NEW ROD-SHAPED ULTRASONIC MICROMOTOR AND ITS DRIVING PRINCIPLE

A new rod-shaped traveling wave ultrasonic micromotor is developed. In the micromotor, five pieces of piezoelectric ceramics clamped by two metal cylinders are used as its stator. The driving principle of the rodshaped ultrasonic motor is simulated. The stator structure and the position to lay these piezoelectric ceramics are calculated to improve the electro mechanical conversion efficiency. A flexible rotor is designed to reduce the radial slip between the stator and the rotor, and to improve the motor efficiency. The prototype motor and its micror driver are tested. The motor is 9 mm in out-diameter, 15 mm in length and 3.2 g in weight. When the motor operates with the first bending frequency （72 kHz） of the stator, its maximal rotational speed and the torque reach 520 r/rain and 4.5 mN · m. Results show that the motor has good stability. The speed fluctuation is controlled within 3% by the frequency automatic tracking technique.

Modeling and Analysis of a Micromotor with an Electrostatically Levitated Rotor

The modeling and evaluation of a prototype rotary micromotor where the annular rotor is supported electrostatically in five degrees of freedom is presented in order to study the behavior of this levitated micromotor and further optimize the device geometry. The analytical torque model is obtained based on the principle of a planar variable-capacitance electrostatic motor while the viscous damping caused by air film between the stator and rotor is derived using laminar Couette flow model. Simulation results of the closed-loop drive motor, based on the developed dynamic model after eliminating mechanical friction torque via electrostatic suspension, are presented. The effects of the high-voltage drive, required for rotation of the rotor, on overload capacity and suspension stiffness of the electrostatic bearing system are also analytically evaluated in an effort to determine allowable drive voltage and attainable rotor speed in operation. The analytical results show that maximum speed of the micromotor is limited mainly by viscous drag torque and stiffness of the bearing system. Therefore, it is expected to operate the device in vacuum so as to increase the rotor speed significantly, especially for those electrostatically levitated micromotors to be used as an angular rate micro-gyroscope.

Dye-Enhanced Self-Electrophoretic Propulsion of Light-Driven TiO_2–Au Janus Micromotors

Light-driven synthetic micro-/nanomotors have attracted considerable attention in recent years due to their unique performances and potential applications. We herein demonstrate the dye-enhanced self-electrophoretic propulsion of light-driven Ti O_2–Au Janus micromotors in aqueous dye solutions. Compared to the velocities of these micromotors in pure water, 1.7, 1.5, and 1.4 times accelerated motions were observed for them in aqueous solutions of methyl blue(10-5g L^(-1)), cresol red(10^(-4)g L^(-1)),and methyl orange(10^(-4)g L^(-1)), respectively. We determined that the micromotor speed changes depending on thetype of dyes, due to variations in their photodegradation rates. In addition, following the deposition of a paramagnetic Ni layer between the Au and Ti O_2 layers, the micromotor can be precisely navigated under an external magnetic field. Such magnetic micromotors not only facilitate the recycling of micromotors, but also allow reusability in the context of dye detection and degradation.In general, such photocatalytic micro-/nanomotors provide considerable potential for the rapid detection and ‘‘on-thefly'' degradation of dye pollutants in aqueous environments.

Dual-Fuel-Driven Bactericidal Micromotor

In this paper, we report fabrication of the bimetallic Janus microsphere, a magnesium microsphere with a silver surface coating, through thermal evaporation technique. Because of the Janus structure, this micromotor can be propelled in two different directions by the surface silver or magnesium ‘engine' and hydrogen peroxide or water fuel. In addition, due to the bactericidal property of silver, this autonomous micromotor is capable of killing bacteria in solution. As compared to the static one, the micromotor is able to kill the bacteria at a much faster rate(about nine times of that of the static one),demonstrating the superiority of the motion one. We thus believe that the micromotor shown in the current study is potentially attractive for the environmental hygiene applications.

