Composite Transducer Research Articles

Models for designing radially polarized multilayer piezoelectric/elastic composite cylindrical transducers

The models for designing multilayer piezoelectric/elastic composite cylindrical transducers with two kinds of radial polarization directions are extended based on the typical sandwiched piezoelectric/elastic transducer, and their dynamic characteristics are performed. Based on the plane stress assumption, dynamic analytical solutions of the transducers subjected to an external harmonic voltage are derived, and the electric admittances are obtained. The effects of polarization directions, the inner radius of the transducers, the distance between two adjacent piezoelectric layers, the number of piezoelectric layers, and piezoelectric material types on the dynamic characteristics of the transducers are discussed. For some special cases, comparisons with other related investigations are also given, and good agreements are found. The present investigation provides a comprehensive understanding of multilayer piezoelectric/elastic composite cylindrical transducers, which have potential applications in the field of ultrasonic and underwater sound.

Modeling and optimization of adjustable multifrequency axially polarized multilayer composite cylindrical transducer

A novel adjustable multifrequency axially polarized multilayer composite cylindrical transducer is developed in this paper. The transducer is composed of two parts: an actuator part and a sensor part. Each part is considered as a multilayer piezoelectric/elastic composite structure. The actuator part is utilized to actuate the transducer, while the senor part is used to adjust its dynamic characteristics through connecting to an external electric resistance. Based on the plane stress assumption, the radial vibration of this new kind of transducer is analyzed, and its input electric admittance is derived analytically. Comparisons with the earlier works are conducted to validate the theoretical solution. Furthermore, numerical analysis is performed to study the effects of the external electric resistance on the transducer’s dynamic characteristics, such as resonance and anti-resonance frequencies, as well as the corresponding electromechanical coupling factor. Numerical results show that the multifrequency cylindrical transducer can be designed through adjusting the external electric resistance and the ratio of piezoelectric layer numbers between the actuator part and the sensor part. In addition, the optimized transducer can be proposed at the matching electric resistance. The proposed cylindrical transducer plays an important role in designing the cymbal transducer, which can be used in underwater sound projectors and ultrasonic radiators.

Research of Ultrasound-Mediated Transdermal Drug Delivery System Using Cymbal-Type Piezoelectric Composite Transducer

Transdermal drug delivery (TDD) implemented by especially low-frequency ultrasound is generally known as sonophoresis or phonophoresis which has drawn considerable wide attention. However, TDD has not yet achieved its full potential as an alternative to conventional drug delivery methods due to its bulky instruments. In this paper, a cymbal-type piezoelectric composite transducer (CPCT) which has advantages over a traditional ultrasound generator in weight, flexibility, and power consumption, is used as a substitute ultrasonicator to realize TDD. First, theoretical research on a CPCT based on the finite element analysis was carried out according to which a series of applicable CPCTs with bandwidths of 20 kHz to 100 kHz were elaborated. Second, a TDD experimental setup was built with previously fabricated CPCTs aimed at the administration of glucose. Finally, the TDD performance of glucose molecule transport in porcine skin was measured in vitro by quantifying the concentration of glucose, and the time variation curves were subsequently obtained. During the experiment, the driving wave form, frequency, and power consumption of the transducers were selected as the main elements which determined the efficacy of glucose delivery. The results indicate that the effectiveness of the CPCT-based delivery is constrained more by the frequency and intensity of ultrasound rather than the driving waveform. The light-weight, flexibility, and low-power consumption of a CPCT can potentially achieve effective TDD.

Sol-gel composite ultrasonic transducers

Sol-gel composite ultrasonic transducers

Preparation and Properties of 1-3 Piezoelectric Composite Transducers

This study demonstrated the preparation of 1-3 piezoelectric composite transducers by using 1-3 piezoelectric composites as the active phases, air as the backing layer and polyurethane as the matching layer. The composite electrode was produced by electroless nickel coating and the effect of the matching layer on transducer performance was investigated in detail. The results showed that the matching layer could improve the receiving sensitivity of the transducer significantly. The receiving response value of the transducer at first increased and then decreased with the increase of the matching layer thickness. This receiving response had the largest head-wave amplitude value when the thickness of the matching layer was about 2.2 mm, which was in good agreement with the theoretical value. The resonance frequency of the transducer in water showed a tendency of low frequencies, and the bandwidth of the transducer in water became much wider than that in air. The reasonable matching layer could improve performance of the transducer effectively.

