Piezoelectric Elements Research Articles

Review of the State and Prospects of Development and Application of Domestic Multilayer Piezoactuator for Rocket and Space Technology and Ground space Infrastructure

The article gives an overview of the state of development and applications of actuators in the world. A method and technology for manufacturing domestic multilayer piezoelectric elements by the method of slip casting from the piezomaterial of the PZT system and multilayer piezoelectric actuators based on them is described. It is noted that in terms of their technical level, multilayer domestic piezo products correspond to the best foreign samples. Preliminary studies of multilayer piezoelectric products in Russia and abroad have confirmed their unique capabilities when they work in space instrumentation and ground structures for monitoring and controlling space objects. The results of studies on the use of multilayer piezo products of JSC "NII "Elpa" and their foreign analogues in systems are given. The results of the study of various design options for piezoelectric platforms of angular and linear displacements with nanometric accuracy are presented. The optimal design options are selected based on the use of special multilayer piezoactuator APM-1 and APM-2 for their use in rocket and space technology instruments and ground-based space infrastructure. The technology developed at JSC Research Institute Elpa makes it possible to create promising multilayer piezo products of various classes and purposes for rocket and space equipment and ground-based space infrastructure.

Jet Velocity and Acoustic Excitation Characteristics of a Synthetic Jet Actuator

The effect of the excitation frequency of synthetic jet actuators on the mean jet velocity issuing from an array of circular orifices is investigated experimentally, focusing on the acoustic excitation characteristics of the actuator’s cavity. Two cavity configurations are considered. In the first configuration, synthetic jets are generated by exciting a single, large cavity having an array of sixteen orifices via sixteen piezoelectric elements. In the second configuration, the cavity volume of the first configuration is divided into eight isolated compartments, each with two orifices and two piezoelectric elements. Several distinct resonant peaks were observed in the frequency response of the synthetic jet actuator built with a single large-aspect-ratio cavity, whereas the case of compartmentalised cavities exhibited a single resonant peak. Acoustic simulations of the large-aspect-ratio-cavity volume showed that the multiple peaks in its frequency response correspond to the acoustic standing-wave mode shapes of the cavity. Due to its large aspect ratio, several acoustic mode shapes coexist in the excitation frequency range aside from the Helmholtz resonance frequency. When the actuator’s cavity volume is compartmentalised, only the Helmholtz resonance frequency is observed within the excitation frequency range.

A NUMERICAL ANALYSIS OF FORCED STEADY-STATE VIBRATIONS OF AN ELECTRO-VISCOELASTIC SYSTEM IN CASE OF A JOINT IMPACT OF ELECTRICAL AND MECHANICAL LOADS

In the current paper an estimation of a mechanical response of a structure on joint mechanical (force and kinematic) and electrical (voltage and current) impacts taking into account different options of their combinations was carried out. A mechanical response was esteemed basing on solution to the problem of natural vibrations for piecewise-homogeneous electro-viscoelastic bodies. A cantilever plate with piezoelectric element attached to its surface was chosen as an object under study. The plate was made of viscoelastic material the mechanical properties of which are described using complex dynamic moduli. A piezoelectric ceramic material was chosen as the one for piezoelectric elements. An amplitude of forced steady-state vibrations of a component of displacement vector that is perpendicular to the surface of the plate was chosen as a quantity that characterize a mechanical response. Variational equation of motion of the object under consideration is formulated based on relations of linear elasticity, linear viscoelasticity and Maxwell’s equations for a conducting media in a quasistatic approximation. Ranges of changing of values of excitation impacts for vibration modes taken into account were chosen on the basis of values of natural vibrations frequencies obtained from the solution to natural vibration problem for electro-viscoelastic bodies. Numerical implementation of the stated problem was performed in finite element software package ANSYS. Some characteristic peculiarities of a mechanical response depending on a type and magnitude of external impact were obtained as the result of the carried out numerical experiments. There was demonstrated that in case of joint impact of two loading factors there reveals an additional capability of control a mechanical response of an electro-viscoelastic system.

A Tiled Ultrasound Matrix Transducer for Volumetric Imaging of the Carotid Artery.

