Transverse Piezoelectric Effect Research Articles

Longitudinal and transverse piezoelectric effects of ferroelectret metamaterials with positive and negative Poisson's ratios

A theoretical model has been developed to express the longitudinal and transverse piezoelectric effects in ferro/piezoelectrets. This model is an extension of the classic model based on layer-dielectric structures that focuses on the longitudinal piezoelectric effect. The improved model reveals that the relation between the longitudinal piezoelectric d33 coefficient and the transverse piezoelectric d31 coefficient is associated with Poisson's ratio μ13 (or μ31) and Young's moduli Y1 and Y3. The polarity of the two coefficients is opposite for materials with a positive Poisson's ratio as normally observed in conventional piezoelectric materials, and the same for materials with a negative Poisson's ratio, i.e., auxetic materials. The experimental results available in the literature and obtained from ferroelectret metamaterials with a honeycomb cross-sectional structure and two-dimensional (2D) symmetric structure, called 2D ferroelectret metamaterials, designed and prepared in this study reasonably agree with theoretical predictions. This study not only extends the scope of the metamaterials by inducing the concept of ferroelectret metamaterials but also provides a strategy for designing ferroelectrets with designable properties.

Implementation and displacement self-sensing of a 4-DOF piezoelectric micromanipulator

This paper reports the development and displacement self-sensing of a new four degrees-of-freedom (DOF) piezoelectric micromanipulator. In particular, each micromanipulator arm can move along the clamping and vertical directions, constructing with two degrees of freedom, and two micromanipulator arms exhibit four degrees of freedom. Thus, it improves operational flexibility. Meanwhile, the self-sensing method avoids additional external sensors when detecting output displacements. The piezoelectric micromanipulator is devised based on the transverse inverse piezoelectric effect of two sets of vertical spatial crossings. Static and dynamic characteristics are analyzed via finite element optimization of geometric parameters. Then, a displacement self-sensing method based on charge integration is proposed. This method measures the generated charge on the clamping arm surface from the piezoelectric wafer deformation under the driving voltage. A self-sensing circuit is designed to obtain the surface charge of the clamping arm. Then, several experiments are conducted to test the micromanipulator. The maximum displacements of the designed micromanipulator are about 66.29 μm and 63.09 μm along clamping and vertical directions. Moreover, output displacements, response time, and inherent frequencies obtained based on the self-sensing method agree well with those with laser sensors. In addition, an operation application for micro-shaft assembly is presented, demonstrating the grasping and docking operations of the micro-shaft in the clamping and vertical directions.

Ferroelectric and negative piezoelectric properties in oxyhydroxide monolayers γ -XOOH (X = Al, Ga, and In)

Two-dimensional (2D) multiferroic materials with coexisting ferroelasticity (FA) and ferroelectricity (FE) have potential applications in high-density data storage and sonar detectors. Here, based on first-principles calculations, we predict a series of stable 2D FA-FE multiferroic structures, namely, γ-XOOH (X = Al, Ga, and In) monolayers. By analyzing the lattice symmetry and orientation distribution of hydroxyls, we find that XOOH monolayers possess both in-plane ferroelastic and ferroelectric polarization, as well as antiferroelectric ordering caused by the anti-parallel alignment of hydroxyls. Interestingly, the perpendicular reorientation of in-plane FE polarization accompanies 90° ferroelastic switching. Moreover, they show an unusual negative transverse piezoelectric effect originated from the clamped-ion term. The multiferroic properties of the XOOH monolayers provide an excellent platform to study electroelastic effects.

