Numerical analysis of characteristics of microactuators driven by liquid crystals

For the purpose of developing liquid crystalline microactuators, the transient behaviors of a nematic liquid crystal between two parallel plates have been computed for various parameters such as applied voltage, the gap between the plates, and the twist and tilt angles at the plates. The Leslie-Ericksen theory has been selected as a constitutive equation. The twist angle has an effect on the induced velocity profiles; for example, the induced flow is planar at the twist angle of 0°, while the flow has an out-of-plane component when the twist angle is not 0°. Transient behaviors of shear stress acting on the plates, the flowrate, and the maximum values of the velocity, and the tilt angle between the plates have been reported. In addition, we have investigated the effects of the applied voltage, the gap between the plates, and the tilt angle at the plates on the above-mentioned values. We can develop microactuators with arbitrary characteristics by suitably controlling the applied voltage, the size of the actuators, and the director anchoring conditions.     

功能材料驱动的微执行器及其关键技术

以新型功能材料为驱动元件的微执行器是精密加工、超精密加工和微机械发展的关键技术之一,对其驱动元件、结构设计、加工制造和精密测控等方面的研究具有重要的科学意义和实用价值。分析了国内外研究热点和具有代表性的压电、形状记忆合金和磁致伸缩材料等功能材料的优异性能及其微执行器的驱动原理和结构特点,阐述了功能材料驱动的微执行器技术的发展趋势,指出了功能材料驱动微执行器技术发展的关键技术。     

微机械电子学系统

本文简要地评述了微机构、微传感器、微执行器的发展,提出了微机械电子学系统的概念,指出了微机械电子学系统的发展前景。     

新型的形状记忆合金／硅薄膜微驱动器

介绍了一种用硅微加工技术制作的ＮｉＴｉ／Ｓｉ 薄膜结构的双向微驱动器。它利用ＮｉＴｉ 形状记忆合金薄膜（ＳＭＡ） 大的相变回复应力和Ｓｉ 衬底膜的反偏置力产生有一定位移量的双向运动。对ＮｉＴｉ 薄膜进行合理的图形化后使得驱动器位移量增大,双向效应显著,响应速度提高。同时图形化后的ＮｉＴｉ 膜也是加热电阻,使驱动结构简单,所需功率减少。驱动器实际驱动面积为３ ×３ｍ ｍ２ 厚度为２０μｍ 。可产生的最大位移为５０μｍ ,最高驱动频率可达１００Ｈｚ。驱动功率可减小到２００ｍ Ｗ。经过１０００ 万次振动后,驱动膜无开裂,性能正常。它已被成功的应用于压缩型微泵,该泵最大流量达３４０μＬ／ｍｉｎ 。     

微机电系统的研究内容与发展现状

概述了微机电系统（MEMS）的定义和特征,从理论基础、技术基础和工程应用三方面,阐述了微机电系统的研究内容,简要介绍了MEMS基础技术及MEMS器件的研究现状。     

Electronic Mosquito: designing a semi-invasive Microsystem for blood sampling, analysis and drug delivery applications

In this study we present an innovative design idea for a semi-invasive blood sampling, analysis and drug delivery device called “Electronic Mosquito” (“e-Mosquito”). The major building blocks of the device are discussed. The principle of operation is described and its feasibility is demonstrated. The integration of the microsystem is outlined and its practical implementation proposed.     

Design and analysis of a polymeric photo-thermal microactuator

This paper presents the modeling, simulation and characterization of a photo-thermally actuated bent-beam microactuator. The microactuator consists of a single polymeric layer (SU-8) fabricated with conventional photolithography techniques. The principle of operation is based on the thermal expansion of the bent-beams that absorb the required heat by laser illumination. This provides an effective non-contact actuation mechanism by laser beam focusing. A theoretical model of the microactuator is derived and verified by finite element simulations and experiments. The experiments show that a bent-beam actuator with 800 m long, 40 m wide, 100 m thick and 6° bent arms achieves a tip displacement of 16 m with an incident laser beam of 50 mW power while keeping the maximum temperature less than 125 °C. This study merges the advantages of photo-thermal actuation with practicality of polymeric materials. To verify the effectiveness of the proposed microactuator mechanism, a microgripper with bent-beam actuator was fabricated and characterized. It has been demonstrated that the opening of the gripping fingers can be increased from 20 to 50 m for a microgripper with 1000 m long fingers with an incident laser power of 50 mW. This polymeric microgripper with photo-thermal actuation provides a way of gentle grasping with electrical isolation, high repeatability and low temperature operation that is particularly crucial for biomanipulation applications. The polymeric photo-thermal actuator described in this study expands the practical applications of microactuators/microgrippers which are critical tools in bioMEMS devices.     

SMA／Si复合膜微驱动器图案优化设计

图形化SMA薄膜的图案及其结构参数的选择对SMA／Si复合驱动膜的性能有决定性的影响，利用有限元方法对两种图案设计进行了对比分析，通过结构分析和温度场分析，图形电阻条变宽的设计有助于进一步提高驱动膜的性能。仿真结果对于优化驱动膜的设计具有指导意义。     

Finite element analysis of a IBM suspension integrated with a PZT microactuator

This paper presents a piezoelectric-based microactuator concept that could provide an economical and easily integrated option for dual stage actuation used in hard disk drives (HDDs). A simple cantilever beam integrated with the PZT actuator was simulated first in order to testify the driving mechanics of the new design. A modern suspension (IBM Deskstar DTLA-307015) integrated with the developed PZT actuator was then simulated by finite element method (FEM). Theoretical dynamic and electrostatic analyses were performed to investigated the resonant frequency and displacement sensitivity. Good dynamic characteristics were obtained. Further simulation was done based on the optimized structure of the actuator/suspension assembly and results show that >1 μm tip stroke can be obtained while the driving voltage is only 20 V. A 10 V is sufficient to get >1 μm tip stroke if double layer PZT actuator is used.     

微型热致动器研究

本论文围绕微型热致动器的研制开发,对热致动方式进行较为深入研究,利用硅微细加工工艺制造出多种型热致动器,并进行了理论分析和实验测试。