High frame rate three-dimensional (3D) ultrasound imaging would offer excellent possibilities for the accurate assessment of carotid artery diseases. This calls for a matrix transducer with a large aperture and a vast number of elements. Such a matrix transducer should be interfaced with an application-specific integrated circuit (ASIC) for channel reduction. However, the fabrication of such a transducer integrated with one very large ASIC is very challenging and expensive. In this study, we develop a prototype matrix transducer mounted on top of multiple identical ASICs in a tiled configuration. The matrix was designed to have 7680 piezoelectric elements with a pitch of 300 μm × 150 μm integrated with an array of 8 × 1 tiled ASICs. The performance of the prototype is characterized by a series of measurements. The transducer exhibits a uniform behavior with the majority of the elements working within the -6 dB sensitivity range. In transmit, the individual elements show a center frequency of 7.5 MHz, a -6 dB bandwidth of 45%, and a transmit efficiency of 30 Pa/V at 200 mm. In receive, the dynamic range is 81 dB, and the minimum detectable pressure is 60 Pa per element. To demonstrate the imaging capabilities, we acquired 3D images using a commercial wire phantom.

A rotational energy harvester utilizing an asymmetrically deformed piezoelectric transducer subjected only to unidirectional compressive stress

Energy harvesting using piezoelectric transduction offers a promising alternative to the conversion of kinetic energy like ambient vibration and rotational motion into useful electricity in self-powered electronic devices. To improve the reliability and effective bandwidth of rotational piezoelectric energy harvesters (RPEHs), a novel rotational energy harvester utilizing an asymmetrically deformed piezoelectric transducer excited by a magnetic attractive force is presented in this paper. Unlike the previous most RPEHs where piezoelectric elements experienced the symmetrical bidirectional strain, the presented piezoelectric transducer was only subjected to unidirectional compressive strain. It made the best use of the deformation characteristics of PZT vibrators where their allowable compressive stress was far greater than the allowable tensile stress, thus reducing the damage possibility of PZT vibrators under unexpected heavy loads. To prove the feasibility and explore the influence of the related structural parameters on the power generation performance, the theoretical analysis, simulation, fabrication and experiments were performed for the novel RPEH. The results showed that some parameters like the number ratio (α) and the rotary radius (R) of the exciting magnets brought a strong impact on the response characteristics of the presented RPEH. With the increasing rotary radius R, both the optimal rotating speed and effective bandwidth were decreased, whereas there were few studies on the effect of the rotary radius R of exiting force in previously reported RPEHs. In the case of rotary radius R = 60 mm, the maximum output voltage of 130 V with α = 0.5 was achieved. A maximum output power of 3.89 mW was obtained across 41 kΩ at the rotating speed of 856 r/min. It is expected this research can provide a beneficial reference for enhancing the reliability of existing RPEHs.

Energy Harvesting in the Crane-Hoisting Mechanism

The subject of the model research contained in this paper is an application of a motion energy–harvesting device on a crane-hoisting mechanism to power independent measurement devices. Numerical experiments focused on the selected motion energy–harvesting device (M-EHS) and its configuration properties in the context of energy-harvesting efficiency in the case of using it on a crane. The results of the computer simulations were limited to the initial specified conditions for the harvester and the movement of the conditions of the crane-hoisting mechanism. The article compares the energy efficiency for the selected construction and parameters of the harvester for specific hoisting speed and the arm length of the motion conversion system. For this purpose, the initial conditions for the crane and the configuration of parameters of the energy harvester were assumed. The results are visualized on the diagram of RMS voltage induced on piezoelectric elements, showing the impact of individual solutions of the proposed motion energy–harvesting device on the efficiency of energy harvesting. The results of the efficiency of the simulations show that the motion harvester ranges from 0.44 V to 14.22 V, depending on the speed of the crane-hoisting mechanism and the length of the arm of the motion conversion system. Still, the design allows for an adjustment to the given conditions by tuning up the M-EHS to a specified excitation frequency and working conditions.

