FEA of CMUTs Suitable for Wide Gas Pressure Range Applications.
FEA of CMUTs Suitable for Wide Gas Pressure Range Applications.
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DOI：
10.1109/ultsym.2010.5935678
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发表时间：
2010-10-11
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影响因子：
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通讯作者：
Khuri-Yakub BT
中科院分区：
文献类型：
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作者：
Ho MC;Kupnik M;Khuri-Yakub BT
超声波换能器在宽压力范围内工作的能力在火炬气的超声波流量测量（UFM）等应用中是必不可少的。我们提出了一种新的电容式微机械超声换能器（CMUTs）的工作模式，在这种模式下，即使在零直流偏置和1atm压力下，板也与腔底保持永久接触。采用有限元分析（FEA）软件研究了这些cmut在1 ~ 20 atm压力范围内的性能。首先，我们进行了静态分析，以确定板的挠度，从而确定间隙高度。此外，从静态分析中，我们获得了用于计算耦合效率的静态和自由电容，并通过模态分析确定了频率低于~ 300 kHz时可能的设计几何形状。我们的计算表明，在不同的压力下，传统操作的cmut在静态工作点上有巨大的变化，而我们提出的模式在1 - 20 atm压力下具有可接受的频率范围（73 - 340 kHz），并且在较低的直流偏置电压下提高了耦合效率。甜甜圈形状的部分电极进一步使我们能够调整耦合效率，从而转化为更好的性能，特别是在更高的压力范围内。有限元分析表明，我们提出的工作模式是一种很有前途的解决方案，适用于火炬气计量应用。
The ability of ultrasound transducers to operate over a wide and varying pressure range is essential in applications such as ultrasonic flow metering (UFM) of flare gas. We propose a new operational mode for capacitive micromachined ultrasonic transducers (CMUTs), in which the plate is in permanent contact with the bottom of the cavity, even at zero DC bias and 1 atm pressure. Finite element analysis (FEA) software was used to investigate the performance of these CMUTs within the pressure range of 1 to 20 atm. First, we performed a static analysis to determine the plate deflection and, thus, the gap height. Further, from the static analysis, we obtained the static and free capacitances for calculating the coupling efficiency, and a modal analysis identified possible design geometries for frequencies lower than ~ 300 kHz. Our calculations show that conventionally operated CMUTs have huge changes in static operational point at different pressures, while our proposed mode exhibits an acceptable frequency range (73 – 340 kHz) over 1 – 20 atm pressure and an improved coupling efficiency at lower dc bias voltages. A donut shape partial electrode further allows us to tune the coupling efficiency, which translates into a better performance, especially at the higher pressure range. FEA shows that our proposed operation mode is a promising solution for flare gas metering applications.