Piezoelectric Deformation Research Articles

Ultrasensitive liquid sensor based on an embedded microchannel bulk acoustic wave resonator

The high-frequency and high-quality factor characteristics of bulk acoustic wave (BAW) resonators have significantly advanced their application in sensing technologies. In this work, a fluidic sensor based on a BAW resonator structure is fabricated and investigated. Embedded microchannels are formed beneath the active area of the BAW device without the need for external processes. As liquid flows through the microchannel, pressure is exerted on the upper wall (piezoelectric film) of the microchannel, which causes a shift in the resonant frequency. Using density functional theory, we revealed the intrinsic mechanism by which piezoelectric film deformation influences BAW resonator performance. Theoretically, the upwardly convex piezoelectric film caused by liquid flow can increase the resonant frequency. The experimental results obtained with ethanol solutions of different concentrations reveal that the sensor, which operates at a high resonant frequency of 2.225 GHz, achieves a remarkable sensitivity of 5.1 MHz/% (221 ppm/%), with an ultrahigh linearity of 0.995. This study reveals the intrinsic mechanism of liquid sensing based on BAW resonators, highlights the potential of AlN/Al0.8Sc0.2N composite film BAW resonators in liquid sensing applications and offers insights for future research and development in this field.

Design, fabrication, and characterization of a deformation-restricted piezoelectric vibration energy harvester triggered by a stopper

Vibration energy harvesting based on piezoelectric effect is emerging as a promising sustainable energy solution for micro-electromechanical systems and wireless sensor networks. Whereas, reliability issues stemming from excessive deformation-induced damage to piezoelectric materials have hindered the progress of piezoelectric vibration energy harvester development. Herein, an indirect triggering method involving a stopper has been implemented to design the deformation-restricted piezoelectric vibration energy harvester (D-RPVEH). This device utilizes the stopper to limit the maximum deformation of the piezoelectric beam, facilitating unidirectional deformation. Consequently, the D-RPVEH delivers enhanced reliability even under unexpected excessive impacts. The feasibility of the proposed principle and design are proved by finite element simulation and experimental test. Most importantly, the research results are found that the simulated end displacement and experimental voltage of PZT beam declined with the decrease of stopper height difference. Moreover, the efficacy of limiting the piezoelectric beam's maximum deformation by implementing the stopper structure is supported by both simulation and experimental findings. The D-RPVEH device can achieve a peak power output of 2.58 mW at frequencies as low as 5.5 Hz, utilizing an optimal load resistance of 30 kΩ. Furthermore, it can illuminate a minimum of 60 blue commercial LEDs connected in series. Therefore, the D-RPVEH not only has good power generation performance but also has high reliability. This design will provide a reference for the research on improving the reliability of PVEH.

Development and analysis of magnet-engaged piezoelectric energy generator under friction-induced vibration

Piezoelectric energy transducers, which can be an efficient solution for the power supply of wireless devices, have been widely researched. This study investigated the characteristics of a magnet-engaged nonlinear piezoelectric energy generator stimulated by friction-induced vibration (FIV), in two distinct design configurations (in-parallel and in-series). A mathematical model was developed, and the dynamic response of the mechanical system and voltage output from the piezoelectric shear deformation were solved using an iterative method. A friction model considering the Stribeck effect was introduced to describe the friction motion. The emergence of a stick-slip motion induced limit cycle and its vanishing delineates the unstable and stable regions of the system, respectively. A critical sliding velocity vc splits the regions. When the sliding velocity exceeds vc, the system remains in stable region with exclusive slip friction behavior. Parameter studies were conducted to explore the effect of decay factor β, dynamic friction coefficient μk, static friction coefficient μstatic, and normal force FN on vc. The results indicate that increasing β and μk can reduce the unstable region and generation of FIV, whereas, increasing FN and μstatic can promote the occurrence of FIV. The energy generation was evaluated by a transient charging simulation that has been experimentally validated in a previous study. The influence of β, μk, μstatic, and FN on the energy generation was also investigated relative to the operating velocity range (OVR) and sum of root mean square charging power (SRCP). The in-parallel systems exhibit a higher SRCP within the same OVR, whereas the in-series systems are more likely to excite FIV with a wider OVR. Additionally, the simulation results of fluctuating working conditions show that both fluctuating FN and v0 have negative effects on the energy generation. The nonlinear in-series system exhibits better robustness with the least affected SRCP and almost unchanged OVR under fluctuating FN and v0.

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.

