梳齿式静电微驱动器稳定性分析与结构优化北大核心

针对典型梳齿式静电微驱动器驱动稳定性差的问题,建立微驱动器驱动稳定性分析模型,系统分析微驱动器驱动稳定性随其各结构参数的变化关系,提出基于稳定性因子的微驱动器驱动稳定性评估方法。提出弹性支撑机构外置方案,建立弹性梁非线性特征模型,基于模型分析结果设计预弯弹性梁结构,建立基于梳齿结构参数的静电力模型,研究不同梳齿结构对驱动器驱动稳定性的影响。研究结果表明,弹性支撑机构外置、预弯弹性梁结构以及线性交叠梳齿结构能够有效提高梳齿微驱动器大位移输出的驱动稳定性。     

静电梳齿驱动器薄膜变形反射镜

提出一种大冲程静电梳齿驱动器微机械薄膜变形反射镜,理论上研究了静电梳齿驱动器微机械薄膜变形反射镜的静电驱动力和变形位移与驱动电压的关系,分析了变形反射镜的驱动稳定性,比较了平板电容驱动器与纵向梳齿驱动器的驱动能力.结果表明,变形反射镜的静电驱动力和变形位移没有关系;在相同的面积下,纵向梳齿驱动器的驱动力比平板电容驱动器的驱动力大很多.     

MEMS交叉梳齿光栅设计和优化

采用MEMS技术设计和制造了一种由梳齿驱动器驱动的新型交叉梳齿光栅,同时优化了该光栅的驱动器结构,着重分析了优化驱动器结构对光栅机械特性和光学传感特性的影响,优化后的光栅相对于未优化时具有更大的位移、更好的光学传感特性。基于PolyMUMPs工艺制作了梳齿驱动器驱动交叉梳齿光栅,并逐步分析了该光栅的加工步骤。结合有限元分析软件,对该MEMS光栅的机械特性进行了分析。分析结果表明,在85V下,该光栅驱动器的位移为2.7μm,而实际测量的位移为2.1μm。通过对该光栅驱动器结构进行优化,得到在同等电压下优化后的光栅驱动器位移较未优化时有显著提高,在85V时,优化后的MEMS光栅驱动器的位移为4.3μm。根据傅里叶光学理论计算得到,该光栅的传感灵敏度与驱动器位移成正比,经过计算得到优化后MEMS光栅的光学传感曲线更加陡峭,具有更好的传感特性。     

基于热模压和切削减薄工艺制备聚合物微静电驱动器

为了满足运输蛋白质、细胞等微纳米级物体的需求,有必要研制聚合物微静电梳齿驱动系统。与硅静电梳齿驱动器相比,聚甲基丙烯酸甲酯(PMMA)静电梳齿驱动器具有成本低、成品率高、驱动电压低和能耗少等优点。首先通过微细加工工艺,制备硅静电梳齿驱动器模具。基于硅模具,利用热模压工艺制备PMMA微驱动器,再通过机械切削工艺释放制备好的PMMA微驱动器结构,得到带基底的PMMA微静电梳齿驱动器,最后通过切削减薄工艺,释放静电梳齿微结构,得到可动的PMMA微静电梳齿驱动器。驱动结果表明,PMMA微静电梳齿驱动器制备工艺具有可行性。     

基于MEMS静电微镜驱动器的光纤相位调制器

设计并制作出了一种基于MEMS静电微镜驱动器的光纤相位调制器。MEMS静电驱动器采用垂直梳齿驱动技术,驱动硅微反射镜沿其法线方向的垂直平移运动以实现入射光波的光相位调制。MEMS静电微镜驱动器与光纤准直器耦合构成MEMS光纤相位调制器,避免了拉伸光纤或改变折射率的困难,具有MEMS技术批量制造、低成本等优势。采用MEMS工艺成功制作出MEMS光纤相位调制器,并实现Michelson光纤干涉仪。利用ASE宽带光源对光纤相位调制器的静态调制特性进行测试,采用Michelson光纤干涉仪对光纤相位调制器的动态调制特性进行测试,结果表明,MEMS光纤相位调制器50V偏压实现了1 550nm光波的2π相位调制,当器件谐振频率为7.15kHz以及交、直流电压幅值分别为12.5V时,响应幅值可达6.8μm,可以实现多个2π的相位的正弦调制。     

三层平板静电驱动MEMS微镜

驱动电压过高是MEMS微镜需要解决的重点问题。根据平板静电驱动器原理,设计了一种新型三层电极平板结构的静电驱动MEMS微镜,分析了此微镜系统的静态特性和动态特性。此微镜系统的设计驱动电压为6.3V,动态响应时间达到1.2ms。     

大位移低电压的静电MEMS驱动器

制作了一种低驱动电压、位移达100μm的梳齿驱动器.为了增加驱动器的驱动位移,对驱动器的侧向稳定性进行了分析.根据分析结论,提出了一种采用小梳齿间隙,高纵/横向弹性常数比预弯曲支撑梁,无初始交叠、梳齿长度线性递增的梳齿驱动器.根据稳定性以及驱动位移和驱动电压的设计要求设计了驱动器的具体参数,并进行了器件制作.测试表明,器件共振点在573Hz,Q因子为35.88,在100μm位移时驱动电压为71V,与理论计算值相差2.1%.     