Design, manufacture, and clamping operation of a 4-DOF piezoelectric micro-gripper

To improve the operational flexibility of the piezoelectric microgripper, a new four-degree-of-freedom piezoelectric microgripper was designed and fabricated. The clamp fingers can move both along the clamping direction and along its vertical direction. Also, clamping experiments were conducted on a φ 300 μm × 20 mm micro-shaft. Based on the transverse inverse piezoelectric effect of two groups of vertical intersections, a new configuration of a four-degree-of-freedom piezoelectric micro-gripper is designed. It can produce micro-displacement along the clamping direction and vertical clamping direction simultaneously. According to the Euler-Bernoulli beam equation, the Lagrangian function method and Hamilton variational principle are used to model the four-degree-of-freedom piezoelectric micro-gripper. Then, based on the optimization of the geometric parameters of the fingers, the static and dynamic characteristics of the microgripper are analyzed by the finite element method. After that, the micro-gripper is made using lithography, gluing, and laser cutting. Finally, the piezoelectric microgripper's static and dynamic characteristics and the micro-shaft's clamping operation are tested by experiments. The experimental results show that the maximum displacement, response time, and natural frequency of the designed micro-gripper along and perpendicular to the clamping direction agree well with the finite element simulation. The designed microgripper exhibits a promising prospect in practical micromanipulation applications.

Tape-Like Vibrational Energy Harvesters Using Flexible Fluorinated Polyethylene Propylene (FEP) Piezoelectret as Transduction Material

Energy harvesting is a promising strategy utilizing renewable energy to power low-power-consumption electronics, such as wireless sensor network (WSN) nodes and wearable electronics. In this article, a tape-like vibrational energy harvester, using flexible fluorinated polyethylene propylene (FEP) piezoelectret films as transduction material, is reported. Due to a specific air-filled parallel tunnel structure, the FEP piezoelectret films in this study exhibit both significant longitudinal and transverse piezoelectric effects and could be made into tape-like flexible transduction devices. The results show that the experimental data are consistent with the theoretical prediction and the finite-element method (FEM) calculation. For a device with an effective area of 18 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times25$ </tex-math></inline-formula> mm and a seismic mass of 0.195 g on one edge, the output power at a resonant frequency of 16 Hz amounts to 3.1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> for an acceleration of 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${g}$ </tex-math></inline-formula> . Owing to the tape-like and flexible transduction elements, the power generated by the device can be enhanced readily by either enlarging area of the transduction elements or multiplying a few transduction elements in series or parallel to meet the power requirement of electronic devices, which makes the practical application flexible.

Electrical Energy Harvesting From Mechanical Motions by Employing Ferroelectrets Featuring Large Transverse Piezoelectric Activity

Fluorinated ethylene propylene (FEP) ferroelectret films with a parallel tunnel structure and significantly transverse piezoelectric effect are utilized to configurate energy harvesters for scavenging kinetic energy. In the device, a dual-steady cantilever beam structure is adopted to amplify the force input, and a stopper is used to control the strain of the film within an elastic deformation range. Results show that the maximum energy can be delivered to the storage capacitor being with the same capacitance of the device as theoretically predicted. For an energy harvester with an active area of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${30}\,\,\text {mm} \times {10}\,\,\text {mm}$ </tex-math></inline-formula> , the energy delivered to the storage capacitor is 23.5 nJ for one push motion with a displacement of 5.5 mm. The energy can be effectively enhanced by increasing the area of the ferroelectret film and multiplying devices in electrical parallel. These energy harvesters could be implemented in some facilities and devices, such as carpets, floors, and buttons, to scavenge the kinetic energy of motions at low frequencies.

