Fabrication of 1-3 Piezocomposites via Soft Mold Method for High-frequency Ultrasound Transducer

doi:10.15541/jim20210282

Abstract

Abstract:

The high-frequency ultrasonic technology has been widely used for the fine structures medical imaging of skin, eye and vessel as its high spatial resolution. 1-3 piezocomposite plays an important part in the high frequency transducer owing to the excellent electromechanical coupling properties of this material even at high frequency. However, its industrial applications were limited by the inefficient fabrication methods and expensive equipment, such as mechanical cutting-filling and plasma/laser etching. In this work, a low-cost and novel soft mold method was developed to fabricate 1-3 piezoelectric composites with high electromechanical coupling coefficient k_t for high frequency ultrasound transducers. The process of soft mold filling, hot-pressed sintering PZT pillars and epoxy curing was ruly carried out. Then, a series of samples with different thicknesses were fabricated and characterized. It demonstrates that the fabricated PZT pillars with pure rhombohedral phase are homogeneous. Besides, the length to diameter ratio of sintered pillars is 10 : 1 and the k_t of the 1-3 piezocomposite reaches as high as 64% for the 30-50 MHz high frequency transducer. The result indicates that the soft mold method is an economical and effective way to fabricate the 1-3 piezoelectric composites for medical and biological imaging in high frequency ultrasound applications.

Key words: 1-3 piezoelectric composite, soft mold method, high frequency ultrasonic, piezoelectric ceramics

CLC Number:

TQ174

TIAN Junting, LI Xiaobing, DING Weiyan, NIE Shengdong, LIANG Zhu. Fabrication of 1-3 Piezocomposites via Soft Mold Method for High-frequency Ultrasound Transducer[J]. Journal of Inorganic Materials, 2022, 37(5): 507-512.

Figures/Tables 7

Fig. 1 Sketch of soft mold method for 1-3 piezocomposites fabrication

Fig. 2 PZT ceramic pillars prepared via soft mold method (a) SEM image of PZT ceramic pillars; (b) SEM image of the details for local pillars; (c) Distribution of Pb, Zr, Ti elements contents along the radial direction of a pillar; (d) XRD pattern of the PZT pillars

Fig. 3 Frequency dependent impedances and phase angles of the PZT/Epoxy 1-3 piezocomposites with different thicknesses

Table 1 Electrical impedance property of 1-3 piezocomposites of the samples with different thicknesses

Sample	l/mm	d/mm	ā/mm	f_r/MHz	f_a/MHz	N/(Hz·m)
1#	0.20	0.30	0.03	6.269	5.493	1254
2#	0.25	0.30	0.03	5.902	5.28	1476
3#	0.30	0.30	0.03	5.549	4.99	1665
4#	0.35	0.30	0.03	5.143	4.62	1800
5#	0.40	0.30	0.03	4.849	4.306	1940
6#	0.45	0.30	0.03	4.18	3.65	1881

Fig. 4 Thickness dependent resonant, anti-resonance frequencies and electromechanical coupling factors for 1-3 piezocomposite

Fig. 5 Frequency dependent impedances and phase angles of the 1-3 piezocomposite in medical high-frequency ultrasound transducer

Table 2 Piezoelectric and acoustic property of the piezoelectric materials for high-frequency transducers

Material	f_a/MHz	k_t	Q_m	Z_a/MRayl
PMNT crystal^[20]	45.0	0.55	100	37
PZT composite^[20]	57.5	0.68	-	15.3
PZT-5H	43.7	0.52	65	34
This work	31.6	0.64	72	10.8