Simulation of 1-3 Piezoelectric Composite Cylindrical Transducer

A cylindrical transducer consisting of 1-3 piezoelectric composite was designed. Several rectangular bar elements were arrayed and adhered on the cylindrical backing to become a tubular transducer. The elements were 1-3 piezoelectric ceramic/polymer composites. The lumped characteristic parameters of 1-3 piezoelectric composite were obtained according to Smith's model. Two type models of transducer were established and simulated by ANSYS. One model was same to the actual transducer element. The other was an approximate element of the piezoelectric tube by using the lumped characteristic parameters. The radial vibration mode of two type models was analyzed. The simulation results indicated that the frequency of transducer were respectively 8.9 kHz and 8.7 kHz under radial vibration mode. The relative deviation in two type models is less than 2%.

Computer Aided Analysis of Systems with MFC Actuators

Work presents an analysis and computer aided simulation of one-dimensional vibrating system with advanced piezoelectric transducer used as vibration actuator. A Macro Fiber Composite (MFC) transducer is used in order to excite vibration of the system. The mechanical subsystem is a cantilever bending beam made of steel. The MFC transducer is bonded to the beams surface. Analytical calculations are based on an approximate Galerkin method. The computer aided simulation and analysis of the considered system was carried out using Siemens NX software.

High temperature, high power piezoelectric composite transducers.

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.

Damage location by ultrasonic Lamb waves and piezoelectric rosettes

An approach based on macro-fiber composite transducer rosettes and ultrasonic guided waves is proposed for damage location in plate-like structures. By using the directivity behaviour of the three macro-fiber composite sensors in each rosette, the direction of an incoming wave generated by scattering from damage can be estimated without knowledge of the wave velocity in the structure. Two rosettes suffice to identify the location of a scatterer in a planar structure. The technique does not have the drawbacks of time-of-flight triangulation, requiring information on wave velocity that complicates the damage location when testing anisotropic materials, tapered sections or any structure under temperature fluctuations. The effectiveness of the piezoelectric rosette method is tested experimentally on an aluminium plate with a simulated damage subjected to temperature variation.

Design of micromachined self-focusing piezoelectric composite ultrasound transducer.

Based on the Fresnel half-wave band interference, a micromachined self-focusing piezoelectric composite ultrasound transducer was proposed in this paper. The theoretical analysis was deduced based on the concept of constructive interference of acoustic waves and electromechanical response of piezoelectric composites. The calculated and simulation results showed that it combined the advantages of composite transducer and plate self-focusing transducer, and can achieve high electromechanical coupling coefficient, low acoustic impedance, high intensity, short focal length and micro size. Because it was based on the micro-electromechanical systems, the fabrication process was accurate and controllable, which made it have good potential for interventional ultrasound imaging, cellular microstructure imaging, skin cancer detection and industrial nondestructive testing applications.

Micromachined PIN-PMN-PT crystal composite transducer for high-frequency intravascular ultrasound (IVUS) imaging.

In this paper, we report the use of micromachined PbIn1/2Nb1/2O3-PbMg1/3Nb2/3O3-PbTiO 3 (PIN-PMNPT) single crystal 1-3 composite material for intravascular ultrasound (IVUS) imaging application. The effective electromechanical coupling coefficient kt(eff) of the composite was measured to be 0.75 to 0.78. Acoustic impedance was estimated to be 20 MRayl. Based on the composite, needle-type and flexible-type IVUS transducers were fabricated. The composite transducer achieved an 86% bandwidth at the center frequency of 41 MHz, which resulted in a 43 μm axial resolution. Ex vivo IVUS imaging was conducted to demonstrate the improvement of axial resolution. The composite transducer was capable of identifying the three layers of a cadaver coronary artery specimen with high resolution. The PIN-PMN-PT-based composite has superior piezoelectric properties comparable to PMN-PT-based composite and its thermal stability is higher than PMN-PT. PIN-PMN-PT crystal can be an alternative approach for fabricating high-frequency composite, instead of using PMN-PT.