大位移低电压的静电MEMS驱动器

制作了一种低驱动电压、位移达100μm的梳齿驱动器. 为了增加驱动器的驱动位移,对驱动器的侧向稳定性进行了分析. 根据分析结论,提出了一种采用小梳齿间隙,高纵/横向弹性常数比预弯曲支撑梁,无初始交叠、梳齿长度线性递增的梳齿驱动器. 根据稳定性以及驱动位移和驱动电压的设计要求设计了驱动器的具体参数,并进行了器件制作. 测试表明,器件共振点在573Hz, Q因子为35.88,在100μm位移时驱动电压为71V,与理论计算值相差2.1%.     

扭梁悬臂梁支撑的扭摆式MEMS永磁双稳态机构

在进行理论分析证实可行性和模拟仿真优化参数后,利用非硅表面微加工方法中的牺牲层工艺制备了一种扭梁悬臂梁支撑的扭摆式MEMS永磁双稳态机构.该双稳态结构尺寸为1.9mm×1.6mm×0.03mm,通过永磁力实现稳态姿态无功耗保持,通过对其单侧触点施加纵向驱动力使之达到30μm的纵向驱动位移,可以实现机构的双稳态姿态切换,可以通过控制永磁体磁片、悬臂梁和扭梁的尺寸来灵活调控稳态切换所需的驱动力矩.此双稳态机构可与电磁驱动、电热驱动和静电驱动等类型的微驱动器联用构成永磁双稳态MEMS微继电器.     

梳齿式静电微驱动器的边缘效应影响分析

针对梳齿式静电微驱动器横向静电力的边缘效应问题,采用基于保角变换的修正公式和有限元法分别进行建模分析。采用修正公式虽然可以减小分析误差,但不能准确捕获边缘效应对驱动器驱动性能的动态影响过程,而有限元法能够准确捕获横向静电力受边缘效应影响而发生突变的过程。通过有限元法分析得出,驱动器的结构参数及其工艺误差均对横向静电力的边缘效应有影响,而驱动电压对边缘效应的影响可以忽略;当梳齿接近完全交叠时,边缘效应的影响显著,驱动器驱动性能具有明显的非线性特征。     

Lateral polysilicon microrelays with a mercury microdrop contact

The authors present two designs for electrostatically actuated polysilicon relays with a stationary mercury microdrop contact: a large displacement cantilever design; and a comb-drive design, both fabricated using the multiuser microelectromechanical systems process of MCNC, Research Triangle Park, NC, USA. Microscale mercury relays combine the high density and batch fabrication of a microscale device with the quality and reliability of a mercury contact. Contact resistances of the devices were found to be ~1 kΩ in air with no attempt made to reduce the oxidation of the polysilicon and mercury surfaces. The devices can switch currents over 10 mA. Switching results are presented. The cantilever device is based on a curved electrode design, providing both relatively large force and large displacement of the tip, which contacts the mercury for switching. Nonlinear modeling of the beam movement is also provided. The comb-drive device has the usual double-folded beam design, but has a mercury drop near its center. Fabrication of 10-μm diameter mercury drops as the last step of the processing sequence is also discussed     

A metal-coated polymer micromirror for strain-driven high-speed multiaxis optical scanning

We have developed a new polymer-based micromirror device capable of high-speed multiaxis out-of-plane scanning motion. The whole device structure integrates a metal-coated three-dimensional polydimethylsiloxane micromirror structure with an optically smooth surface and a single layer of silicon-on-insulator electrostatic comb-drive actuators. The high-strain mechanical elasticity of the polymer material allows for translating the in-plane comb-drive motions into three-degree-of-freedom scanning motion with a single actuator layer. The simple structure design and rapid response characteristics of the demonstrated device may lead to high-yield high-performance scanning micromirror technology.     

