微机械悬臂梁谐振传感器的关键技术与应用研究

发布时间：2018-03-04 21:32

本文选题：微悬臂梁　切入点：谐振频率　出处：《西安交通大学》2017年博士论文　论文类型：学位论文

【摘要】：本文针对电力设备、新能源发电中电流检测以及工业控制、石油勘探、内燃机等动力系统中流体密度/黏度在线测量的迫切需求,以微机械悬臂梁谐振传感器为研究对象,对传感器的基础理论、设计和优化、加工、性能测试和应用实验等方面进行了系统研究,实现了电流以及流体密度/黏度的在线测量。本文所取得的主要成果有:(1)建立了变截面微悬臂梁的挠度与表面应力之间的数学关系式,提出了变截面微悬臂梁一阶谐振频率和综合灵敏度的计算公式,以优化微悬臂梁的结构,提高微悬臂梁的综合灵敏度。(2)建立了一阶弯曲模态下微悬臂梁测量流体密度时的灵敏度数学模型,由此推导了矩形微悬臂梁宽度临界值的数学表达式。通过流固耦合仿真研究,优化微悬臂梁的结构形状和工作模态,以提高密度测量的灵敏度,并提高微悬臂梁的品质因子进而扩大流体黏度的测量范围。(3)提出了品质因子原则、谐振频率原则以及传感器输出原则等来指导微悬臂梁谐振传感器的结构设计,并确定了传感器采用电磁激励和压阻检测的工作方式。(4)绘制了传感器芯片的版图结构,制定了传感器芯片的工艺流程,制作出了微悬臂梁传感器芯片,实现了传感器的封装。(5)搭建了微悬臂梁传感器实验系统,开发了数据采集与处理软件。建立了微悬臂梁传感器的在四种谐振模态下的等效电路模型。研究了仪器参数与传感器工作条件等对微悬臂梁传感器谐振频率的影响。提出了改变惠斯通电桥供电电流或者线圈激励电压实现传感器频率调谐的机理。(6)基于微悬臂梁传感器实验系统,对所研制的不同形状微悬臂梁谐振传感器在不同的谐振模态下进行了有机试剂的密度/黏度测量实验研究,实验结果表明,在620.83kg/m~3到866.87 kg/m~3的密度测量范围内,实验数据与文献数据的最大偏差小于2.00%,在217.9μPa·s到961.8μPa·s的流体黏度范围内,最高测量精度小于11.00%,且微悬臂梁谐振传感器工作于高阶模态有利于提高黏度测量精度。此外,提出了微悬臂梁谐振传感器实现直流电流测量的工作机理,并通过实验得到了微悬臂梁谐振传感器在不同模态下测量直流电流的精度和灵敏度,在电流为0.5 m A到4.0 m A范围内,最高测量精度为0.92%,最大灵敏度为 6.702 Hz/mA~2。
[Abstract]:In order to meet the urgent need of on-line measurement of fluid density / viscosity in power systems such as power equipment, new energy generation, and industrial control, oil exploration, internal combustion engine, this paper takes the micro-mechanical cantilever resonant sensor as the research object. The basic theory, design and optimization, machining, performance test and application experiment of the sensor are systematically studied. The on-line measurement of current and fluid density / viscosity is realized. The main results obtained in this paper are: 1) the mathematical relationship between deflection and surface stress of a variable cross section micro cantilever beam is established. In order to optimize the structure of the micro-cantilever beam, a formula for calculating the first-order resonant frequency and the comprehensive sensitivity of the micro-cantilever beam with variable section is presented in order to optimize the structure of the micro-cantilever beam. The mathematical model of sensitivity of micro-cantilever beam for measuring fluid density in first order bending mode is established, and the mathematical expression of critical value of width of rectangular micro-cantilever beam is derived. In order to improve the sensitivity of density measurement and improve the quality factor of micro cantilever beam, the principle of quality factor is put forward in order to optimize the structure shape and working mode of micro cantilever beam and then expand the measuring range of fluid viscosity. The resonant frequency principle and sensor output principle are used to guide the structure design of micro-cantilever resonant sensor, and it is determined that the sensor uses electromagnetic excitation and piezoresistive detection to work out the layout of the sensor chip. The process flow of the sensor chip is established, the microcantilever sensor chip is made, the sensor package is realized, and the experimental system of the micro cantilever beam sensor is built. The software of data acquisition and processing is developed, and the equivalent circuit model of micro cantilever beam sensor under four resonant modes is established. The influence of instrument parameters and sensor working conditions on the resonant frequency of micro cantilever beam sensor is studied. The mechanism of frequency tuning of the sensor by changing the supply current or coil excitation voltage of the Wheelstone bridge is proposed. The mechanism is based on the microcantilever sensor experimental system. The density / viscosity measurements of organic reagents for different shape microcantilever resonant sensors in different resonant modes have been studied. The experimental results show that the density measurement ranges from 620.83 kg / m ~ (3) to 866.87 kg/m~3. The maximum deviation between the experimental data and the literature data is less than 2.00. In the range of 217.9 渭 Pa 路s to 961.8 渭 Pa 路s, the maximum measurement accuracy is less than 11.00. Moreover, the micro-cantilever resonant sensor can improve the accuracy of viscosity measurement by working in higher-order modes. The working mechanism of DC current measurement by micro-cantilever resonant sensor is presented. The precision and sensitivity of micro-cantilever resonant sensor in different modes are obtained by experiments. In the current range of 0.5 Ma to 4.0 Ma, the highest measurement accuracy is 0.92 and the maximum sensitivity is 6.702 Hz 路mA-2.
【学位授予单位】：西安交通大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TP212

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