Laterally driven electrostatic repulsive-force microactuators usingasymmetric field distribution

We present a new electrostatic actuation method using a lateral repulsive-force induced by an asymmetric distribution of planar electrostatic field. The lateral repulsive-force has been characterized by a simple analytical equation, derived from a finite element simulation. Quality-factors are estimated from the computer simulation based on creep flow model. A set of repulsive-force polycrystalline silicon microactuators has been designed and fabricated by a four-mask surface-micromachining process. Static and dynamic response of the fabricated microactuators has been measured at the atmospheric pressure for the driving voltage range of 0-140 V. The static displacement of 1.27 μm is obtained at the dc voltage of 140 V. The resonant frequency of the repulsive-force microactuator increases from 11.7 kHz to 12.7 kHz when the dc induction voltage increases from 60 V to 140 V. The measured quality-factors are increased from 12 to 13 in the voltage range of 60-140 V. Fundamental characteristics of the force, frequency and quality-factor of the electrostatic repulsive-force microactuator have been discussed and compared with those of the conventional electrostatic attractive-force microactuator     

Design and characterization of an electrothermally driven monolithic long-stretch microdrive in compact arrangement

An electrothermally driven long stretch microdrive (LSMD) is presented for planar rectilinear motions in hundreds of micrometers. Design concept is based on connecting several actuation units in series to form a cascaded structure to accumulate relative displacement of each unit, and two cascaded structures are further arranged in parallel by a connection bar to double output force. The proposed area-saving design features monolithic compliant structure in compact arrangement to achieve long stroke. In experiments, the maximum reversible operating voltage is 3 V. In addition, the voltage-displacement relation shows good linearity within /spl plusmn/5% in 0.5-3.0 V. Fabricated nickel LSMD can generate displacement up to 215 /spl mu/m (W=8 /spl mu/m, /spl theta/=0.2/spl deg/, D=34 /spl mu/m) at 3 dc volts (669 mW). The maximum operation temperatures of tested LSMDs at 3 V are below 300 /spl deg/C. Output forces up to 495 /spl mu/N are measured by in situ passive micromechanical test beams. The LSMD can be operated at 100 Hz without degradation on displacement. Two geometrical design parameters, bent angle and constraint bar width, are also investigated analytically and experimentally.     

A simple approach to characterizing the driving force of polysilicon laterally driven thermal microactuators

Based on the elastic analysis of structures, a simple approach to calculating the driving force for polysilicon laterally driven thermal microactuators is presented by using their deflection. The driving force obtained through the deflection is compared with available results measured by force testers fabricated on the same substrate as the microactuators. Reasonable agreement has been achieved. The approach allows one to predict the driving force for the microactuators as their deflection is designed.     

Thermal behavior modeling and characteristics analysis of electrothermal microactuators

Microsystem Technologies - Electrothermal microactuators possess a number of desirable attributes including ease of fabrication and large force and displacement capabilities relative to other types...     

Theoretical modal analysis and parameter study of Z-shaped electrothermal microactuators

Microsystem Technologies - This paper presents a comprehensive modal analysis of Z-shaped beam electrothermal microactuators for the first time. Both longitudinal and lateral vibrations are taken...     

Optimal profit-maximizing system design data envelopment analysis models

This research introduces a new type of data envelopment analysis (DEA) model termed the optimal system design (OSD) DEA model. Conventional DEA models evaluate DMUs’ performances given their known input and output data. The OSD DEA models take this one step further. They optimally design a DMU’s resource allocation in terms of profit maximization given the DMU’s total available budget. The need to design optimal systems is quite common and is sometimes necessary in practice. In actual fact, this study demonstrates that through the OSD DEA models, we can provide DMUs with more information than optimal portfolios of resources such as optimal budgets and budget congestion, i.e., the more the budget is consumed, the less the maximal profit. The proposed OSD DEA models are linear programs, and thus can be solved by the standard LP solvers to obtain DMUs’ optimal designs. However, to derive the DMUs’ corresponding optimal budgets, and to verify if the DMUs provide evidence of budget congestion, we need to modify the solvers, which may not be trivial. Therefore, this study exploits the special structures of the models to develop a simple solution method that can directly not only derive both a DMU’s optimal design and optimal budget, but can also check for the existence of budget congestion.     

