微谐振器结构性能的有限元分析

微谐振器是试飞测试系统的重要组成部件,微谐振器的性能影响到试飞测试系统的精确度.为了提高微谐振器的性能,在传统结构的基础上,提出改变微谐振器中折叠梁、驱动梳齿等结构的尺寸来改善其性能.运用有限元法对不同结构尺寸下的微谐振器进行模态、品质因子分析.仿真结果表明,横向微谐振器的一阶模态频率的大小很大程度上受到折叠梁尺寸的影响;静电梳齿的尺寸设计中,梳齿的宽度是影响驱动力和品质的一个关键因素.仿真结果表明,对提高微谐振器的性能具有一定的指导意义.     

微机械音叉谐振器动力学分析与仿真

根据双端固定音叉谐振器的动力学原理,建立了其参数模型.该模型基于MAST语言,包含几个子模型,模型有利于验证外围电路和减少计算时间.对于工作谐振模态频率的求解,解析计算和有限元仿真结果一致(相对误差小于1%).通过模态分析和结构参数敏感性分析提出合理的选择参数可以使工作模态频率远离高阶模态频率.减少音叉梁固接端的弹性系数有利于抑制低阶模态的扰动.结构参数敏感性分析表明工作频率随音叉梁长度增大而减小,随其宽度的减小而增大.结构厚度对频率不产生影响.     

（中国微米纳米技术学会文章）一种硅微机械结构振动幅度的电学测量方法及实验研究

本文针对硅微机械结构振动幅度由于封装难以计算机视觉测量及电学测量中的精度受接口电路参数影响的问题,在对静电梳齿驱动、平板电容检测的硅微谐振结构进行建模分析后,提出基于单边带电压比的电学测量振动幅度的方法并分析了测量方法的原理。实验表明研制的某硅微机械谐振加速度计在受迫振动下的振动幅度为0.25um,频谱分析还表明存在上电噪声引起的振动幅度,该测试方法还能应用于硅微谐振结构的谐振频率测量,同时为高品质因数的硅微机械谐振结构的可静电自激驱动提供了依据。     

基于硅微梳齿型谐振器的MEMS动态测试研究

在利用激光多普勒对硅微梳齿型谐振器多阶振动频率进行提取的基础上,结合频闪显微干涉测试技术对其谐振频率及其振幅进行了动态测试,并根据测试结果推导了谐振器的动态应力值.实验测试结果及应力推导结果与ANSYS的仿真结果相符合.     

静电刚度式谐振微加速度计设计

运用梁的横向振动特性分析了梁振动频率与平行板电容形成的静电刚度的关系,并以此设计了静电刚度式谐振微加速度计。在加速度作用下,检测质量产生的惯性力使电容器极板发生位移来改变电容结构的间隙大小,从而使谐振频率发生变化,通过检测频率变化量来测量输入加速度的大小。根据加速度计的工作原理说明检测过程中梁的机械刚度保持不变,只与产生静电刚度的电容间隙变化相关,减小了检测信号对机械误差与残余应力的依赖性。运用加工参数进行理论计算得出加速度计的灵敏度为21．17Hz／gn,在CoventorWare2005中进行仿真表明：加速度计的固有频率为23．94kHz,灵敏度约为20Hz／gn,与理论设计值相近。     

谐振式传感器间歇工作方法的仿真研究

提出了一种新的谐振式传感器的工作方法,采用线性调频信号激励谐振器,当激励信号断开后,谐振器将以其谐振频率做自由振动,通过测量谐振器自由振动状态下的振动频率,即可测得谐振器的固有频率.文中通过仿真分析,对比了正弦信号激励和线性调频信号激励时,谐振器的储能情况和谐振器响应信号的幅度.仿真结果表明采用线性调频信号激励可以较好地实现谐振式传感器的间歇工作方法.     

静电梳齿执行器分辨率和稳定性分析

通过探讨典型的静电梳齿执行器的分辨率和稳定性的机理,揭示目前研究的典型等高度静电梳齿执行器的横向位移与驱动电压具有非线性关系.分辨率存在线性度差的问题.鉴于目前大多数通过增加梳齿结构平面复杂度来改善分辨率的方法存在的微制造困难.本文提出在不显著影响横向位移的条件下通过改变梳齿结构高度来改善分辨率的方法,事例仿真结果验证了梳齿变高度方法对改善分辨率的有效性,同时得到在梳齿变高度条件下静电梳齿执行器的稳定性有细微的下降的结论.     