Research on a novel non-linear magnetically coupled piezoelectric self-powered mouse

Based on the charging problem of wireless mouse, a magnetically coupled piezoelectric self-powered mouse is proposed in this paper. The piezoelectric self-powered mouse innovatively combines piezoelectric technology and scroll wheel structure into one. Moreover, the coupling in the structure deforms the piezoelectric element by magnetic force, avoiding damage to the piezoelectric element by direct contact. The introduction of non-linear forces improves the energy harvesting efficiency of the energy harvester. The distance between the piezoelectric cantilever beam and the rollers, and the number of magnets on the rollers are used as the study variables in this experiment. At a speed of 550 r/min, when the distance between the magnet attached to the free end of the piezoelectric cantilever beam and the mouse wheel is 17 mm and the number of magnets on the wheel is 4, the whole piezoelectric energy harvesting device has the maximum peak-to-peak voltage generated is 25.15 V. Through the design of the cantilever beam, greater deflection can be produced under the conditions of external force and size determination. The design of the structure is highly compatible with the actual mouse structure, which provides a great possibility to further combine the piezoelectric element with the mouse structure.

Study on Suppression of Transverse Mechanical Coupling of Rectangular Double-Laminated Bending Vibration Elements

Rectangular double-laminated piezoelectric elements are widely used in low frequency transducers. At present, most of these piezoelectric elements use a piezoelectric ceramic laminated structure. In this work, the bending vibration properties of double-laminated piezoelectric ceramic elements with different transverse dimensions were analyzed by the finite element method. It was found that there was a strong transverse mechanical coupling, and the transverse dimensions had a great effect on the bending vibration. To suppress the transverse mechanical coupling effect, a double-laminated piezoelectric element based on a 2-2 piezoelectric composite was designed. The simulation results show that the bending vibration performance of the double-laminated composite element is not affected by the transverse size. The 2-2 piezoelectric composite double-laminated and ceramic elements were prepared. In addition, simulation and experimental results indicate that the transverse mechanical coupling of the bending vibration of the piezoelectric composite double-laminated element is effectively suppressed, the vibration frequency is reduced by about 100 Hz, and the vibration displacement is increased by 2.2 times, in comparison with the piezoelectric ceramic double-laminated element.

USE OF PESOELECTRIC EFFECTS IN IN MEASUREMENT TECHNOLOGY

This article discusses the process of the piezoelectric effect observed in semiconductor materials, and the possibility of using piezoelectric elements that produce this effect in measuring technology. The prospects for the use of piezoelectric elements in various measurement techniques are considered.

Electric control of a phononic crystal constituted of Piezoelectric layers using Schottky diode

A one-dimensional piezoelectric phononic crystal (PPC) consisting of a periodic pattern made of two perfectly bonded materials: one active (piezoelectric), the other passive (elastic) and exhibiting a strong acoustic impedance contrast is studied. We are interested in the tunability of piezoelectric inclusions in order to control the propagation of ultrasonic waves in the MHz range from a nonlinear electrical component connected to the terminals of the piezoelectric elements. After modeling the dynamic resistance of the Schottky diode, based on the piezoelectricity equations, a one-dimensional analytical model is proposed to take into account the resistive impedance effect of this diode connected to the electrodes of the active plate. Thus, we have shown that the application of various electrical boundary conditions (EBCs) on the electrodes (open-circuit, short-circuit, connecting an electrical load) allows to change the effective properties of the piezoelectric plate in particular and those of the PPC in general. The dispersion of the waves is then electrically tuned and, depending on the applied EBCs, we have demonstrated numerically the possibility of opening Bragg or hybridization gaps in the PPC band structure.

Reliability analysis of smart laminated composite plates under static loads using artificial neural networks

