A self-test and dynamics characterization circuit for MEMS electrostatic actuators

This paper presents a high-bandwidth capacitance estimation and driving circuit especially tailored for its use with MEMS electrostatic actuators. The circuit can be integrated as a part of a system comprising an electrostatic actuator to provide self-testing and failure prediction capabilities and also as a simple and low-cost actuator dynamics characterization system capable of measuring both periodic and non-periodic movements.     

System integration of high voltage electrostatic MEMS actuators

A system integration for High Voltage (HV) electrostatic MicroElectroMechanical Systems (MEMS) actuators is introduced on a micro-Printed Circuit Board. The system includes a programmable microcontroller, a programmable DC/DC converter, a multi output HV interface and electrostatic MEMS actuators. The system produces high output voltages (10–300 V) and can control a large variety of MEMS capacitive loads (1 to 50 pF) by combining diverse semiconductor technologies. This system proves that technologies, such as low voltage CMOS of different processes, high voltage DMOS and MEMS, can interact, communicate and even be integrated as a System In Package (SIP), providing significant size and cost reductions. The system was programmed to control electrostatic MEMS actuator. The DC/DC converter was made from components of different technologies and two addressable high voltage CMOS interfaces were fabricated with DALSA's 0.8 μm High Voltage process. A prototype of the global system has been built and tested.     

基于MEMS静电微镜驱动器的光纤相位调制器

设计并制作出了一种基于MEMS静电微镜驱动器的光纤相位调制器。MEMS静电驱动器采用垂直梳齿驱动技术,驱动硅微反射镜沿其法线方向的垂直平移运动以实现入射光波的光相位调制。MEMS静电微镜驱动器与光纤准直器耦合构成MEMS光纤相位调制器,避免了拉伸光纤或改变折射率的困难,具有MEMS技术批量制造、低成本等优势。采用MEMS工艺成功制作出MEMS光纤相位调制器,并实现Michelson光纤干涉仪。利用ASE宽带光源对光纤相位调制器的静态调制特性进行测试,采用Michelson光纤干涉仪对光纤相位调制器的动态调制特性进行测试,结果表明,MEMS光纤相位调制器50V偏压实现了1 550nm光波的2π相位调制,当器件谐振频率为7.15kHz以及交、直流电压幅值分别为12.5V时,响应幅值可达6.8μm,可以实现多个2π的相位的正弦调制。     

Polymer MEMS actuators for underwater micromanipulation

Conventional MEMS actuators are not suitable for underwater applications such as cell grasping due to two main reasons: 1) their required actuation voltage are typically higher than 2 V, which would cause electrolysis in water and 2) they have small displacement/deflection due to their inherent driving principles. In this paper, three-different types of novel polymer-based MEMS underwater actuators developed in our laboratory are discussed: 1) ionic conducting polymer films (ICPF) actuator, which actuates by stress gradient induced by ionic movement due to electric field; 2) parylene thermal actuator, which actuates due to the induced stress gradient across a structure made of different layers of materials with different thermal expansion coefficients; and 3) polyaniline (PANI) actuator, which actuates due to its volumetric change caused by a reversible electrochemical oxidation-reduction (redox) reaction. All these polymer micro actuators can be actuated underwater with large deflections and require less power input than conventional MEMS actuators. The experimental results from characterizing these prototype actuators are presented in this paper.     

Microfabricated electrostatic actuators for hard disk drives

A dual-stage servo system which utilizes a high-bandwidth secondary actuator has been proposed for magnetic hard disk drives. Microfabricated actuators are promising candidates for this secondary actuator, since they offer the benefits of extremely small size and weight and may be batch fabricated for reduced production cost. This paper presents the design of an electrostatic microactuator which produces sufficient output force to move a 1.6-mg picoslider from a conventional disk drive at frequencies above 2 kHz. A linear second-order actuation model is developed and fit to experimental data. The prototype device is shown to have an open-loop resonance frequency of 532 Hz when loaded with the picoslider, and a DC-voltage-to-position gain of 0.12 μm/V. A closed-loop bandwidth of 2.5 kHz is achieved using a simple PD controller     

A new formulation of fringing capacitance and its application to the control of parallel-plate electrostatic micro actuators

Though the effect of fringing field in electrostatic parallel-plate actuators is a well-understood phenomenon, the existing formulations often result in complicated mathematical models from which it is difficult to determine the deflection of the moving plate for given voltages and hence, they are not suitable for accurate actuation control. This work presents a new formulation for tackling the fringing field, in which the effect of fringing field is modeled as a variable serial capacitor. Based on this model, a robust control scheme is constructed using the theory of input-to-state stabilization (ISS) and backstepping state feedback design. This method allows loosening the stringent requirements on modeling accuracy without compromising the performance. The stability and the performance of the system using this control scheme are demonstrated through both stability analysis and numerical simulation.     

基于移动电源电容测试电路的设计

本文针对目前市场一些无量商家虚假标示移动电源容量的现象,利用C8051F410单片机控制系统设计了测量移动电源容量的电路.电路通过C8051F410的数据采集功能对移动电源放电过程中的电流、时间、电压进行采集,再积算出放电的电量并通过显示电路显示.能够帮助消费者有效的评价商品,防止上当受骗.     