压电型微固体模态陀螺的模态及谐振分析

压电型微固体模态陀螺利用压电体的特殊振动模态来工作,它是一种不同于微振动陀螺的全固态微陀螺.在压电型微固体模态陀螺中不存在整体运动的部件和弹性支撑结构,因此抗冲击、抗震动能力强.同时,它对真空封装没有特殊的要求,因此稳定性好,长期工作可靠性高.文中详细介绍了压电型微固体模态陀螺的工作机理,建立了该种新型微陀螺的结构模型,并对压电块的振动模态和自激谐振进行了有限元分析,获得了满足要求的工作振动模态.通过谐振分析,进一步验证了提出的结构模型的有效性.本文为压电型微固体模态陀螺的制作提供了理论依据.     

静电梳微振子结构和特性研究

较系统地研究了静电梳驱动微振子的结构和工作原理，导出了微振子的谐振频率、品质因子及跨导等参数，以及相应的力学和电学模型，并研究了空气粘滞效应对品质因子的影响，在此基础上，设计出几种不同尺寸，不同形状的微型谐振子结构，并用表面微机械加工方法成功地制成了能横向振动的静电梳微振子，实测得到的谐振频率在７．５￣９．０ｋＨｚ范围内，在空气中品质因子为１００左右，与理论计算能较好符合。     

嵌套环式MEMS陀螺刚度轴偏角误差和电极未对准误差辨识

作为一种工作在简并模态的陀螺,嵌套环式MEMS陀螺因其更强的抗冲击特性、对外界振动更低的敏感性以及更灵活的电极配置等优势被作为一个重要的微机电陀螺发展方向。然而,在加工过程中产生的谐振结构不对称误差会导致陀螺模态不匹配,严重限制陀螺的性能。面对批量化生产的谐振器,需要用一种便于实施的结构误差辨识方法挑选高品质的谐振器加工高性能陀螺。本文分析了刚度轴偏角误差和电极未对准误差对陀螺的影响,然后,提出了基于静电修调理论的误差辨识方法。最后,用三支嵌套环陀螺完成了辨识实验,证实了方法的可行性,辨识过程中得到的修调电压还可直接用于静电修调。     

一种基于谐振音叉的新型差动式硅微加速度计设计与分析

为提高谐振式加速度计灵敏度、稳定性以及减小加速度计体积,本文提出一种结构新颖的谐振式硅微加速度计。采用一级微杠杆机构对质量块惯性力进行放大,通过一对差动布置的双端固支音叉谐振器的固有频率变化检测惯性力,从而实现对加速度的测量。该加速度计可采用体硅加工工艺,给出了总体工艺流程。采用解析和有限元分析方法对加速度计敏感元件进行了分析,有限元分析结果与解析分析结果相吻合,有限元分析可得加速度计灵敏度为57.4 Hz/gn。分析结果表明该加速度计结构具有高灵敏度、高温度稳定性和小体积等优点。     

谐振式微加速度传感器的有限元分析

有限元分析用来评估一种新颖的谐振微加速度传感器,仔细分析新结构的几个主要振动模态,优化结构参数,证实这种硅基谐振式微加速度传感器的灵敏度高于1 000 Hz/gn.而且在有限元分析的基础上对实际制造的非完全匹配的双端固定音叉的特点和对于测量的不良影响进行分析.     

Design of microresonators under uncertainty

A methodology for robust design analysis of microelectromechanical systems is presented by considering the example of comb microresonators and uncertainty in parameters governing the resonant frequency and the transconductance values. Analytical models for the variability in the resonant frequency and transconductance are developed as function of the parameter uncertainty, and used as objective functions sought to be minimized in a robust design endeavor. An enumeration search over the design space is utilized to determine the optimal design of microresonators that minimize the variability subject to constraints on performance requirements. The results are presented over a wide interval of operating resonant frequency, and can be used in the robust design of microresonators.     

A method to simulate the vibrating characters of the resonator for resonant MEMS gyroscope

This paper proposes one study method of resonant MEMS gyroscope based on the circuit in order to solve problems such as long verification cycle and high cost of the MEMS gyroscope structure design. Firstly, on the basis of Euler–Bernoulli beam theory, this study establishes resonant beam vibration equation, obtains semi-Mathieu equation after normalization, namely parameter excitation characteristic equation of the frequency micro gyroscope, then deduces the characteristic equation in consideration of the damping condition, and uses the parameter perturbation method to study the output characteristic of gyroscope under ideal and damping states. Then, the analog circuit is innovatively used to obtain the characteristic equation of gyroscope under ideal and damping states, subsequently, the characteristic equation is normalized. It is realized that the dynamics equation is equivalent to the analog circuit. Finally, the experimental study is carried out, and experimental device for the frequency micro gyroscope harmonic oscillator parameter excitation characteristic is produced. Meanwhile, the analog circuit output waveform and frequency change correctness are verified by using the Runge–Kutta method and the parameter perturbation method, respectively. The experimental results show that the experiment device can be used to study the nonlinear vibration characteristics of the gyroscope.     

