Dynamic Behavior of Microelectromechanical Systems (MEMS) in Liquid Environments

本项目的目的是研究简单的微电子机械系统(MEMS)结构在均匀液体和固液悬浮中的运动。这些结构将包括设计为将垂直于固体基板移动的梁，以及设计为与基板平行滑动的“穿梭”板。我们将考察几何形状、间隙高度、表面特性和流体特性对器件性能的影响。“启动”运动将通过量化最初受电力偏转的横梁和航天飞机的“回弹”行为来进行研究。正常的振荡运动将用激光测振法进行量化。启动和振荡滑动运动将通过使用高帧频数码相机对航天飞机进行成像来观察和量化。对于这两种形式的振荡运动，将计算机械品质因数Q和频移。流体运动的细节将通过可视化和图像处理技术进行研究。实验结果将与现有的摩擦和润滑、液/固表面粘附力和液体阻尼力的物理模型进行比较，以阐明影响器件性能的主要物理因素。结果还将用于测试和确定参数关系中的极限，并为制造可靠和最佳的微型机械设备提出设计规则。这项研究是对液体中MEMS器件的流体/结构相互作用的开拓性研究。由于这样的装置在各种行业中都是可取的，因此实验数据和分析将在许多应用中对工程师有用。参数关系和设计规则最终将允许工程师优化制造方法和系统性能，同时将代价高昂的试错过程降至最低。

The objective of this project is to investigate the motion of simple microelectromechanical systems (MEMS) structures immersed in homogeneous liquids and solid/liquid suspensions. The structures will include beams designed to move normal to solid substrates and 'shuttle' plates designed to slide parallel with the substrates. The influence of geometry, gap height, surface characteristics, and fluid properties on device performance will be examined. 'Start-up' motion will be investigated by quantifying 'spring-back' behavior in beams and shuttles initially deflected by electrical forces. Normal oscillatory motion will be quantified using laser vibrometry. Start-up and oscillatory sliding motion will be observed and quantified by imaging shuttles with a high-frame-rate digital camera. The mechanical quality factor Q and frequency shift will be calculated for the two forms of oscillatory motion. Details of fluid motion will be investigated by visualization and image processing techniques. The experimental results will be compared with existing physical models on friction and lubrication, liquid/solid surface adhesion, and liquid damping forces to elucidate the dominant physical factors responsible for device performance. The results will also be used to test and determine limits in parametric relationships and to suggest design rules for the fabrication of reliable and optimal microscale mechanical devices. This study represents a pioneer investigation of fluid/structure interactions for MEMS devices in liquids. Since such devices are desirable in a variety of industries, the experimental data and analysis will be useful to engineers in many applications. The parametric relationships and design rules will ultimately allow engineers to optimize manufacturing methods and system performance while minimizing costly trial-and-error procedures.