Piezoelectric Actuators Research Articles

Ultrahigh Piezoelectric Response Obtained by Artificially Generating a Large Internal Bias Field in BiFeO3–BaTiO3 Lead‐Free Ceramics

AbstractPiezoelectric actuators are vital devices that convert electrical signals into mechanical strain, offering rapid and precise responses. Lead‐based piezoceramics have traditionally been the preferred choice for commercial piezoelectric actuators, while the low Curie temperature and the rising environmental concerns hinder their applications at high temperatures. In this study, a novel strategy is proposed to achieve high piezoelectric responses in lead‐free 0.67Bi1.05FeO3–0.33BaTiO3 (67BF‐33BT) ceramics with high Curie temperature by artificially generating a large internal bias field through repeat poling and aging treatments. A comprehensive exploration of how this internal bias field responds to applied electric fields and temperature variations has been conducted. The results suggest that the internal bias field originates from two aspects, one arises from the free charges that compensate for the depolarization field, while the other is attributed to the highly oriented defect dipoles. As a result of this internal bias field, the ceramics exhibit asymmetric strain–electric field (S–E) behaviors, resulting in a high strain (ε = 0.21%) and an extremely high piezoelectric coefficient (d33* = 1033.70 pm V−1) when subjected to low electric field (20 kV cm−1), along with good temperature stability from room temperature (RT) to 100 °C.

Thermal Protection of Piezoelectric Actuators Using Complex Electrical Power Measurements and Simplified Thermal Models

This article describes a method for estimating the temperature of high-power piezoelectric actuators when a direct temperature measurement is impractical. The heat flow is estimated from the real component of the electrical power; then, the temperature is estimated by a transfer function that approximates the thermal response of the system. The transfer function can be derived analytically from a lumped-element approximation or calibrated experimentally by using a system identification method. The proposed method is demonstrated on a piezoelectric stack actuator used in a high-speed nanopositioning device. A second-order transfer function estimates the temperature to within 3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C of a reference measurement for a range of operating conditions. The proposed method is suitable for protecting piezoelectric actuators in applications where direct temperature measurement is impractical, for example, due to space or wiring constraints.

Research on a Locking Device for Power-Off Locking and 2-DOF Backward Motion Suppression of a Piezoelectric Platform

Inertial positioning platforms driven by piezoelectric actuators have been employed in many precision applications. However, challenges including unstable pose keeping and intractable displacement backward still exist. In this study, a locking device is designed and embedded in a piezoelectric inertial rotary platform to achieve the functions of power-off locking and 2-DOF backward motion suppression. The vertical output displacement of the locking end is converted from the horizontal elongation of the PZT stack by the flexible hinge mechanisms of the locking device, which is used to lock the rotor of the rotary platform. Theoretical and simulation analyses of the locking mechanism are performed and its dominant parameters are optimized. A prototype is fabricated and a series of experiments are performed. Compared with the inertial rotary platform without the locking device, the locking ability is increased by 4.55 times and the backward ratio is reduced from over 60% to below 12%. The application of locking device not only improves the pose keeping ability of the inertial positioning platform, but also improves its displacement output characteristics through backward motion suppression.

Development and analysis of two-dimensional point-ahead angle mechanism for space gravitational-wave detection.

To detect low-frequency gravitational waves, it is necessary to eliminate the interference of geo-noise and build a laser interference gravitational-wave detection device in space. Space gravitational-wave detection missions, namely Taiji, LISA, and Tianqin, have been planning to achieve picometer sensitivity on an interferometer arm of several million kilometers to meet the gravitational-wave detection requirements. Because of the orbit evolution and the time delay in interferometer arms, the direction of the transmitted laser beam changes; consequently, a remote telescope cannot receive the laser beam to complete the inter-satellite laser interference. In this study, a two-dimensional point-ahead angle mechanism (2DPAAM) is designed and demonstrated to solve the aforementioned problem. Based on the design concept of aligning the rotation center with the mirror surface center, the 2DPAAM employs a four-link flexible-hinge structure, length expanding and contracting piezoelectric stack actuators, and closed-loop control of capacitive sensors to realize two-dimensional picometer-stable, high-precision rotation. A static model is established to analyze the rotational characteristics, and finite element analysis is performed to study the mechanical properties and to verify the rotational characteristics. The yaw and pitch stiffness errors are ∼0.93% and 5.9%, respectively, when the theoretical results are compared with the simulation results. A series of experiments are conducted on the developed 2DPAAM, and the results show that the rotary ranges of yaw and pitch motions attain ±270 and ±268µrad, respectively. The rotational accuracies of both yaw and pitch motions attain ∼0.35µrad, and the optical path difference is less than 10pm/Hz when the frequency is between 1mHz and 1Hz, by analogy.

