论参考。由于能陷效应存在,QCM非电极区的范围要大于电极区,非电极区在质量测量中不容忽视,所以接着分析了非电极区在QCM质量测量过程中的影响。3、在液相下QCM的谐振频率偏移量与液体的粘弹性有关,在已知液体粘度和密度的情况下,可以通过公式计算出理论的QCM谐振频率偏移量。然后分别以水和有机试剂为被测物,测量QCM的频移并与理论频移值对比,实测值与理论值的最大误差不大于8.2%。
[Abstract]:QCM(Quartz Crystal Microbalanceis a kind of sensor device based on piezoelectric effect for micro-mass measurement, which appeared in the 1960s. Because of its accuracy, simple structure, low cost and real-time monitoring, it can be used in biomedicine. Environmental protection and other fields are widely used. However, the linear relationship between mass and resonance frequency offset must be fitted first before it can be put into use, which limits the application of QCM. In addition, the surface electrode has an effect on the forced vibration. The existence of different electrodes in different regions leads to different displacement of particles in different regions under inverse piezoelectric effect, so there are differences in the mass sensitivity of QCM in different positions, so there are problems of low repeatability and large measurement error in the application of QCM. In this paper, based on the piezoelectric and vibration characteristics of quartz crystal, the mass sensitivity calculation method of QCM is derived. The main content of this paper is to introduce the piezoelectric effect of quartz crystal based on the characteristics of quartz crystal. The frequency and temperature characteristics and the equivalent circuit of quartz crystal resonator. Based on the piezoelectric equation of quartz crystal and the displacement equation of particle, the forced vibration of quartz crystal resonator is analyzed in different regions. The mass sensitivity distribution of QCM is analyzed by Matlab simulation. The results show that the mass sensitivity of QCM electrode center is the largest. The influence of electrode thickness, electrode size, quartz wafer thickness and electrode density on the mass sensitivity was analyzed by Matlab simulation. In order to provide a theoretical reference for the design, because the energy trapping effect exists in the non-electrode region of QCM is larger than that of the electrode region, the non-electrode region can not be ignored in the mass measurement. Therefore, the influence of non-electrode region on QCM mass measurement is analyzed. The resonance frequency offset of QCM in liquid phase is related to the viscoelasticity of liquid. When the viscosity and density of liquid are known, The theoretical QCM resonance frequency offset can be calculated by the formula, and then the frequency shift of QCM is measured using water and organic reagent as the measured object, and compared with the theoretical frequency shift, the maximum error between the measured value and the theoretical value is not greater than 8.2.
【学位授予单位】:电子科技大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:TP212
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