Advanced Sensor Technology Based on Oxide Thin Film—MEMS Integration

Many of the most significant advances in achieving improved sensor performance have been tied to the integration of thin film oxides with micromachined and microelectronic technologies (MEMS). Arrays of microcantilever beams or microhotplates show great promise as chemical sensor platforms exhibiting enhanced selectivity and markedly reduced power dissipation. Microcantilever beams demonstrate exceptional sensitivity to chemical, thermal and other physical stimuli. Microhotplates, provide the opportunity to discriminate between chemical species by control of reaction rates. We review recent key developments in the micromachining of suitable structures, the means for incorporating active oxide films and the performance of individual and arrays of sensor devices.     

浅析MEMS传感器在智能家居领域的应用

随着物联网技术的发展,智能家电已进入千家万户,从大到一台冰箱,小到一个开关的智能设备构成了智能家居体系.物联网使智能家电能通过互联网连接进行信息交换,智能家电感知外部世界获取信息则是通过传感器实现的.当前智能家居领域的应用场景不断细化,对传感器的尺寸、功耗、价格有了更高的需求.以下介绍MEMS传感器的技术及应用、MEM...     

Gas Sensors Based on Piezoelectric Micro-Diaphragm Transducer

ABSTRACT

We have fabricated high sensitive gas sensor based on piezoelectrically driven micro-diaphragm transducers. The micro-diaphragm transducer was fabricated using micro-electro-mechanical-system (MEMS) technique. The diol based sol-gel derived Pb(Zr_0.52,Ti_0.48)O₃(PZT) film was used as a piezoelectric actuating layer. We have used the resonant frequency change of micro-diaphragm transducer upon mass increase as a sensing signal. The resonant frequency values were measured by analysis of electrical signals from the micro-diaphragm transducer. The fundamental resonant frequency of the micro-diaphragm was in the range of 250 to 360 kHz, depending on their physical boundary conditions. The mass sensitivity of bare micro-diaphragm transducer was 66.5 Hz/ng. Two polymer sensing layers such as the polymethylmethacrylate (PMMA) and polydimethylsiloxane (PDMS) films were used to estimate the gas sensing behavior of microtransducers for various vapors of organic compounds. PMMA was used to detect primary alcohols while PDMS was used for toluene and benzene. The resonant frequency of micro-diaphragm transducer was shifted toward lower frequency range as the vapor concentration increased. With PMMA gas sensing layer, the micro-diaphragm showed a gas sensitivity of 0.456 Hz/ppm for ethanol vapor. When the PDMS gas sensing layer was used, the micro-diaphragm showed a gas sensitivity of 0.143 Hz/ppm for toluene vapor. When the test vapors were removed from the reaction chamber, the resonant frequencies of micro-diaphragm sensors were completely recovered to their initial state.     

基于MEMS技术的热式质量流量传感器

本文主要介绍了用MEMS技术制造的热式质量流量传感器工作的基本原理,并进行了制造工艺和性能描述以及相关领域的应用。     

Double‐Switch Series‐Resonant Cell‐Voltage Equalizer Using a Voltage Multiplier for Series‐Connected Energy Storage Cells

Series connections of energy storage cells, such as lithium‐ion cells and electric double‐layer capacitors (EDLCs), require cell‐voltage equalizers to ensure years of operation. Conventional equalizers require multiple switches, magnetic components, and/or secondary windings of a multiwinding transformer in proportion to the number of series connections, which usually makes them complex, expensive, bulky, and less extendable with increasing series connections. A double‐switch series‐resonant equalizer using a voltage multiplier is proposed in this paper. The double‐switch operation without a multiwinding transformer achieves simplified circuitry and good modularity at reduced size and cost, compared to conventional equalizers. Operational analyses were separately performed for the following two functional parts of the proposed equalizer: a series‐resonant inverter and a voltage multiplier. The mathematical analyses derived a dc‐equivalent circuit of the proposed equalizer, with which simulation analyses of even an hour's duration can be completed in an instant. Simulation analyses were separately performed for both the original and equivalent circuits. The simulation results of the derived circuit correlated well with those of the original circuit, thus verifying the derived dc‐equivalent circuit. A 5‐W prototype of the proposed equalizer was built for eight cells connected in series and an experimental equalization was performed for series‐connected EDLCs from an initially voltage‐imbalanced condition. The voltage imbalance was gradually eliminated over time, and the standard deviation in the cell voltages decreased to approximately 5 mV at the end of the experiment, thus demonstrating the equalization performance of the proposed equalizer.     