Architected Piezoelectric Metamaterial With Designable Full Nonzero Piezoelectric Coefficients

Abstract Piezoelectric metamaterials have received extensive attention in the fields of robotics, nondestructive testing, energy harvesting, etc. Natural piezoelectric ceramics possess only five nonzero piezoelectric coefficients due to the crystal symmetry of ∞mm, which has limited the development of related devices. To obtain nonzero piezoelectric coefficients, previous studies mainly focus on assembling piezoelectric ceramic units or multiphase metamaterials. However, only part of the nonzero piezoelectric coefficients or locally piezoelectric electromechanical modes are achieved. Additionally, it still remains a challenge for manipulating the piezoelectric coefficients in a wide range. In this work, full nonzero piezoelectric coefficients are obtained by symmetry breaking in the architected piezoelectric metamaterial. The piezoelectric coefficients are designable over a wide range from positive to negative through manipulating the directions of each strut for the three-dimensional architected lattice. The architected metamaterials exhibit multiple positive/inverse piezoelectric modes, including normal and shear deformation. Finally, a smart gradient architected piezoelectric metamaterial is designed to take advantage of this feature, which can sense the position of the normal and shear force. This work paves the way for the manipulation of piezoelectric metamaterial in a wide range with designable full nonzero piezoelectric coefficients, thereby enabling application potential in the fields of smart sensing and actuation.

Research on a rotary piezoelectric wind energy harvester with bilateral excitation.

This paper describes a rotary piezoelectric wind energy harvester with bilateral excitation (B-RPWEH) that improves power generation performance. The power generating unit in the current piezoelectric cantilever wind energy harvester was primarily subjected to a periodic force in a single direction. The B-RPWEH adopted a reasonable bilateral magnet arrangement, thus avoiding the drawbacks of limited piezoelectric cantilever beam deformation and unstable power generation due to unidirectional excitation force. The factors affecting the power generation were theoretically analyzed, and the natural frequency and excitation force of the piezoelectric cantilever have been simulated and analyzed. A comprehensive experimental research method was used to investigate the output performance. The B-RPWEH reaches a maximum output voltage of 20.48Vpp when the piezoelectric sheet is fixed at an angle of 30°, the Savonius turbine number is 3, and the magnet diameter is 8mm. By adjusting the fixed angle of the piezoelectric sheet, the number of Savonius wind turbine blades, and the magnet diameter, the maximum voltage is increased by 52.38%, 4.49%, and 245.95%, respectively. The output power is 24.5 mW with an external resistor of 8 kΩ, and the normalized power density is 153.14 × 10-3 mW/mm3, capable of powering light-emitting diodes (LEDs). This structure can drive wireless networks or low-power electronics.

Model Development of a Hybrid Battery-Piezoelectric Fiber System Based on a New Control Method.

By increasing the application of smart wearables, their electrical energy supply has drawn great attention in the past decade. Sources such as the human body and its motion can produce electrical power as renewable energy using piezoelectric yarns. During the last decade, the development of the piezoelectric fibers used in smart clothes has increased for energy-harvesting applications. Therefore, the energy harvesting from piezoelectric yarns and saving process is an important subject. For this purpose, a new control system was developed based on the combination of the sliding mode and particle swarm optimization (PSO). Using this method, due to the piezoelectric yarn cyclic deformation process, electrical power is produced. This power is considered the input voltage to the controlling system modeled in this article. This system supplies constant voltage to be saved in a battery. The battery supplies power for the electrical elements of smart fabric structure for different applications, such as health care. It is shown that the presence of PSO led to the improvement of system response and error reduction by more than 30%.

Block symmetric-triangular preconditioners for generalized saddle point linear systems from piezoelectric equations

Based on the symmetric-triangular (ST) decomposition technique, a class of block ST (BST) preconditioners are proposed for generalized saddle point linear systems arising from the meshfree discretization of piezoelectric equations. By applying the BST preconditioners, we first transform the generalized saddle point linear systems into symmetric positive definite ones, which then can be solved in a fast and efficient way by the classical conjugate gradient (CG) or the preconditioned CG (PCG) iteration methods. Two practical BST preconditioners are presented and analyzed in detail. Eigen-properties and upper bounds of the condition numbers of the preconditioned matrices are proved. Implementation aspects are discussed. Finally, two numerical experiments arising from the piezoelectric strip shear deformation problem and the piezoelectric strip bending problem are presented. Numerical results show that the iteration steps of the PCG methods are independent of the number of degrees of freedom and the proposed BST preconditioners perform much better than some existing preconditioning techniques.

