Fabrication of distributed electrostatic micro actuator (DEMA)

A distributed electrostatic micro actuator (DEMA) has been proposed. The actuator has many small driving units which consist of two wave-like insulated electrodes. Both ends of insulated electrodes are connected to each other, and the driving unit has narrow gap for deformation caused by electrostatic forces. The driving units have large area of electrodes and are distributed in series and in parallel. So, a strong electrostatic force can be obtained, and the deformation and the generated force of the actuator would be large. Macro model of the DEMA was fabricated with polyimide films, and the deformation of the actuator was measured. When the applied voltage was 200 V, the deformation ratio was 36%. A micro actuator was fabricated by use of photolithography and electroplating. The displacement of 28 μm was observed when applied voltage was 160 V. Experimental results of the micro actuator were compared with the results simulated by finite element method (FEM) analysis     

The design and simulation of a novel out-of-plane micro electrostatic actuator

This paper presents a mechanism of developing a novel out-of-plane micro electrostatic actuator capable of causing large out-of-plane deflection. The performance of the actuator is evaluated and simulated by MEMCAD software. Initial analysis results indicated that the usage of both the novel U-shape suspension beam and the electrostatic actuation mechanism permit large rotations motion with respect to the increment of the numbers of electrodes. Moreover, stable rotational motion can be achieved by varying the dimensions of electrode and gap spacing. This design advantage brings the possibility of developing other three-dimensional (3D) structures for on and/or out-of-wafer applications such as optical switch or display.     

毫米级静电微扑翼驱动器的结构设计、工艺与测试

针对仿昆虫扑翼飞行器核心动力装置——微驱动器的结构特点和研究难点,设计了一种基于静电驱动原理的毫米(mm)级微扑翼驱动器,并针对各个部件研究了整套加工工艺与测试方法.运动优化与升力测试结果表明:微扑翼驱动器(翼展9 mm,重量3 mg)以91 Hz的频率实现了±40°的拍动和±25°的扭转运动,输出1.5 mg的升力,升重较以往静电微扑翼驱动器有大幅提升.研究成果为实现仿昆虫微型飞行器的自主飞行提供了新的方向,并奠定了理论与试验基础.     

A CAE system for micromachines: Its application to electrostatic micro wobble actuator

This paper describes a new computer-aided engineering (CAE) system for micromachines 10⁻⁶−10⁻³ m in size. An automatic finite-element (FE) mesh-generation technique, which is based on the fuzzy knowledge processing and computational geometry techniques, is incorporated into the system, together with a commercial FE analysis code, MARC, and a commercial solid modeler, DESIGNBASE. The system allows a geometry model of interest to be automatically converted to different FE models, depending on the physical phenomena of the micromachines to be analyzed, i.e., electrostatic analysis, stress analysis, modal analysis, and so on. The FE models are then automatically analyzed using the FE analysis code. Out of the whole process of analysis, the definition of a geometry model, the designation of local node patterns and the assignment of material properties and boundary conditions to the geometry model are the only interactive processes to be done by the user. The interactive operations can be processed in a few minutes. The other processes, which are time consuming and labour intensive in conventional CAE systems, are fully automatically performed in a popular engineering workstation environment. With the aid of multilayer neural networks, the present system also allows us to obtain automatically a design window in which a number of satisfactory design solutions exist in a multi-dimensional design parameter space, considering coupled multiple phenomena such as static and dynamic deformation, thermal conduction, electrostatics, and so on. This CAE system is successfully applied to evaluate an electrostatic micro wobble actuator. As a typical CAE evaluation, we identify the quantitative conditions for operating the micro wobble actuator, considering both structural and electrostatic phenomena.     

Rotational micro actuator for microsurgery

In this paper an innovative hydrostatic micro actuator system for controlling the rotational degree of freedom of microsurgery instruments is presented. From the possible hydrostatic motor designs, an annular gear motor in orbit configuration has been chosen based on its suitability for micro manufacturing. The innovative actuator design includes a rotor-integrated control mechanism for connecting the actuator’s individual positive-displacement chambers. First a macro-model of the new actuator was fabricated and tested. The obtained test results already confirm the functionality and show the actuator’s exciting potential. The important design parameters were identified and a mathematical model was developed and is presented in this paper. Thereby optimized design parameters enable a further miniaturization and the use within minimal invasive surgery tools. A potential application of this novel device is discussed in the context of endovascular and interventional resection treatment. Combined with a shape memory alloy actuator a tool for the resection of calcified aortic valves was developed. Because of its small size it is possible to integrate it into a trocar channel.     