The applications of smart structures with integrated piezoelectric elements have been expanding in the last few decades due to the abilities of such structures to withstand mechanical loads and operate as sensors or actuators using their electromechanical coupling. The available manufacturing techniques can result in uncertainties in the structure's geometric parameters, which, coupled with uncertainties in material properties, can lead to unexpected failures or unreliable performance. This paper presents a reliability analysis of a smart laminated composite plate made of a graphite/epoxy cross-ply substrate with a piezoelectric fiber-reinforced composite (PFRC) actuator layer under static electrical and mechanical loads. A coupled finite element (FE) model was developed in COMSOL Multiphysics, from which nondimensional stresses and displacements were calculated. To investigate the effects of randomness in the material and geometric properties, an artificial neural network (ANN) model was developed and trained using generated FE data. Monte Carlo Simulation (MCS) and First- and Second-Order Reliability Methods (FORM/SORM) were then used to shed light on the significance of considering randomness in the various material and geometric parameters and the effect of such uncertainty on the resulting nondimensional stresses and displacements. A coefficient of variation (CV) study identified the piezoelectric stress coefficient as the most significant contributing factor to the variation of all nondimensional parameters. Variation in the nondimensional parameters also increases under the application of an electric load. ANN-based FORM, SORM, and MCS all indicate a pattern of low probability of failure until a threshold value of about 3% of input parameter variation is reached, beyond which there is a rapid nonlinear increase in failure probability with increasing input parameter variation.

Engineering nonreciprocal wave dispersion in a nonlocal micropolar metabeam

Active metamaterials with electronic control schemes can exhibit nonreciprocal and/or complex elastic coefficients that result in non-Hermitian wave phenomena. Here, we investigate theoretically and experimentally a non-Hermitian micropolar metabeam with piezoelectric elements and electronic nonlocal feed-forward control. Since the nonlocal feed-forward control breaks spatial reciprocity, the proposed metabeam supports nonreciprocal flexural wave propagation, featuring unidirectional amplification/attenuation and non-Hermitian skin effect. Theoretical homogenization modeling is developed to consider the nonlocal effect into an effective complex bending stiffness. The unidirectional wave amplification/attenuation is attributed to the energy conversion between electrical power and mechanical work. The non-Hermitian skin effect, characterized by a winding number, is the manifestation of the flexural nonreciprocity and admits an extensive number of localized bulk eigenmodes on open boundaries. The nonlocal metabeam is also employed to engineer the anomalous wave dispersion such as tunable roton-like dispersion and band tilting. The nonlocal micropolar metabeam could pave the ways for designing non-Hermitian topological mechanical metamaterials featuring programmable nonreciprocal wave transmission and engineering roton-like wave dispersion relations under ambient environments.

Enhancement of Guided Wave Detection and Measurement in Buried Layers of Multilayered Structures Using a New Design of V(z) Acoustic Transducers

This paper presents the possibility of enhancement of the generation and detection of poorly energetic acoustic-guided waves in multilayered structures using a new design for a V(z) transducer. By defining a modified V(z) transducer composed of segmented piezoelectric elements, the acoustical energy can be directed towards specific angles in such a way as to generate guided waves that are poorly energetic. By comparing the results using this new design to those obtained with a classical V(z) transducer, it is shown that the generation and detection of such waves is greatly improved, especially for poorly energetic waves that belong to a buried layer in a multilayered structure. This is especially seen on the components of the spectra of V(z). The modeling of the modified V(z) signature for a multi-element focused transducer is widely detailed first. Then, in order to illustrate the advantages of our proposed method, a three-layer structure (aluminum/epoxy/steel) is discussed. The interest of this method for the characterization of elastic properties of “buried” layers through specific guided waves that are detected with great difficulty—or even not at all—with a classical V(z) transducer is demonstrated, especially for the A0 and S0 modes corresponding to the steel layer inside the three-layer structure. In this study, we also develop a specific tracking method for particular guided waves possessing large phase velocity variations over the considered frequency range, as is the case for the S0 mode of the steel sub-layer.

Influence of material functional heterogeneity on non-stationar oscillations of piezoceramic bodies