Friction induced vibration and energy generation study of two-degree-of-freedom piezoelectric coupled system

Friction induced vibration (FIV) and its application for energy generation through two-degree-of-freedom (2-DOF) piezoelectric coupled structure are modelled, described, and studied in this work. The FIV mathematical model of 2-DOF system in the direction of friction is established. A 2-DOF energy generator is designed as a sample structure to transform single direction continuum friction motion to high frequency vibration for energy generation. During the operation of a moving plate compressed and sliding on top of the friction excitation module, varying friction force and contact status (sliding and stick) will lead to the dynamic piezoelectric compression deformation, which can generate continuum electrical power for energy absorbing and harvesting applications. Through numerical simulation and parameter studies, the influences of different stiffness ratios, mass ratios, normal force, velocity, acceleration, structure parameter and friction coefficients on the system power generation are analyzed. Through simple structural design, W level power generation can be obtained with few piezoelectric materials. This work revealed the possibility of transforming low frequency excitation to high frequency vibration of general 2-DOF structure for energy generation.

Piezoelectric property of PZT nanofibers characterized by resonant piezo-force microscopy

Nano-piezoelectric materials have drawn tremendous research interest. However, characterization of their piezoelectric properties, especially measuring the piezoelectric strain coefficients, remains a challenge. Normally, researchers use an AFM-based method to directly measure nano-materials’ piezoelectric strain coefficients. But, the extremely small piezoelectric deformation, the influence from the parasitic electrostatic force, and the environmental noise make the measurement results questionable. In this paper, a resonant piezo-force microscopy method was used to accurately measure the piezoelectric deformation from 1D piezoelectric nanofibers. During the experiment, the AFM tip was brought into contact with the piezoelectric sample and set to work at close to its first resonant frequency. A lock-in amplifier was used to pick up the sample’s deformation signal at the testing frequency. By using this technique, the piezoelectric strain constant d33 of the Lead Zirconate Titanate (PZT) nanofiber with a diameter of 76 nm was measured. The result showed that d33 of this PZT nanofiber was around 387 pm/V. Meanwhile, by tracking the piezoelectric deformation phase image, domain structures inside PZT nanofibers were identified.

Force‐Electric Coupling of Nanoscale Ferroelectric Domains Based on Piezoelectric Force Microscopy (PFM)

Piezoelectric and ferroelectric materials are widely used in various types of microelectronics due to their excellent mechanical and electrical coupling characteristics. In recent years, piezoelectric force microscopy has developed into a powerful tool for analyzing nanoscale ferroelectric materials. However, quantitative analysis based on PFM is difficult to properly study it. This article studies the related issues of PFM quantitative analysis. First, the relationship between the effective piezoelectric coefficient and piezoelectric coefficient of different materials is analyzed from the PFM nanometer scale to analyze the force‐electric coupling effect. The study found that the effective piezoelectric coefficient is closely related to the intrinsic electroelastic constant of the material. Secondly, the analysis of the nanoscale piezoelectric deformation of ferroelectric materials shows that under the conductive SPM probe, as the clustering with the probe increases, the in‐plane displacement first increases and then decreases, and the out‐of‐plane displacement gradually decreases. Finally, the half‐width region of the nanoscale ferroelectric response domain was analyzed by PFM. Taking the in‐plane and out‐of‐plane domains of 180° and 90° domains as examples, the relationship between the response boundary domain and the tip radius was analyzed, and the results showed that whether the PFM can effectively solve the problem of detection and analysis depends on the half‐width of the response boundary domain, and the resolution of the vertical PFM is higher than that of the lateral PFM.

Electrical Power Generation Using Dynamic Piezoelectric Shear Deformation Under Friction

A new electrical power generation device based on high-frequency dynamic piezoelectric shear deformation under friction is developed. During the operation of a moving plate compressed and sliding on the top of a piezoelectric patch with constant velocity, dynamic shear deformation of the elastic piezoelectric patch is excited by periodic friction force and status (sliding and stick) variation. The dynamic piezoelectric shear strain can then generate continuous electrical power for energy absorbing and harvesting applications. The design of the piezoelectric couple device is first provided, and its mechanism, dynamic response and electric power generation under friction are described by a detailed iteration model. By comparing with previous experimental results, the accuracy of the proposed model is proven. Through numerical studies, the influences of the equivalent mass of the system, the velocity of the sliding object, the static friction coefficient and its lower limit, as well as the friction force delay rate on the power generation are obtained and discussed. The numerical results show that with the proposed design, up to 50-Watt maximum electrical power could be generated by a piezoelectric patch with a dimension of 20times 2times 6 cm under continuous friction with the moving plate at the velocity of 15 m/s. The possible bi-linear elastic stiffness variation of the system is also introduced, and the threshold of bi-linear elastic deformation, where the system stiffness changes, can be optimized for obtaining the highest power generation.

