Journal ArticleDOI
Capacitive micromachined ultrasonic transducers: next-generation arrays for acoustic imaging?
Omer Oralkan,Arif Sanli Ergun,J.A. Johnson,Mustafa Karaman,Utkan Demirci,K. Kaviani,Thomas H. Lee,Butrus T. Khuri-Yakub +7 more
TLDR
The first pulse-echo phased array B-scan sector images using a 128-element, one-dimensional (1-D) linear CMUT array is presented and preliminary investigations on the effects of crosstalk among array elements on the image quality are performed.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 128/spl times/128 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.read more
Citations
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Journal ArticleDOI
Ultrasonic arrays for non-destructive evaluation: A review
TL;DR: The use of ultrasonic arrays for non-destructive evaluation has been extensively studied in the literature as mentioned in this paper, where the main advantages of arrays are their increased flexibility over traditional single element transducers, and their ability to produce immediate images of the test structure.
Journal ArticleDOI
Post-processing of the full matrix of ultrasonic transmit-receive array data for non-destructive evaluation
TL;DR: This paper describes an alternative approach in which the full matrix of time domain signals from every transmitter–receiver pair is captured and post-processed and shown to offer significant performance advantages for NDE.
Journal ArticleDOI
Capacitive micromachined ultrasonic transducers for medical imaging and therapy
TL;DR: The presented results prove the CMUT as a MEMS technology for many medical diagnostic and therapeutic applications as well as the progression of developing several generations of fabrication processes.
Journal ArticleDOI
Capacitive micromachined ultrasonic transducers: fabrication technology
TL;DR: It was concluded that wafer-bonded cMUT technology was superior in terms of process control, yield, and uniformity because the number of steps and consequent process time were reduced and turn-around time was improved significantly.
Journal ArticleDOI
Integration of 2D CMUT arrays with front-end electronics for volumetric ultrasound imaging
Ira O. Wygant,Xuefeng Zhuang,David T. Yeh,Omer Oralkan,Arif Sanli Ergun,Mustafa Karaman,Butrus T. Khuri-Yakub +6 more
TL;DR: Combining the transducers array and IC allows for better utilization of large arrays, improves receive sensitivity, and may lead to new imaging techniques that depend on transducer arrays that are closely coupled to IC electronics.
References
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Journal ArticleDOI
Surface micromachined capacitive ultrasonic transducers
TL;DR: A theoretical model is proposed that agrees well with observed transducer behavior and is used to demonstrate that microfabricated ultrasonic transducers constitute an attractive alternative to piezoelectric transducers in many applications.
Journal ArticleDOI
Synthetic aperture imaging for small scale systems
TL;DR: Multi-element synthetic aperture imaging methods suitable for applications with severe cost and size limitations are explored in this article, where each method uses different spatial frequencies and acquisition strategies for imaging, and therefore different sets of active transmit/receive element combinations.
Journal ArticleDOI
High-speed ultrasound volumetric imaging system. I. Transducer design and beam steering
TL;DR: The authors describe the design considerations and preliminary evaluation of a high-speed, online volumetric ultrasound imaging system that uses the principles of pulse-echo, phased array scanning with a 2-D array transducer.