Recent progress on the design and fabrication of micromotors and their biomedical applications

The advancement in the micro-/nanofabrication techniques has greatly facilitated the development of micromotors.A variety of micromotors have been invented with powerful functions,which have attracted a broad range of interests from chemistry, physics,mechanics,biology and medicine.In this paper,we reviewed recent progress in micromotors and highlighted representative works.The mechanisms of micromotors by internal and external energy sources were described.We described general fabrication strategies of the popular micromotors (wire,tubular,helical and Janus)including bottom-up and top-down approaches.In the application section,we primarily focused on the biological applications,such as biological cargo delivery, biosensing and surgery.At last,we discussed the current challenges and provided future prospects.

Micromotor-derived composites for biomedicine delivery and other related purposes

Biocompatible designed micromotor has attracted more and more concerns in the field of biomedicine due to their self-propulsion and delivery abilities.Such micromotors,mostly consisting of alkali earth metals,hydrogels,or other motile biomaterials,can effectively transform chemical energy into mechanical or kinetic energy to achieve the expected delivery of cargos to the sites of action.Except for conveying power,the modifiable surface and inner cavity of micromotors guarantee that their potential as versatile delivery systems for therapeutic agents.Here,this review generalizes the propelling mechanisms,composites,and shapes of micromotors.Besides,the application of micromotor-derived composites for biomedicine delivery and other versatile purposes are also discussed.

Optimization of the Drag Forces of Shell Janus Micromotor:A Study Based on Hydrodynamical Analysis and Numerical Simulation

Micromotors are widely used in cell operation,drug delivery and environmental decontamination due to their small size,low energy consumption and large propelling power.Compared to traditional Janus micromotor,the shell Janusmicromotor has better motion performance.However,the structural optimization of itsmotion performance is still unclear.The main factor restricting the motion performance of shell Janus micromotors is the drag forces.In the current work,theoretical analysis and numerical simulation were applied to analyze the drag forces of shell Janus micromotors.This study aims to design the optimum structure of shell Janus micromotors with minimum drag forces and obtain the magnitude of drag forces considering both the internal and external fluids of the shell Janus micromotors.Moreover,the influence of the motor geometry and Reynolds number on the drag coefficient was analyzed using numerical simulations.The results provide guidance for the optimum flow velocity,opening diameter and shell thickness to achieve minimum drag force.

KEY TECHNOLOGY FOR PRACTICAL 1-mm-DIAMETER ELECTROMAGNETIC MICROMOTOR

A 1 mm diameter electromagnetic micromotor was developed as a crux component for MEMS application. The motor has a novel layer structure with a 1 mm diameter rotor in the middle of two stators with the same size. The stator uses multiple layers, slotless and concentrated planar winding. The rotor adopts multipolar permanent magnet with high performance. Ruby bearing is used to prolong operating lifetime of the micromotor. The stator winding, consisting of 6 layer coils, 42 turns, and 9 pairs, is fabricated with microprocessing techniques. The micromotor has long operation lifetime, its running speed is stable and controllable, and rotational direction can be easily reversed. Maximum achieved rotational speed of 18000 r/min with maximum output torque of 1.5 μ N·m has been obtained. This paper presented the key technology for developing this kind of micromotor including the design of structure, magnetic circuit, heat problem, friction improvement, microprocessing techniques, and so on.

钯-铂基双面神微马达的运动行为研究

为了研究双金属基微马达的驱动机制,利用磁控溅射技术制备聚苯乙烯(PS)@钯Pd-铂Pt双面神微马达,采用扫描电子显微镜和光学显微镜表征该微马达的结构、形貌和运动行为,并通过对比实验和数值模拟推测验证该微马达驱动机制。结果表明:PS@Pd-Pt微马达由Pd、 Pt双金属层在PS微球表面半包覆形成,具有双面神结构,直径约为2μm;PS@Pd-Pt双面神微马达在过氧化氢H_(2)O_(2)溶液中一开始朝着PS侧正向运动,随后速度逐渐减小,然后发生自发转向朝着Pd-Pt双金属侧反向运动;该微马达正向运动的驱动机制为Pt催化H_(2)O_(2)产生的非离子型自扩散泳以及Pt层厚度不均匀导致的自电泳共同作用,反向运动的机制为外部Pt与内部Pd双金属形成的自电泳作用。

