Finite element modeling and experimental characterization of crosstalk in 1-D CMUT arrays
Finite element modeling and experimental characterization of crosstalk in 1-D CMUT arrays
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DOI：
10.1109/tuffc.2007.256
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发表时间：
2007-02-01
影响因子：
3.6
通讯作者：
Khuri-Yakub, Butrus T.
中科院分区：
文献类型：
--
作者：
Bayram, Baris;Kupnik, Mario;Khuri-Yakub, Butrus T.
串扰是超声换能器阵列的元件之间的能量耦合。这种耦合会降低医学成像和治疗等应用中传感器的性能。在本文中，我们展示了电容式微机械超声换能器（CMUT）中的引导界面、波的实验演示。我们将实验结果与使用商用软件包 (LS-DYNA) 对在传统模式和折叠模式下运行的一维 CMUT 阵列进行的有限元计算进行比较。用单极电压脉冲激发阵列中间的元件，并使用激光干涉仪沿浸没在大豆油中的阵列元件的中心线测量位移。我们对覆盖有 4.5 μm 聚二甲基硅氧烷 (PDMS) 层的相同 CMUT 阵列重复了测量。主要串扰机制是在流固界面中传播的色散导模。虽然在传统操作中发射器元件的中心频率为 5.8 MHz，分数带宽为 130%，但在频率 2.1 MHz 处观察到色散导模的最大振幅，并且截止频率为 4 MHz。在折叠操作中，在4.0 MHz的频率处观察到色散导模的最大振幅，并且截止频率为10 MHz。折叠操作中的串扰水平 (-39 dB) 低于传统操作中的串扰水平 (-24.4 dB)。 PDMS 的覆盖范围不会显着影响串扰水平，但会降低两种操作模式的相速度。还观察到兰姆波模式 An 和 So，串扰水平分别为 -40 clB 和 -65 dB。我们观察到有限元和实验结果之间非常吻合。
Crosstalk is the coupling of energy between the elements of an ultrasonic transducer array. This coupling degrades the performance of transducers in applications such as medical imaging and therapeutics. In this paper, we present an experimental demonstration of guided interface, waves in capacitive micromachined ultrasonic transducers (CMUTs). We compare the experimental results to finite element calculations using a commercial package (LS-DYNA) for a 1-D CMUT array operating in the conventional and collapsed modes. An element in the middle of the array was excited with a unipolar voltage pulse and the displacements were measured using a laser interferometer along the center line of the array elements immersed in soybean oil. We repeated the measurements for an identical CMUT array covered with a 4.5-mu m polydimethylsiloxane (PDMS) layer. The main crosstalk mechanism is the dispersive guided modes propagating in the fluid-solid interface. Although the transmitter element had a center frequency of 5.8 MHz with a 130% fractional bandwidth in the conventional operation, the dispersive guided mode was observed with the maximum amplitude at a frequency of 2.1 MHz, and had a cut-off frequency of 4 MHz. In the collapsed operation, the dispersive guided mode was observed with the maximum amplitude at a frequency of 4.0 MHz, and had a cut-off frequency of 10 MHz. Crosstalk level was lower in the collapsed operation (-39 dB) than in the conventional operation (-24.4 dB). The coverage of the PDMS did not significantly affect the crosstalk level, but reduced the phase velocity for both operation modes. Lamb wave modes, An and So, were also observed with crosstalk levels of -40 clB and -65 dB, respectively. We observed excellent agreement between the finite element and the experimental results.