On the Design of a Fast Mechanical Switch-Based Amplified Piezoelectric Actuator

On the Design of a Fast Mechanical Switch-Based Amplified Piezoelectric Actuator

Design and experimental study of a planar piezoelectric actuator with resonant actuation

Planar piezoelectric actuators, which can achieve high-precision motions over a wide range, have been widely applied in high-end equipment fields. However, the existing planar piezoelectric actuators can no longer meet the high actuation characteristics required for the rapidly development of these fields, which include large travel, high resolution, fast speed, planar three degrees of freedom (3-DOF) and a compact structure. A planar piezoelectric actuator with resonant actuation is proposed and tested in this work. The actuator consists of four symmetrically configured uniform bending-bending hybrid piezoelectric units, which coordinate to achieve large travel and planar 3-DOF characteristics. A vibration isolation mechanism adopting thin beam structure with low stiffness in coupling directions is designed to achieve vibration isolation among the units. The actuator can operate in high frequency resonance mode and low frequency stepping mode, allowing for the achievement of high-speed and high-resolution characteristics. A prototype is fabricated and tested. A compact structure measuring 53 mm × 53 mm × 13 mm and weighing only 30.2 g has been achieved. The maximum linear and rotary speeds have been tested to be over 400 mm/s and 13 rad/s, respectively. The linear and rotary resolutions are 0.42 μm and 12.9 μrad, respectively. The proposed actuator achieves characteristics of large travel, high resolution, fast speed, 3-DOF and a compact structure.

Design and Analysis of a Micro Displacement Actuator Based on Stick-slip Principle Using Piezoelectric Ceramic

This work introduces a triangular shape piezoelectric actuator using the principle of piezoelectric ceramic bending vibration and stick-slip motion. The lateral displacement of the driving foot is used to press the slider, while the vertical displacement is used to drive the slider. The structural dimensions are determined by simulation considering the required parameters. Finite element software is used to analyze the static performance. The dynamic performance of the actuator are simulated and analyzed, including its response to different input voltages and frequencies. Dynamic model provides a comprehensive understanding of the behaviour of the actuator during operation and further reveals the principle. The actuator combines piezoelectric bending vibration and stick-slip motion with the merits of compactness, high accuracy and fast response.

A miniature multi-DOF ring-shaped piezoelectric actuator capable of driving both flat and spherical movers

In this paper, a novel miniature piezoelectric actuator was proposed with a compact ring structure and four driving teeth. The prominent feature was that the ring-shaped piezoelectric actuator could not only drive multiple types of movers, but also achieve multi-DOF motions by using the hybrid and traveling vibration modes. On the one hand, the four teeth were driven by only one ring-shaped piezoelectric actuator instead of four actuators separately, and were arranged circumferentially capable of supporting and driving both flat and spherical movers. On the other hand, the 4th-order radial and axial vibration modes were degenerated to achieve linear motions in the ox and oy directions; while two 3rd-order axial vibration modes were hybrid to realize the rotary motion around oz direction. FEM (finite element method) was employed to determine parameters and verify the working principles. Then, a prototype with a size of about Φ60 × 13 mm3 and a weight of 40 g was fabricated, and the characteristics were tested. Experimental results showed that the maximum speed, resolution and load realized in the linear motions were 23.3 mm/s, 0.7 μm, and 200 g, respectively; while that in the rotary motions were 0.8 rad/s, 11.5 μrad, and 200 g, respectively. The multi-DOF motions were successfully achieved by degenerating different vibration modes of the same ring structure.

