基于边缘电场传感器的大范围位移测量方法

主要研究基于边缘电场传感器的位移测量方法,由于在测量位移时交叉指型传感器互导电容的变化具有周期性,因而可以实现大范围的位移测量.运用Ansoft Maxwell有限元仿真软件对边缘电场传感器的二维半波长模型进行了仿真分析,仿真结果表明当传感器工作区间内有物体移动时,会改变传感器的电场分布,使传感器互导电容发生周期变化.设计了一个简单的、低成本的调理电路,可以将电容变化转化为电压输出信号,得到边缘电场传感器输出电压与电容的关系.对电极尺寸为35 mm×30 mm×0.02 mm的边缘电场传感器进行了测量实验,实验结果与仿真结果吻合较好.     

中国微米纳米_基于电场的快速暂态过电压测量

提出了一种基于电场的VFTO测量方法,以实现气体绝缘变电站(Gas Insulated Substations GIS)开关操作引起的快速暂态过电压(Very Fast Transient Overvoltage VFTO)的测量.通过MEMS电场传感器测量GIS母线周围的电场,进行大量试验确定电场强度与母线电压的线性关系,并对传感器进行标定,实现VFTO的测量.从理论上对GIS变电站不同负载的VFTO建模并进行仿真数值计算;使用扫频法、方波响应法对电场传感器的响应特征进行了测试,高频截止频率>134 MHz;在实验室内进行了高幅值电压测量实验,在云南电网公司超高压试验研究基地进行GIS变电站现场VFTO测量实验,结果表明利用电场传感器能够进行快速暂态过电压的测量.     

新型电场传感器应用于输电线电场测量

基于高性能的微电子机械系统(MEMS)工频电场传感器系统开展了高压架空输电线下电场测量应用研究.为了获得电场分布规律,基于模拟电荷法,建立了输电导线的二维电场计算通用模型.传感器系统核心敏感芯片基于电荷感应原理,采用MEMS技术加工制作.在0~1000kV/m工频电场范围内,传感器系统的总不确定度为1.53%,分辨力达到了20V/m.仿真与测试结果表明:35kV与10kV输电线下的电场计算结果与传感器系统的测量结果偏差分别为6%和10%,并与传统的Narda EFA-300电磁场分析仪测量结果具有较好的一致性.     

微型折叠式三维电场传感器

提出一种基于柔性衬底和三维组装方法的新型三维电场传感器.利用柔性衬底的折叠,构建一种互相垂直的新型三维电场传感器,研究了测量空间电场时的耦合,提出解耦算法,标定灵敏度矩阵,实现了空间电场三个方向分量的准确测量;通过一系列的温湿度实验研究了三维结构的形变,证明了三维电场传感器结构稳定可靠.实验结果表明:所研制的三维电场传感器不仅能消除耦合干扰,实现空间电场分量的准确测量,测量误差在3.61％以内;而且通过新的三维组装方法,大大减少了三维电场传感器的质量、体积,折叠工艺简化了三维传感器的组装,有利于批量化生产.     

杂质不完全离化对MISiC气体传感器的影响

研究了杂质不完全离化对金属-绝缘体-碳化硅(MISiC)传感器性能的影响.考虑到Pool-Frenkel效应和外加电场的作用,建立了MISiC器件空间电荷区泊松方程.运用准中性近似,对所建立的泊松方程进行数值计算,得到了空间电荷区的电势分布,进而得到MISiC传感器的,I-V与C-V特性.实验结果表明:室温下SiC器件中杂质不完全离化,随着温度的升高,杂质离化率增大.在外加电场的作用下,杂质的离化率增加,并最终导致MISiC器件I-V与C-V曲线的移动.     

