Piezoelectric hydrophones from optimal designs, Part I: fabrication (original) (raw)

Microconfigured piezoelectric artificial materials for hydrophones

Journal of Materials Science, 2007

Piezoelectric PZT–air composites with a complex design optimized for hydrophones were fabricated as arrays of hundreds of 60 μ units using a microfabrication technique involving coextrusion of mixtures of thermoplastic with PZT powder or carbon powder. The measured piezoelectric coefficient was 300 pC/N with a figure of merit of 18 pm2/N, in excellent agreement with the predicted properties.

On the use of homogenization theory to design optimal piezocomposites for hydrophone applications

Journal of the Mechanics and Physics of Solids, 1997

We consider an optimal design of composite hydrophones consisting of parallel piezoelectric PZT rods that are embedded in a porous polymer matrix. Given the material properties of the polymer and PZT ceramic, we have optimally designed the piezocomposite to maximize the hydrostatic coupling factor, hydrophone figure of merit, or electromechanical coupling factor, using the methods of homogenization theory. The optimal composite is obtained by using a two-step procedure : (i) first we find the ideal structure of the matrix material by weakening the polymer by an optimal arrangement of pores, and (ii) then we embed the PZT rods in this matrix. The design parameters are the shape, volume fraction, and spatial arrangement of the piezoceramic rods, and the structure of the matrix material. It turns out that the optimal matrix is highly anisotropic and is characterized by negative Poisson's ratios in certain directions. The optimal composites possess performance characteristics that are significantly higher than those of a piezocomposite with an isotropic polymer matrix. The results can be viewed as theoretical upper bounds on the hydrophone performance.

Porous piezoelectric ceramic hydrophone

The Journal of the Acoustical Society of America, 1999

The construction and evaluation of a hydrophone based on porous piezoelectric ceramics with high d h g h figure of merit ͑FOM͒ is described. It has been shown that, in order to improve the hydrophone signal-to-noise ratio, a piezoelectric material with a high FOM should be employed. A porous piezoelectric material has been prepared by mixing calcined lead zirconate titanate ͑PZT͒ powder with fine particle starch powder. Square plate samples have been cold pressed from this material, which were then heated to eliminate the organic component, sintered, electroded, and poled in a high electric field. An optimum pore volume fraction of approximately 40% has been selected in order to obtain materials with high piezoelectric coefficients and reasonably good mechanical resistance. For this composition a hydrostatic figure of merit of approximately 10 Ϫ11 m 2 /N has been obtained that is a few orders of magnitude higher than traditional piezoceramics. Square plate elements were assembled in a planar hydrophone which was made watertight with polyurethane resin. The hydrophone was characterized by different measurements performed in a water tank, by using a pulsed sound technique. Results on acoustical sensitivity measurements, directivity, equivalent noise pressure level, and sensitivity variation with pressure are presented and discussed.

Optimal design of 1-3 composite piezoelectrics

An optimal design problem for piezoelectric composite hydrophones is considered. The hydrophone consists of parallel piezoelectric rods embedded in a porous transversely isotropic polymer matrix. We find the shape, volume fraction, and spatial arrangement of the piezoceramic rods, and the structure of the matrix material that maximizes the hydrophone performance characteristics. We found that the optimal composite consists of a hexagonal array of rods with small volume fraction, in a highly anisotropic matrix that is characterized by negative Poisson's ratios in certain directions. The performance characteristics of hydrophones with such a matrix are significantly higher than those with an isotropic polymer matrix. The results can be viewed as theoretical upper bounds on the hydrophone performance.

Some aspects of the piezoceramic materials utilized in sensitive hydrophones

Sensors and Actuators A: Physical, 1997

This paper establishes the experimental observations of the correspondence between lhe characteristics of piezoceramic materials and the sensitivity of narrow-band frequency hydrophones, The hydrophoncs realized in the laboratory are of narrow bandwidth with high sensiti~,ity. They can be successfully utilized in marine communication (voice communication between divers or data transmission) because they are like selective filters for the ultrasonic frequencies.

