梳齿的不平行对电容式微机械传感器阶跃信号响应的影响

分析了梳齿电容式传感器在三种电容驱动方式下,梳齿电容极板的不平行对传感器受到阶跃加速度信号作用时可靠工作条件的影响。得到了梳齿倾斜效应对传感器阶跃加速度响应影响的分析模型。结果表明梳齿电容在同样的电压驱动下,若电容极板的倾斜角变到0.5°时,对于单边电容结构、双边电容结构和有力反馈的双边电容结构,传感器能够承受的临界阶跃加速度分别变为电容极板完全平行时的0.34、0.44、0.52。并针对DRIE工艺刻蚀梳齿的原理,讨论了改进梳齿不平行的方法。     

平面电容传感器参数优化设计及实验

平面电容传感器的性能指标由结构参数决定,如何优化结构参数使传感器达到良好的性能是传感器设计的关键.基于三维有限元仿真模型,研究了感应面积一定的条件下,电极对数、电极宽度与间距比对传感器信号强度、灵敏度及穿透深度的影响.采用神经网络方法优化结构参数,在保证穿透深度的条件下,获得较好的信号强度.研制了不同结构参数的PCB型平面电容传感器,并将其用于介电材料检测,实验结果证明了传感器参数优化测量的有效性.     

同面多电极电容传感器结构仿真研究

通过电磁场有限元分析软件ANSYS仿真同面双电极结构电容传感器在极板长、宽、间隙的不同组合下对电容变化率的影响,得出极板长、宽、间隙的最佳组合,构建了同面八电极电容传感器,分析比较在地屏蔽、极间屏蔽、外围屏蔽下传感器极板间电位分布和在不同屏蔽下传感器的灵敏度.仿真表明:增加屏蔽后不仅可以提高传感器的灵敏度,还可以获得比较均匀的敏感场.仿真研究结果为同面多电极电容传感器的结构设计提供了依据.     

基于柔性电极结构的薄膜电容微压力传感器

基于柔性电极结构,本文设计、制作了薄膜电容微压力传感器,在阐述传感器工作原理的基础上,提出了两种设计思路,即基于柔性纳米薄膜的电容式微压力传感器和具有微结构的柔性电极薄膜电容式微压力传感器,并结合传感器的结构和柔性材料的加工特性,进一步提出了相应的力敏特性材料结构优化思路和加工流程,利用该流程得到了一种结构轻薄、工艺简单、高灵敏度的微压力传感器。经测试,本文制作的压力传感器的灵敏度能够达到218 fF/mmHg,在智能穿戴和可植入压力检测等领域显示出较好的应用前景。     

内置式电容层析成像系统传感器优化设计

电容层析成像系统重建图像的质量主要依赖于系统的观测矩阵,即灵敏度矩阵,灵敏度矩阵的特性又由传感器的结构参数所决定的。本文提出了采用反映灵敏度矩阵特性的条件数作为主要的电容传感器优化设计指标,结合表示传感器电极总体灵敏程度的电容变化量指标,兼顾最大、最小电容测量值满足测量范围的要求,进行综合优化设计。通过有限元方法,分析了内置式传感器电极结构参数对电容测量值和灵敏度矩阵的影响,并利用综合指标进行了优化,获得了一组内置式传感器的优化结构参数。     

梳齿式电容加速度传感器等效并联电阻对器件输出产生的影响

梳齿式电容加速度传感器检测电容的测量结果会受到除感应电容之外的其他等效电路参数的影响。梳齿式电容加速度传感器的结构与多层瓷片电容（MLCC）的结构类似,因此可以借鉴多层瓷片电容中等效电路参数的研究方法对电容加速度传感器中的等效电路参数进行研究。本文将对梳齿式电容加速度传感器检测结构中的等效电路参数进行建模,并分析这些等效电路参数对测试结果产生的影响。     

基于微位移定位系统MEMS梳齿位移传感器的研究

MEMS硫齿位移传感器是一种基于MEMS技术电容理论的传感器,具有体积小、重量轻、性能稳定、功耗低和易于集成等特点.首先探讨了梳齿传感器的工作原理,随后介绍了使用梳齿传感器有效检测微动工作台位移的方法,并进行了结构失效和梳齿电极不平行失效的可靠性分析.通过采用这种传感器可以达到提高微位移定位平台系统的集成度、精度、分辨...     