一种偏振检测QKD系统相位调制器驱动电路设计

回顾了相位编码方式实现协议的量子密钥分发实验研究的演进历程和最新进展,选取基于Michel son干涉仪的相位编码、偏振检测单向QKD系统为实验平台,提出一种以单片机和FPGA为核心的相位调制器驱动电路设计方法,并给出了相应实验结果,达到了预期的实验目的.     

Miniaturized surface-driven electrostatic actuators: design and performance evaluation

A series of miniaturized, surface-driven rotary and linear electrostatic actuators was designed and fabricated. The finite element analysis method was used to aid in the design and analysis of the electrostatic drive mechanism. The actuators, consisting mainly of a copper-coated 200 /spl mu/m-thick glass epoxy stator board and a 34 /spl mu/m-thick carbon-coated polyethylene-terephthalate (PET) film slider, were fabricated using modified printed circuit board techniques. These actuators, able to carry mechanical loads up to 375 times their own weight, can be used as micro conveyers or robots in an automated micromachine assembly environment for a wide range of applications.     

Application of MEMS technology in automotive sensors and actuators

Sensors and actuators are the critical system components that collect and act on information in the analog environment and link it to the world of digital electronics. The functional groups of sensors, software, controller hardware, and actuators from the backbone of present and future automotive systems. Unit volumes for sensors and actuators in the automotive industry are measured in millions per year and at a unit cost of a few dollars. The design of sensors and actuators has increasingly made use of microelectromechanical systems (MEMS) technology. This technology is well suited to producing a class of micromachined sensors and actuators that combines signal processing and communications on a single silicon chip or contained within the same package. This paper contains a discussion of the issues in producing MEMS sensors and actuators from the concept selection stage to the manufacturing platform. Examples of commercial and emerging automotive sensors and actuators are given, which illustrate the various aspects of device development. Future trends in MEMS technology as applied to automotive components are also discussed     

用于数字闭环加速度计的差动电容检测电路

数字闭环加速度计是加速度计领域最新的研究课题,它具有直接输出数字信号、累积误差小,采样时间短等优点,因此对差动电容检测电路的要求也很高。本文为满足数字闭环加速度计的需要设计的单载波调制解调型差动电容检测电路,分析了方案优缺点,给出了系统和检测电路的原理框图,以及各个功能模块的电路图和传递函数,最后通过实验验证,得到该电路满足灵敏度高,分辨性能好的要求,并且该电路在其他微弱信号检测领域也具有一定的实用意义。     

Highly sensitive capacitance measurement for sensors

Very small capacitance changes from a capacitive transducer can be measured using a custom-designed signal-processing chip. The chip features a switched-capacitor integrator with chopper stabilisation to remove the effects of offset, 1/f noise and switch charge injection; the circuit is insensitive to stray capacitance. The achievement of high resolution and low drift is demonstrated.<>     

Parametric vibration for electromechanical integrated electrostatic harmonic drive

In this paper, the electromechanical coupled force between flexible ring and stator of the drive system is presented. The radial displacement of the flexible ring subjected to electric field force is obtained. A critical voltage is found beyond which the flexible ring and the stator will make contact. Considering the ring contacting with the stator as a curved beam fixed at ends, an electromechanical coupled dynamic equation of the drive system is developed. From the equation, the natural frequencies and vibrating modes of the drive system are given. The periodic variable voltage is expressed as disturbance on natural frequency of the drive system and the forced response of the drive system to voltage excitation is investigated. Using Laplace transformation, the forced frequency response of the drive system to voltage excitation is obtained as well. Changes of the forced frequency response along with drive parameters are discussed. Influences of the linear excitation caused by changing boundary angle on the system vibrations are also investigated. The response frequencies are dependent on exciting frequency and natural one. As the exciting frequency is close to the natural frequency of the drive system, the resonance occurs. The flexible ring radius, clearance between the ring and stator, etc. has obvious influences on the frequency responses of the drive system.     

A six-phase multilevel inverter for MEMS electrostatic induction micromotors

The construction of miniaturized rotating electric machines through microfabrication techniques is becoming a reality. Applications of such micromotors include miniaturized pumps, compressors, fans, coolers, and turbogenerators. However, the characteristics of these devices make the design of power electronics for them challenging. These characteristics include high-voltage and high frequency operation, tightly constrained operating waveforms and timing, and capacitive input impedances. This paper explores the design of power electronics for microfabricated electrostatic induction machines. We describe the structure and operation of these machines, and establish the operating requirements of power converters for them. We provide a comparison of inverter topologies for this application, and propose an appropriate architecture. The design and experimental evaluation of a prototype six-phase, five-level inverter for this application is presented. The inverter operates at frequencies up to 2 MHz and at voltages up to 300 V, and meets the stringent waveform and timing constraints posed by this application.     