The influence of material functional heterogeneity on mechanical oscillations of piezoelement under non-stationary electrical loading is investigated. Within the assumption of functional distribution of material characteristics by thickness of the piezoelectric element, which corresponds to the physical properties of the body, a unified system of solving equations was obtained to describe the thickness fluctuations of piezoelectric plates, cylinders, and balls. For controllingof accuracy, the calculation is carried out using an explicit and implicit difference scheme.
 Unsteady oscillations of a flat piezoceramic layer, cylinder, and sphere are investigated with a parabolic distribution of all material characteristics along the thickness of the element. It is assumed that the average value of the function along the thickness is equal to the tabular value of the material characteristic, and the value on electrodes is proportional to the area of electrodes. At such conditions, we obtained a decrease in the speed of disturbances propagation and a slight change in the amplitude associated with the curvature of the element. The increase in amplitude reaches 3% for balls. It should be noted that at given load oscillations occur in the compressed zone without entering the undeformed state. The considered cylinder and ball have a rather large curvature, for bodies with a smaller curvature the influence of the described effect will be smaller. The additional analysis indicates that the shape of the distribution curve under described above conditions also has little effect on the results.
 It was established that the effect of functional heterogeneity within the same material has little effect on the oscillations of the piezoelement, that is, it is really possible to average the material characteristics by thickness at calculating, since the deviation between the results is within acceptable limits (up to 2.5%). Also, an important result is the confirmation of the assumption that for curved bodies such as cylinder and sphere, the material characteristics can be considered constant on thickness, regardless of the curvature of the body.
 The proposed technique can be applied for studyingof the vibrations of different geometries bodies with significantly heterogeneous functional material or what are combined from several materials with a gradient transition between them.

ANALYSIS OF CURRENT STATE AND MAIN TENDENCIES IN DEVELOPMENT OF METHODS FOR MEASURING OIL VISCOSITY DURING PIPELINE TRANSPORTATION

There are factors that cause the necessity of viscosity measurement on the main oil pipelines. The article presents the principles of various existing viscometers and the latest research in this area. The authors consider the characteristics of oil flow, trunk pipelines and trends in the oil industry. They analyse viscometric methods from the point of view of the control of trunk oil flows. The authors evaluate the methods, on the basis of which they make recommendations for their modernisation for the control of main oil streams. The research showed the absence of a method that meets all the requirements of the main oil flow and the trends of development of the oil industry. According to the authors it is necessary to make further research of measuring methods based on piezoelectric elements and capacitive sensors and possibly implement them in new oil pipelines. Authors believe that the greatest potential for the oil industry has a radical modernization of the bubble pneumatic method to suit the specific features of the control object (main oil flow).

Nasal Breath Input: Exploring Nasal Breath Input Method for Hands-Free Input by Using a Glasses Type Device with Piezoelectric Elements

Research on hands-free input methods has been actively conducted. However, most of the previous methods are difficult to use at any time in daily life due to using speech sounds or body movements. In this study, to realize a hands-free input method based on nasal breath using wearable devices, we propose a method for recognizing nasal breath gestures, using piezoelectric elements placed on the nosepiece of a glasses-type device. In the proposed method, nasal vibrations generated by nasal breath are acquired as sound data from the devices. Next, the breath pattern is recognized based on the factors of breath count, time interval, and intensity. We implemented a prototype system. The evaluation results for 10 subjects showed that the proposed method can recognize eight types of nasal breath gestures at 0.82\% of F-value. The evaluation results also showed that the recognition accuracy is increased to more than 90\% by limiting gestures to those with a different breath count or different breath interval. Our study provides the first glasses type wearable sensing technology that uses nasal breathing for hands-free input.

Design and Fabrication of 15-MHz Ultrasonic Transducers Based on a Textured Pb(Mg1/3Nb2/3)O3-Pb(Zr, Ti)O3 Ceramic.

Ultrasound medical imaging is an entrenched and powerful tool for medical diagnosis. Image quality in ultrasound is mainly dependent on performance of piezoelectric transducer elements, which is further related to the electromechanical performance of the constituent piezoelectric materials. With rising need for piezoelectric materials with better performance and low cost, a highly 〈001〉 textured piezo ceramic, Pb(Mg1/3Nb2/3)O3-Pb(Zr, Ti)O3, has been developed. Recently, textured ceramic materials can be produced at low cost and exhibit high piezoelectric strain constants and large electromechanical coupling coefficients. In this work, 15-MHz ultrasonic transducers with an effective aperture of 2.5 mm in diameter based on these highly 〈001〉 textured ceramics have been successfully fabricated. The fabricated transducers achieved a central frequency of 15 MHz, a fractional bandwidth of 67% (at -6 dB), a high effective electromechanical coupling coefficient [Formula: see text] of 0.55, and a low insertion loss (IL) of 21 dB. Ex vivo ultrasonic imaging of a porcine eyeball was used to assess the tomography quality of the transducer. The results show that utilized textured ceramic has a great potential in developing ultrasonic devices for biomedical imaging purposes.

