Integration of 2D CMUT arrays with front-end electronics for volumetric ultrasound imaging

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 55; no. 2; pp. 327 - 342
• Main Authors: Wygant, I.O., Xuefeng Zhuang, Yeh, D.T., Oralkan, O., Ergun, A.S., Karaman, M., Khuri-Yakub, B.T.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.02.2008; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic signal processing; Acoustics; Algorithms; Arrays; Bandwidth; Bonding; Electronics; Electronics, Medical - instrumentation; Equipment Design; Equipment Failure Analysis; Exact sciences and technology; Frequency; Fundamental areas of phenomenology (including applications); Image Enhancement - instrumentation; Image Enhancement - methods; Image Interpretation, Computer-Assisted - instrumentation; Image Interpretation, Computer-Assisted - methods; Imaging; Imaging, Three-Dimensional - instrumentation; Imaging, Three-Dimensional - methods; Integrated circuit interconnections; Integrated circuit noise; Integrated circuits; Joining processes; Physics; Preamplifiers; Reproducibility of Results; Sensitivity and Specificity; Signal Processing, Computer-Assisted; Systems Integration; Three dimensional; Transducers; Transduction; acoustical devices for the generation and reproduction of sound; Two dimensional; Ultrasonic imaging; Ultrasonic transducer arrays; Ultrasonic transducers; Ultrasonography - instrumentation; Pulse echo method; Circuit design; Ultrasound imaging; Capacitive transducer; Flip-chip; Interface circuit; MHz range; High pressure; Synthetic aperture; Integrated circuit; Tridimensional image; Acoustic antenna; Plane antenna; Acoustic image; Custom circuit; Ultrasonic transducer; Ultrasound; Wafer; Transducer network
• ISSN: 0885-3010; 2373-7840; 1525-8955; 1525-8955
• DOI: 10.1109/TUFFC.2008.652

For three-dimensional (3D) ultrasound imaging, connecting elements of a two-dimensional (2D) transducer array to the imaging system's front-end electronics is a challenge because of the large number of array elements and the small element size. To compactly connect the transducer array with electronics, we flip-chip bond a 2D 16 times 16-element capacitive micromachined ultrasonic transducer (CMUT) array to a custom-designed integrated circuit (IC). Through-wafer interconnects are used to connect the CMUT elements on the top side of the array with flip-chip bond pads on the back side. The IC provides a 25-V pulser and a transimpedance preamplifier to each element of the array. For each of three characterized devices, the element yield is excellent (99 to 100% of the elements are functional). Center frequencies range from 2.6 MHz to 5.1 MHz. For pulse-echo operation, the average -6-dB fractional bandwidth is as high as 125%. Transmit pressures normalized to the face of the transducer are as high as 339 kPa and input-referred receiver noise is typically 1.2 to 2.1 rnPa/ radicHz. The flip-chip bonded devices were used to acquire 3D synthetic aperture images of a wire-target phantom. Combining the transducer array and IC, as shown in this paper, 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.