一种扭转谐振式MEMS电场传感器

提出了一种基于微机电系统(MEMS)的扭转谐振式电场传感器。该微型电场传感器的感应电极与屏蔽电极采用共面叉指结构,首次采用扭转谐振的工作方式,显著提高了微型电场传感器的灵敏度。介绍了传感器的工作原理、结构设计、有限元仿真及实验。实验结果表明:在0～50 kV/m电场范围内,该传感器的线性度为0. 14%,3个往返行程的总不确定度优于0. 43%。在增益电阻为100 MΩ的情况下,传感器灵敏度达到4. 55 mV/(kV/m),相对已有传感器灵敏度提高了1个数量级。     

温度自补偿型光纤Bragg光栅土压力传感器设计

针对传统土压力传感器长期稳定性差、抗电磁干扰能力不强以及组网难度大等问题,根据传感器与土介质的匹配原则,设计了一种光纤Bragg光栅（FBG）温度自补偿土压力传感器,可实现温度和土压力2个参量的同时测量.对传感器灵敏度系数、匹配性等参数进行了理论分析计算.根据分析结果,加工封装传感器并对其进行了压力校准和温度自补偿性能实验.实验表明：传感器的输出波长分别与温度和土压力均呈线性关系,压力灵敏度系数为272.19 pm/MPa,输出分辨率为0.36％,线性相关度为99.989％;温度灵敏度系数为21.16 pm/℃,线性相关度99.998％,在0～40℃范围内具有良好的温度自补偿能力,其性能参数符合工程应用要求.     

基于电场传感器阵列的无人机输电线跟踪与定位方法

输电线的跟踪与定位是无人机(UAV)实现自主巡检输电线的关键要素.针对目前输电线跟踪与定位方法存在易受天气和环境因素影响、成本较高以及数据处理困难等缺陷,提出了一种基于电场传感器阵列的输电线跟踪与定位方法,计算出当前UAV的航向角偏转角度、输电线与UAV的距离以及仰角,并设计了电场传感器及信号调理电路,进行了实验验证....     

基于电场感应的冰层厚度检测传感器及其系统的研究

给一个金属电极通过电阻施加交流激励,当冰或水作为电介质接近该电极时,电极周围的电场发生改变,表现为该电极与"虚地"形成的电容的改变.利用这一电场感应机理,设计了同面多电极电容式冰层厚度传感器; 利用MAXWELL软件对传感器检测机理进行了仿真,并通过实验验证了利用电场感应的方法测量冰层厚度的可行性,仿真结果和实验结果证明该方法能实现定点冰层厚度的准确测量.     

电导法原油含水率测量传感器的模型优化与仿真

电导法原油含水率测量是基于阵列电极传感器的一种测量方法,电极系的结构与参数对传感器性能有着重要影响.拟研究电极系传感器结构的优化设计方法,在建立传感器电场分布理论模型的基础上,利用ANSYS有限元软件仿真电极系传感器不同参数下的电场分布,分析电极环宽度、激励电极对间距、测量电极间距等参数对传感器性能的影响.依据仿真结果,确定传感器的优化参数,并对传感器进行了灵敏度的模拟测试,测试结果显示:传感器灵敏度仿真结果与实际测试结果一致性较好;在高含水(大于85%)的油水两相流含水率测试精度可达3%.测试结果验证了传感器理论和仿真分析方法的有效性,为优化设计传感器提供一种有效的方法.     

Fabrication, experiment of a microactuator using magnetic fluid for micropump application

This paper presents the characteristics of the first microactuator using magnetic fluid (MF). MF actuators with flat and corrugated diaphragms are fabricated by the micromachining technique and their deflections are measured. The MF actuator consists of an inductor, a fluid chamber filled with magnetic fluid, and a parylene diaphragm. In the presence of the magnetic field, magnetic fluid easily deforms its shape and generates some pressure. The relation between the MF pressure and magnetic flux density is obtained by the comparison of the deflection for the applied air pressure with that for the MF pressure. At 110 Gauss, the deflection of MF actuator with corrugated parylene diaphragm is more than 200 μm and the generated MF pressure is 2.8 kPa. The successful operation of the first MF actuator shows the high potential for the application to the micromachined devices.     