Piezoelectric Power Generation from the Vortex-Induced Vibrations of a Semi-Cylinder Exposed to Water Flow

The aim of this work is to design a piezoelectric power generation system that extracts power from the vibration of a cantilever beam. A semi-cylinder placed in a water stream and attached to the beam is excited into vortex-induced vibrations (VIV), which triggers the piezoelectric deformation. The mechanical system is modelled using parametric equations based on Hamilton’s extended principle for the cantilever beam and the modified Van der Pol model for the bluff body (the semi-cylinder). These equations are simulated using the MATLAB software. The dimensions of the model, the flow velocity and the resistance are treated as design parameters and an optimization study is conducted using MATLAB to determine the combination of optimal values at which maximum power is extracted. The key findings of this research lie in the identification of the effect of changing the design parameters on output power. In addition to the numerical simulation, a finite element analysis is carried out on the bluff body and the hydrodynamic forces and velocity profiles are observed. It is determined that the vibration amplitudes increase with increasing diameter of the bluff body, length of the bluff body and water velocity.

Lateral deformations of a crystal of potassium acid phthalate in an external electric field

The anisotropy of deformations in potassium acid phthalate crystals arising under the action of an external electric field up to 1 kV mm−1 applied along the [001] polar axis was studied using X-ray diffraction methods at room temperature. Electrical conductivity was measured and rocking curves for reflections 400, 070 and 004 were obtained by time-resolved X-ray diffractometry in Laue and Bragg geometries. Two saturation processes were observed from the time dependences of the electrical conductivity. A shift in the diffraction peaks and a change in their intensity were found, which indicated a deformation of the crystal structure. Rapid piezoelectric deformation and reversible relaxation-like deformation, kinetically similar to the electrical conductivity of a crystal, were revealed. The deformation depended on the polarity and strength of the applied field. The deformation was more noticeable in the [100] direction and was practically absent in the [001] direction of the applied field. X-ray diffraction analysis revealed a disordered arrangement of potassium atoms, i.e. additional positions and vacancies. The heights of potential barriers between the positions of K+ ions and the paths of their possible migration in the crystal structure of potassium acid phthalate were determined. The data obtained by time-resolved X-ray diffractometry and X-ray structure analysis, along with additional electrophysical measurements, allow the conclusion that the migration of charge carriers (potassium cations) leads to lateral deformation of the crystal structure of potassium phthalate in an external electric field.

Analytical Modeling and Simulation of S-Drive Piezoelectric Actuators

This paper presents a structural geometry for increasing piezoelectric deformation, which is suitable for both micro- and macro-scale applications. New and versatile microstructure geometries for actuators can improve device performance, and piezoelectric designs benefit from a high-frequency response, power density, and efficiency, making them a viable choice for a variety of applications. Previous works have presented piezoelectric structures capable of this amplification, but few are well-suited to planar manufacturing. In addition to this manufacturing difficulty, a large number of designs cannot be chained into longer elements, preventing them from operating at the macro-scale. By optimizing for both modern manufacturing techniques and composability, this structure excels as an option for a variety of macro- and micro-applications. This paper presents an analytical compact model of a novel dual-bimorph piezoelectric structure, and shows that this compact model is within 2% of a computer-distributed element model. Furthermore it compares the actuator’s theoretical performance to that of a modern actuator, showing that this actuator trades mechanical efficiency for compactness and weight savings.

Power-Generation Optimization Based on Piezoelectric Ceramic Deformation for Energy Harvesting Application with Renewable Energy

Along with the increase in renewable energy, research on energy harvesting combined with piezoelectric energy is being conducted. However, it is difficult to predict the power generation of combined harvesting because there is no data on the power generation by a single piezoelectric material. Before predicting the corresponding power generation and efficiency, it is necessary to quantify the power generation by a single piezoelectric material alone. In this study, the generated power is measured based on three parameters (size of the piezoelectric ceramic, depth of compression, and speed of compression) that contribute to the deformation of a single PZT (Lead zirconate titanate)-based piezoelectric element. The generated power was analyzed by comparing with the corresponding parameters. The analysis results are as follows: (i) considering the difference between the size of the piezoelectric ceramic and the generated power, 20 mm was the most efficient piezoelectric ceramic size, (ii) considering the case of piezoelectric ceramics sized 14 mm, the generated power continued to increase with the increase in the compression depth of the piezoelectric ceramic, and (iii) For piezoelectric ceramics of all diameters, the longer the depth of deformation, the shorter the frequency, and depending on the depth of deformation, there is a specific frequency at which the charging power is maximum. Based on the findings of this study, PZT-based elements can be applied to cases that receive indirect force, including vibration energy and wave energy. In addition, the power generation of a PZT-based element can be predicted, and efficient conditions can be set for maximum power generation.