Numerical analysis of the effective properties of inhomogeneously polarized porous piezoelectric ceramics with ni-doped pore walls taking into account the influence of volume fractions of metal and pores

The paper considers a porous piezoelectric composite with metal layers deposited on the interface between the piezoelectric and vacuum phases. Such metal layers can be added technologically to improve the mechanical and electromechanical properties of the composite. To find the effective moduli, we designed a simple representative cubic volume of a unit cell consisting of a piezoelectric matrix with a compound spherical pore in its center. In turn, the compound pore includes the pore itself and a hollow metal sphere on its surface. The composite's three phases were all modeled as piezoelectric materials. The conducting interface layer was modeled as a piezoelectric material with very high dielectric constants, small piezoelectric moduli, and elastic properties of the employed metal, while the vacuum pore was modeled as a piezoelectric material with marginal moduli. The mathematical formulation of boundary value homogenization problems with full contact conditions on the interface boundaries, based on the Hill energy criterion, was described. By solving nine boundary value problems of electroelasticity with different boundary conditions for displacements and electric potential by the finite element method, a complete set of effective moduli of the piezoelectric composite is determined. The importance of considering the inhomogeneous polarization due to the presence of pores and metallic inclusions was discussed. An approximate method was proposed for determining the inhomogeneous polarization field in a piezoceramic matrix, based on a preliminary solution of the electrostatic problem for dielectrics and locating the element coordinate systems rotated along the polarization vector. The paper describes the results of computational experiments for a piezocomposite consisting of PZT-5H piezoceramic matrix, pores, and nickel layers on the pore surfaces. Comparisons between the effective properties of this composite with different volume fractions of metal and the conventional porous piezocomposite were provided, depending on the porosity and taking into account the inhomogeneous polarization. Significant differences were observed for some piezomoduli and dielectric constants, which are promising for various practical applications of the considered composites in piezoactuators using the phenomenon of the transverse piezoelectric effect.

High performance fluorinated polyethylene propylene ferroelectrets with an air-filled parallel-tunnel structure

Fluorinated polyethylene propylene (FEP) ferroelectrets with an air-filled parallel-tunnel structure and regularly distributed bipolar space charges can stimulate integration of ferroelectrets in transducers due to their unique piezoelectric and mechanical properties. Such FEP ferroelectret films exhibit not only large longitudinal piezoelectric activity but also a strong transverse piezoelectric effect which allows for application in flexible transducers either working in 33 mode or in 31 mode. In this article, the transducer relevant properties of FEP ferroelectret films have been characterized. The experimental results show that the directly measurable, quasi-static piezoelectric d 33- and g 31-coefficients of the FEP films reach up to 4700 pC N-1 and 4.3 Vm N-1, respectively, and dynamic values in the frequency range from 10 to 100 Hz are 2600–1500 pC N-1 and 1.2–0.78 Vm N-1, respectively. No significant reduction of d 33-coefficient is observed at strains up to 2.1%, showing a high elasticity of the film. Both isothermal decay of d 33-coefficient and short circuit thermally stimulated discharge (TSD) current spectra show that the ferroelectric FEP films exhibit excellent thermal stability. After 14-day of storage in an atmosphere with a relative humidity of 99%, 75% of the initial piezoelectric d 33-coefficient was still retained. Also a mechanical test with 1.6 million cycles does not harm the piezoelectric coefficients indicating that air-filled parallel-tunnel FEP ferroelectret films are promising candidates for a variety of flexible transducer applications.

High Voltage Monitoring with a Fiber-Optic Recirculation Measuring System

Optical technologies for measuring electrical quantities have unique properties and significant advantages in the high-voltage electric power industry; for example, the use of optical fibers ensures the high stability of measuring equipment to electromagnetic interference and galvanic isolation of high-voltage sensors; external electromagnetic fields do not influence the data transmitted from optical sensors via fiber-optic communication lines; problems associated with ground loops are avoided, and there are no side electromagnetic radiation or cross-coupling between the channels. The structure and operation principle of a quasi-distributed fiber-optic recirculation system for monitoring high voltages are presented. The sensitive element of the system is a combination of a piezoceramic tube with an optical fiber beam waveguide where the inverse transverse piezoelectric effect occurs. The electrical voltage measurement principle is based on recording the change in the recirculation frequency under the applied voltage influence. When the measuring sections are arranged in ascending order of the measured effective voltages relative to the receiving-transmitting unit, a relative resolution of 0.30–0.45% for the PZT-5H and 0.8–1.2% for the PZT-4 is achieved in the voltage range of 20–150 kV.