Electromagnetic silicon MEMS resonator

We have fabricated a silicon MEMS resonator aiming at multimodal sensors, and evaluated vibration characteristics by electromagnetic drive and induced electromotive force detection. The resonance frequency of the driving voltage of 0.6 Vpp shows torsional vibration of approximately 87 kHz, and the resonance frequency is shifted toward the low‐frequency side as the driving voltage increases. Resonance characteristics due to temperature change and film stress were evaluated.     

分级绝缘电压互感器倍频感应耐压试验的分析

为检查分级绝缘电压互感器的绝缘缺陷,需要对其进行倍频感应耐压试验。笔者提出了倍频感应耐压试验时试验电压的几种测量方法,对耐压试验中电压互感器的容升电压的产生原因及其对试验的影响进行了分析,对耐压试验的电压持续时间进行了说明,指出耐压试验前后空载试验结果的对比是判断被试电压互感器是否合格的依据。     

电阻式电压传感器结构设计及误差特性研究

从路的角度分析了电阻式电压传感器的误差特性 ,从场的角度比较了几种结构方案的幅值误差、相角误差及最大场强 ,优化出最佳方案 ,并分析了该方案幅值误差的频率特性     

光学电压传感器分压结构的缺陷及改进方法

现有的光学电压传感器多基于光功率检测模式,其测量范围与测量灵敏度受到电光晶体半波电压的限制。纵向调制的多片晶体叠层结构可以解决半波电压限制的问题,但仅适用于1 000 kV电压等级。此外,仿真结果表明这一结构中晶体内的电场分布极不均匀,受震动与热胀冷缩等因素的影响,光路或晶体的相互位置易产生偏移而引入积分电压误差。文中以110 kV电压等级为例,对多片晶体叠层结构进行了改进,简化了传感系统的结构,并将MgTiO₃陶瓷按照一定的要求安装在锗酸铋(BGO)晶体的外部以改善晶体的内电场分布,可以把积分电压误差从0.275%降低至0.01%以下。改进后的结构可用于各种电压等级。最后,通过实验验证了新方法的有效性。     

一种线性测量电光相位延迟的光学电压传感器

提出了一种采用晶体劈直接线性测量电光相位延迟的新型光学电压传感器,将晶体的电光相位延迟转换为光斑条纹的移动,通过测量光斑的位移量获得相位延迟。理论上分析推导了光斑位移量与晶体电光相位延迟角之间的线性关系,给出了光斑位移量的计算方法,并进行了实验验证。实验结果表明,新型光学电压传感器能够测量的相位延迟角达到320°,线性度良好。     

A Low‐Loss Medium‐Voltage Inverter Applying Series Connected General Purpose 1.2 kV Insulated Gate Bipolar Transistors with Accurate Voltage Balancing Techniques

This paper presents a medium‐voltage inverter applying series connected general‐purpose 1.2 kV insulated gate bipolar transistors (IGBTs) as a switching device to achieve low switching losses compared to inverters applying high‐voltage IGBTs with over 3 kV rating. Gate signal synchronization, which is essential to keep the balance of collector‐emitter voltages across the IGBTs, is achieved by magnetically coupling all gate lines using a simple two‐windings transformer. In order to obtain better voltage balancing, influence of stray capacitance distribution associated with an insulating substrate in a two‐in‐one IGBT module on the voltage sharing is investigated, and an optimized layout of heat sinks for the IGBT modules is proposed. To validate some performances concerning the device losses and the voltage sharing, a 170 kVA inverter based on three 1.2 kV IGBTs connected in series is built and evaluated. The experimental results are shown. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

电子式电压互感器传感元件的分析及实验

简要介绍了各类新型电子式电压互感器的研发情况,并对阻容分压电压传感元件做了理论分析和实验研究,重点在于该传感元件对输入电压信号的响应能力。实验结果反映出这种新型传感元件稳态测量准确可靠、暂态响应迅速,线性好,无饱和,满足电力系统测控和继电保护对电压信号的取样要求。     

基于模间干涉的全光纤电压传感器设计

介绍了一种新型的光纤电压传感器结构和工作原理,分析了系统中椭圆芯双模光纤的传输模式和模间相干光斑的变化,采用熔接的方式进行相干光接收来获得正交相位漂移信号,根据模间群折射率差与光程差的关系设计调整光纤的长度,依据石英晶体和空气的绝缘强度进行传感光纤匝数设计,讨论了含源零差探测法的相位跟踪原理,给出了相位检测框架图及实验结果,分析表明该设计方案能达到相位跟踪的目的。     

