Design Considerations for Frequency Shifts in a Laterally Finite FBAR Sensor in Contact With the Newtonian Liquid
Design Considerations for Frequency Shifts in a Laterally Finite FBAR Sensor in Contact With the Newtonian Liquid
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与牛顿液体接触的横向有限 FBAR 传感器频移的设计注意事项
DOI：
10.1109/tuffc.2020.3006186
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发表时间：
2020-07
期刊：
影响因子：
--
通讯作者：
Yong Yook-Kong
中科院分区：
文献类型：
--
作者：
Zhao Zinan;Wang Bin;Qian Zhenghua;Kuznetsova Iren;Ma Tingfeng;Yong Yook-Kong
研究了厚度剪切（TSh）模和横向有限薄膜体声波谐振器（FBAR）中的模式耦合振动。利用边界条件和界面连续性条件，得到了与两种液体接触的FBAR传感器的精确色散曲线，并与无液体接触的裸传感器的色散曲线进行了比较。描述主TSh模态分支和不需要的模态分支之间的模式耦合的频谱，通过采用基于变分原理构造的侧向自由边缘处的弱边界条件来计算。给出了传感器和液体层中机械位移的模态振型，并观察到由于液体接触和横向边缘效应引起的模态变换。研究了液体厚度对频谱的影响。数值结果表明，液层中剪切波的产生导致频谱曲线沿着频率轴移动，是FBAR传感器频率移动的主要因素。纵波引起频谱曲线沿着横向纵横比轴移动。然后，对于给定的FBAR传感器，液体厚度变化也可能导致频率偏移。因此，在真实的应用中，应根据频谱选择合适的振动模式，以避免强的模式耦合，并消除由液体厚度变化引起的频率偏移。
Mode-coupled vibrations in a thickness-shear (TSh) mode and laterally finite film bulk acoustic resonator (FBAR) with one face in contact with Newtonian (linearly viscous and compressional) liquid are investigated. With boundary conditions and interface continuity conditions, exact dispersion curves in FBAR sensors contacting with two kinds of liquids are obtained, and they are compared with the dispersion curves in a bare sensor without liquid contact. Frequency spectra, describing mode couplings between the main TSh modal branch and undesirable modal branches, are calculated by employing weak boundary conditions at lateral free edges constructed based on the variational principle. Mode shapes of mechanical displacements in both the sensor and liquid layer are presented, and mode transformations are observed due to the liquid contact and lateral edge effect. The effect of liquid thickness on frequency spectra is also studied. Numerical results reveal that the generation of shear wave in the liquid layer results in the shifts of spectrum curves along the frequency axis and hence it is the main factor of frequency shifts of FBAR sensors. The compressional wave causes the shifts of spectrum curves along the lateral aspect ratio axis. Then for a given FBAR sensor, the liquid thickness changes could also cause frequency shifts. Therefore, desirable vibration modes should be chosen based on the frequency spectra to avoid strong mode couplings and to eliminate frequency shifts induced by the liquid thickness changes in real applications.
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发表时间：
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期刊：
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期刊：
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