Analytical model of electrostatic actuators for micro gas pumps

We analytically predict the performance of electrostatic actuators for diaphragm micro gas pumps by combining energy minimization and the analytical solution for membrane deformation under uniform pressure. The tangential strain of the membrane is considered in the calculation of membrane deflection. Models for both single- and double-cavity pumps are established to define the restriction of the upper cavity on the membrane during actuation. The shape lines of the membrane in a double-cavity structure are demonstrated under different voltages. The influence of dielectric thickness and cavity geometry on pumping consequence is also discussed. In accordance with other simulation results on diaphragm displacement and chamber pressure rise, an electrostatic diaphragm micro gas pump with a relatively thin dielectric layer and a cavity of comparatively small depth and radius suitably generates high pressure rise. Furthermore, a double-cavity structure enhances pressure rise for the restriction of the upper cavity on the membrane during deformation.

     

Modelling of silicon condenser microphones

Several models concerning the sensitivity of capacitive pressure sensors have been presented in the past. Modelling of condenser microphones, which can be considered to be a special type of capacitive pressure sensor, usually requires a more complicated analysis of the sensitivity, because they have a strong electric field in the air gap. It is found that the mechanical sensitivity of condenser microphones with a circular diaphragm, either with a large initial tension or without any initial tension, increases with increasing bias voltage (and the corresponding static deflection), whereas the mechanical sensitivity of other capacitive pressure sensors does not depend on the static deflection. It is also found that the mechanical sensitivity increases with increasing input capacitance of a preamplifier. In addition, the open-circuit electrical sensitivity and, consequently, the total sensitivity too, also increases with increasing bias voltage (or static deflection). However, the maximum allowable sound pressure at which the diaphragm collapses, an effect that has to be taken into account, decreases with increasing static deflection in most cases, ulthnately resulting in an optimum value for the bias voltage. The model for microphones with a circular highly tensioned diaphragm has been verified successfully for two microphone types.     

Analytical model of electrostatic actuators for micro gas pumps

We analytically predict the performance of electrostatic actuators for diaphragm micro gas pumps by combining energy minimization and the analytical solution for membrane deformation under uniform pressure. The tangential strain of the membrane is considered in the calculation of membrane deflection. Models for both single- and double-cavity pumps are established to define the restriction of the upper cavity on the membrane during actuation. The shape lines of the membrane in a double-cavity structure are demonstrated under different voltages. The influence of dielectric thickness and cavity geometry on pumping consequence is also discussed. In accordance with other simulation results on diaphragm displacement and chamber pressure rise, an electrostatic diaphragm micro gas pump with a relatively thin dielectric layer and a cavity of comparatively small depth and radius suitably generates high pressure rise. Furthermore, a double-cavity structure enhances pressure rise for the restriction of the upper cavity on the membrane during deformation.     

On gravitational lensing in the presence of a plasma

We discuss in detail our new results in the field of gravitational lensing in a plasma. We show that gravitational deflection by a point mass in a homogeneous plasma differs from vacuum deflection and depends on the frequency of the photon. This frequency dependence resembles the properties of a refractive prism spectrometer, whose strongest action takes place for very long radio waves. We also derive the photon deflection angle by a point mass in an inhomogeneous plasma. Then we consider a more general case of photon deflection by a mass distribution in an inhomogeneous plasma. Our approach allows us to consider two effects simultaneously: the gravitational deflection in a plasma which differs from the vacuum case (a new effect), and the non-relativistic effect (refraction) connected with the plasma inhomogeneity.     

Analysis of fluid flow and deflection for pressure-balanced MEMS diaphragm valves

Based on the linear plate theory for an elastic thin plate and the Bernoulli equation for a steady incompressible and inviscid fluid flow, the effect of fluid flow on the deformation of microelectromechanical systems (MEMS) diaphragm valve is investigated both analytically and numerically. For a given configuration of diaphragm valve, a relationship between the applied pressure and resulting contact area between diaphragm and valve seat is derived. Possible instability of such a system under the pressure-balanced mechanism is demonstrated with both analytical and numerical solutions for the deflection. Deflection as a function of flow speed, radius of outlet orifice, inlet gap, and bending stiffness of diaphragm are presented. In addition, the effect of diaphragm making contact with the valve seat due to pressure differential and fluid flow is analyzed and a relation between the contact zone and the external pressure is obtained. The results of the analysis suggest important parameters in the design of MEMS diaphragm valves and can be used as a basis in the design of such valves.     