一种税控收款机打印模块电机的驱动电路

介绍了税控收款机打印模块电机的工作原理。并讲述了驱动步进电机的集成电路MTD2003F的原理以及设计要点,给出应用的实际电路[编者按]     

Analysis, testing and optimisation of electrostatic comb-drive levitational actuators

This work presents an analysis of the levitation effect in electrostatic comb fingers and of its possible use for vertical or torsional actuation of micromachined structures. Two different levitational mechanical resonators were designed and fabricated in a thick-polysilicon technology. A study of the dependence of the force intensity on the geometric parameters of the actuators were performed using FEM simulations, and information about critical geometrical parameters in the design of operative levitational actuators were obtained. The devices were characterized and the obtained results were compared with FEM simulations. Antonio Molfese received the M.S. degree cum laude in Electronic Engineering from the University of Pisa, Italy on March 2003. In the summer 2003 he was at IMEC, Belgium for an internship. On November 2003 he received the diploma degree cum laude in Industrial and Information Engineering from Scuola Superiore Sant'Anna di Studi Universitari e Perfezionamento of Pisa, Italy. He is currently pursuing the Ph.D. degree in Information Engineering at University of Pisa and he is working at IEIIT-Sezione di Pisa of Italian National Research Council (CNR) as research assistant. His main research interests include design, modeling and characterization of micro-electro-mechanical systems and microfluidics. Giovanni Pennelli was born on October 23, 1967 in Lucca, Italy. He graduated in 1992, cum laude, in Electronic Engineering. He obtained his Ph.D. in 1997 for a thesis entitled "New Materials for a Silicon-Based Optoelectronics". He moved to the University of Glasgow in April 1997 to work as a Research Assistant in the MBE group concerned with optoelectronic device fabrication and process development. He developed some MBE grown structures for HEMT applications. In September 2000, Dr Pennelli has been appointed assistant professor in the Department of Information Engineering, University of Pisa, Italy, pursuing research in electron beam lithography and nanometer scale process development. Francesco Pieri received the laurea and the Ph.D. degree in Electrical Engineering, both from the University of Pisa, Italy, in 1996 and 2000 respectively. He joined the Department of Information Engineering of the same University as an assistant professor in 2001. His current research interests include applications of porous silicon to sensors and microtechnologies, and development of microelectromechanical systems. Andrea Nannini received his laurea degree in Electronic Engineering from the University of Pisa, Italy, in 1982; He received his Ph.D. degree in 1987 at the end of the first Italian Ph.D. course held by the University of Padova, Italy. From 1988 to 1992 he was a Researcher at the “Scuola Superiore di Studi Universitari e Perfezionamento S. Anna” – Pisa- Italy. Since 1992 he joined the Department of Information Engineering of the University of Pisa as an Associate Professor. Since November 2000 he is a full professor of “Sensor and Microsystem Design”. He is currently chairman of the postgraduate school of Electronic Engineering and vice-chairman of the PhD school of Information Engineering of the University of Pisa. His main research interests concern solid state sensors, microelectronic devices and technologies, MEMS.     

An analog drive loop for a capacitive MEMS gyroscope

The linear model and the design of an analog drive loop for the drive (primary) resonator in a capacitive gyroscope are presented. Four different types of gain control topologies are compared and analyzed with both P- and PI-type controllers. The simple model proposed in the paper allows the small signal properties of the loop to be predicted. The theoretical models based on the small signal analysis are compared to the simulated and measured results. A proportional amplitude controller, together with the rest of the drive loop, is implemented using a high-voltage 0.35-μm CMOS technology and a nominal supply of 3 V. Clock generation using a PLL and the drive loop signal as the reference are also discussed in the paper.     

Simple capacitance transducer for instantaneous angular-velocity measurement

To measure accurately the instantaneous angular velocity of a low-inertia stepper motor, a simple noncontact capacitance transducer has been developed. The capacitance has a value linear1 related to angular displacement of the motor shaft. The basic design is discussed, and construction details and practical result are give.     

Characterization of TiAl alloy films for potential application in MEMS bimorph actuators

In this letter, we demonstrate the feasibility of applying TiAl alloy film for the fabrication of bimorph actuators. The TiAl alloy films were prepared by thermal annealing at 400°C of Ti/Al multilayers, which were deposited by DC magnetron sputtering from Ti and Al targets. The microstructure and surface morphology of TiAl alloy films were analyzed by X-ray diffraction and scanning electron microscopy, which showed that TiAl alloy film is formed in the mixed phases of TiAl₃ and Ti₃₆Al₆₄, depending on the deposition conditions. The resistivity of TiAl film is about 9 μΩ cm, and the stress is about 200 MPa. Our nano-indentation measurements showed that the Young's modulus and hardness of TiAl alloy films are 175 and 6.5 GPa, respectively, which are larger than that of Al and comparable to Si. We have successfully fabricated the bimorph actuators based on the TiAl alloy films and our test cantilevers up to 500 μm long showed very straight with tip bending as small as ±5 μm, indicating negligible stress gradient in TiAl film. Our preliminary testing results indicated that TiAl alloy film has potential application for bimorph actuators.