一种非硅微加工技术制作的电热微驱动器

介绍了一种由非硅微加工技术制作的电热微驱动器。基于双金属效应,采用聚合物SU-8胶和金属镍作为功能材料和结构材料,铜为牺牲层材料制作电热微驱动器。利用ANSYS有限元分析软件进行仿真,模拟驱动位移随加热时间的变化关系,并由此得出驱动力的大小,比较结果后确定结构参数。再通过光刻、掩模电镀和牺牲层刻蚀等工艺,加工制作出了电热微驱动器样品,并对样品进行了观测和分析。     

Design and fabrication of novel micro electromagnetic actuator

This study designs, fabricates, and characterizes a novel micro electromagnetic actuator comprising a PDMS diaphragm, a polyimide-coated copper micro coil, and a permanent magnet. When an electrical current is passed through the micro coil, a magnetic force is induced between the coil and the magnet which causes the diaphragm to deflect, thereby creating an actuation effect. The experimental results demonstrate that the diaphragm deflection can be accurately controlled by regulating the current passed through the micro coil. It is shown that the maximum diaphragm deflection within elastic limits is 150 μm; obtained by passing a current of 0.6 A through a micro coil with a line width of 100 μm. The micro actuator proposed in this study is easily fabricated and is readily integrated with existing bio-medical chips due to its planar structure.     

A high-stroke, high-pressure electrostatic actuator for valve applications

This paper presents a novel large-stroke electrostatic valve actuator for high-pressure applications. The combination of pressure balancing and flexible electrode structures ensures large flow gaps at a low actuation voltage. A simulation tool was built to evaluate the design parameters. Design specific, as well as general optimisations are performed. The model shows a 5.6 times (theoretical) performance improvement compared to earlier designs. A micromachined test structure was fabricated and evaluated. Measurement results are presented and discussed.     

微小型静电泵的球塞型阀门设计

对微型静电泵的阀门设计进行理论分析和计算.以球塞型阀门为重点,讨论了入水阀和出水阀的区别,给出了阀门套在开启状态下,流量与球塞上下面间的压力差、阀门套面积之间的关系式,以及不同内径泵的阀门套最小半径与流量和压力差的关系式,由阀门套半径、流速计算了雷诺系数并核对了所选流量系数;研究了球塞施加于蛛网的作用力,进行了蛛网的强度核验,并讨论了网丝直径的选用等.     

An earthworm-like micro robot using shape memory alloy actuator

A novel bio-mimetic micro robot with wireless control and wireless power supply using shape memory alloy (SMA) actuator is developed. There have been many kinds of mobile micro robot using the micro actuators such as ionic polymer metal composite (IPMC), micro motors and piezo actuators. These actuators generally require electric cable for power supply, which might highly influence the mobility of the micro robot. Therefore, a perfect wireless micro robot comprising telemetry and batteries is realized using only one SMA spring actuator and one silicone bellow. The SMA actuator and bellow play a role in contraction and extension of an earthworm muscle respectively. Based on theoretical analysis, specifications of a SMA actuator and a bellow are properly selected. For temporal stopping, setae of earthworm mimicked claws are employed. On the issue of control, the proposed robot is controlled according to On/Off signal via wireless communication. The operation is customized through tuning of on-/off-time of an actuator and using different type batteries such as a lithium, silver oxide and alkaline battery. After the design and experiment, we find out that the earthworm-like micro robot without wired power supply and control can move freely without limitation of working space and be fabricated easily.     

A novel self-aligned electrostatic vertical actuator using plastic deformation technology

A novel method is presented to fabricate a self-aligned electrostatic vertical actuator using plastic deformation technology. The model of the vertical actuator is proposed and simulated using finite element analysis method. The fixed combs and movable combs, and spring beams are patterned using one mask and fabricated by DRIE technology simultaneously. The fixed combs and movable combs have staggered distance of 21.8 μm in the vertical direction on the condition of self-alignment using plastic deformation technology. The electrostatic vertical actuator has achieved large vertical drive displacement at low voltage. The measurement results show that the maximum drive displacement runs up to 17 μm at 17 V voltage between the fixed combs and movable combs. Experimental results verify the usefulness of the guidelines obtained from simulation and calculation.     

High aspect ratio electrostatic micro actuators using LIGA process

High-power electrostatic microactuators using LIGA process have been fabricated. Comb drive type actuators and a wobble motor were designed and fabricated. A basic structure of the microactuators was composed of movable and fixed electrodes of Ni, a sacrificial layer of SiO₂ and a Si substrate, and carried out by one mask process. As design rules, a minimum resist width of 2 μm, resist height of 120 μm, maximum width of movable parts of 10 μm, minimum width of fixed parts of 40 μm and driving voltage of about 100 V, were decided. A 120 μm-thick PMMA resist was formed on a Si substrate by a casting method. The PMMA was exposed using a compact SR source “AURORA”, using an X-ray mask with 7 μm-thick Au absorber on a 2 μm-thick poly-Si membrane. The exposed PMMA was developed by a developer. Ni microstructures with 100 μm-height, 2 μm-minimum width, 2 μm-minimum gap, and then maximum aspect ratio of 50, were made by electroforming. Ni microstructures used for movable electrodes were separated from the substrate by lateral etching of SiO₂. After lateral etching of SiO₂, Au wires were bonded to electrodes. Actuation of the comb drive type actuator and rotation of the wobble motor were confirmed. The applied voltage to the comb drive actuator and the wobble motor were 65 and 125 V.     

