Design and Fabrication of Ultrafine Piezoelectric Composites

Abstract

Making fine scale (<20 μm) piezoelectric composites for high frequency (>50 MHz) ultrasound transducers remains challenging. Interdigital phase bonding (IPhB), described in this paper, presents a new technique developed to make piezoelectric composites at the ultrafine scale using a conventional dicing saw. Using the IPhB technique, a composite structure with a pitch that is less than the dicing saw blade thickness can be created. The approach is flexible enough to make composites of different combination of pitch and volume ratio. Using a conventional dicing saw with a 50 μm thick blade, composite with a 25 μm pitch and a volume ratio of 61 percent are fabricated. Such a composite is suitable for fabrication of ultrasonic transducers and arrays with central frequencies of up to 85 MHz. Single element transducers working at central frequencies of 50–60 MHz were made of these composites as a mean to characterize the acoustic performance. Measurement results of the transducers show that the longitudinal electromechanical coupling coefficient is greater than 0.6 and that there are no noticeable lateral resonances in the frequency range of 55-150 MHz. Design criteria for fine scale elements are also discussed based on theoretical results from finite element analysis (FEA).

Keywords

Composite high frequency transducer ultrasound

Get full access to this article

View all access options for this article.

References

Foster

Pavlin

Lockwood

Principles and applications of ultrasound backscatter microscope, IEEE Trans Ultrason Ferroelect Freq Contr 40, 608–617 (1993).

Foster

Zhang

Zhou

A new ultrasound instrument for in vivo microimaging of mice, Ultrasound Med& Biol 28, 1165–1172 (2002).

Lerch

Simulation of piezoelectric devices by two-and three-dimensional finite elements, IEEE Trans Ultrason Ferroelect Freq Contr 37, 233–247 (1990).

Smith

. The role of piezocomposites in ultrasonic transducers, in Proc 1989 IEEE Ultrason Symp pp. 755–766 (1989).

Canata

Zhou

Shung

. Development of a high frequency (35MHz) linear ultrasonic array using 2–2 composite elements, in Proc 2004 IEEE Ultrason Symp, pp. 894–897 (2004).

Ritter

Shrout

Tutwiler

Shung

. A 30-MHz piezo-composite ultrasound array for medical imaging applications, IEEE Trans Ultrason Ferroelect Freq Contr 49, 217–230 (2002).

Lukacs

Sayer

Lockwood

Foster

. Laser micromachineed high frequency ultrasonic arrays, in Proc 1999 IEEE Ultrason Symp, pp. 1209–1212 (1999).

Liu

Harasiewicz

Foster

. Interdigital pair bonding for high frequency (20–50) ultrasonic composite transduc ers, IEEE Trans Ultrason Ferroelect Freq Contr 48, 299–306 (2001).

Canata

Shung

. A comparison of model and experiment for a high frequency(35 MHz) linear ultrasonic array, in Proc 2003 IEEE Ultrason Symp, pp. 1658–1662 (2003).

10.

Michau

Mauchamp

Dufait

Piezocomposite 30MHz linear array for medical imaging: design challenges and performances evaluation of a 128 elements array, in Proc 2004 IEEE Ultrason Symp, pp. 898–901 (2004).

11.

Leedom

Krimholtz

Matthaei

. Equivalent circuits for transducers having arbitrary even-or odd-symmetry piezoelectric excitation, IEEE Trans Son Ultrason 18, 128–141 (1971).