高Q值音叉式微陀螺静电自激驱动研究

为了提高检测精度,对研制的具有滑膜阻尼的音叉式微机械陀螺采用静电自激驱动方式,它能够使驱动振动自动稳定在驱动模态的固有频率上,并保持恒定的驱动振动速度幅度。分析了静电自激驱动电路工作原理,采用自动增益控制(AGC)设计制作了相应的检测电路,实现了Q值为325、谐振频率为2.04 kHz微陀螺的闭环恒幅自激振动。     

硅微振动陀螺仪驱动器自激驱动研究

为了提高硅微机械陀螺仪的检测精度,稳定驱动振动速度的幅度和频率,采用了硅微机械陀螺仪自激驱动方式.该方式能够使驱动振动自动稳定在陀螺仪驱动模态的谐振频率上.同时,采用自动增益控制(AGC)保持恒定的驱动振动幅度.根据自激驱动电路原理和现有的陀螺样品,建立了陀螺仪驱动动力学方程的等效电路模型.设计、制作了自激驱动电路,仿真和实验结果表明该方法切实可行.     

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。     

对称解耦硅微陀螺仪结构设计研究

硅微机械陀螺仪的驱动模态和敏感模态间的交叉耦合制约了其性能的提高。设计了一种对称解耦硅微机械陀螺仪,它的驱动机构与检测机构都做线性滑膜阻尼振动且完全解耦,使得驱动和敏感模态之间的耦合小、结构振动平稳性好、品质因数高。该微陀螺仪的驱动与检测支承梁完全相同且对称分布,使得驱动模态和敏感模态的谐振频率受加工误差和温度变化的影响近乎相同,所以频率匹配性好,结构的灵敏度大大提高。实验测试结果表明对称硅微机械陀螺仪的耦合误差得到了有效减小,并且它的驱动和检测谐振频率仅相差6Hz,其品质因数在空气条件下分别为145和117,检测模态的品质因数与采用压膜阻尼振动方式进行检测的硅微机械陀螺仪相比有了显著提高。     

基于复合静电驱动结构的硅微机械扭转微镜

为了改善硅微机械扭转微镜的机电耦合特性,降低器件的驱动电压并提高其工作可靠性,提出了几种新颖的基于复合静电驱动结构的硅微机械扭转微镜.提出的硅微机械扭转微镜将垂直扭转梳齿静电驱动结构、侧壁平行板电容静电驱动结构有机结合,实现了两种静电驱动方式的复合驱动,同时设计了内外双镜面结构,通过内外双镜面结构,实现了微镜的差动复合驱动,理论分析、模拟仿真与测试结果表明,通过上述两个方面新颖的设计,新结构显著降低了器件的驱动电压.同时为了提高器件的工作可靠性,在设计折叠梁柔性支撑结构时,将梁的不同位置设计成不同的厚度,对于硅微机械扭转微镜扭转过程中容易疲劳的梁部分加大了其厚度,从而在不影响器件扭转性能的前提下,明显提高了器件的可靠性.利用有限元方法对器件的力学特性和机电耦合特性进行了系统的仿真,获得了影响器件机电特性的关键结构参数.器件基于SOI晶片,采用表面硅工艺与体硅工艺相结合的方式加工制造,采用SOI晶片显著降低了微镜镜面的表面粗糙度,提高了其光反射能力.最后利用原子力显微镜对微镜镜面的表面粗糙度进行了测量和分析,实验结果表面微镜表面具有16nm的表面粗糙度,完全可以满足光学应用的需要.     

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。     

微机械陀螺的仿真与优化

微机械陀螺依靠振动模态频率来测量旋转角速度,通常微机械结构的振动模态相当复杂。虽然已有很多文章研究了如何调节驱动模态和敏感模态以获得最大的敏感度,却很少有人分析微机械陀螺的振动模态。振动模态与陀螺结构的设计参数有极大的关系,这些参数包括陀螺检测质量的尺寸、支撑系统的类型和尺寸,以及用以制造陀螺主体的多晶硅的残余应力。研究了一个静电驱动、电容检测、敏感垂直轴角速度的陀螺(也称平面陀螺)。同时,用有限元法分析法对微机械陀螺的结构进行了分析。     

静电梳齿微谐振器结构参数化设计

从理论上分析静电梳齿微谐振器的机械力学特性,给出了活动梳齿的横向谐振频率解析解。鉴于目前静电微谐振器模拟仿真中存在的问题,提出利用基于MAST语言实现的MEMS宏模块建立微谐振器系统级通用仿真模型,为验证外围电路提供了基础。仿真结果与理论模态分析相一致,验证了模型的有效性。通过谐振频率对结构参数的敏感性分析为优化谐振器性能提供基础,使工作模态远离其他高阶模态;合理安排激励电极,抑制一阶模态扰动。敏感性仿真表明:在横向振动微谐振器中,工作模态谐振频率随梁长的增加而减小;随梁宽的增加而增大;结构层厚度对横向振动频率没有影响;梳齿部分所有参数的变化造成频率的反向变化。     

