50 kHz Capacitive Micromachined Ultrasonic Transducers for Generation of Highly Directional Sound with Parametric Arrays
50 kHz Capacitive Micromachined Ultrasonic Transducers for Generation of Highly Directional Sound with Parametric Arrays
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DOI：
10.1109/tuffc.2009.1019
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发表时间：
2009-01-01
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：
Wygant, Ira O.;Kupnik, Mario;Khuri-Yakub, Butrus T.
在这项研究中，我们检查了用真空密封腔的电容性微机械超声传感器（CMUT）使用参数阵列传输方向声。我们使用有限元建模来设计具有40 mu m和60毫米m厚的膜的CMUT，分别具有46 kHz和54 kHz的共振频率。用于制造CMUTS的晶圆粘结方法可很好地控制设备性能，以及具有大直径膜和深腔的CMUT的能力。每个CMUT的直径为8厘米，由284个圆形膜组成。每个膜的直径为4毫米。制造的CMUT的表征表明，它们的中心频率分别为46 kHz和55 kHz和3 dB的带宽1.9 kHz和5.3 kHz，分别为40毫米M-和60毫米M-M-M-thick膜设备。 DC偏置电压为380 V和350 V，AC激发为200 V峰峰，CMUTS产生的平均声压水平，标准化为设备表面，为1,35 dB和129 dB（re 20 mu pa） ）， 分别。当用参数阵列生成5 kHz声音时，我们在3 m处测量声音，6 dB梁宽为8.7度，声压水平为58 dB。为了了解探测器的非线性如何（例如，用于进行声音水平测量的麦克风的非线性）如何影响测得的声压水平，我们进行了有没有声音的低通滤波器进行麦克风前面的测量；测得的声音水平与压力场的数值模拟一致。本文介绍的结果表明，产生高强度超声的大区域。可以制造用于使用参数阵列传输定向声音。
In this study, we examine the use of capacitive micromachined ultrasonic transducers (CMUTs) with vacuum-sealed cavities for transmitting directional sound with parametric arrays. We used finite element modeling to design CMUTs with 40-mu m- and 60-mu m-thick membranes to have resonance frequencies of 46 kHz and 54 kHz, respectively. The wafer bonding approach used to fabricate the CMUTs provides good control over device properties and the capability to fabricate CMUTs with large diameter membranes and deep cavities. Each CMUT is 8 cm in diameter and consists of 284 Circular membranes. Each membrane is 4 mm in diameter. Characterization of the fabricated CMUTs shows they have center frequencies of 46 kHz and 55 kHz and 3 dB bandwidths of 1.9 kHz and 5.3 kHz for the 40-mu m- and 60-mu m-thick membrane devices, respectively. With dc bias voltages of 380 V and 350 V and an ac excitation of 200 V peak-to-peak, the CMUTs generate average sound pressure levels, normalized to the device's surface, of 1,35 dB and 129 dB (re 20 mu Pa), respectively. When used to generate 5 kHz sound with a parametric array, we measured sound at 3 m with a 6 dB beamwidth of 8.7 degrees and a sound pressure level of 58 dB. To understand how detector nonlinearity (e.g., the nonlinearity of the microphone used to make the sound level measurements) affects the measured sound pressure level, we made measurements with and without an acoustic low-pass filter placed in front of the microphone; the measured sound levels agree with numerical simulations of the pressure field. The results presented in this paper demonstrate that large-area CMUTs, which produce high-intensity ultrasound. can be fabricated for transmitting directional sound with parametric arrays.