横向电场激励的FBAR仿真设计及其凝血检测

发布时间：2018-04-30 07:34

本文选题：薄膜体声波谐振器 + 横向电场激励　；参考：《山东科技大学》2017年硕士论文

【摘要】：薄膜体声波谐振器(Film Bulk Acoustic Resonator,FBAR)是一种微型化、频率高、成本低、可集成的压电器件,在新一代无线通信系统已经取得商业化的应用。此外,FBAR因谐振频率高而具有高灵敏性,为微质量传感器、压力传感器、生化传感器等传感器的发展带来了新的生机。生化传感器一般应用在液体环境中,传统的纵波模式FBAR在液体环境中Q值衰减较大,而剪切波模式FBAR在液体环境中能够保持较高的Q值。本文以横向电场激励的剪切波模式FBAR作为研究对象,研究内容如下:1.在分析传统纵波模式FBAR的基础上,推导了由平行电极激励的横向电场FBAR的工作原理,并建立了相应的理论模型。利用有限元分析法对器件结构进行了优化仿真,设计多组仿真实验,系统地研究了电极间距、电极长度和电极宽度对器件性能的影响。发现电极间距的大小对电极间横向电场的分布影响较大,进而影响器件的Q值;电极宽度主要影响有效区域面积内质点位移分布;电极长度对器件的Q值和电场分布的影响较小。2.基于仿真优化结果,利用微纳加工工艺制备了固体装配型剪切波模式FBAR。并分别测试了器件在空气、水和磷酸盐缓冲液三种典型环境下器件的阻抗特性和导纳特性。发现器件的谐振在磷酸盐缓冲液中的衰减较大,三种不同测试环境下的Q值分别为537, 453,183。基于FBAR的MBVD (Modified Butterworth-VanDyke)等效电路模型,提取电路参数,拟合了三种不同测试环境中所对应的等效电路。通过器件的电学分析,得出溶液的电导性增大器件的损耗。3.基于FBAR谐振频率对所载装溶液粘度变化反应的特性,面向FBAR的生化传感器应用要求,将制备的剪切波模式FBAR应用于凝血实时检测,验证了横向电场激励的FBAR在生化传感领域的可行性。外源性凝血发生时,在凝血酶形成过程中血液粘度无明显变化,频率响应曲线保持不变。在纤维蛋白原转化为纤维蛋白过程中血液粘度上升,频率响应曲线开始下降。直到纤维蛋白形成结束后血液的粘度保持不变,频率响应曲线也相应保持不变。经过多组测试并与医用凝血时间检测仪的结果对比,确定了响应频率下降到95%的特征点为凝血结束点。进一步研究了 Ca2+浓度对凝血时间的影响,发现Ca2+浓度越高,凝血强度越强,凝血时间越少。
[Abstract]:Thin Film Bulk Acoustic Resonator (FBA) is a kind of piezoelectric devices with high frequency and low cost. It has been commercially used in the new generation of wireless communication systems. In addition, FBAR has high sensitivity because of its high resonant frequency, which brings new vitality to the development of micro mass sensor, pressure sensor, biochemical sensor and so on. Biochemical sensors are generally used in liquid environment. The traditional P-wave mode FBAR attenuates greatly in liquid environment, while the shear-wave mode FBAR can maintain a higher Q value in liquid environment. In this paper, the shear wave model FBAR excited by transverse electric field is taken as the research object. The research contents are as follows: 1. Based on the analysis of the traditional P-wave mode FBAR, the working principle of the transverse electric field FBAR excited by parallel electrodes is deduced, and the corresponding theoretical model is established. The finite element method is used to optimize the structure of the device, and several simulation experiments are designed. The effects of electrode spacing, electrode length and electrode width on the performance of the device are systematically studied. It is found that the distance between electrodes has a great influence on the distribution of transverse electric field between electrodes, and then on the Q value of the device, and the electrode width mainly affects the distribution of particle displacement in the effective area. The influence of electrode length on the Q value and electric field distribution of the device is small. Based on the results of simulation and optimization, the solid assembly shear wave mode FBARs were fabricated by micro-nano machining process. The impedance and admittance characteristics of the device in air, water and phosphate buffer were measured. It is found that the resonance of the device attenuates greatly in the phosphate buffer. The Q values of the three different test environments are 537 and 453183 respectively. The equivalent circuit model of MBVD modified Butterworth-Van Dyke based on FBAR is presented. The circuit parameters are extracted and the corresponding equivalent circuits in three different test environments are fitted. Through the electrical analysis of the device, it is concluded that the conductivity of the solution increases the loss of the device. 3. Based on the characteristics of the FBAR resonance frequency response to the viscosity change of the loaded solution and the application requirements of the biochemical sensor for FBAR, the prepared shear wave mode FBAR is applied to the real-time detection of coagulation. The feasibility of FBAR excited by transverse electric field in the field of biochemical sensing is verified. During the process of thrombin formation, the blood viscosity did not change obviously and the frequency response curve remained unchanged. In the process of fibrinogen conversion to fibrin, the blood viscosity increased and the frequency response curve began to decrease. The viscosity of blood remained unchanged and the frequency response curve remained unchanged until the end of fibrin formation. After many groups of tests and compared with the results of the medical coagulation time detector, the characteristic point that the response frequency decreased to 95% was determined to be the end point of coagulation. The effect of Ca2 concentration on coagulation time was further studied. It was found that the higher the Ca2 concentration, the stronger the coagulation intensity and the less the coagulation time.
【学位授予单位】：山东科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN751.2;TP212

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