Bayram Baris
Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara 06800, Turkey.
J Acoust Soc Am. 2015 Aug;138(2):614-23. doi: 10.1121/1.4923361.
In this study, radiation impedance of a capacitive micromachined ultrasonic transducer composed of square-shaped membranes arranged in m × m configuration (m = 1 - 5) is investigated using finite element analysis (FEA) of a commercially available software package(ANSYS). Radiation impedance is calculated for immersed membranes operating in conventional and collapse modes. Individual membrane response within the multi-membrane configuration is analyzed, and excited modes and their effects on radiation impedance and the pressure spectra are reported. This FEA provides an accurate behavior of the acoustic coupling of a thin membrane in a multi-membrane configuration, and extends above the anti-resonance frequency. The first resonance frequency of the membrane is excited for m × m (m ≥ 3) configuration in conventional mode and for m × m (m ≥ 2) configuration in collapse mode. Therefore, this frequency is determined to be responsible for the adverse effects observed in radiation impedance and pressure spectrum. A membrane configuration, which is missing the central membrane from the full m × m configuration is proposed, and is investigated with the FEA. This study is beneficial for the design of precise transducers suited for biomedical applications.
在本研究中，使用商业软件包（ANSYS）的有限元分析（FEA）研究了由以m×m配置（m = 1 - 5）排列的方形膜组成的电容式微机械超声换能器的辐射阻抗。计算了在传统模式和坍塌模式下工作的浸没膜的辐射阻抗。分析了多膜配置中单个膜的响应，并报告了激发模式及其对辐射阻抗和压力谱的影响。这种有限元分析提供了多膜配置中薄膜声耦合的准确行为，并扩展到反谐振频率以上。在传统模式下，对于m×m（m≥3）配置，在坍塌模式下，对于m×m（m≥2）配置，膜的第一谐振频率被激发。因此，确定该频率是在辐射阻抗和压力谱中观察到的不利影响的原因。提出了一种从完整的m×m配置中缺失中央膜的膜配置，并通过有限元分析进行了研究。本研究有利于设计适用于生物医学应用的精密换能器。