Bio-applications of ionic polymer metal composite transducers

Traditional robotic actuators have advanced performance which in some aspects can surpass that of humans, however they are lacking when it comes to developing devices which are capable of operating together with humans. Bio-inspired transducers, for example ionic polymer metal composites (IPMC), which have similar properties to human tissue and muscle, demonstrate much future promise as candidates for replacing traditional robotic actuators in medical robotics applications. This paper outlines four biomedical robotics applications, an IPMC stepper motor, an assistive glove exoskeleton/prosthetic hand, a surgical robotic tool and a micromanipulation system. These applications have been developed using mechanical design/modelling techniques with IPMC ‘artificial muscle’ as the actuation system. The systems are designed by first simulating the performance using an IPMC model and dynamic models of the mechanical system; the appropriate advanced adaptive control schemes are then implemented to ensure that the IPMCs operate in the correct manner, robustly over time. This paper serves as an overview of the applications and concludes with some discussion on the future challenges of developing real-world IPMC applications.

Pipe Defect Visualization and Quantification Using Longitudinal Ultrasonic Modes

In this study, a new ultrasonic wave based imaging techniques developed using longitudinal ultrasonic waves for detecting defects in pipeline structures. Ultrasonic waves are gaining popularity for pipeline monitoring because of its sensitivity to small defects and a long sensing range. Based on the merits of the ultrasonic waves, several research groups have developed ultrasonic wave based imaging techniques for pipeline monitoring. Conventionally, a pure torsional mode is often generated using shear-mode piezoelectric transducers or electromagnetic acoustic transducers (EMAT) and used for pipe damage detection. In this study, a new ultrasonic wave based imaging technique is developed using a longitudinal wave mode instead of the pure torsional mode. The longitudinal mode is generated using inexpensive macro fiber composite (MFC) transducers attached at one end of the pipe, eliminating the need for the shear-mode transducers or EMATs. Then, the reflections generated by the interaction of the incident longitudinal mode with a defect are measured in a pulse echo manner. Using a normal mode expansion technique, flexural modes are extracted from the reflected signals. When a defect-induced reflected wave mode is propagated back along the longitudinal direction of the pipe, its dispersive nature is minimized and best-compensated at the defection location. Therefore, by virtually propagating each defect-induced flexural mode back in the wave propagation direction, an image which visualizes the focusing of the back-propagated flexural modes can be obtained and the defect location can be identified. Numerical simulations and experimental tests are conducted to demonstrate that a wall-thinning in a steel pipe can be detected and quantified using the proposed imaging technique.

Energy Harvesting from Ambient Vibrations with Arbitrary In-Plane Motion Directions Using a Magnetostrictive/Piezoelectric Laminate Composite Transducer

A magnetoelectric (ME) vibration energy harvester has been designed to scavenge sufficient energy from ambient vibration with arbitrary motion directions in a plane and over a range of frequencies. In the harvester, a circular-cross-section cantilever rod is adopted to extract the vibration energy due to its ability to host accelerations in arbitrary in-plane motion directions. The magnetic coupling between the magnet and the ME transducer results in nonlinear oscillation of the cantilever rod with increased frequency bandwidth. To achieve optimal vibration energy harvesting performance, the effects of the nonlinear vibration and the harvester parameters including the magnetic circuit and the separation distance on the electrical output and the␣working bandwidth are analyzed. The experimental results show that the harvester can scavenge vibration energy in arbitrary in-plane directions, exhibiting a bandwidth of 4.0 Hz and maximum power of 0.22 mW at acceleration of 0.6g (with g = 9.8 m s−2).

