عنوان مقاله
ترانسدیوسرهای فراصوتی میکروماشین شده خازنی: نسل آتی آرایه های بکاررفته برای تصویربرداری صوتی
فهرست مطالب
مقدمه
آرایه های CMUT
کار آزمایشی
بازسازی تصویر
تجزیه و تحلیل نتایج
نتیجه گیری
بخشی از مقاله
مرحله دوم مدارهای الکترونیکی با انتخاب کانال انتقال و دریافت و بزرگنمایی سیگنال های اکو ورودی سرو کار داشت. به طور نوعی از سیستم برای جمع آوری اسکن هایA از کلیه ترکیبات کانال انتقال و دریافت استفاده شده است که در این موردهر بار تنها یک کانال انتقال و هشت کانال دریافت، انتخاب می گردد.
در تصویربردار اولتراسوند آرایه فازدار مرسوم و متداول(CPA) ، کلیه المان های آرایه همزمان باهم فعال شده و بدین طریق یک پرتو با کانون ثابت فراتر از مینیموم عمقf# تشکیل می شود، در صورتی که از کانون دینامیکی به این دلیل استفاده می گردد که کلیه المان ها همزمان باهم سیگنال اکو را دریافت می کنند.
کلمات کلیدی:
Capacitive Micromachined Ultrasonic Transducers: Next-Generation Arrays for Acoustic Imaging? Omer Oralkan, ¨ Student Member, IEEE, A. Sanlı Ergun, Associate Member, IEEE, Jeremy A. Johnson, Student Member, IEEE, Mustafa Karaman, Member, IEEE, Utkan Demirci, Student Member, IEEE, Kambiz Kaviani, Student Member, IEEE, Thomas H. Lee, Member, IEEE, and Butrus T. Khuri-Yakub, Fellow, IEEE Abstract—Piezoelectric materials have dominated the ultrasonic transducer technology. Recently, capacitive micromachined ultrasonic transducers (CMUTs) have emerged as an alternative technology offering advantages such as wide bandwidth, ease of fabricating large arrays, and potential for integration with electronics. The aim of this paper is to demonstrate the viability of CMUTs for ultrasound imaging. We present the first pulse-echo phased array B-scan sector images using a 128-element, one-dimensional (1-D) linear CMUT array. We fabricated 64- and 128-element 1-D CMUT arrays with 100% yield and uniform element response across the arrays. These arrays have been operated in immersion with no failure or degradation in performance over the time. For imaging experiments, we built a resolution test phantom roughly mimicking the attenuation properties of soft tissue. We used a PC-based experimental system, including custom-designed electronic circuits to acquire the complete set of 128128 RF A-scans from all transmit-receive element combinations. We obtained the pulse-echo frequency response by analyzing the echo signals from wire targets. These echo signals presented an 80% fractional bandwidth around 3 MHz, including the effect of attenuation in the propagating medium. We reconstructed the B-scan images with a sector angle of 90 degrees and an image depth of 210 mm through offline processing by using RF beamforming and synthetic phased array approaches. The measured 6-dB lateral and axial resolutions at 135 mm depth were 0.0144 radians and 0.3 mm, respectively. The electronic noise floor of the image was more than 50 dB below the maximum mainlobe magnitude. We also performed preliminary investigations on the effects of crosstalk among array elements on the image quality. In the near field, some artifacts were observable extending out from the array to a depth of 2 cm. A tail also was observed in the point spread function (PSF) in the axial direction, indicating the existence of crosstalk. The relative amplitude of this tail with respect to the mainlobe was less than 20 dB. Manuscript received January 21, 2002; accepted July 24, 2002. This work was supported by the United States Office of Naval Research and CBYON, Inc. O. Oralkan and K. Kaviani are with the Edward L. Ginzton Labo- ¨ ratory, Stanford University, Stanford, CA 94305-4088 and the Center for Integrated Systems, Stanford University, Stanford, CA 94305- 4070 (e-mail: ooralkan@stanford.edu). A. S. Ergun, M. Karaman, U. Demirci, and B. T. Khuri-Yakub are with the Edward L. Ginzton Laboratory, Stanford University, Stanford, CA 94305-4088. J. A. Johnson is with the Department of Neurosurgery, Image Guidance Laboratory, School of Medicine, Stanford University, Stanford, CA 94305-5327. T. H. Lee is with the Center for Integrated Systems, Stanford University, Stanford, CA 94305-4070. I. Introduction
