Manufacturing and experimental investigation of 2-2 piezocomposite transducer arrays (original) (raw)
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A 20 MHz high density linear array transducer is presented in this paper, This array has been developed using an optimized ceramic-polymer composite material. The electro-mechanical behaviour of this composite, especially designed for high frequency applications, is characterised and the results are compared to theoretical predictions. To support this project, a new method of transducer simulation has been implemented. This simulation software takes into account the elementary boundary phenomena and allows prediction of inter-element coupling modes in the array. The model also yields realistic computed impulse responses of transducers, A miniature test device and water tank have been constructed to perform elementary acoustic beam pattern measurements. It is equipped with highly accurate motion controls and a specific needle-shaped target has been developed. The smallest displacement available in the three main axes of this system is 10 microns. The manufacturing of the array transd...
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Physics Letters A, 2021
Analytical models can be useful tools to develop efficient transducers dedicated to a specific application field. This work proposes a homogenization technique for establishing the effective coefficients and parameters of 1-3 piezocomposite whose both phases are piezoelectrically active. Such piezocomposite materials may have homogenized electromechanical properties resulting from positive hybrid effect. A numerical simulation of the effective parameters resulting from a PZT-5A / PVDF-TrFE composition shows that, volume fraction influences significantly on the properties of the piezocomposite and consequently on its behavior in service. As an end-user application for ultrasound imaging, those piezocomposite materials are effectively integrated in a piezocomposite transducer, coupled with a dedicated backing. The resulting characteristics in terms of impulse response and associated electroacoustic echo are compared and discussed for typical configurations. A method for the optimization of the design of such piezocomposite transducer is presented. Specific estimators based on the bandwidth flatness BWF and bandwidth amplitude product BWA are proposed as stable and smooth criteria for an optimization procedure.
2-2 PZT-polymer composites for high frequency (<20 MHz) ultrasound transducers
2002 IEEE Ultrasonics Symposium, 2002. Proceedings., 2002
The aim of this research is to produce single element and array transducers with resonance frequencies ranging from 20 to 50 MHz. By using tape-cast PZT with fugitive phase, PZT/polymer 2-2 composites can be made for higher sensitivity and bandwidth than existing high frequency technologies. Tape casting methods for fabricating 2-2 PZT/polymer composites were developed with specific emphasis placed on achieving uniform beam and kerf thickness. Initial prototypes were fabricated into single element transducers, and the effect of composite uniformity was determined from impedance measurements. Targeted applications for this technology are disposable catheter transducers for intravascular imaging.
Design considerations for 1-3 composites used in transducers for medical ultrasonic imaging
Ceramic polymer piezoelectric composites with 1-3 connectivity have become an important tool in the design and manufacture of thickness mode transducers for medical diagnostic ultrasonic imaging. The major reasons for this are that, relative to piezoelectric ceramics alone, the composite can be designed with higher thickness coupling coefficient. acoustic impedance can be more closely matched to human tissue, arid low frequency lateral resonances can be suppressed. These improvements can lead to higher sensitivity and bandwidth in the transducer and reduce ringing due to unwanted modes of vibration. This paper compares annular array transducers made from ceramics alone to those made with composites to demonstrate the advantages of composites, and examines some of the trade-offs involved in optimizing composite designs for this application. Effects of varying Young's modulus and Poisson's ratio of the polymer phase on coupling coefficient and high frequency lateral resonances of the composite are presented.
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Piezocomposite design for dedicated ultrasonic imaging applications requires precise homogenization models for predicting the electromechanical characteristics of the new material. Thus, several homogenization models have been developed. As part of this work, we applied several analytical homogenization models for piezocomposite of 2–2 and 1–3 connectivities. To validate these analytical models, a comparative study was made between various models and experimental measurements. As a result, these homogenized electromechanical properties are effectively used for the calculation and comparison of electroacoustic response for typical transducers aimed at ultrasound imaging applications. An optimal design of transducer aimed at ultrasound imaging applications is proposed as a dedicated imaging performance index, elaborated through a trade-off between sensitivity and bandwidth.
Modeling and experimental study of transducers made with piezoelectric composite material
Le Journal de Physique IV, 1999
The topic of this work is the experimental and theoretical study of a cylindrical acoustic transducer made with a 1.3 piezoelectric composite material. This material consists in PZT ceramic rods embedded in a polymer matrix. A modeling of this ideal transversally periodic structure is proposed. It is based on a finite element approach derived from homogenization techniques mainly used for composite material studies. The analysis focuses on a representative unit cell with specific boundary conditions on the lateral surfaces taking accurately into account the periodicity of the structure. The first step proposed is the development of a tridimensional Fortran code especially adapted for this problem. It then allowed the set up of different nonredundant linear combinations of degrees of freedom that could be linked to the ANSYS FEM code allowing to progress toward the modeling of the complete problem. The motion of the faces of an experimental transducer vibrating in the quasi-static mode has been analyzed using Laser Doppler vibrometry technique. Experimental and modeling results are in good agreement and justify the proposed approach.
UNIDIMENSIONAL MODELING AND CONSTRUCTION OF A 1-3 PIEZOELECTRIC COMPOSITE TRANSDUCER
2000
In many applications, such as medical imaging and nondestructive testing, broadband ultrasonic transducers capable of producing short pulses are required. Combining a piezoelectric element and a passive polymer to form a piezoelectric composite allows the development of transducers with high bandwidth and sensitivity, and low radial coupling. This work presents the modeling and construction of an ultrasonic transducer using a 1-3 piezoelectric composite. A simple physical model is used to calculate the effective properties of the composite. This model can be applied when the lateral spatial scale of the composite is sufficiently small so that the composite can be treated as an effective homogeneous medium. The effective properties are used in a distributed matrix model to calculate the electrical impedance of the composite. It is used the dice-and-fill technique to construct a 1-3 lead zirconate titanate(PZT)/epoxy 800 kHz, 20 mm diameter composite. The simulated results of the electrical impedance are compared with the experimental results measured by an impedance analyzer equipment. Finally, the ultrasonic transducer is constructed using the piezoelectric composite. The impulse response of the transducer is measured and compared with the theoretically obtained using the distributed matrix model. The experimental results show excellent agreement with the simulated ones. , Ouro Preto, MG
High temperature, high power piezoelectric composite transducers
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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...