基于高定向热解石墨(HOPG)的电刷针表面修饰技术

目的旨在应对有刷微电机中的电刷与换向器间的磨损问题,尤其是由电弧侵蚀引发的性能和寿命下降。方法通过在电刷与换向器的接触界面引入HOPG材料,探索其在抑制电弧侵蚀和改善接触表面磨损方面的效果。重点测试了电刷针在HOPG表面修饰下的磨损行为与失效机制,并与传统材料进行对比。通过载流摩擦磨损试验,模拟实际工况,研究了在引入HOPG前后,换向器和电刷针之间不同的磨损机制,尤其是电弧侵蚀与机械磨损之间的转变。结果采用HOPG作为表面修饰材料显著减少了电弧侵蚀,使电刷针的失效机制从严重的电弧侵蚀转变为机械磨损,显著改善了电机运行中的磨损状况。HOPG表面表现出了优异的润滑性能,抑制了电刷针与换向器之间的电弧侵蚀现象。相比于传统材料,HOPG修饰的表面在长时间运行后表现出更低的磨损程度,同时保持了良好的电接触性能。结论基于HOPG的表面修饰技术,为解决有刷微电机中电弧侵蚀引发的磨损问题提供了新的解决方案。通过有效抑制电弧侵蚀,改善了电刷与换向器之间的磨损机制,使电刷针的失效模式从电弧侵蚀转变为机械磨损,具备提高有刷微电机工作寿命的潜力。

高性能AgPd50/806电刷材料工艺研究

针对高性能Ag Pd50/806电刷材料的工艺进行了深入研究,旨在提高其在微电机中的工作稳定性和使用寿命。研究首先分析了AgPd50/806合金的微观结构和力学性能,通过调控材料配方和增加固溶时效处理来改善工艺,实现了合金内部结构的均匀性和致密性,显著提升了材料的硬度、回弹位移量(1400μm)及抗拉强度(735 N/mm^(2))和延伸率(4.75%)。测试结果表明,优化后的Ag Pd50/806电刷材料在高温、高湿和振动等恶劣条件下表现出优异的可靠性和耐磨性,工作寿命长达290 h以上,其电接触性能和机械性能优于大多用传统工艺和其他合金制备的电刷材料。

某智能锁具电机停转原因分析及解决措施

某智能锁具在存放和使用过程中发生直流有刷电机停转现象。利用万用表、体视显微镜、扫描电子显微镜、能谱仪、红外光谱仪等手段对停转电机的参数、污染物宏观微观形貌、污染物微区成分进行分析;对污染物来源进行排查;结果表明:产品中所用黑色塑料外壳中的磷系阻燃剂在高温高湿环境中通过水解和热氧老化挥发形成磷酸二氢铵,沉积在电刷和换向器上,导致电刷和换向器之间接触不良。进而无电流流向线圈,导致电机不转。并提出了相应的措施,为进一步提高电机使用可靠性提供有益依据。

电磁型平面微电机及其制作工艺

为得到一种尺寸小、输出力矩大、转速高的直流可调速微电机,提出了一种利用微机械加工工艺制作微电机的方法。定子和转子都做成平面结构,定子线圈采用了平面型、无槽式集中绕组;线圈之间采用了三相星形连接方式,采用了微机械LIGA工艺和硅微机械加工工艺;转子采用钕铁硼永磁材料,进行轴向充磁,成辐射状间隔分布。装配时转子分布于定子两侧,不但减小了电机尺寸,还有利于定子的散热。把装配完毕的微电机接通三相半控控制电路对其转速和力矩进行了测试,测试结果表明,电机运转平稳,输出力矩大。