Efficient Bone Conduction Hearing Device With a Novel Piezoelectric Transducer Using Skin as an Electrode.

Bone conduction hearing aids are the only non-surgical devices used for conductive hearing loss. However, they are impractical for lifelong use since they require close contact of the transducer with the head skin, causing skin erosion and discomfort. Bone conduction hearing implants and active middle ear implants do not present these issues; however, they require surgery and can sometimes cause issues in the skin surrounding the devices. This study aimed to develop a new bone conduction hearing device that does not exert pressure on the skin or require surgery. Our device modified a piezoelectric element by using the skin of a pinna as one of the two electrodes of a conventional piezoelectric device. We compared the sound transmission of a speaker, a conventional piezoelectric device, or the new device to the Guinea pig cochlea, a physiological sound transducer to the auditory nerve, in normal and air-conductive hearing loss conditions. The novel device transmitted sound to the cochlea even after causing air-conductive hearing loss. Its bone conduction was more efficient than the speaker and the conventional piezoelectric device. We developed a novel type of bone conduction device that efficiently transmits sound to the cochlea by skipping the external auditory canal, tympanic membrane, and middle ear ossicles. This device does not exert pressure on the skin that can result in skin damage, an adverse effect of a conventional bone conduction hearing aid. Our novel hearing device can be used as a substitute for current bone-conduction hearing devices.

Characterization of Wrist Motions and Bionic Energy Harvesting for Wrist Wearables

Wrist-worn smart wearable devices, such as smartwatches and wristbands, are showing a high growth trajectory for decades in the wearable technology market. However, most wrist-worn generators are confined into watch bodies, which undermines the functionality of the wearables. In this study, we first characterize the dynamic properties of wrist motions and propose four rules for the design of wrist-worn energy harvesters. Based on the design rules, we then present a bionic piezoelectric energy harvester, composed of an inner band, an outer band with a piezoelectric array, and a watch body. The two-layer band structure mimics two branches of a Y-shaped hyoid bone of the woodpecker’s head. A finite element model is built to study the mechanical and electrical responses of the design. The model is validated by an experiment and is utilized to find the optimal thickness and positions of piezoelectric elements. Based on the optimizations, we fabricate a prototype with a piezoelectric array as the energy harvesting unit. With an ac–dc rectifier, the prototype is tested to characterize the electrical responses in four wrist motions. The result shows that the average power output of a bionic harvester is 2.10 mW in shaking arm motion, higher than previously reported wrist-worn generators. Finally, we demonstrate that the prototype enables to sustainably power a screen of a smartwatch, a wireless temperature monitoring system, and a commercial electronic thermohygrometer, respectively.

Enhancement of Ultrasonic Transducer Bandwidth by Acoustic Impedance Gradient Matching Layer.

High-performance broadband ultrasound transducers provide superior imaging quality in biomedical ultrasound imaging. However, a matching design that perfectly transmits the acoustic energy between the active piezoelectric element and the target medium over the operating spectrum is still lacking. In this work, an anisotropic gradient acoustic impedance composite material as the matching layer of an ultrasonic transducer was designed and fabricated; it is a non-uniform material with the continuous decline of acoustic impedance along the direction of ultrasonic propagation in a sub-wavelength range. This material provides a broadband window for ultrasonic propagation in a wide frequency range and achieves almost perfect sound energy transfer efficiency from the piezoelectric material to the target medium. Nano tungsten particles and epoxy resin were selected as filling and basic materials, respectively. Along the direction of ultrasonic propagation, the proportion of tungsten powder was carefully controlled to decrease gradually, following the natural exponential form in a very narrow thickness range. Using this new material as a matching layer with high-performance single crystals, the −6 dB bandwidth of the PMN-PT ultrasonic transducer could reach over 170%, and the insertion loss was only −20.3 dB. The transducer achieved a temporal signal close to a single wavelength, thus there is the potential to dramatically improve the resolution and imaging quality of the biomedical ultrasound imaging system.