Design of Novel Sequential Engagement Vertical Comb Electrodes for Analog Micromirror

The vertical comb-drive actuator (VCA) is a promising component to drive analog as well as scanning micromirrors. This work demonstrates the concept of using ldquosequential engagement of vertical comb electrodesrdquo to improve the linearity and to maximize the deflection for analog micromirror. This concept is achieved by varying the in-plane distribution of comb electrodes. The simulation and experiment results of vertical comb-drive actuator VCA with four different electrode-distribution designs demonstrated the feasibility of this study. In comparison, a modified (curved-profile) VCA was remarkably improved the performance of conventional (straight-profile) VCA. Experiments show that the curved-profile VCA improves the nonlinearity by 34% and increases the maximum angular motion for 2.3-fold.     

Thermally excited silicon microactuators

A cantilever-type micromachined silicon actuator based on the bimetal effect used extensively for the fabrication of temperature-controlled electrical switches is described. The silicon actuator consists of a Si-metal sandwich layer and an integrated poly-Si heating resistor as a driving element. Due to the low heat capacity of the transducer element, a high temperature increase per input power unit can be achieved. For a (Si-Au)-cantilever-type actuator, 500-μm long and several micrometers thick, a specific deflection of approximately 0.1 μm/K at the free end has been measured. The design considerations, fabrication process, and experimental results of the actuator are discussed     

MEMS-based integrated head/actuator/slider for hard disk drives

We propose a new integrated head/actuator/slider concept for hard disk drives. This slider is batch fabricated on the sacrificial layer of a wafer together with an electrostatic microactuator via micromachining technology. We present the basic integrated head/actuator/slider design, the fabrication and flying-height tests of a micromachined slider body, and the design, fabrication, and testing of a prototype electrostatic microactuator. Slider warpage was analyzed and successfully suppressed to within 0.1 μm. The slider was flown over a glass disk at heights of 26-81 nm and at linear velocities of 5-13 m/s. The test results of the electrostatic microactuator showed a stroke of 0.55 μm, a very high mechanical resonant frequency of 34 kHz due to its low moving mass of 0.85 μg, and a large force, estimated to be 21.3 μN, generated by the actuator     

遥感用硅PIN二极管

本工作研制适合于在0.5～1.1μm和0.55～0.75μm波段内工作的硅PIN光电二极管。叙述了器件的设计考虑和制造,分别采用双面扩散和高阻外延片单面扩散两种方法制造该器件,达到了预期的要求。文中给出了器件的光谱响应、暗电流、探测率,响应速度及响应均匀性等结果,并进行了讨论。研制出的器件性能良好,探测率D*为7×10~(12)cmHz~(1/2)/w左右。     

Design of a bidirectional MEMS actuator with high displacement resolution, large driving force and power-free latching

This paper describes the design and ANSYS modeling of a bidirectional thermal inchworm MEMS actuator featuring high actuation resolution (0.1 μm) combined with large driving force (100 mN) and power-free latching. A promising application of this device is for precision in-package positioning of optical fibers, but the actuator also has potential for wider use. The inchworm mechanism includes two E-shaped metallic actuators facing each other and a pusher between them that couples to a moveable object such as an optical fiber. Nickel is chosen as the material of the actuators due to its desirable electrical, thermal, and mechanical properties, and availability in fabrication facilities. Electrothermal actuation is used to move the pusher as well as the optical fiber in the desired direction by inputting electric currents in a particular sequence. A transient thermal-mechanical analysis shows the feasibility of the input sequence that drives the inchworm actuation.     

A digital library for a flexible low-voltage organic thin-film transistor technology

This paper presents the design, fabrication and characterization of digital logic gates, flip-flops and shift registers based on low-voltage organic thin-film transistors (TFTs) on flexible plastic substrates. The organic transistors are based on the p-channel organic semiconductor dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) and have channel lengths as short as 5 μm and gate-to-contact overlaps of 20 μm. The organic TFT is modeled which allows us to simulate different logic gate architectures prior to the fabrication process. In this study, the zero-VGS, biased-load and pseudo-CMOS logic families are investigated, where their static and dynamic operations are modeled and measured. The inverter and NAND gates use channel length of 5 μm and operate with a supply voltage of 3 V. Static and dynamic master-slave flip-flops based on biased-load and pseudo-CMOS logic are designed, fabricated and characterized. A new design for biased-load dynamic flip-flops is proposed, where transmission gate switches are implemented using only p-channel transistors. 1-stage shift registers based on the new design and fabricated using TFTs with a channel length of 20 μm operate with a maximum frequency of about 3 kHz.     

嵌入式静电驱动控制电源设计

分析了静电驱动原理以及失效原因,针对静电驱动的特点设计了用于静电驱动的控制电源,该电源采用内嵌DAC的ADuC842系统作为控制芯片,与信号采集及反馈电路一同构成闭环控制系统,控制DC-DC变换器产生大范围的稳定电压.输出电压范围15～80 V,电压文波<800 mV.