应用于激光雷达的二维静电微镜设计

设计了一种应用于激光雷达的二维静电驱动谐振式微机电系统(MEMS)扫描微镜.基于MEMS技术对微镜加工工艺进行设计,简化了电隔离槽制备工艺,利用在绝缘体上硅(SOI)晶圆顶层硅刻蚀微镜结构的同时刻蚀电隔离槽,无需填充绝缘材料,实现动静梳齿的电绝缘;利用SOI晶圆底层硅的背面刻蚀结构,实现机械结构的连接,保证二维微镜结构...     

微石英音叉陀螺的方波驱动及解调电路研究

在分析微石英音叉陀螺的工作原理及电学特性的基础上,对微石英音叉陀螺的驱动电路和微弱角速度信号的提取方法进行了研究;论证了方波驱动的可行性,提出了在自激驱动回路中加入移相环节,使微石英音叉陀螺的驱动振动频率等于其机械谐振频率,分析了开关同步相敏解调在角速度信号的提取中的应用及其对噪声的抑制能力;设计并分析了一个用方波驱动微石英音叉陀螺,用开关同步相敏解调完成信号解调的电路,该电路结构简单,工作可靠,性价比高.     

硅微阵列陀螺仪的仿真、设计与测试

为了提高硅微机械陀螺仪的精度和工作可靠性,提出了一种新的硅微阵列陀螺仪结构设计方案。该陀螺仪由4个质量块构成,采用半解耦结构设计,结构完全对称,驱动模态和检测模态的频率匹配性好。分析了硅微阵列陀螺仪的结构和工作原理,并利用ANSYS有限元软件进行了结构仿真,通过调节结构参数实现了各驱动模态与敏感模态固有频率的匹配。对阵列陀螺仪样品进行了测试,实验测试结果表明,驱动模态存在3个振型,同频反相振动的幅值最大,与仿真结果一致。     

Theory and FEM simulation study of the double-clamped resonant beam with slit-structure

In this paper, we established the vibration model of double-clamped resonant beam with slit structure, and we theoretically analyzed the effect of rectangular slits with round corners on vibration amplitude and natural frequency of the resonant beam. The effect of rectangular slits on detection sensitivity of resonant beam is also analyzed. According to the theoretical analysis, computational studies of slit size and location influence on vibration amplitude, natural frequency and detection sensitivity of the resonant beam were carried out. Meanwhile, stress concentration of proposed slit structure with rounded corners was calculated by finite element method (FEM) and was compared with the stress concentration of slit with right corners. Finally, for resonant beams with slits of different size and location, theoretical calculation results and the FEM simulation results of natural frequency were compared. Theoretical analysis and FEM simulation are in good agreement.     

基于多频扫描的硅微谐振压力传感器测试方法

为了对硅微谐振压力传感器进行快速、高精度的开环特性测试,提出了一种基于多频扫描的频率特性测试方法.通过数字电路将多个不同频率的扫频信号叠加作为驱动信号,以实现在整个测试频带范围内高效且高精度的频率特性测试.搭建了以现场可编程门阵列(FPGA)为核心的多频扫描测试系统,采用4个正弦扫频信号叠加进行测试,结果表明:多频扫描测试与稳态扫描测试精度基本一致,但测试效率提高了4倍.多频扫描测试方法在保证测试精度的前提下,显著提高了测试效率,能够更好地满足高Q值传感器及其在批量生产过程中的测试需求.     

A micro electromagnetic low level vibration energy harvester based on MEMS technology

This paper presents a micro electromagnetic energy harvester which can convert low level vibration energy to electrical power. It mainly consists of an electroplated copper planar spring, a permanent magnet and a copper planar coil with high aspect ratio. Mechanical simulation shows that the natural frequency of the magnet-spring system is 94.5 Hz. The resonant vibration amplitude of the magnet is 259.1 μm when the input vibration amplitude is 14 μm and the magnet-spring system is at resonance. Electromagnetic simulation shows that the linewidth and the turns of the coil influence the induced voltage greatly. The optimized electromagnetic vibration energy harvester can generate 0.7 μW of maximal output power with peak–peak voltage of 42.6 mV in an input vibration frequency of 94.5 Hz and input acceleration of 4.94 m/s² (this vibration is a kind of low level ambient vibration). A prototype (not optimized) has been fabricated using MEMS micromachining technology. The testing results show that the prototype can generate induced voltage (peak–peak) of 18 mV and output power of 0.61 μW for 14.9 m/s² external acceleration at its resonant frequency of 55 Hz (this vibration is not in a low ambient vibration level).     

