Resonance modes and losses in 1-3 piezocomposites for ultrasonic transducer applications

Geng, Xuecang; Zhang, Q. M.

doi:10.1063/1.369265

Cited by 42 publications

(15 citation statements)

References 16 publications

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“…It has been reported that the presence of polymers is a primary limiting factor for use of piezocomposites in harsh environmental conditions [26]. A wide variety of polymers has been used as the passive components in piezocomposites.…”

Section: Composite Materialsmentioning

confidence: 99%

High Temperature, High Power Piezoelectric Composite Transducers

Lee

Zhang

Bar‐Cohen

et al. 2014

Sensors

157

106

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Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined.

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Section: Composite Materialsmentioning

confidence: 99%

High Temperature, High Power Piezoelectric Composite Transducers

Lee

Zhang

Bar‐Cohen

et al. 2014

Sensors

157

106

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“…Low Y r polymer matrix is preferred for 1-3 composite filler as it improves electromechanical coupling of composites [27] . In addition, polymer (I) shows low viscosity and attenuation coefficient, which reflect low elastic loss [28][29] . This may allow for better electromechanical performance of composites (I) under high drive operations.…”

Section: Characterization Methodsmentioning

confidence: 99%

Smart materials for high power applications

2013

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Various PZT/epoxy 1-3 composites were investigated for high power applications. "Hard" lead zirconate titanates (PZT4 and PZT8) were chosen for active piezoelectrics owing to their high mechanical quality factors, Q m s, while the passive polymers were selected based on the desired properties for high power composites -low elastic loss, low elastic modulus and high thermal conductivity. The results demonstrated that the composites with high thermal conductivity polymers generally have degraded electromechanical properties with significantly decreased mechanical quality factors, whereas the composites filled with low loss and low moduli polymers were found to have higher Q m s with higher electromechanical coupling factors k t : Q m ~ 200 and k t ~ 0.68 for PZT4 composites; Q m ~ 400 and k t ~ 0.6 for PZT8composites. The effects of high drive field on the behavior of 1-3 composites were further investigated by varying active and passive components. Improved high power characteristics of 1-3 piezoelectric composites were achieved by selection of optimized composite components, with enhanced electromechanical efficiency and thermal stability under high drive conditions. I． INTRODUCTIONPiezoelectric transducers are widely employed in a range of medical applications, including ultrasound diagnostic imaging and ultrasound therapy, such as high intensity focused ultrasound (HIFU), which has recently attracted lot of attentions as a therapeutic treatment for benign prostatic hypertrophy, prostate cancer, bladder cancer, liver cancer, and benign and malignant lesions of the kidney and breast, and expected to provide patients with a noninvasive, nonionizing therapy for these lesions [1] . HIFU destroy targeted tissues by rapidly heating them to temperatures approaching 60 o C or higher, as a result of absorption of high acoustic energy from the transducer. The single-transducer approach uses frequencies between 0.5 and 10MHz, with focusing the intensity varies per procedure between 10 2 and 10 4 W/cm 2 , over a time period of 1 to 30 seconds. A phased-array transducer designed for HIFU typically is constructed of 1-3 PZT/epoxy composite elements that provide high acoustic power over a higher bandwidth [2] .Currently, high power applications are limited by the internal power dissipation, which will generate heat and increasing hysteretic effects resulting in thermal instability. For the generation of high power ultrasound, high electromechanical coupling k ij and mechanical quality factor Q m of piezoelectric materials are desired, where the high electromechanical coupling factor permits effective energy conversion from electrical energy to mechanical energy and allows for increased transducer bandwidth, while the high mechanical quality factor reduces heat generation under high drive condition [3] .*

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“…For the same reason, the width ( w ) of the piezoelectric elements should be less than v L /(2 f ), where v L is the lateral wave velocity of a piezoelectric element. The general guideline for the spatial scale of a 1–3 composite is the stopband edge resonant frequency should be located more than two times the fundamental thickness resonant frequency, which gives the following conditions for the composite design [15], [16]:

s < \frac{v_{normalS}}{4 f}, and w < \frac{v_{normalL}}{4 f} .

…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

Design of low-loss 1-3 piezoelectric composites for high-power transducer applications

Lee

Zhang

2012

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Lead zirconate titanate (PZT)/polymer 1–3 composites have improved electromechanical properties compared with monolithic counterparts, but possess a low mechanical quality factor, limiting their use in high-power transducer applications. The goal of this work was to improve the mechanical quality factor of 1–3 PZT/polymer composites by optimizing the polymer materials. Theoretical analysis and modeling were performed for optimum composite design and various polymers were prepared and characterized. 1–3 piezocomposites were constructed and their electromechanical properties were experimentally determined. The results demonstrated that the composites with high-thermal-conductivity polymers generally have degraded electromechanical properties with significantly decreased mechanical quality factors, whereas the composites filled with low-loss and low-moduli polymers were found to have higher mechanical quality factors with higher electrome-chanical coupling factors: Qm ~ 200 and kt ~ 0.68 for PZT4 composites; Qm ~ 400 and kt ~ 0.6 for PZT8 composites. The improved mechanical quality factor of 1–3 piezocomposites may offer improved performance and thermal stability of transducers under high-drive operation.

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Resonance modes and losses in 1-3 piezocomposites for ultrasonic transducer applications

Cited by 42 publications

References 16 publications

High Temperature, High Power Piezoelectric Composite Transducers

High Temperature, High Power Piezoelectric Composite Transducers

Smart materials for high power applications

Design of low-loss 1-3 piezoelectric composites for high-power transducer applications

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