Cell‐by‐cell approximate Schur complement technique in preconditioning of meshfree discretized piezoelectric equations

AbstractThe radial point interpolation meshfree discretization is a very efficient numerical framework for the analysis of piezoelectricity, in which the fundamental electrostatic equations governing piezoelectric media are solved without mesh generation. Due to the mechanical‐electrical coupling property and the piezoelectric constant, the discrete linear system is sparse, of generalized saddle point form and often very ill conditioned. In this work, we propose a technique for constructing a family of cell‐by‐cell approximate Schur complement matrices, to be used in preconditioning to accelerate the convergence of Krylov subspace iteration methods for such problems. The approximate Schur complement matrices are simply and cheaply constructed in the process of the meshfree discretization and have a sparse structure. It is proved that the so‐constructed approximate Schur complement matrices are spectrally equivalent to the exact Schur complement matrix, which leads to very fast convergence when used in preconditioning. In addition, nondimensionalization of the piezoelectric equations is considered to make the computations more stable. The robustness and the efficiency of the proposed preconditioners is illustrated numerically on two test problems, arising from a piezoelectric strip shear deformation problem and a piezoelectric strip bending problem. Numerical results show that the number of iterations to achieve a given tolerance is independent of the number of degrees of freedom as well as of the various problem parameters.

Competing anticlastic and piezoelectric deformation at large deflections

In bending of a purely elastic beam or plate, it is well established that the cross-sectional shape changes character with decreasing bending radius-of-curvature and that the transition can be characterized by the Searle parameter. In a piezoelectric structure, the cross-sectional deformation is affected by the opposite anticlastic and electromechanical bending curvatures. The behavior is consequently more complicated and it is an open question how the cross-sectional shape develops with increasing bending. In this paper, analytical solutions are used to study the cross-sectional deformation of piezoelectric cantilever-actuators taking both anticlastic and electromechanical bending effects into account. We consider unimorph and bimorph actuators. In the case of electrical actuation, as for the purely mechanical case, we find that the Searle parameter is an important parameter characterizing the shape of the cross-section. A load scaling rule gives a criterion for fixed cross-section-deflection for different actuator widths. Using this scaling rule, the Searle parameter is kept unchanged. The analytical results are verified by non-linear finite element analysis using electric potential and mechanical moment as applied loads.

Bluetooth sneaker with Arduino embedded in it based on lattice structure

Energy crisis has become a worldwide problem, and clean energy, new energy and renewable energy are the focus of attention today. With the continuous improvement of people's living standards, more and more people participate in fitness. At this time, the stampede pressure generated by human walking will be a form of energy dissipation. Secondly, people's pursuit of quality of life is also increasing day by day, in the process of daily walking shoes are expected to have massage, temperature regulation and other multi-functional characteristics. According to the existing survey, this kind of shoes with multi-function is more attractive in the market, and it is easier to get the unanimous praise of consumers. This kind of multifunctional sports shoes takes into account the various possibilities of people when they are exercising. Under the basic conditions of ensuring safety, they pay more attention to comfort and save energy, giving full play to the maximum function of sports shoes. However, the current research and development of multi-functional sports shoes need to use the battery for power supply, the function is not perfect, large quality, low efficiency of electromechanical conversion and independent load and power generation function, so there is an urgent need for a high-efficiency intelligent sports shoes to meet the needs of the market. People in the process of walking, the foot will have corresponding pressure on the soles, namely the vibration source produces vibration, and multi-functional sports shoes mainly through the matrix collection equipment energy collection, when the lattice structure, piezoelectric material deformation and generate electric field, on the surface of piezoelectric materials under vibration force can reduce charge spacing, polarization is reduced, at this point, electric current can be generated by connecting wires, thus realizing the conversion of mechanical energy into electrical energy, which can power the graphene heating plate.

Bulk piezo-photovoltaic effect in LiNbO3

The deformations arising in iron-doped lithium niobate crystals (LiNbO3:Fe) under laser illumination were registered by changes in the parameters of X-ray diffraction rocking curves. The piezoelectric deformation as a result of the bulk photovoltaic effect was separated from heating according to the different kinetics of these processes using a set of time-resolved X-ray diffraction techniques. The dependence of the peak shift on the diffraction order confirmed the manifestation of the bulk piezo-photovoltaic effect. Additionally, the measurements of an external electric field influence on the diffraction peaks parameters were carried out as well as the measurements of the electrophysical and bulk photovoltaic characteristics of the crystal.