References 20

[1]	MA X W, CAO W W. Single crystal high frequency intravascular ultrasound transducer with 40 micron axial resolution. IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2020,67(4):810-816.
[2]	LI S, TIAN J, JIANG X. A micromachined PMN-PT single crystal composite circular array for intravascular ultrasound imaging. Journal of Engineering and Science in Medical Diagnostics and Therapy, 2019,2(2):021001.
[3]	XU J L, ZHANG Z, LIU S X, et al. Optimizing the piezoelectric vibration of Pb(Mg_1/3Nb_2/3)O₃-0.25PbTiO₃ single crystal by alternating current polarization for ultrasonic transducer. Applied Physics Letters, 2020,116(20):202903.
[4]	SMITH W A, AULD B A. Modeling 1-3 composite piezoelectrics: thickness-mode oscillations. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 1991,38(1):40-47.
[5]	LEE J S, MOON J Y, CHANG J H. A 35 MHz/105 MHz dual-element focused transducer for intravascular ultrasound tissue imaging using the third harmonic. Sensors, 2018,18(7):2290.
[6]	ZHOU D, CHEUNG K F, CHEN Y, et al. Fabrication and performance of endoscopic ultrasound radial arrays based on PMN-PT single crystal/epoxy 1-3 composite. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 2011,58(2):477-484.
[7]	WANG J S, CHEN M Z, ZHAO X Y, et al. Fabrication and high acoustic performance of high frequency needle ultrasound transducer with PMN-PT/Epoxy 1-3 piezoelectric composite prepared by dice and fill method. Sensors and Actuators A: Physical, 2021,318:112528.
[8]	CHEN R H, LAN C L. Fabrication of high-aspect-ratio ceramic microstructures by injection molding with the altered lost mold technique. Journal of Microelectromechanical Systems, 2001,10(1):62-68.
[9]	CERTON D, PATAT F, LEVASSORT F,et al. Lateral resonances in 1-3 piezoelectric periodic composite: modeling and experimental results. Journal of the Acoustical Society of America, 1997,101(4):2043-2051.
[10]	BENT A A, HAGOOD N W. Piezoelectric fiber composites with interdigitated electrodes. Journal of Intelligent Material Systems and Structures, 1997,8(11):903-919.
[11]	WANG S N, LI J F, WATANABE R, et al. Fabrication of lead zirconate titanate microrods for 1-3 piezocomposites using hot isostatic pressing with silicon molds. Journal of the American Ceramic Society, 2004,82(1):213-215.
[12]	WANG S N, LI J F, LI X H,et al. Processing of PZT microstructures. Sensors and Materials, 1998,10(6):375-384.
[13]	DONG Y Z, ZHOU Z Y, LIANG R H, et al. Correlation between the grain size and phase structure, electrical properties in BiScO₃-PbTiO₃-based piezoelectric ceramics. Journal of the American Ceramic Society, 2020,103(9):4785-4793.
[14]	PENG J, LUO H S, HE T H, et al. Elastic, dielectric, and piezoelectric characterization of 0.70Pb(Mg_1/3Nb_2/3)O₃-0.30PbTiO₃ single crystals. Materials Letters, 2005,59(6):640-643.
[15]	LIU C G, DJUTH F, ZHOU Q F,et al. Micromachining techniques in developing high-frequency piezoelectric composite ultrasonic array transducers. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 2013,60(12):2615-2625.
[16]	CANNATA J M, RITTER T A, CHEN W H,et al. Design of efficient, broadband single-element (20-80 MHz) ultrasonic transducers for medical imaging applications. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 2003,50(11):1548-1557.
[17]	FANG R R, ZHOU Z Y, LIANG R H, et al. Effects of CuO addition on the sinterability and electric properties in PbNb₂O₆- based ceramics. Ceramics International, 2020,46(15):23505-23509.
[18]	ZIPPARO M, SHUNG K K, SHROUT T R. Piezoceramics for high-frequency (20 to 100 MHz) single-element imaging transducers. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 1997,44(5):1038-1048.
[19]	KRIMHOLTZ R, LEEDOM D A, MATTHAEI G L. New equivalent circuits for elementary piezoelectric transducers. Electronics Letters, 1907,6(13):398-399.
[20]	ZHOU Q F, XU X C, GOTTLIEB E J,et al. PMN-PT single crystal, high-frequency ultrasonic needle transducers for pulsed- wave Doppler application. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 2007,54(3):668-675.