Coded Control of a Multilayer Piezo Actuator Producing Nano- and Micromotion

The mechanical and control characteristics of a multilayer piezo actuator producing nano- and micromotion are derived, in the case of coded control. The static and dynamic characteristics of such actuators with longitudinal, transverse, and shear piezoelectric effects are determined.

High-voltage monitoring by the fiber-optic recirculating measuring system

Optical technologies for measuring electrical quantities attract great attention due to their unique properties and significant advantages over other technologies used in high-voltage electric power industry: the use of optical fibers ensures high stability of measuring equipment to electromagnetic interference and galvanic isolation of high-voltage sensors; external electromagnetic fields do not influence the data transmitted from optical sensors via fiber-optic communication lines; problems associated with ground loops are eliminated, there are no side electromagnetic radiation and crosstalk between the channels. The structure and operation principle of a quasi-distributed fiber-optic high-voltage monitoring system is presented. The sensitive element is a combination of a piezo-ceramic tube with an optical fiber wound around it. The device uses reverse transverse piezoelectric effect. The measurement principle is based on recording the change in the recirculation frequency under the applied voltage influence. When the measuring sections are arranged in ascending order of the measured effective voltages relative to the receiving-transmitting unit, a relative resolution of 0,3–0,45 % is achieved for the PZT-5H and 0,8–1,2 % for the PZT-4 in the voltage range 20–150 kV.

Design of flexible piezoelectric gyroscope for structural health monitoring

This Letter reports a piezoelectric bending sensor configuration based on a complementary design of four identical flexible piezoelectric sensors using both theoretical analysis and experimental demonstration. The active material used here for sensing is a flexible ferroelectret polymer, which possesses a cellular internal structure with distributed trapped charges. The transverse piezoelectric effect is observed by changing the permanent macroscaled dipole moments upon bending. It has been found that the voltage output for the sensor is linearly related to the bending curvature. Angular displacement is determined by monitoring the output of four orthogonal devices on a rod. Different types of surface stress can also be determined by measuring output polarities from an antiparallel electrical connection. The proposed sensor configuration in this work is capable of providing a nondestructive evaluation of structural health by measuring a 2D bending vector.

Performance of Self-Powered, Water-Resistant Bending Sensor Using Transverse Piezoelectric Effect of Polypropylene Ferroelectret Polymer

The significant growth of wearable electronics is in constant search for optimizing systems with high flexibility and self-powering capacity. In this work, we utilize flexible polypropylene ferroelectret (PPFE) thin film polymer with the large transverse piezoelectric coefficient for bending curvature self-powered sensing. The electric energy comes from the geometry distortion of the built-in macro dipoles with initial surface charge distributions. Theoretical analysis based on constitutive electromechanical equations and bi-layer bending mechanics provide a detailed understanding of the sensing mechanism and its applicability. Different evaluation methods are used to have a more comprehensive understanding of the electromechanical responses under different bending conditions. It has been found that the velocity and magnitude of the mechanical input influence the average voltage output, while instantaneous voltage is not dependent on the latter. The robustness of the material is also investigated, where the device shows no performance degradation by immersion into the water up to 12 hours and under 10k bending cycles. Thermal stability tests reveal degradation starting at ~ 75°C and an immediate failure of the device at ~ 150°C. Finally, an application is demonstrated by showing the potential use of the characterized system as a self-powered sensor for athletic assessment.