Radially Sandwiched Composite Transducers Composed of the Radially Polarized Piezoelectric Ceramic Circular Ring and Metal Rings

Radially Sandwiched Composite Transducers Composed of the Radially Polarized Piezoelectric Ceramic Circular Ring and Metal Rings

Outstanding work of Kim Benjamin on 1–3 composite transducers and acoustic analysis

Kim Benjamin was one of the most productive acoustic system researchers that I have known. Kim, myself, and Walter Boober developed acoustic techniques that increased the productivity of the NUWC acoustic facility by a factor of 10. Kim and I produced a number of patents related to the use of 1–3 composite transducers in naval sonars. The last effort with Kim produced a small diameter, broad band transducer that was tested successfully. Kim was a Fellow of the ASA and is greatly missed.

Magnetoelectric coupling characteristics of five-phase laminate composite transducers based on nanocrystalline soft magnetic alloy

A five-phase laminate composite transducer based on nanocrystalline soft magnetic FeCuNbSiB alloy is presented, whose magnetoelectric (ME) coupling characteristics have been investigated. It is found that the resonant ME voltage coefficient of FeCuNbSiB/Terfenol-D/Pb(Zr1-x,Tix)O3 (PZT)/Terfenol-D/FeCuNbSiB (FMPMF) five-phase transducer is much larger than that of traditional Terfenol-D/PZT/Terfenol-D (MPM) transducer, resulting from the enhancement of the effective mechanical quality factor and effective piezomagnetic coefficient of the transducers. Appropriate FeCuNbSiB layer thickness is propitious to the resonant and low-frequency ME coupling characteristics. The maximum resonant ME voltage coefficient achieves 4.81 V/Oe with FeCuNbSiB layer thickness is 60 μm under the DC bias magnetic field Hb = 77 Oe, which is 1.48 times as great as that of traditional MPM transducer. In addition, the maximum ME voltage coefficient at low frequency is 51.2 mV/Oe under the DC bias magnetic field Hb = 442 Oe, which is 1.26 times as great as that of traditional MPM transducer. It indicates that the mentioned five-phase laminate composite transducers have great potential for the application of highly sensitive dc magnetic field sensing and vibration energy harvesting.

A transversely coupled phononic surface acoustic wave transducer

A concept is demonstrated for the development of a phononic surface acoustic wave interdigital transducer (IDT) able to excite acoustic waves in a transverse manner with respect to the applied electric field. The basic principles of the design and fabrication of the transversely coupled phononic transducer are presented. More specifically, the IDT consists of a regular interdigital electrode configuration on which a 2D array of low profile masses is superimposed. The transversely coupled mode of excitation is explained in terms of the specific localization of the elastic energy along with the operation within the complete frequency bandgap of the composite transducer grating. The experimental results provide solid evidence for the suggested mode of operation.

A vibration energy harvester using magnet/piezoelectric composite transducer

In this research, a vibration energy harvester employing the magnet/piezoelectric composite transducer to convert mechanical vibration energy into electrical energy is presented. The electric output performance of a vibration energy harvester has been investigated. Compared to traditional magnetoelectric transducer, the proposed vibration energy harvester has some remarkable characteristic which do not need binder. The experimental results show that the presented vibration energy harvester can obtain an average power of 0.39 mW for an acceleration of 0.6g at frequency of 38 Hz. Remarkably, this power is a very encouraging power figure that gives the prospect of being able to power a widely range of wireless sensors in wireless sensor network.

Cymbal Piezoelectric Composite Transducer for Soccer Robot Attitude Detection Application

This paper proposed a soccer robots attitude detection method based on the principle and vibration mode of cymbal piezoelectric composite transducer. Cymbal piezoelectric composite transducers and MEMS-based three-axis low-g sensor were set on some different support points of soccer robot's joint to accomplish attitude detection. The signal processing circuit and algorithm software were designed. The research results showed that the performance parameters of the soccer robot falling down attitude detection system based on cymbal piezoelectric composite transducer are better than the other sensor, such as the sensitivity, correct, undetected fall and stability duration, etc. The experiment results showed that the detection accuracy for falling down of the soccer robot can be 98% and the stability duration can be 60 minutes.