陶瓷致动器及其应用

本文介绍压电和电致伸缩陶瓷致动器用的材料,致动器的结构形式与特点,部分新应用以及致动器今后的发展趋势。     

分割电极片状压电致动器—（二）位移特性及狭缝宽度对其影响的实？…

研究了悬臂梁式分割电极片状压电致动器的位移特性，理论分析表明，分割电极缝宽度会减小致动器自由端的位移输出，但光缝宽度小于致动器电极宽度的１０％时，可忽略狭缝宽度的影响。致动器端部位称的结果大于理论计算值。与现有磁头悬浮臂尺寸相近的致动器在，２０Ｖ－５０Ｖ的电压驱动下均可获得１μｍ－２μｍ的致动位移。对９８５０道／厘米的密度磁盘，该位移能覆盖至少一个磁道宽度，满足磁头定位两级间伺服系统对第二级致动器     

微系统工程中的新型致动器——意义，示例与再发展的可能性

现代致动器对于德国工业中出口产品的行业至关重要，因为它通过其竞争能力发挥决定性作用。特别是对于配有压电、磁致伸缩和电致伸缩固体变换器的新型致动器，对于具有形状记忆合金、电磁流变和电致伸缩流变液体的致动器以及电化学致动器，微型致动器和电磁小型驱动机构，存在明显上升的趋势。     

磁性LIGA微致动器

在许多微系统工程的研究工作中,预测微致动器有着巨大的应用潜力。因为在不断增多的微型化中有了适当的标度,又因为有可能在一块基板上相当简单地并行加工,所以,静电驱动原理得到多方的重视。与之不同磁性致动器的制造要求三维结构:一个碱性材料制作的铁磁心,它被线圈所环绕。随着微技术加工方法的进步,这一问题最近得到解决。     

分割电极片状压电致动器——(二)位移特性及狭缝宽度对其影响的实验研究

研究了悬臂梁式分割电极片状压电致动器的位移特性。理论分析表明，分割电极狭缝宽度会减小致动器自由端的位移输出，但当狭缝宽度小于致动器电极宽度的１０％时，可忽略狭缝宽度的影响。致动器端部位移的测试结果大于理论计算值。与现有磁头悬浮臂尺寸相近的致动器，在２０Ｖ～５０Ｖ的电压驱动下均可获得１μｍ～２μｍ的致动位移。对９８５０道／厘米的密度磁盘，该位移能覆盖至少一个磁道宽度，满足磁头定位两级伺服系统对第二级致动器位移的基本要求。     

大驱动力高刚度纳米致动新原理研究

提出了一种将高位移分辨率的压电陶瓷致动器与大驱动力的电磁致动器进行有机结合，实行优势互补的新方法。基于新原理研制的实验样机获得了较好的技术性能指标，即驱动力300N，刚度95N／μm；分辨率1nm；最大位移4μm。研究工作为大驱动力高刚度纳米致动开辟了一条新的途径。     

压电式合成射流致动器的设计与实验研究

采用两种不同的压电陶瓷片制作了压电振子,基于压电振子设计了不同喷口形式和压电振子布局形式的合成射流致动器.实验中利用热线风速仪对致动器喷口中心的速度进行了测量.结果表明,所设计的合成射流致动器喷口峰值速度达22.55 m/s,致动器典型布局时方形缝倾斜角对喷口峰值速度影响较大,90°法向射流比45°倾斜射流能获得更大的喷口动能,射流法向喷出时致动器典型布局比侧面布局能获得更多的喷口动能.     

V型电致热微驱动器的力学特性分析

运用能量法推导并建立了一种V型悬臂粱电热微致动器的力学模型。利用该力学模型得到了致动器的力学特性 ,并且与相关的实验结果进行了对比。由理论分析和实验对比发现 ,用于制造该电热微致动器的多晶硅材料在微米级尺度下的热膨胀系数与温度之间不再遵循宏观状态下的线性函数关系     

V型电致热微驱动器的力学特性分析

运用能量法推导并建立了一种V型悬臂粱电热微致动器的力学模型.利用该力学模型得到了致动器的力学特性,并且与相关的实验结果进行了对比.由理论分析和实验对比发现,用于制造该电热微致动器的多晶硅材料在微米级尺度下的热膨胀系数与温度之间不再遵循宏观状态下的线性函数关系.     