Exact analysis of antibody-coated silicon biological nano-sensors (SBNSs) to identify viruses and bacteria

In this paper, the vibration analysis of a Silicon Biological Nano-sensor (SBNS) with full coverage of Myosin as biologically adsorbent layer is investigated based on modified nonlocal Euler–Bernoulli beam model. This SBNS works based on calculating the shift of resonant frequency in the presence of Myosin layer and adsorbed viruses and bacteria. For this end, the effects of surface stresses, nonlocal parameter, and rotary inertia as well as the mass and stiffness of the adsorbent layer are taken into account, which can play a major role in changing the resonant frequency and the precision of SBNSs at nano-scale. The results illustrate that the effects of adsorbent layer, surface stresses, nonlocal parameter and rotary inertia may reduce resonant frequency of SBNS, which is significant especially at nano-scale. Finally, for the purpose of verification assessment, the numerical results were compared with the results of other studies and showed complete agreement. The present study can provide helpful insights for the design and characterization of accurate biological Nano-sensors.

     

MEMS石英振梁高增益谐振电路的设计与分析

介绍了一种基于新型高阻抗QVBA的高增益谐振电路设计和谐振电路的分析测试实验。利用阻抗分析仪4294A测得石英振梁的等效参数,对石英振梁的电气特性进行分析,发现高阻抗石英振梁起振比普通晶振需要更高增益。基于双门振荡电路,利用运算放大器在开环系统中具有无限增益的理论,提高谐振电路的驱动能力。同时采用谐波抑制网络,指出谐波抑制网络可以抑制无用的频率避免传感器输出信号出现泛音频率,并提高谐振电路的稳频速度。考虑电噪声对输出波形质量的影响,在电路的输入部分采用滤波电容,并在电路的输出部分采用反向器整形,使电路输出标准的方波信号。最后利用安捷伦DSO5012A型号示波器和频率计对高增益谐振电路和石英振梁组成的谐振系统进行测试,测试结果表明本文设计的谐振电路与石英振梁组成的谐振系统可以输出标准的方波信号,输出频率精度达到10-5 kHz,在振动稳定以后频率变化小于0.1 Hz,无泛音频率出现,对研究高精度MEMS加速度计传感器具有重要意义。     

Shaped comb fingers for tailored electromechanical restoring force

Electrostatic comb drives are widely used in microelectromechanical devices. These comb drives often employ rectangular fingers which produce a stable, constant force output as they engage. This paper explores the use of shapes other than the common rectangular fingers. Such shaped comb fingers allow customized force-displacement response for a variety of applications. In order to simplify analysis and design of shaped fingers, a simple model is developed to predict the force generated by shaped comb fingers. This model is tested using numerical simulation on several different sample shaped comb designs. Finally, the model is further tested, and the use of shaped comb fingers is demonstrated, through the design, fabrication, and testing of tunable resonators which allow both up and down shifts of the resonant frequency. The simulation and testing results demonstrate the usefulness and accuracy of the simple model. Finally, other applications for shaped comb fingers are described, including tunable sensors, low-voltage actuators, multistable actuators, or actuators with linear voltage-displacement behavior.     

动态轴向载荷下谐振梁振动响应分析

在航空航天飞行控制中,为实现关键参数的高精度高动态测量,急需发展具有快速响应特性的谐振式传感器。谐振式传感器本质上是输入与谐振器振动状态之间的映射。这种映射一般通过跟随输入的轴向载荷调制谐振梁的固有频率实现。高动态应用中的核心问题是动态轴向载荷下谐振梁的振动响应。利用基本的微元力学平衡关系建立了动态轴向力作用下谐振梁振动行为的数学模型。此模型比Mathieu方程的适用面更广,在一般假设下更难以进行解析或数值求解。为此引入了等效电路方法进行模型求解。通过对等效电路的仿真,得到了谐振梁在多种典型动态载荷下的振动响应。动态轴向载荷对于谐振梁的作用具有强烈的非线性和独特的规律,值得进一步深入研究探讨。     

A new analytical model of single-stage microleverage mechanism in resonant accelerometer

Microleverage mechanism which is widely applied in microelectromechanical systems (MEMS) transfers and amplifies force or displacement from input to output. In this work, one-stage microleverage mechanism is integrated into a biaxial micro resonant accelerometer to improve sensitivity. Force amplification factor of the microleverage is analyzed and deduced by integral method. The results from theoretical model match well with the ones from finite element method (FEM) simulation, which proves that the proposed model is relatively accurate and the width of lever beam is a quite important parameter in design. The resonant accelerometer is successfully fabricated by MEMS technology. Preliminary experiments are conducted and demonstrate differential sensitivity of 71 Hz/g for the accelerometer with resonant frequency of 267.726 kHz.