双阵列式电容传感器特性研究

针对电容层析成像技术的局限性,提出了新型双阵列电容传感器。利用传感器相邻极板灵敏度不均匀的特点,通过测量相邻极板电容以获得传感器内部局部浓度,重建管道内部传感器截面的相浓度分布。建立有限元模型,对不同电极数的电容传感器结构进行分析,研究了管道介电常数、电极覆盖率等传感器参数对灵敏场不均匀度的影响,得出优化的传感器参数。实验结果显示,该方法可以有效获取传感器截面局部浓度。     

叉指电容传感特性及应用研究

通过COMSOL Multiphysics仿真软件建立叉指电容传感器的二维模型,运用施瓦茨-克里斯托费尔平面映射及保角变换法得到叉指电容在边缘效应影响下的计算公式。详细分析了电极覆盖率、电极宽度以及电极厚度等关键参数对传感特性的影响,并给出参数设计的最优方案,针对典型应用领域进行原理分析及模拟仿真。结果表明,基于叉指电极的传感器灵敏度高,可靠性好,为传感器的设计和检测技术提供了必要的参考。     

目标导体对近感电容传感器电极电容影响研究

电容传感器是利用探测电极间电容的变化来实现目标近感探测的.对两电极电容传感器,分别探讨了探测大目标导体和小目标导体时电极的自电容、互电容以及等效电容的变化趋势,结果表明,电容传感器在遇目标后,其电极间的自电容均会增大,而互电容则减少.大目标导体会导致电极间等效结构电容增大,而小目标导体的介入不会影响电极间的等效结构电容.     

MEMS resonators that are robust to process-induced feature width variations

A stability analysis and design method for MEMS resonators is presented. The frequency characteristics of a laterally vibrating resonator are analyzed. With the fabrication error on the sidewall of the structure being considered, the first and second order frequency sensitivities to the fabrication error are derived. A simple relationship between the proof mass area and perimeter, and the beam width, is developed for single material structures, which expresses that the proof mass perimeter times the beam width should equal six times the area of the proof mass. Design examples are given for the single material and multi-layer structures. The results and principles presented in the paper can be used to analyze and design other MEMS resonators.     

Dynamics and control of a MEMS angle measuring gyroscope

This paper presents an algorithm for controlling vibratory MEMS gyroscopes so that they can directly measure the rotation angle without integration of the angular rate, thus eliminating the accumulation of numerical integration errors incurred in obtaining the angle from the angular rate. The proposed control algorithm consists of a weighted energy control and a mode tuning control. The weighed energy control compensates unequal damping terms and keeps the amplitude of oscillation constant in an inertial frame by maintaining the prescribed total energy. The mode tuning control continuously tunes mismatches in spring stiffness in order to maintain a straight line of oscillation for the proof mass. The simulation results demonstrate the feasibility of the control algorithm and the viability of the concept of using a vibratory gyroscope to directly measure rotation angle.     

A dual-axis MEMS capacitive inertial sensor with high-density proof mass

This paper reports a novel dual-axis microelectromechanical systems (MEMS) capacitive inertial sensor that utilizes multi-layered electroplated gold. All the MEMS structures are made by gold electroplating that is used as a post complementary metal-oxide semiconductor (CMOS) process. Due to the high density of gold, the Brownian noise on the proof mass becomes lower than those made of other materials such as silicon in the same size. The single gold proof mass works as a dual-axis sensing electrode by utilizing both out-of-plane (Z axis) and in-plane (X axis) motions; the proof mass has been designed to be 660 μm × 660 μm in area with the thickness of 12 μm, and the actual Brownian noise in the proof mass has been measured to be 1.2 \({\upmu}{\text{G/}}\sqrt {\text{Hz}}\) (in Z axis) and 0.29 \({\upmu}{\text{G/}}\sqrt {\text{Hz}}\) (in X axis) at room temperature, where 1 G = 9.8 m/s². The miniaturized dual-axis MEMS accelerometer can be implemented in integrated CMOS-MEMS accelerometers to detect a broad range of acceleration with sub-1G resolution on a single sensor chip.     

具有输入非线性的MEMS振动陀螺零点校正方法

针对Micro-electro-mechanical system (MEMS)振动陀螺仪加工制造过程中产生的几何结构中心与质量块重心不重叠导致严重陀螺漂移和噪声的问题, 在考虑陀螺自身非线性、控制输入非线性和外部干扰的情况下, 提出一种基于超稳理论的非线性控制策略对MEMS陀螺仪进行零点校正. 该方法在MEMS 陀螺仪非线性模型中引入一Hurwitz矩阵对模型进行变换以满足系统的严格正实要求, 利用向量范数的性质得到合适的控制律以满足Popov不等式, 从而保证了闭环控制系统的全局渐近稳定性. 仿真结果显示, 提出的非线性控制策略可以使系统状态迅速收敛到零, 并且对系统参数摄动表现出较强的鲁棒性.     