基于MEMS工艺的电热致动器研究进展

基于MEMS工艺的电热致动器具有与集成电路兼容的驱动电压、大的致动位移和致动力,比静电致动器、压电致动器和磁致动器有更大的优势,是现阶段致动方式的研究热点.高精度、高可靠度、可控和稳定性好的电热致动器是未来研究的新方向.针对MEMS微加工工艺制作的固体材料电热致动器,综述了电热致动器的结构形式、典型应用、模型建立以及测试方法的研究现状和主要研究成果.对电热致动器的结构设计、建模分析和测试技术方面的关键技术和存在的主要问题进行了分析和展望,以期为基于MEMS工艺的电热致动器的设计、分析和测试提供借鉴和参考.     

负载刚度对电热微执行器输出性能的影响分析

针对微机电系统中电热微执行器和位移放大机构都具有柔性的事实,从理论上分析了作为负载系统的柔性位移放大机构对微执行器输出位移的影响,并用有限元方法对二者的工作性能进行了仿真.结果表明,电热微执行器外接负载的刚度和执行器本身刚度的比值是影响整个组合器件性能的重要因素.最后用深层反应离子刻蚀技术(DRIE)在硅隔离衬底(SOI)上加工了电热微执行器和柔性位移放大机构,并对其进行了测试,测试结果与有限元分析结果符合得很好.     

Dynamic characteristics of micro-optothermal expansion and optothermal microactuators

The dynamic characteristics of micro-optothermal (OT) expansion and novel OT microactuators are theoretically analysed using a heat transient model and finite element modelling thermal simulation. Three different-shaped microactuators are machined by an excimer laser micromachining system using a single layer material; first with a single OT expansion arm; second with a bi-direction microactuator (BDMA); and third with a bi-direction microswitch (BDMS). A red laser diode (650 nm) with a maximum power output of 30 mW and an adjustable frequency of 0?20 Hz is used as an irradiation light source. The experimental results show that the maximum response frequency of the OT microactuators can be at least 15 Hz, and the deflections of the BDMA (about 13 μm at 10 mW, 2 Hz) and the BDMS (about 10 μm at 8 mW, 2 Hz) are significantly magnified compared with the OT expansion (1.32 μm at 10 mW, 2 Hz) of the single arm, proving the feasibility of the enlarged bi-direction deflection/vibration of the microactuators. The expansion and deflection amplitude of the microactuators decrease as the laser frequency increases, and the experimental data and curves greatly agree with the theoretical predictions. The new method of OT microactuators can be widely applied in the fields where simple structure, easy fabrication, large displacement and wireless controlling are required.     

微执行器的研究与展望

在微机电系统中,微执行器是核心部件。为了优化设计微执行器,通过对比近年来各种微执行器的研究和发展,系统地总结了线性位移微执行器所采用的驱动原理、驱动方式和应用以及存在的优缺点等。针对热执行器,提出了个人的一些见解。     

微驱动器的原理与应用

为了优化设计微驱动器,笔者通过对比近年来各种微驱动器的研究和发展,系统地概括总结了微驱动器所采用的主要的驱动原理、驱动方式和加工技术及其存在的优缺点等。并在此基础上,首次将微驱动器按功能进行了分类。     

Application of polyimide to bending-mode microactuators with Ni/Fe and Fe/Pt magnet

Out-of-plane polyimide (PI) electromagnetic microactuators with different geometries are designed, fabricated and tested. Fabrication of the electromagnetic microactuators consists of 10 μm thick Ni/Fe (80/20) permalloy deposition on PI diaphragm by electroplating process, electroplating of copper planar coil with 10 μm thick, bulk micromachining, and excimer laser selective ablation. They are fabricated by a novel concept to avoid the etching selectivity and residual stress problems during wafer etching. A simulation model is created by ANSYS software to analyze the microactuators. The external magnetic field intensity (H_ext) generated by the planar coil is simulated by this software. Besides, to provide bi-directional and large deflection angles of the microactuators, hard magnet Fe/Pt is deposited at low temperature of 300 °C by sputtering onto the PI diaphragm to produce a perpendicular magnetic anisotropic field. This magnetic field can enhance the interaction with H_ext to induce attractive and repulsive bi-directional force to provide a larger displacement. The results of the magnetic microactuators with and without hard magnetic are compared and discussed, respectively. The preliminary result reveals that the electromagnetic microactuators with hard magnet exhibit a greater deflection angle than that without one.     