Structural–parametric model electroelastic actuator nano– and microdisplacement of mechatronics systems for nanotechnology and ecology research

The structural ndash parametric model the decision of the wave equation the parametric structural schematic diagram the transfer functions of the electroelastic actuator of the mechatronics system for the nanotechnology and the ecology research are obtained Effects of geometric and physical parameters of the piezoactuator and the external load on its dynamic characteristics are determined The parametric structural schematic diagram and the transfer functions of the piezoactuator for the transverse longitudinal shift piezoelectric effects are obtained from the structural ndash parametric model of the piezoactuator For calculation of the mechatronics systems for the nanotechnology with the piezoactuator it rsquo s the parametric structural schematic diagram and the transfer functions are determined The generalized parametric structural schematic diagram of the electroelastic actuator is constructed

Structural-Parametric Model of Electromagnetoelastic Actuator for Nanomechanics

The generalized parametric structural schematic diagram, the generalized structural-parametric model, and the generalized matrix transfer function of an electromagnetoelastic actuator with output parameters displacements are determined by solving the wave equation with the Laplace transform, using the equation of the electromagnetolasticity in the general form, the boundary conditions on the loaded working surfaces of the actuator, and the strains along the coordinate axes. The parametric structural schematic diagram and the transfer functions of the electromagnetoelastic actuator are obtained for the calculation of the control systems for the nanomechanics. The structural-parametric model of the piezoactuator for the transverse, longitudinal, and shift piezoelectric effects are constructed. The dynamic and static characteristics of the piezoactuator with output parameter displacement are obtained.

Structural-Parametric Model of Electromagnetoelastic Actuator for Nanomedicine and Nanobiotechnology

The generalized parametric structural schematic diagram the generalized structural parametric model the solution of wave equation the generalized matrix transfer function of the electromagnetoelastic actuator are determined The dynamic and static characteristics of the actuator are obtained The parametric structural schematic diagram and the transfer functions are determined for calculation of the control systems of the nanomedicine and the nanobiotechnology The structural parametric model of the piezoactuator for the transverse longitudinal shift piezoelectric effects are constructed

Parametric block diagrams of a multi-layer piezoelectric transducer of nano- and microdisplacements under transverse piezoelectric effect

A structural-parametric model and parametric block diagrams of a piezoelectric transducer in the transverse piezoelectric effect are obtained with regard to the counter-electromotive force. The transfer functions of the multi-layer piezoelectric transducer of nano- and microdisplacements are determined with regard to the influence of geometric and physical parameters of the multi-layer piezoelectric transducer, the counter-electromotive force, and the external load.

Block diagrams of a multilayer piezoelectric motor for nano- and microdisplacements based on the transverse piezoeffect

A parametric block model and block diagrams of a multilayer piezoelectric motor based on the transverse piezoelectric effect with account for the electromotive counterforce emerging at its stress as a result of response to the applied force in the direct piezoelectric effect are obtained. Transfer functions of the piezoelectric motor with regard to its geometric and physical parameters, electromotive counterforce, and external load are determined.

Dynamic characteristics of multilayer piezoelectric nano- and micromotors

The dynamic characteristics of piezoelectric nano- and micromotors with parallel and code control in longitudinal and transverse piezoelectric effects are determined. Corresponding transfer functions are obtained.

Heteropolar Charging of Ferroelectrets for Flexible Keyboards and Tactile Sensors

Ferroelectrets are flexible and conformable polymer transducer foils with a dominant longitudinal piezoelectric effect. Ferroelectrets also have a negligible transverse piezoelectric effect, which makes them ideal for the fabrication of roll- and bendable keyboards. Cellular polypropylene ferroelectrets with heteropolar charge patterns are useful for a simple and effective key encoding. The preparation of charge patterns is, however, a technical challenge. We have investigated and produced such structures in cellular polypropylene ferroelectrets by corona poling, in combination with shadow masks and unstructured and structured counter electrodes. Furthermore, we have also produced lateral charge distributions by contact poling with specially designed high voltage electrodes. We discuss the two different poling concepts and the related problems, their strengths, weaknesses and experimental pitfalls. We found in particular contact poling to be a reliable and well reproducible poling method for an effective preparation of heteropolar charge patterns of ferroelectrets.