一种高灵敏度硅微机械陀螺的设计与制造

设计与制造了一种高灵敏度的硅微机械陀螺。陀螺用静电来驱动,用连接成惠斯顿电桥的压阻式力敏电阻应变计来检测。主梁、微梁 质量块结构实现了高灵敏度。比较硬的主梁提供了一定的机械强度,并且提供了高共振频率。微梁很细,检测时微梁沿轴向直拉直压。力敏电阻应变计就扩散在微梁上,质量块很小的挠动就能在微梁上产生很大的应力,输出很大的信号。5V条件下,陀螺检测部分的理论灵敏度达到27.45mV/gn。压阻式四端器件用来监测驱动振幅,可以反馈补偿压阻的温度系数。检测模态的Q值达260使陀螺能在大气下工作。陀螺利用普通的n型硅片制造,为了刻蚀高深宽比的结构,使用了深反应离子刻蚀(DRIE)工艺。     

Vibration-based automatic power-generation system

Two types of electric power generator systems that automatically extract power from oscillating motion of a human body or vibration of machines and structures are proposed and studied. The first system utilizes self-excited rotation of an eccentric rotor that rotates in one direction in synchronization with the applied oscillating motion. Connecting an electrical load to the generator increases the damping about the rotor axis, and numerical analysis shows that there exists an upper limit to this damping to maintain the self-excited rotation mode. Excessive damping reduces the rotor to a swinging motion, resulting in decreased power output. The second type utilizes resonant vibration of a permanent magnet unit suspended by a set of springs. In order to maximize the output power, a micro controller changes the connection of the generator coils, which in effect changes the electro-mechanical damping, to keep the vibration amplitude within the allowable stroke. Theoretical analysis and experimental results are presented for both systems.     

Design and FEM simulation study of the electro-thermal excitation resonant beam with slit-structure

This paper proposes a slit-resonant beam based on the double clamped resonant beam theory of silicon micro-machined resonant pressure sensors. The slit structure can enhance surface alternating stress in the root area of beam while vibrating. Finite element method (FEM) is applied to calculate the stress concentration magnification, and we carry out a computational study of the effects of size and location of slit structure in terms of mechanical properties of resonant beam, such as stress concentration on resonant beam and natural frequency of resonant beam, as well as sensing performance, such as resonant beam amplitude sensitivity. Our simulations show that the slit structure could strengthen the stress concentration and increase the amplitude detection sensitivity, and the variations of these parameters can substantially influence the performance of slit structure. The research of stress concentration, caused by silt structure, could provide reference for further optimization and design for the resonant beam.     

High quality factor silicon cantilever driven by piezoelectric thin film actuator for resonant based mass detection

A high quality factor (Q-factor) piezoelectric lead zirconate titanate (PZT) thin film actuated single crystal silicon cantilever was proposed in this paper for resonant based ultra sensitive mass detection. Intrinsic energy dissipation and other negative effects from PZT-electrode stack were successfully compressed by separating the PZT actuator from the resonant structure. Excellent Q-factor, which is comparable to silicon cantilever (without actuator) and several times larger than that of latest reported other integrated cantilevers, was successfully obtained under both atmospheric pressure and reduced pressures. For a 30 μm-wide 100 μm-long cantilever, the Q-factor was measured as 1,113 and 7,279 under the pressure of 101.2 KPa and 35 Pa, respectively. Besides, it was found that greater Q-factor can be achieved at high vibration mode by the proposed structure. However, support loss became significant because of the increased actuator’s vibration amplitude which in turn leads to unexpected energy dissipation. Therefore, an optimized structure using node-point actuation was suggested and discussed in last section of this paper.     

Non-linear vibration behavior of thin multilayer diaphragms

The vibration spectrum of piezoelectrically driven (ZnO) thin silicon diaphragms in the driving frequency range up to 200 kHz has been studied. The response of the structure on the driving conditions (a.c. voltage amplitude and frequency) is presented. The limits of the linear plate theory and specific non-linear effects are discussed. Non-linear effects in the vibration behavior occur for vibration amplitudes even smaller than 4% of the diaphragm thickness. Superharmonic, harmonic and subharmonic vibration modes are observed. The vibration amplitudes of the subharmonic modes are of the same order as the diaphragm thickness. The characteristic non-symmetric resonance peaks of the subharmonic vibration modes indicate the existence of a hard-spring effect in the system. In the case of a system with a hard-spring effect, the concept of vibration modes with fixed resonance frequencies fails.