A nodal analysis method for simulating the behavior of electrothermal microactuators

This paper presents a novel approach to verify and optimize surface micromachined electrothermal microactuators by using a nodal analysis method. The nodal analysis method for the mechanical and electrostatic devices is a schematic-based method which simplifies the design of MEMS devices significantly. A variety of the surface micromachined electrothermal microactuators have been widely applied in various areas due to the high force provided at a relatively low input voltage. These electrothermal microactuators can also be decomposed into essential elements of beams and anchors. This paper presents the nodal analysis method for the electrothermal microactuators. The temperature dependent properties for the thermal conductivity, electrical resistivity and thermal expansion coefficient of polysilicon beams are included. The effect of the effective axial length for the beams due to lateral deflection and large axial stress is also taken into account. This approach is verified by ANSYS and the simulation data agrees well with each other. It extends the general nodal analyses method to simulate the electrothermal microactuators.     

Data driven webpage color design

This paper presents a design framework for automatic webpage coloring regarding several fundamental design objectives: proper visual contrasts, multi-color compatibility and semantic associations. The objective functions are formulated with data-driven probabilistic models: the Color Contrast model concerning visual saliencies is trained on 52,000 basic components parsed from 500 popular webpages. Color Compatibility and Semantics are modeled from a dataset of manually tagged and rated color schemes from Adobe Kuler. To incorporate the multi-objectives in optimization, the framework adopts a lexicographic strategy, which determines the best choices by optimizing the objectives one by one in a user specified sequence. We demonstrate the effectiveness of the models and the flexibility of the framework in two typical web color design scenarios: fine tuning a colored page and recoloring a page with a specified palette. Independent perception experiments verify that the system-generated designs are preferable to those generated by nonprofessionals.     

Electrothermally activated paraffin microactuators

A new family of electrothermally activated microactuators that can provide both large displacements and forces, are simple to fabricate, and are easily integrated with a large variety of microelectronic and microfluidic components are presented. The actuators use the high volumetric expansion of a sealed, surface micromachined patch of paraffin heated near its melting point to deform a sealing diaphragm. Two types of actuators have been fabricated using a simple three mask fabrication process. The first device structure consists of a 9 μm thick circularly patterned paraffin layer ranging in diameter from 400 to 800 μm all covered with a 4-μm-thick metallized p-xylylene sealing diaphragm. All fabricated devices produced a 2.7-μm-peak center deflection, consistent with a simple first order theory. The second actuator structure uses a constrained volume reservoir that magnifies the diaphragm deflection producing consistently 3.2 μm center diaphragm deflection with a 3-μm-thick paraffin actuation layer. Microactuators were constructed on both glass and silicon substrates. The actuators fabricated on glass substrates used between 50-200 mW of electrical power with response times ranging between 30-50 ms. The response time for silicon devices was much faster (3-5 ms) at the expense of a larger electrical power (500-2000 mW)     

Enhancing displacement of lead-zirconate-titanate (PZT) thin-film membrane microactuators via a dual electrode design

A common design of piezoelectric microactuators adopts a membrane structure that consists of a base silicon diaphragm, a layer of bottom electrode, a layer of piezoelectric thin film, and a layer of top electrode. In particular, the piezoelectric thin film is often made of lead-zirconate-titanate (PZT) for its high piezoelectric constants. When driven electrically, the PZT thin film extends or contracts flexing the membrane and generating an out-of-plane displacement. Many manufacturing defects, however, could significantly reduce the designed actuator displacement. Examples include residual stresses, warping, non-uniform etching of the silicon diaphragm, and misalignment between the top electrode and the silicon diaphragm. The purpose of this paper is to develop a dual top-electrode design to enhance the actuator displacement. In this design, the top electrode consists of two disconnected (thus independent) electrode areas, while a continuous bottom electrode serves as the ground. The two top electrodes are located in two regions with opposite curvature when the diaphragm deflects. When the two top electrodes are driven in an out-of-phase manner, the actuator displacement is enhanced. Finite element analyses and experimental measurements both confirm the feasibility of this design. When manufacturing defects are present, experimental results indicate that the actuator displacement can be optimized by adjusting the phase difference between the dual top electrodes.     

Recent progress of microactuators and micromotors

This paper gives a concise review of IC-compatible micromachining technologies and various types of microactuators fabricated by such technologies. A system architecture oriented to micro systems is proposed. Promising fields of application are briefly overviewed.     

