雙電極耦合效應之研究

Analysis of vibrations coupling in mesa-shaped multi-channel quartz crystal microbalances

杜炎勳(Yan-shiun Du)

指導教授 ： 吳光鐘

國立臺灣大學/工學院/應用力學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.00204

摘要

本文主要分成兩部份，第一部分討論QCM的平台設計(mesa design)的相關研究與階梯設計(step design)的反耦合效應，第二部份將討論雙電極QCM的設計。

QCM於正常工作時，大部份能量應集中在電極區下方，但在特定幾何尺寸下QCM的能量集中效應會有大幅減少的現象。當此現象發生時，量測工作會產生頻率漂移與不準確性。在本論文中，我們採用有限元素法與Mindlin梁理論去分析在此尺寸下的QCM振動，由結果顯示彎曲波是造成QCM能量不集中的主因。接下來再進一步討論階梯平台設計對剪力波與彎曲波的反耦合效應。

當操作雙電極QCM時，兩電極彼此會相互影響，使得兩者的量測工作會受到干擾，產生其不準確性。本文的主要目地就是將平台設計應用到雙電極QCM上，增加個別工作電極的能量井效應，增加量測時的準確性與穩定度，並嘗試尋找其最佳化設計。

關鍵字

雙電極石英晶體微天平 ； 壓電材料 ； 能量井效應 ； 平台設計 ； 有限元素分析模擬

並列摘要

The principle of the QCM design is based on the energy trapping phenomena of the quartz. But under certain specific geometries of QCM, the energy trapping effect ratio will diminish abruptly and the measurement accuracy will be decreased appreciably under those geometries. In this study we used finite element method and the Mindlin beam theory to analyze the geometry under which such a phenomenon occurs. It is shown that the flexural wave is the main reason for the loss of energy trapping. We further discuss the wave decoupling ability of stepped mesa design and how this improves the characteristics of bi-mesa resonators.
In the model of multi-channel QCM, the electrodes will interfere each other during operation and the measurement accuracy is reduced. Here, we applied the mesa design to the multi-channel QCM so that the energy trapping effect ratio could be increased. We further compared the efficiency between the conventional multi-channel QCM and the multi-channel QCM with mesa design.

並列關鍵字

multi-channel quartz crystal microbalance ； piezoelectric material ； energy trapping effect ； mesa design ； finite element method analysis

參考文獻

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