微电热驱动器中偏置层的分析

设计了一种电热微驱动器,根据几何关系、泰勒公式和材料力学求得偏置层结构末端的位移公式,并验证了采用镍作为偏置层材料的合理性.通过Coventorware软件中的有限元模块进行仿真分析,得出施加驱动电压为5 V,响应时间为5 ms,驱动器的初始温度为300 K时,得出偏置层宽度W1与驱动器位移d的曲线关系.通过验证驱动器的最大应力为235 MPa,小于镍的许用应力,确定驱动器在W1=20μm可以进行可靠的工作.分析偏置层厚度和宽度的加工误差对驱动器末端位移的影响,可得在对偏置层进行加工时要严格控制偏置层厚度H1的加工误差.     

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.

     

Research on electrostatic actuator polymer thin-film for controlling light scattering phenomena

The purpose of this paper is based on micro fabrication technology, while integrating planar waveguide technology and the scattering phenomenon generated by electro-statically actuator thin film, to develop a 2-dimensional display technology capable of being cleared and re-displayed. For thin film displacement, the restoration of inward elasticity needs to be overcome. During thin film displacement, attraction due to suction occurs when coming into contact with light waveguide; electrostatic force and elastic force are restored and mutually balanced, causing display to light up. On the other hand, when input voltage is released, electrostatic force stops and thin film is restored to original position, causing display to darken. The design structure uses SU-8 as supporting posts, and PDMS as the electrostatic thin film suspended above the glass substrate (light waveguide). The experimental results show that a waveguide with an electrode length of 250 μm (sub-pixel length), a micro-post height of 27 μm, and a PDMS film thickness of 16 μm requires an actuator voltage of 314 V; and a micro-post height of 27 μm, and a PDMS film thickness of 8 μm requires an actuator voltage of 189 V. Thus, with an arrayed micro-electrode design, electronic paper and panels with large color display area could be manufactured.     

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.     

静电刚度式谐振微加速度计设计

运用梁的横向振动特性分析了梁振动频率与平行板电容形成的静电刚度的关系,并以此设计了静电刚度式谐振微加速度计。在加速度作用下,检测质量产生的惯性力使电容器极板发生位移来改变电容结构的间隙大小,从而使谐振频率发生变化,通过检测频率变化量来测量输入加速度的大小。根据加速度计的工作原理说明检测过程中梁的机械刚度保持不变,只与产生静电刚度的电容间隙变化相关,减小了检测信号对机械误差与残余应力的依赖性。运用加工参数进行理论计算得出加速度计的灵敏度为21．17Hz／gn,在CoventorWare2005中进行仿真表明：加速度计的固有频率为23．94kHz,灵敏度约为20Hz／gn,与理论设计值相近。     

微位移系统中压电陶瓷驱动器迟滞建模

针对超精密微位移系统中压电陶瓷驱动器的迟滞非线性问题,提出了一种基于遗传反向传播(BP)神经网络的压电陶瓷迟滞非线性建模方法.通过电涡流位移传感器获取压电陶瓷驱动器不同电压值下所对应的位移值;利用六次多项式拟合获得迟滞的数学模型,从而建立基于遗传BP神经网络的迟滞,模型.实验结果显示:该迟滞模型在神经网络测试下的最大误差为0.082 1 μm,平均绝对误差为0.0158 μm.表明,所建的迟滞模型能够较精确地反映出压电陶瓷驱动器的迟滞特性,同时为微位移控制系统设计提供了一定的理论基础.     

Design and manufacturing of mobile micro manipulation system with a compliant piezoelectric actuator based micro gripper

This paper presents a new design of mobile micro manipulation system for robotic micro assembly where a compliant piezoelectric actuator based micro gripper is designed for handling the miniature parts and compensation of misalignment during peg-in-hole assembly is done because piezoelectric actuator has capability of producing the displacement in micron range and generates high force instantaneously. This adjusts the misalignment of peg during robotic micro assembly. The throughput/speed of mobile micro manipulation system is found for picking and placing the peg from one hole to next hole position. An analysis of piezoelectric actuator based micro gripper has been carried out where voltage is controlled through a proportional-derivative (PD) controller. By developing a prototype, it is demonstrated that compliant piezoelectric actuator based micro gripper is capable of handling the peg-in-hole assembly task in a mobile micro manipulation system.