Measurement of static and dynamic mechanical behavior of micro and nano-scale thin metal films: using micro-cantilever beam deflection

We present the results of a novel micro-beam deflection test used to investigate the static and dynamic mechanical behavior of submicron-thick metal films. The method demonstrated in this study allows researchers to observe the motion of micro and nano-scale thin films responding to electrostatic loads, by means of laser reflection measurements at frequency rates of up to 500 Hz. Researchers fabricated a supporting frame and a novel triangular shaped “paddle” beam designed to provide uniform plane stress distribution while undergoing deflection. A simple geometric calculation, based on cantilever deflection, enabled the degree of strain to be determined, which in turn provided the Young’s modus for aluminum film of a given thickness. We also studied the dynamic behavior using the dynamic frequency response of the beam, generated by electrostatic forces under various loads and vacuum pressure conditions. Our results showed that air damping has a significant influence on the free damping behavior of specimens, and only a minor influence on damping frequency. We determined the loss angle and frequency using sweep frequency and free damping methods, which were very consistent with paddle resonant frequencies. The loss angle obtained from a simple silicon micro-beam was 2.001 × 10^−4°using the free damping method and 2.23 × 10^−4°using the sweep frequency method. The dynamic response loss mechanism measured in this experiment provides incentive for the further study of grain boundary motion and dislocation motion in thin films.     

Design and pressure analysis for bulk-micromachined electrothermal hydraulic microactuators using a PCM

Paraffin wax exhibits a volumetric expansion of ∼15%, at around its melting point. By exploiting this phenomenon, high performance bulk-machined electrothermal hydraulic microactuators have been demonstrated. The microactuators have been integrated into microfluidic valves, microgrippers and micropipettes. The paraffin wax is confined within a bulk-micromachined silicon container. This container is sealed using an elastic diaphragm of PDMS, while it is heated via gold microheaters located on an underlying glass substrate. All the layers used to make up the containers are bonded together using a unique combination of overglaze paste and PDMS. The hydraulic pressure of expanding paraffin wax was determined using the deflection theory of a circular plate. For the first time, the hydraulic pressure of expanding paraffin wax was calculated using the theory of large deflections for a circular plate and measured data from the type-A microgripper. This theory has been exploited for the deflection analysis of micromachined thin elastic diaphragms. In order to calculate the hydraulic pressure, the theory of large deflections of a circular plate is calculated using the measured actuation height, the PDMS diaphragm dimension of the microgripper (type-A) and mechanical properties of the PDMS. The hydraulic pressure was calculated to be approximately 0.12 MPa. All the devices were successfully demonstrated and operated at either 10 or 15 V.     

Lattice Boltzmann model for elastic thin plate with small deflection

In this paper, a lattice Boltzmann model for solving problems of elastic thin plate with small deflection is proposed. In order to recover the Sophie–Germain equation for elastic thin plate by lattice Boltzmann method, we transform the equation into a set of Poisson equations. Two sets of distribution functions are employed in the lattice Boltzmann equation to recover the Poisson equations. Based on this model, some problems on the rectangular elastic thin plate with small deflection are simulated. The comparisons between the numerical results and the analysis solutions are given in detail. The numerical examples show that the lattice Boltzmann model can be used to solve problems of the elastic thin plate with small deflection.     

压阻式金刚石压力传感器的优化设计

介绍了一种新型金刚石高温压力传感器的优化设计方法。采用薄板弯曲理论研究了均匀载荷作用下多晶金刚石方膜在小挠度和大挠度下的应变分布情况。对设计时应当考虑的主要问题包括金刚石力敏电阻条的掺杂浓度，电桥的形式，电阻条在膜片上的分布以及电阻条的有效长度和形状等进行了讨论。利用模拟程序确定了力敏电阻条的最优有效长度，分析了敏感膜片厚度，方块电阻等因素对电阻条有效长度和输出响应的影响。