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A Boundary Element Model for CMUT-Arrays Loaded by a Viscoelastic Medium.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control ( IF 3.6 ) Pub Date : 2019-11-21 , DOI: 10.1109/tuffc.2019.2954579
Maxime Hery , Nicolas Senegond , Dominique Certon

The present work is an extension of a model previously developed by our group to simulate the electroacoustic response of CMUT-based (Capacitive Micromachined Ultrasonic Transducers) linear arrays acoustically loaded by a fluid medium. The goal is to introduce the viscoelasticity effects of the propagation medium into the modeling. These effects are mainly due to the passivation layer used to protect the transducer, i.e., a silicon polymer a few hundred micrometers thick. The passivation layer is also required to ensure good acoustic coupling between the transducer front-face and human skin. The theoretical approach relies on the determination of a new boundary matrix to simulate the acoustic coupling between the CMUT array and the viscoelastic medium. The complete numerical implementation of a 3D Green's function for a viscoelastic half-space is hence described. In order to reduce computing time, an optimization was carried out through vectorization and parallelization methods. A comparison is then performed with the analytical solutions, from the literature, obtained for elastic half-space. An experimental validation of shear viscosity effects is performed through electrical impedance measurements of the CMUT linear arrays loaded by oils of varying viscosity. A very good agreement is obtained, showing that the model correctly takes the shear viscosity effects on the mechanical response of the CMUT into account; i.e., a shift in the resonance frequency and a diminution in the mechanical quality factor are observed.

中文翻译:

粘弹性介质加载的CMUT阵列的边界元模型。

目前的工作是我们小组先前开发的模型的扩展,该模型用于模拟由流体介质声学加载的基于CMUT的(电容式微机械超声换能器)线性阵列的电声响应。目的是将传播介质的粘弹性效应引入模型中。这些影响主要归因于用于保护换能器的钝化层,即几百微米厚的硅聚合物。还需要钝化层以确保换能器正面与人体皮肤之间的良好声耦合。该理论方法依赖于确定新的边界矩阵来模拟CMUT阵列与粘弹性介质之间的声耦合。3D Green的完整数值实现 因此描述了粘弹性半空间的s函数。为了减少计算时间,通过矢量化和并行化方法进行了优化。然后与从弹性半空间获得的文献中的解析解进行比较。剪切粘度效应的实验验证是通过对粘度变化的油加载的CMUT线性阵列的电阻抗进行测量的。获得了很好的一致性,表明该模型正确地考虑了剪切粘度对CMUT的机械响应的影响。即观察到共振频率的偏移和机械品质因数的减小。通过矢量化和并行化方法进行了优化。然后与从弹性半空间获得的文献中的解析解进行比较。剪切粘度效应的实验验证是通过对粘度变化的油加载的CMUT线性阵列的电阻抗进行测量的。获得了很好的一致性,表明该模型正确地考虑了剪切粘度对CMUT的机械响应的影响。即观察到共振频率的偏移和机械品质因数的减小。通过矢量化和并行化方法进行了优化。然后与从弹性半空间获得的文献中的解析解进行比较。剪切粘度效应的实验验证是通过对粘度变化的油加载的CMUT线性阵列的电阻抗进行测量的。获得了很好的一致性,表明该模型正确地考虑了剪切粘度对CMUT的机械响应的影响。即观察到共振频率的偏移和机械品质因数的减小。剪切粘度效应的实验验证是通过对粘度变化的油加载的CMUT线性阵列的电阻抗进行测量的。获得了很好的一致性,表明该模型正确地考虑了剪切粘度对CMUT的机械响应的影响。即观察到共振频率的偏移和机械品质因数的减小。剪切粘度效应的实验验证是通过对粘度变化的油加载的CMUT线性阵列的电阻抗进行测量的。获得了很好的一致性,表明该模型正确地考虑了剪切粘度对CMUT的机械响应的影响。即观察到共振频率的偏移和机械品质因数的减小。
更新日期:2020-04-22
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