Design and fabrication of a 40-MHz annular array transducer

This paper investigates the feasibility of fabricating a five-ring, focused annular array transducer operating at 40 MHz. The active piezoelectric material of the transducer was a 9-/spl mu/m thick polyvinylidene fluoride (PVDF) film. One side of the PVDF was metallized with gold and forms the ground plane of the transducer. The array pattern of the transducer and electrical traces to each annulus were formed on a copper-clad polyimide film. The PVDF and polyimide were bonded with a thin layer of epoxy, pressed into a spherically curved shape, then back filled with epoxy. A five-ring transducer with equal area elements and 100 /spl mu/m kerfs between annuli was fabricated and tested. The transducer had a total aperture of 6 mm and a geometric focus of 12 mm. The pulse/echo response from a quartz plate located at the geometric focus, two-way insertion loss (IL), complex impedance, electrical crosstalk, and lateral beamwidth all were measured for each annulus. The complex impedance data from each element were used to perform electrical matching, and the measurements were repeated. After impedance matching, f/sub c/ /spl sim/ 36 MHz and -6-dB bandwidths ranged from 31 to 39%. The ILs for the matched annuli ranged from -28 to -38 dB.

[1]  D. Turnbull,et al.  44-MHz LiNbO/sub 3/ transducers for UBM-guided Doppler ultrasound , 2003, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[2]  J.W. Hunt,et al.  The design of protection circuitry for high-frequency ultrasound imaging systems , 1991, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[3]  K. Shung,et al.  Design of efficient, broadband single-element (20-80 MHz) ultrasonic transducers for medical imaging applications , 2003, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[4]  R. Krimholtz,et al.  Equivalent Circuits for Transducers Having Arbitrary Even- Or Odd-Symmetry Piezoelectric Excitation , 1971, IEEE Transactions on Sonics and Ultrasonics.

[5]  F. Foster,et al.  The design and fabrication of high frequency poly(vinylidene fluoride) transducers. , 1989, Ultrasonic imaging.

[6]  F. Foster,et al.  Fabrication of high frequency spherically shaped ceramic transducers , 1994, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[7]  S.L. Garverick,et al.  Unit-delay focusing architecture and integrated-circuit implementation for high-frequency ultrasound , 2003, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[8]  Daniel H Turnbull,et al.  Ultrasound biomicroscopy-Doppler in mouse cardiovascular development. , 2003, Physiological genomics.

[9]  G. R. Lockwood,et al.  Design of a 40 MHz annular array , 2001, 2001 IEEE Ultrasonics Symposium. Proceedings. An International Symposium (Cat. No.01CH37263).

[10]  K. Shung,et al.  A 35 MHz linear ultrasonic array for medical imaging , 2002, Proceedings of the 13th IEEE International Symposium on Applications of Ferroelectrics, 2002. ISAF 2002..

[11]  B. Khuri-Yakub,et al.  Capacitive micromachined ultrasonic transducers: next-generation arrays for acoustic imaging? , 2002, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[12]  F. Foster,et al.  A history of medical and biological imaging with polyvinylidene fluoride (PVDF) transducers , 2000, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[13]  H Ermert,et al.  Comparison of High Frequency Ultrasound and Optical Coherence Tomography as Modalities for High Resolution and Non Invasive Skin Imaging. Vergleich von hochfrequentem Ultraschall und optischer Kohärenztomographie als Modalitäten für die hochauflösende und nichtinvasive Abbildung der Haut , 2003, Biomedizinische Technik. Biomedical engineering.

[14]  D. A. Christopher,et al.  Advances in ultrasound biomicroscopy. , 2000, Ultrasound in medicine & biology.

[15]  L. Brown.  Design considerations for piezoelectric polymer ultrasound transducers , 2000, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[16]  J.W. Hunt,et al.  An Annular Array System for High Resolution Breast Echography , 1982 .

[17]  G.R. Lockwood,et al.  Design and fabrication of annular arrays for high-frequency ultrasound , 2004, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[18]  G.R. Lockwood,et al.  Low-cost, high-performance pulse generator for ultrasound imaging , 2002, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[19]  L From,et al.  A 40-100 MHz B-scan ultrasound backscatter microscope for skin imaging. , 1995, Ultrasound in medicine & biology.

[20]  D. Turnbull,et al.  44-MHz LiNbO3 transducers for UBM-guided Doppler ultrasound. , 2003, IEEE transactions on ultrasonics, ferroelectrics, and frequency control.

[21]  Timothy A. Ritter,et al.  High-frequency single-element and annular array transducers incorporating PVDF , 2000, Medical Imaging.

[22]  K. Shung,et al.  A 30-MHz piezo-composite ultrasound array for medical imaging applications , 2002, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[23]  F. Stuart Foster,et al.  In vivo ultrasound biomicroscopy in developmental biology , 2002 .

[24]  F. S. Foster,et al.  Beyond 30 MHz [applications of high-frequency ultrasound imaging] , 1996 .

[25]  G. R. Lockwood,et al.  Miniature polymer transducers for high-frequency medical imaging , 1998, Medical Imaging.

[26]  D J Coleman,et al.  Three-dimensional high-frequency ultrasonic parameter imaging of anterior segment pathology. , 1995, Ophthalmology.

[27]  J C Bamber,et al.  Differentiation of common benign pigmented skin lesions from melanoma by high‐resolution ultrasound , 2000, The British journal of dermatology.

[28]  F. Foster,et al.  Modeling and optimization of high-frequency ultrasound transducers , 1994, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[29]  M Arditi,et al.  Transient fields of concave annular arrays. , 1981, Ultrasonic imaging.

[30]  Shuvo Roy,et al.  Miniature high frequency focused ultrasonic transducers for minimally invasive imaging procedures , 2003 .

[31]  K. Kirk Shung,et al.  Design of a 50-MHz annular array using fine-grain lead titanate , 2002, SPIE Medical Imaging.

[32]  K. Raum,et al.  Pulse-echo field distribution measurement technique for high-frequency ultrasound sources , 1997, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.