Mechanical quality factor of microcantilevers for mass sensing applications
Mechanical quality factor of microcantilevers for mass sensing applications
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DOI：
10.1117/12.759393
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发表时间：
2007-12
期刊：
影响因子：
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通讯作者：
Jian Lu;T. Ikehara;Yi Zhang;T. Mihara;R. Maeda
中科院分区：
文献类型：
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作者：
Jian Lu;T. Ikehara;Yi Zhang;T. Mihara;R. Maeda
机械品质因数（Q因数）对于基于谐振的质量传感器的检测限制是必不可少的，因为它决定信噪比。本文研究了大气压力条件下不同的能量耗散机制，包括空气阻尼、支撑损耗和热弹性阻尼（TED）对微悬臂梁Q因子的影响。在各种悬臂梁几何形状的贡献进行了分析。讨论了采用弹性波理论描述支护损失效应的郝志成模型的成立条件。研究发现，在5 μ m厚的硅悬臂梁中，当悬臂梁长度大于140 μm时，空气阻尼是能量耗散的主要原因。当悬臂梁长厚比小于20时，在较短的悬臂梁处，支撑损失和TED变得显著。因此，可以通过增加悬臂厚度来抑制空气阻尼来改善微悬臂的Q因子，但不能无限地改善，因为当悬臂厚度增加时，支撑损失变得与空气阻尼相当。此外，研究发现，随着层数的增加，多层微悬臂梁的Q值显著降低。
Mechanical quality factor (Q-factor) is essential to detect-limitation of a resonant based mass sensor because it determines signal to noise ratio. This paper studies the effects of different energy dissipation mechanisms, including air damping, support loss and thermoelastic damping (TED), on Q-factor of a microcantilever under atmospheric pressure conditions. The contribution of each mechanism was analyzed at various cantilever geometry. And the precondition to Z.Hao's model, which describes the support loss effect by elastic wave theory, was discussed. It was found that in 5 μm-thick silicon cantilevers, air damping was the predominant reason to energy dissipation when cantilever length was larger than 140 μm. The support loss and TED became noteworthy at shorter cantilevers when cantilever length to thickness ratio (L/t) was less than 20. Q-factor of a microcantilever thus can be improved by increasing the cantilever thickness to suppress air damping, but not infinitely because the support loss became comparable to air damping when cantilever thickness was increased. Moreover, it was found that the Q-factor of a multi-layered microcantilever was degraded markedly with the increase of layer numbers.