title: Integration of 2D CMUT arrays with front-end electronics for volumetric ultrasound imaging.
abstract: 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 x 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 mPa/pHz. 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.
authors.affiliation: Edward L Ginzton Laboratory, Stanford University, Stanford, CA 94305, USA. iwygant@stanford.edu
authors.forename: Ira O
authors.initials: IO
authors.lastname: Wygant
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Zhuang
authors.forename: David T
authors.initials: DT
authors.lastname: Yeh
authors.forename: Omer
authors.initials: O
authors.lastname: Oralkan
authors.forename: A
authors.initials: A
authors.lastname: Sanli Ergun
authors.forename: Mustafa
authors.initials: M
authors.lastname: Karaman
authors.forename: Butrus T
authors.initials: BT
authors.lastname: Khuri-Yakub
mesh_terms: D000465:Algorithms; D004582:Electronics, Medical / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D018511:Systems Integration; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation*