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.

Chinese herb pollen derived micromotors as active oral drug delivery system for gastric ulcer treatment

Considerable efforts have been devoted to treating gastric ulcers.Attempts in this field tend to develop drug delivery systems with prolonged gastric retention time.Herein,we develop novel Chinese herb pollen-derived micromotors as active oral drug delivery system for treating gastric ulcer.Such Chinese herb pollen-derived micromotors are simply produced by asymmetrically sputtering Mg layer onto one side of pollen grains.When exposed to gastric juice,the Mg layer can react with the hydrogen ions,resulting in intensive generation of hydrogen bubbles to propel the micromotors.Benefiting from the autonomous motion and unique spiny structure,our micromotors can move actively in the stomach and adhere to the surrounding tissues.Besides,their special architecture endows the micromotors with salient capacity of drug loading and releasing.Based on these features,we have demonstrated that our Chinese herb pollen-derived micromotors could effective deliver berberine hydrochloride and show desirable curative effect on the gastric ulcer model of mice.Therefore,these Chinese herb pollen-derived micromotors are anticipated to serve as promising oral drug delivery carriers for clinical applications.

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。

Motion-based pH sensing using spindle-like micromotors

In this study, we report a spindle-like micromotor. This device, which is fabricated using a one-step electrospinning method, consists of biodegradable polycaprolactone and an anionic surfactant. Intriguingly, not only can the resulting micromotor move autonomously on the surface of water for a long period of time （-40 min） due to the Marangoni effect, but it also exhibits a pH sensing behavior due to variations in the surface tension caused by the release of surfactant under different pH conditions. More interestingly, we reveal that the motion-based pH sensing property is size-dependent, with smaller structures exhibiting a higher sensitivity. In addition, since polycaprolactone is a biode- gradable material, the micromotor described in this study can be easily degraded in solution. Hence, features such as one-step fabrication, motion readout, and biodegradability render this micromotor an attractive candidate for sensing algplications.

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。

体相微马达双气泡聚并驱动的界面演化机制

微纳米马达是建立微流体环境与宏观操控的桥梁,气泡微马达的驱动速度高,这一优势在实际应用中不可替代.管式气泡马达适用于复杂场景但能量转化率低,气泡驱动的Janus微球马达效率高但仅适用于气液界面附近.鉴于此,本文提出通过双气泡聚并方式驱动Janus微球马达的新体系,调和了高能量转化率与界面受限的矛盾.在实验中,借助高速摄像记录了双气泡聚并驱动微马达的~100μs级过程,气泡聚并紧邻微球发生,通过释放的能量驱动微球显著运动,其融合过程是独特的可动曲壁受限下的气液界面演化问题.进一步结合伪势格子Boltzmann数值方法探究了气泡聚并驱动的流体动力学机制.研究结果揭示了不同时段气泡聚并的细节,给出了气泡颗粒尺寸比等因素对微球位移、初始动能转换率的影响,确认了双气泡聚并释放表面能的高效驱动机制.

基于微电机遥控的继电保护顺控防误操作系统

传统变电站内顺控操作系统主要针对一次设备,不包含对二次保护硬压板的顺序控制,导致顺控工作并不能从根本上改变现有依靠人工逐项操作的工作模式。为此,文中设计了基于微电机遥控的继电保护顺控防误操作系统。设计了继电保护硬压板防误操作告警模块,通过硬压板分位触点的断开与闭合发出告警信息。在典型操作票操作逻辑的基础上,使用一键式微电机遥控防误操作模块支持调度远方程序操作,并通过地线解闭锁管理模块规范管理地线。设计一键式防误操作流程,利用循环冗余校验码分别检测发送端和接收端出现的误码,在顺控操作过程中实现防误操作。实验结果表明,该系统电压输出的上下波动幅度范围为-2.5~2.5 V,且输出波形与理想波形一致,具有良好的防误操作效果。

柔性PCB绕组径向磁通微型永磁电机设计

采用无槽结构的高速微型永磁电机在检测设备、医疗器械等方面应用广泛,但无槽电机绕组制作复杂,使用绕组印制技术可以简化绕组的制作过程。目前已有的印制技术多以刚性印制电路板(PCB)为载体应用于轴向磁通电机,对于径向磁通的高速电机来说,刚性PCB已无法满足绕组沿圆周方向分布的需求,柔性PCB绕组应运而生,不过目前还没有完整的柔性PCB绕组电机设计方案。因此,设计了一款高速微型柔性PCB绕组电机,针对柔性PCB绕组特有的缠绕不等距问题,提出了使用平均半径的解决方案,并通过仿真对电机进行了分析。结果表明,平均半径法解决了绕组缠绕不等距的问题,所设计的柔性PCB绕组电机能达到电机技术要求且具有良好的热稳定性。

微电机零部件BMC注塑工艺技术浅析

随着微电机技术的不断发展,电机结构也不断的标准化、集成化,以满足产线大批量生产以及产线自动化的要求;其中,微电机中的关键零部件定子组件及转子组件的制造工艺也发生深刻变化,有通过钣金件作为定转子组件、负载安装连接结构的,也有通过BMC材料作为定转子组件、负载安装连接结构的;随着工业制造4.0的到来,微电机制造厂商也不断的摸索如何实现微电机制造的自动化、智能化,以满足市场低成本、高效率的需求;而BMC注塑作为微电机关键零部件的常用工艺之一,在实现微电机电气安全要求的同时,更能满足这种情形下的要求,给企业带来更高效的经济收益;所以,微电机的零部件注塑工艺技术尤为关键,其工艺水平高低,将制约微电机的制造成本,本文将围绕微电机注塑工艺相关技术进行分析,给微电机制造实际运用提供一些参考。

MnO_(2)基微马达在环境治理和生物医疗中应用的研究现状

对微马达及相关领域的概念进行了简单阐述,详细介绍了近几十年来发展迅速的MnO_(2)基微马达,重点围绕MnO_(2)基微马达的推进机理和其在环境治理及生物医疗的应用进行阐述。MnO_(2)因为独特的催化特性被广泛地应用于微马达领域,从易于控制反应速率及良好的水污染治理的角度出发,总结了近十几年MnO_(2)基微马达的制备方法、驱动方式、运动性能及其在环境治理及生物医疗的研究进展,着重展示了在国内外研究中MnO_(2)基微马达在水污染治理、水安全检测以及相关医疗疾病治疗方面的成功应用。最后,对MnO_(2)基微马达在未来的发展方向与挑战进行了展望。

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。