一种微型柱体超声电机的研究

对压电陶瓷片的布局方式与力系数之间的关系进行了分析,证明了压电陶瓷片粘贴在金属弹性体一阶弯振的波谷位置时其激振效率是最高的。研制了一种新型定子结构的微型柱体超声电机。该电机直径5mm,长30mm,重量4.2g。当驱动电压峰峰值为200V,驱动频率为53kHz时,电机最大转速为350r/min,堵转力矩为2.5×10?3N?m。因为这种电机结构比较简单紧凑,便于实现进一步的微型化。所以又利用压电陶瓷管为激励元件,研制出直径2mm,长度7mm,重量为0.258g的微型柱体超声电机。在驱动电压峰峰值为60V,驱动频率75kHz时电机的转速为813r/min。文中详细介绍了这2个微型电机的工作原理、结构特点和设计方法。

一种用于微型工厂的毫米级全方位移动微机器人设计与分析

介绍了一种尺寸为9 mm×8 mm×8 mm的全方位移动微机器人.采用独特的双轮结构实现了转向时轮与地面的纯滚动.该微机器人由3个直径2 mm的电磁微马达驱动;其中2个用于直线驱动,另一个用于转向.动力学分析揭示了微马达驱动力矩与双轮结构尺寸及各种摩擦之间的关系.仿真计算及实验表明微机器人具有良好的负载能力,满足微型工厂中搬运工作的要求.

高分子PTC材料在微电机自保中的应用

本文研究了高分子ＰＴＣ材料的性能，并利用高分子ＰＴＣ材料将传统的微电机改造成了具有自保结构的新型微电机。实测数据与理论设计吻合较好。

毫米级全方位移动微型装配机器人设计、运动学分析与控制

介绍了一种用于微型工厂的毫米级移动微装配机器人,其具有独特的全方位运动结构.微机器人由4个直径3 mm的电磁微马达驱动,并装备有一对微型夹钳.通过分析运动学矩阵的秩,证明了微机器人的全方位特性,并建立了微夹钳的运动学方程.设计了基于计算机视觉的微机器人控制系统,给出了微机器人定位和驱动方法.实验证明了微机器人的负载能力、机动性以及控制系统的有效性.

压电微马达研究进展

利用网络和图书馆对国际上 1996年至今的压电微马达研究进展进行了调研。分别介绍了压电薄膜、陶瓷的行波、驻波类微马达的最新研究情况 ,同时也对一种具有与压电微马达特性相同的静电超声微马达的研究作了说明 。

轴向磁化永磁微电机磁场分析及设计方法研究

在轴向磁化永磁电机设计中,为研究尺寸效应对其性能的影响,采用有限元方法对这种双转子电机的磁场进行了仿真计算,得出了轴向磁化永磁电机转子的气隙磁密波形分布。分析了转子外形尺寸、充磁极数、磁体厚度和气隙长度对气隙磁密的影响,即随着气隙长度的增加,充磁极数多的其气隙磁密幅值的减小幅度大于充磁极数少的;随着磁体厚度的增加,气隙磁密为一上升曲线,当磁体厚度达到某一点时,气隙磁密幅值基本为一常数;减小转子直径时,随着磁体厚度的降低,平均半径处气隙磁密幅值的减小幅度越来越不明显,但为不使气隙磁密波形变形严重,永磁转子径向长度需至少大于1.5 mm。磁场分析结果可对该类电机微小型化过程中的设计起指导作用。对计算结果做了理论分析,并将计算结果和实验结果进行了比较,计算值和实测值基本一致。

卧式板型直线超声电机的微型化

基于L1B4板型直线超声电机,研制了一种外型尺寸为36mm×5mm×4mm的卧式板型微型直线超声电机。论述了电机的工作原理和运行机理,使用解析法和有限元法进行了微型化结构设计,分析了定子的振动模态,并实现了频率简并。通过模拟压电激励的动态频率响应,对比了样机的5片压电陶瓷布置方案和常用的两片压电陶瓷布置方案的共振位移响应曲线,证实了采用5片压电陶瓷布置方案增大了输出端点处产生的振动位移。样机特性测试实验表明,当激励信号电压为150Vpp,频率为62kHz时,电机最大速度为183.7mm/s,输出推力为50mN。预期该电机可以用于电机安置空间比较狭窄且需要一定动力的直线驱动场合。