1 000 kV绝缘筒式高压工频成套装置存在的问题

通过对国内研制的1000kV绝缘筒式高压工频成套装置调研并结合使用经验，高压工频成套装置仍有不完善的地方，在此提出供专业人士参考。     

光纤电压传感器的温度补偿方法

针对光纤电压传感器存在的温度稳定性问题,分析了多种温度补偿方法。根据实验得到的数据,对比了各方法补偿前后的效果,认为单一的补偿方法难以达到设计要求,提出了集双光路补偿、温控法和软件补偿为一体的综合补偿方法,达到了0．1％的精度。     

变频谐振耐压装置的动态试验容量计算

由于频率的变化及品质因素的不确定性,很难准确计算变频谐振耐压装置的试验容量,以致出现准备工作不足、延长工作时间、电源及装置过载发热等问题。为此,归纳了有关公式,并提出经验参数,全面评估电源及装置容量,使变频谐振耐压装置试验容量输出的每个环节可控、在控。     

一种最小电压跟踪的感应电能传输系统调频调谐方法

感应电能传输(IPT)系统在进行电能传输的过程中,系统负载受到外部环境以及系统不同工况的影响而发生变化,进而导致一次侧回路等效阻抗发生变化,并且一次侧回路等效阻抗的变化量难以用准确的数学表达式表示。这种情况导致IPT系统一次侧回路不谐振,逆变器工作在非软开关状态,增大了一次侧电源的容量。为解决这一问题,以基于串联-并联补偿的一次侧恒流的IPT系统为研究对象,分析系统一次侧谐振状态受二次侧整流性负载影响的原因,采用一种最小电压跟踪的调频调谐方法,以实时检测的当前降压直-直变换器输出电压值为反馈量,控制逆变器的输出电压频率,通过不断跟踪降压直-直变换器输出的电压的最小值,使系统一次侧回路恢复到谐振状态。实验结果表明,所采用的方法能够有效地恢复一次侧回路的谐振状态,降低了一次侧电源的容量需求,使逆变器工作在软开关状态。     

PIEZOELECTRICALLY DRIVEN MICROTRANSDUCER MASS SENSORS

ABSTRACT

Various types of piezoelectrically driven microtransducers which have a similar physical dimension, i.e., microcantilever, microdiaphragm and microbridge, were fabricated by micro electromechanical system (MEMS) technique and are compared on the mass sensing behavior. The diol based sol-gel derived Pb(Zr_0.52,Ti_0.48)O₃ (PZT) thin film capacitors were integrated for the piezoelectric actuation. We have used the resonant frequency change of microtransducer upon mass increase as a sensing mechanism. The resonant frequency of the microtransducer was measured by analysis of electrical signals from microtransducer such as impedance, capacitance, phase and dielectric loss. The fundamental resonant frequencies of the microcantilever, microbridge and microdiaphragm with similar dimension (～300 μm) were about 26 kHz, 260 kHz and 290 kHz, respectively. The mass sensitivities of bare microtransducers were measured by metallic thin film deposition and analysis of spectral responses from microtransducers. When various microtransducers are compared, the microcantilever exhibited the highest gravimetric sensitivity factor (Δf/Δm×f₀ = 694.4 cm²/g), followed by the microbridge and microdiaphragm. However, the microbridge showed the highest mass sensitivity (Δf/Δm = 137.5 Hz/ng) among those transducers.     

基于无线传感器网络的高压输电线监测系统研究

将无线传感器网络技术应用于高压输电线路的监测系统中,通过环境传感器采集线路的应力、温度和震动等环境信息,实现高压输电线路实时环境量监测,并结合微型摄像机实现对异物侵入、违章作业、人为偷盗的远程视频监测及录像;设计了高压输电线上传感器节点的组网模式,通过遗传算法优化传感器节点的运行模式,在满足系统特定信息采集功能及网络连通性的前提下,有效地实现了网络负载的均衡配置,优化了网络的能量管理。     

高压静电除尘用电源调压特性的分析

为了得到高压静电除尘电源工作于串联谐振断续电流模式下的调压特性及选择一种适宜的控制方式,在分析电路工作原理的基础上,通过数学公式推导出了反映电路输出特性的解析表达式,分析了控制参数对电路调压特性的影响。通过仿真主要研究了调频、调占空比和调输入电压3种控制方式下电路特性的对比,结果表明,采用调节输入电压的控制方式具有较低的谐振电流峰值和有效值,是一种适合于高压静电除尘的控制方式,最后通过样机给出了实验结果。