Model driven design and aspect weaving

A model is a simplified representation of an aspect of the world for a specific purpose. In complex systems, many aspects are to be handled, from architectural aspects to dynamic behavior, functionalities, user-interface, and extra-functional concerns (such as security, reliability, timeliness, etc.). For software systems, the design process can then be characterized as the weaving of all these aspects into a detailed design model. Model Driven Design aims at automating this weaving process, that is automatically deriving software systems from theirs models. This paper explores the relationship between modeling and aspect weaving. It points out some of the challenges related to such automatic model weaving, illustrating them with the example of a weaving process for behavioral models represented as scenarios. This work has been partially supported by the AOSD-Europe Network of Excellence.

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语用网驱动的上下文感知系统设计

针对传统的语义网本体和上下文感知系统不适合处理现实世界中动态知识这一问题,借鉴了语用网在表达动态知识方面的优势,提出了语用网驱动的上下文感知系统,设计了语用网驱动的上下文感知系统框架。该系统采用了一种高效、新颖的上下文获取技术,可以更加准确地捕获用户的真实意图,并在此基础上通过推理得到具有决策能力的高层上下文。最后通过基于智能体的上下文感知服务发现方法,实现“以用户为中心”的个性化推荐服务。     

Optimal design of arch-networks

Optimality criteria for minimum volume design are derived for a class of arch-networks comprising of pin-supported arches contained in vertical planes. The supports lie in a horizontal plane and the loads are applied vertically. It is assumed that the arches transmit loads by axial compression and the interaction among arches at intersections is by vertical reactions. It is shown that in the optimal arch-network, the centroids of all arches lie on a single surface and each individual arch is of an optimal form. An iterative numerical procedure to obtain the optimal solution for a given layout plan of arches and the loading on it is presented. Two examples are provided for the purpose of illustration.     

直接数字频率合成器DDS的优化设计

在深入理解DDS基本原理的基础上,采用多级流水线控制技术对DDS的VHDL语言实现进行了优化,并进行了异步接口的同步化设计,给出了DDS系统的时序仿真结果及其在FPGA中的资源占有率。     

Optimal cutting design and analysis for fault-tolerant scheme of redundant memories

Fault-tolerant design for memory production is beginning to play an important role in increasing the yield rate of manufacturing. To improve the reliability of memory manufacturing, there are many methods that have been proposed. One of the most used technologies is replacing the faulty cells with spare memory interleaved in the memory. Nowadays, laser-cutting technology improves the yield of memories because of the enhancement of the use of spare lines. However, the issue of choosing a cutting location significantly affects the utilisation of spare lines. A bad cutting location can even render it useless. To use spare lines more efficiently, this article proposes two algorithms. The first one is designed to seek out a good cutting location. It corrects some defects of previous algorithms and provides a better approach to finding cutting candidates. In addition, because most heuristic solution-finding algorithms do not work properly under the condition of cutting memory, the second algorithm, called modification of most-repair is proposed to help make the decision as to whether or not a solution exists for the faulty pattern. We can find an optimal solution by combing these two algorithms. The experimental results show that our proposed algorithms increase the reparable percentage of a 1024-by-1024 memory from 55 to 100% and also improve both the reliability of memory manufacturing and the flexibility of spare lines.     

模式驱动的系统安全性设计的验证

随着万维网和移动计算技术的广泛应用,系统安全性得到了越来越多的关注,使用安全模式对系统安全解决方案进行设计并验证是提升系统安全性的一种有效途径。现有方法根据系统安全需求选择适用的安全模式,在此基础上将模式组合为系统的安全解决方案,并通过模型检测方法验证其安全性。但是,这些方法往往将方案看作整体进行验证,忽略了内部安全模式的组合细节,难以在包含大量模式的复杂系统中定位缺陷。提出一种模式驱动的系统安全性设计的验证方法,首先使用代数规约语言SOFIA描述安全模式及其组合,以构建系统安全解决方案的形式化模型;然后将SOFIA规约转换为Alloy规约后,使用模型检测工具验证模式组合的正确性和系统的安全性。案例研究表明,该方法能够有效地验证系统安全解决方案的正确性。     

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.     

单超声电机驱动两足行走机器人的设计分析研究

鉴于超声电机低速大扭矩的优点,采用了单超声电机来驱动两足行走机器人,选用PRO/E对机构进行了结构设计,运用ADAMS对模型进行了仿真和运动学、动力学分析,对机器人的关键尺寸进行了优化设计。研究证明:该机构合理可行,为今后物理样机的制造提供了重要依据。