A novel approach to the analysis of squeezed-film air damping in microelectromechanical systems
A novel approach to the analysis of squeezed-film air damping in microelectromechanical systems
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DOI：
10.1088/0960-1317/27/1/015012
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发表时间：
2017-01-01
影响因子：
2.3
通讯作者：
Zhang, TieJun
中科院分区：
文献类型：
--
作者：
Yang, Weilin;Li, Hongxia;Zhang, TieJun
挤压膜阻尼（SFD）是影响微机电系统（MEMS）性能的一种重要现象。MEMS中的总阻尼力主要包括粘性阻尼力和弹性阻尼力。品质因数（Q因子）通常用来评价MEMS中的阻尼。在这项工作中，我们测量的Q因子的谐振器通过实验在很宽的压力水平。事实上，MEMS的实验表征具有一些局限性，因为很难在非常高的真空下进行实验，并且也很难从整体Q因子测量中区分阻尼机制。另一方面，SFD的经典理论分析仅限于强假设和简单几何。本文提出了一种新的数值方法，这是基于格子玻尔兹曼模拟，研究微机电系统中的SFD。我们的方法考虑了压缩空气流的动力学以及MEMS中的流体-固体相互作用。结果表明，数值模拟可以直接预测Q因子，模拟结果与实验数据吻合较好。分别研究了压力、振幅和驱动频率等因素对SFD的影响。在综合仿真的基础上，对粘性阻尼力和弹性阻尼力进行了定量比较。所提出的数值方法以及实验表征，使我们能够揭示有见地的MEMS挤压膜空气阻尼的物理。
Squeezed-film damping (SFD) is a phenomenon that significantly affects the performance of micro-electro-mechanical systems (MEMS). The total damping force in MEMS mainly include the viscous damping force and elastic damping force. Quality factor (Q factor) is usually used to evaluate the damping in MEMS. In this work, we measure the Q factor of a resonator through experiments in a wide range of pressure levels. In fact, experimental characterizations of MEMS have some limitations because it is difficult to conduct experiments at very high vacuum and also hard to differentiate the damping mechanisms from the overall Q factor measurements. On the other hand, classical theoretical analysis of SFD is restricted to strong assumptions and simple geometries. In this paper, a novel numerical approach, which is based on lattice Boltzmann simulations, is proposed to investigate SFD in MEMS. Our method considers the dynamics of squeezed air flow as well as fluid-solid interactions in MEMS. It is demonstrated that Q factor can be directly predicted by numerical simulation, and our simulation results agree well with experimental data. Factors that influence SFD, such as pressure, oscillating amplitude, and driving frequency, are investigated separately. Furthermore, viscous damping and elastic damping forces are quantitatively compared based on comprehensive simulation. The proposed numerical approach as well as experimental characterization enables us to reveal the insightful physics of squeezed-film air damping in MEMS.