Global Linearization Identification and Compensation of Nonresonant Dispersed Hysteresis for Piezoelectric Actuator

Global Linearization Identification and Compensation of Nonresonant Dispersed Hysteresis for Piezoelectric Actuator

Modeling and Control of a Linear Piezoelectric Actuator

To improve the output displacement of piezoelectric actuators, a linear piezoelectric actuator based on a multistage amplifying mechanism with a small volume, large thrust, high resolution, high precision, and fast response speed is proposed. However, inherent nonlinear characteristics, such as hysteresis and creep, significantly affect the output accuracy of piezoelectric actuators and may cause system instability. Therefore, a complex nonlinear hysteresis mathematical model with a high degree of fit was established. A Play operator was introduced into the backpropagation neural network, and a genetic algorithm (GA) was used to reduce the probability of the fitting of the neural network model falling into a local minimum. Moreover, simulation and experimental test platforms were constructed. The results showed that the maximum displacement of the actuator was 558.3 μm under a driving voltage of 150 V and a driving frequency of 1 Hz. The complex GA-BP neural network model of the piezoelectric actuator not only exhibited high modeling accuracy but also solved the problems of strong randomness and slow convergence. Compared with other control algorithms, the GA-BP fuzzy PID control exhibited higher control precision.

Design of a yarn feeder based on a piezoelectric actuator

Yarn feeding is a crucial step in various stages of the textile industry, and plays an important role in ensuring the stable operation of knitting machines. In response to the working environment of yarn feeders and the periodic intermittent yarn usage in loop forming systems, this paper proposes a new type of piezoelectric-actuated yarn feeder with the characteristics of small size, low energy consumption, switchable yarn feeding modes, and self-locking. The working principle of the new yarn feeder is systematically analyzed and simulated, and the performance of the yarn feeder is experimentally investigated and compared with theoretical analysis. The relationship curves between yarn feeding speed and driving frequency, as well as yarn feeding speed and driving voltage peak-to-peak value, are drawn, and the stability segmentation line of the yarn feeder is defined. The yarn feeding accuracy of the proposed yarn feeder is verified, and the displacement-time relationship curves of yarn under different conditions are plotted to explore the yarn feeding characteristics. In summary, the proposed piezoelectric-actuated yarn feeder has good performance and can meet the needs of practical production processes. It provides a valuable reference for the combination of piezoelectric driving and the textile industry.

Integrated multi-material and multi-scale optimization of compliant structure with embedded movable piezoelectric actuators

Piezoelectric actuators embedded in compliant structures have many potential applications, which call for effective design approaches. Existing optimization driven design methods focus on the piezoelectric actuator location or the macro topology of the host compliant structure while ignoring the possibility to exploit the use of multiple materials and hierarchical material design. In this study, an integrated, density-based multi-material and multi-scale optimization method for compliant structures with embedded movable piezoelectric actuators is proposed. The design variables in the optimization represent the location of the piezoelectric actuators and the layout of the macro/micro host structures. To mitigate the risk of suboptimal designs, the three sets of design variables are simultaneously optimized using gradient-based optimization where the gradients are computed using the adjoint method. A material interpolation model that describes the piezoelectric actuators, multiple lattice materials of the host structure as well as their coating layer is proposed. To illustrate the formulation, several compliant structures embedded with movable piezoelectric actuators are designed such that the displacement at an output port is maximized. Macro and micro volume fractions, and overlapping of piezoelectric actuators are constrained in the optimization.

Tunable quantum dots in monolithic Fabry-Perot microcavities for high-performance single-photon sources

Cavity-enhanced single quantum dots (QDs) are the main approach towards ultra-high-performance solid-state quantum light sources for scalable photonic quantum technologies. Nevertheless, harnessing the Purcell effect requires precise spectral and spatial alignment of the QDs’ emission with the cavity mode, which is challenging for most cavities. Here we have successfully integrated miniaturized Fabry-Perot microcavities with a piezoelectric actuator, and demonstrated a bright single-photon source derived from a deterministically coupled QD within this microcavity. Leveraging the cavity-membrane structures, we have achieved large spectral tunability via strain tuning. On resonance, a high Purcell factor of ~9 is attained. The source delivers single photons with simultaneous high extraction efficiency of 0.58, high purity of 0.956(2) and high indistinguishability of 0.922(4). Together with its compact footprint, our scheme facilitates the scalable integration of indistinguishable quantum light sources on-chip, therefore removing a major barrier to the development of solid-state quantum information platforms based on QDs.