带有凸条平板的MEMS结构压膜阻尼效应分析

针对带有凸条平板的MEMS结构压膜阻尼效应,利用基本Reynolds方程和特定的第一类边界条件,给出一种压膜阻尼系数的解析分析方法。在带有凸条平板的MEMS微开关设计与制作的基础上,利用引入该压膜阻尼系数的Simulink模型仿真分析了微开关的动态响应特性,得到的阈值加速度与其落锤测试结果是一致的,从而验证了所提出的带有凸条平板压膜阻尼效应理论分析的正确性。     

Reduction of squeeze-film damping in a wafer-level encapsulated RF MEMS DC shunt switch

This paper presents the design, fabrication and characterization aspects of a wafer-level encapsulated RF MEMS shunt switch with a perforated base substrate and a corrugated diaphragm. A three-wafer stacking concept was proposed to achieve a RF MEMS shunt switch based on metal-metal contact. The introduction of damping holes in the base substrate wafer is proven to be an effective way to reduce squeeze-film damping and thus increase the switching speed of the switch. It is also demonstrated by analytical calculation that some factors play important roles on the damping characteristics, such as the physical location of damping holes in the base substrate, hole size, and number of holes per radius ring. By means of the implementation of damping holes, the pull-in and release time of the fabricated MEMS switch are significantly reduced by about 13 times, from 5.4 ms to 0.435 ms and 40.6 ms to 3.2 ms, respectively.     

新型MEMS热流陀螺的制造

MEMS热流陀螺是一种基于热流体理论的新型陀螺.该器件利用封闭腔体内的气体作为敏感元件,代替了常规MEMS陀螺的复杂振动结构和悬挂质量块,具有抗大冲击、体积小、重量轻、成本低、可批量化生产等优点.本研究的目的是为了验证MEMS热流陀螺的可行性,主要介绍该器件的研制过程,包括流体场仿真和工艺实现.最后得到了MEMS热流陀螺及其输出曲线,测试结果很好地验证了基于热流体理论的MEMS热流陀螺的可行性.     

圆片级低真空封装的MEMS压电振动能量收集器结构设计

MEMS低真空封装技术能为MEMS器件的可动部分提供低阻尼环境,降低能量损耗,有效提高器件的能量转换效率,具有重要的研究意义和应用前景,是MEMS技术的研究热点和难点。为了进一步提高MEMS压电振动能量收集器的输出性能,提出了圆片级低真空封装的共质量块MEMS压电悬臂梁阵列振动能量收集器新结构,通过有限元分析方法对器件结构参数进行了优化设计,在优化结构参数下仿真器件输出性能：在610 Hz、2 gn加速度下,器件的输出电压为8.88 V,输出功率为1220μW,能满足实际应用需求;根据器件结构设计了加工工艺流程,对低真空封装结构的实现和封装工艺探索具有重要意义。     

Fluid Effects in Vibrating Micromachined Structures

Squeeze film damping and hydrodynamic lift for a micromechanical perforated proof mass are calculated and measured. This paper has resulted in closed-form expressions that can be used to design accelerometers, tuning-fork gyroscopes (TFGs), and other micromechanical devices. The fluid damping and lift are determined using finite-element analyses of the normalized and linearized governing equations where the boundary condition of the pressure relief holes is derived using pipe flow analysis. The rarefaction of gas is incorporated in the governing equations based on slip flow condition. As a further check, a one-dimensional (1-D) network model is developed to account for the boundary condition of the holes on a tilted proof mass. Both closed-form and numerical solutions are compared against experimental data over a range of pressures.hfillhbox[1221]     

Dynamic simulation of a contact-enhanced MEMS inertial switch in Simulink?

A novel contact-enhanced design of MEMS (micro-electro-mechanical system) inertial switch was proposed and modeled in Simulink^?. The contact effect is improved by an easily realized modification on the traditional design, i.e. introducing a movable contact point between the movable electrode (proof mass) and the stationary electrode, therefore forming a dual mass-spring system. The focus of this paper is limited to a vertically driven unidirectional one for the purposes of demonstration, but this design concept and Simulink^? model is universal for various kinds of inertial micro-switches. The dynamic simulation confirmed the contact-enhancing mechanism, showing that the switch-on time can be prolonged for the dynamic shock acceleration and the bouncing effect can be reduced for the quasi-static acceleration. The threshold acceleration of the inertial switch is determined by the proof mass-spring system’s natural frequency. Since the inertial switches were fabricated by the multilayer electroplating technology, the proof mass thickness were assigned two values, 100 and 50 μm, in order to get threshold levels of 56 and 133 g respectively for the dynamic acceleration of half-sine wave with 1 ms duration. Other factors that influence the dynamic response, such as the squeeze film damping and the contact point-spring system’s natural frequency were also discussed. The fabricated devices were characterized by the drop hammer experiment, and the results were in agreement with the simulation predictions. The switch-on time was prolonged to over 50 μs from the traditional design’s 10 μs, and could reach as long as 120 μs. Finally, alternative device configurations of the contact-enhancing mechanism were presented, including a laterally driven bidirectional inertial switch and a multidirectional one.