A single-crystal acoustic hydrophone for increased sensitivity

The Journal of the Acoustical Society of America, 2013

This study describes the development of an underwater surveillance hydrophone based on next generation Lead Magnesium Niobate-Lead Titanate (PMN-PT) single-crystal piezoelectric as the hydrophone substrate. Although PMN-PT can possess much higher piezoelectric sensitivity than traditional PZT piezoelectrics, it is highly anisotropic and therefore there is a large gain in sensitivity only when the crystal structure is oriented in a specific direction. Because of this, simply replacing the PZT substrate with a PMN-PT cylinder is not an optimal solution because the crystal orientation does not uniformly align with the circumferential axis of the hydrophone. Therefore, we have developed a novel composite hydrophone that maintains the optimal crystal axis around the hydrophone circumference. An composite hydrophone cylinder was fabricated from a single <110> cut PMN-PT rectangular plate. Solid end caps were applied to the cylinder and the sensitivity was directly compared with a solid PZT-5A cylindrical hydrophone of equal dimensions in a hydrophone test tank. The charge sensitivity showed a 9.1 dB improvement over the PZT hydrophone and the voltage sensitivity showed a 3.5 dB improvement. This was in relatively good agreement with the theoretical improvements of 10.1 dB and 4.5 dB respectively Published by the Acoustical Society of America through the American Institute of Physics Brown et al.

Multiobjective Pareto-Based Optimization of pMUT Hydrophone With Piezoelectric Active Diaphragm

Volume 3: Engineering Systems; Heat Transfer and Thermal Engineering; Materials and Tribology; Mechatronics; Robotics, 2014

The design of high-sensitive hydrophones is one of the research interests in underwater acoustics. Due to progress of micro-and nanotechnology the most attention of researchers is attracted by the transducers that use the microelectromechanical system (MEMS) concept. Piezoelectric micro-machined ultrasonic transducers (pMUTs) present a new approach to sound detection and generation that can overcome the shortcomings of conventional transducers. For accurate ultrasound field measurement, small size hydrophones which are smaller than the acoustic wavelength are required for providing an omnidirectional response and avoid spatial averaging.

Hydrophone Arrays Assembled from PZT Ceramic Foams

Integrated Ferroelectrics, 2004

A 3 × 3 hydrophone array for low frequency applications was constructed from reticulated PZT ceramic foams. The hydrophone array was tested for receiving sensitivity and compared with single element PZT-air and dense PZT hydrophones. The composite array showed a flat response in the 20 kHz-100 kHz frequency range while the single element hydrophone displayed broadening radial resonance around 50 kHz. The flat, broadband response indicates that the radial resonance is suppressed by both porous nature of the PZT-air composites and the array construction of the hydrophone. The sensitivity of the array hydrophone was -205 dB re 1 VµPa −1 .

Finite element modelling of dense and porous piezoceramic disc hydrophones

Ultrasonics, 2005

The acoustic characteristics of dense and porous piezoceramic disc hydrophones have been studied by finite element modelling (FEM). The FEM results are validated initially by an analytical model for a simple disc of dense piezoceramic material and then it is extended to a porous piezoceramic disc replicating a foam-reticulated sample. Axisymmetric model was used for dense piezoceramic hydrophone due its regular geometric shape. 3-dimensional model was used for the porous piezoceramics, since the unit cell model is inadequate to fully represent transducers of finite lateral dimensions. The porous PZT discs have been synthesised by foam-reticulation technique. The electrical impedance and the receiving sensitivity of the hydrophones in water are evaluated in the frequency range 10-100 kHz. The model results are compared with the experimental data. The receiving sensitivity of piezocomposite hydrophones is found to be reasonably constant over the frequency range studied. The sharp resonance peaks observed for the dense piezoceramic hydrophone has broadened to a large extent for porous piezoceramic hydrophones, indicating higher losses. The flat frequency response suggests that the 3-3 piezocomposites are useful for wide-band hydrophone applications.

Comparative Study of Different Piezo-Electric Materials Based Ultrasonic Transducer Model

In recent years, MEMS (micro-electrical mechanical systems) microphones have been used as low-cost alternatives to more costly phased arrays condenser microphones. More study of MEMS has shown significant importance for miniaturized mechanical system, based on silicon technology. Prior to fabrication of MEMS device design and simulation are extensively need to avoid expensive time and cost. The goal of the present work is to described the design of piezo electric transducer; particularly ultrasonic microphone. This microphone device is generally useful for generation of sound either in air or in water. COMSOL Multiphysics 4.1 is versatile software is used to solve the microphone device with 3D partial differential equations. In this paper, 2D axis-symmetry model geometry of phase arrays microphone was designed with lead zirconate titanate (Pb [Zr x Ti 1-x ] O 3) and barium sodium niobate (Ba 2 NaNb 5 O 15) piezo-electric materials. To investigate with the lead contact PZT with respect to lead free BNN materials has been carried out. The surface and radial displacement of the microphone structure of both the materials with pressure are studied.