Reversible and Rapid Laser Actuation of Liquid Crystalline Elastomer Micropillars with Inclusion of Gold Nanoparticles

It is highly desirable for liquid crystal elastomer (LCE) based microactuators to activate and actuate in a highly controlled fashion without perturbing the surrounding environment. To reach this goal, in this study, a novel experimental protocol is developed to successfully incorporate gold nanosphere (AuNS) and gold nanorod (AuNR) into polyacrylate based LCE elastomer to fabricate LCE/AuNR and LCE/AuNS micropillars or microactuators. The effect of gold nanoparticle inclusion has been studied by spectroscopy (UV–vis‐near‐infrared), microscopy (transmission electron microscopy), thermal analysis (differential scanning calorimetry and thermogravimetric analysis), and x‐ray scattering (wide‐angle x‐ray scattering and small‐angle x‐ray scattering). Finite element analysis is performed to examine the feasibility of utilizing the photothermal effect of AuNR/AuNS to enable photothermal actuation of LCE/AuNR and LCE/AuNS micropillars. The comparative experimental studies on the thermal and photothermal actuation behavior of the LCE, LCE/AuNS, and LCE/AuNR micropillar suggested that AuNR is an excellent candidate for developing high‐performance LCE actuators with photothermal actuation capability. With inclusion of less than 1 wt% of AuNR, the very high maximum actuation strain (30%) and rapid response (a few seconds) have been achieved in LCE/AuNR micropillar actuators under 635 nm laser irradiation.     

Versatile Microfluidic Platforms Enabled by Novel Magnetorheological Elastomer Microactuators

Microfluidic systems enable rapid diagnosis of diseases, biological analysis, drug screening, and high‐precision materials synthesis. In spite of these remarkable abilities, conventional microfluidic systems are microfabricated monolithically on a single platform and their operations rely on bulky expensive external equipment. This restricts their applications outside of research laboratories and prevents development and assembly of truly versatile and complex systems. Here, novel magnetorheological elastomer (MRE) microactuators are presented including pumps and mixers using an innovative actuation mechanism without the need of delicate elements such as thin membranes. Modularized elements are realized using such actuators, which can be easily integrated and actuated using a single self‐contained driving unit to create a modular, miniaturized, and robust platform. The performance of the microactuators is investigated via a series of experiments and a proof‐of‐concept modular system is developed to demonstrate the viability of the platform for self‐contained applications. The presented MRE microactuators are small size, simple, and efficient, offering a great potential to significantly advance the current research on complex microfluidic systems.     

Electrostatic microactuators for precise positioning of neural microelectrodes

Microelectrode arrays used for monitoring single and multineuronal action potentials often fail to record from the same population of neurons over a period of time likely due to micromotion of neurons away from the microelectrode, gliosis around the recording site and also brain movement due to behavior. We report here novel electrostatic microactuated microelectrodes that will enable precise repositioning of the microelectrodes within the brain tissue. Electrostatic comb-drive microactuators and associated microelectrodes are fabricated using the SUMMiT V (Sandia's Ultraplanar Multilevel MEMS Technology) process, a five-layer polysilicon micromachining technology of the Sandia National labs, NM. The microfabricated microactuators enable precise bidirectional positioning of the microelectrodes in the brain with accuracy in the order of 1 microm. The microactuators allow for a linear translation of the microelectrodes of up to 5 mm in either direction making it suitable for positioning microelectrodes in deep structures of a rodent brain. The overall translation was reduced to approximately 2 mm after insulation of the microelectrodes with epoxy for monitoring multiunit activity. The microactuators are capable of driving the microelectrodes in the brain tissue with forces in the order of several micro-Newtons. Single unit recordings were obtained from the somatosensory cortex of adult rats in acute experiments demonstrating the feasibility of this technology. Further optimization of the insulation, packaging and interconnect issues will be necessary before this technology can be validated in long-term experiments.     

A magnetically driven linear microactuator with new driving method

Electromagnetically driven microactuators are of interest because they have the potential to generate large deflections. Thus, we have been studying magnetically driven microactuators. This time, a magnetically driven linear microactuator has been newly developed by using microfabrication techniques. The microactuator is composed of a mobile microplatform (mover) with some permanent magnets (PMs) and a stator with a large number of planar coils. In this paper, two types of microplatforms are fabricated and compared with each other. Furthermore, static and dynamic characteristics of the magnetically driven linear microactuator are discussed.     

薄膜型超磁致伸缩微执行器的研究现状

超磁致伸缩薄膜是一种性能优良的新型微驱动元件,文章介绍了超磁致伸缩薄膜驱动的原理,综述了薄膜型超磁致伸缩微执行器的开发和最新研究成果,重点介绍了薄膜型超磁致伸缩微执行器在微流体控制系统、线性超声微马达及微小型行走机械中的应用,并对超磁致伸缩薄膜的微执行器中的应用进行了展望。