A novel active and passive integrated vibration isolator based on piezoelectric stack: Characteristic analysis and experimental investigation

Passive vibration isolation has the advantages of simple structure, high reliability, and strong ability to absorb high-frequency vibration. Active vibration isolation has wide application range, strong controllability, and good vibration suppression effect for specific frequency band. Active and passive integrated vibration isolation technology combines the characteristics of both and has obvious advantages in dealing with the complex vibration environment in modern engineering practice. In this work, piezoelectric stack actuator is selected as the active control output source and vulcanized butyl rubber is used as the passive vibration absorber. The dynamic model of the novel active and passive integrated isolator is established, then the effects of different parameters on its vibration transmission performance are studied. Furthermore, a typical two-degree-of-freedom vibration isolation system model is established. By comparing the change of vibration transmissibility under different feedback forms, the design of the feedforward–feedback composite controller is applied. Finally, a double-layer vibration isolation test platform is built to verify the vibration reduction capability of the active and passive integrated isolator. The experimental results show that both the passive vibration absorption and active vibration suppression functions of this novel vibration isolator are particularly effective.

Numerical and experimental characterization of a piezoelectric actuator for microfluidic cell sorting

Piezoelectric actuators offer great opportunities for precise and low-cost control of fluids at the microscale. Microfluidic systems with integrated piezoelectric actuators find application as droplet generators, micropumps, and microsorters. To accelerate device design and optimization, modeling and simulation approaches represent an attractive tool, but there are challenges arising from the multiphysics nature of the problem. Simple, potentially real-time approaches to experimentally characterize the fluid response to piezoelectric actuation are also highly desirable. In this work, we propose a strategy for the numerical and experimental characterization of a piezoelectric microfluidic cell sorter. Specifically, we present a 3D coupled multiphysics finite-element model of the system and an easy image-based approach for flow monitoring. Sinusoidal and pulse actuation are considered as case studies to test the proposed methodology. The results demonstrate the validity of the approach as well as the suitability of the system for cell sorting applications.

Characterizing the electric field- and rate-dependent hysteresis of piezoelectric ceramics shear motion with the Bouc-Wen model

Piezoelectric technology is widely used in the field of precision drives. However, when piezoelectric actuators are employed at high voltages and high frequencies, their hysteresis can greatly affect the accuracy of such systems. The Bouc-Wen model has typically been used by researchers to characterise the hysteresis of piezoelectric materials. Besides, to extract the parameters of this model from experimental data, particle swarm optimization (PSO) is often employed. However, the majority of such studies only considers hysteresis as a function of the electric field strength and not as a function of actuation frequency. In addition, most of such existing reports have focused on longitudinal type piezo actuators. In this context, the research presented here complements this body of knowledge by demonstrating the application of the PSO algorithm for determining the parameters of the Bouc-Wen model when hysteresis depends not only on the electric field but also on the rate of the driving signal and when applied on a shear-type piezoelectric actuator. The obtained experimental data showed that with the increase of electric field strength, both the piezoelectric coefficient and hysteresis value increased significantly, and that with the increase of frequency, the piezoelectric coefficient decreased, while the hysteresis value changed slightly. The variations of the Bouc-Wen model parameters with the electric field and frequency were identified and then used to predict the shear motion trajectory of the piezoelectric stack. It was found that in the identified range of electric field and frequency, the predicted error rate of the hysteresis loop amplitude was less than 16.5% with a minimum value of 0.1%, and the error rate of the hysteresis loop width was less than 14.5% with a minimum value of 2.7%. Based on the identified electric field- and rate-dependent Bouc-Wen model, a novel finite element (FE) model was also proposed to analyse the effect of electrical and mechanical coupling on the piezoelectric movement.

Actuation Force Modeling and Identification for Piezoelectric Actuator With Neural Network Compensator and Nonlinear Hysteresis

Actuation Force Modeling and Identification for Piezoelectric Actuator With Neural Network Compensator and Nonlinear Hysteresis

Utilizing piezoelectric actuators to micro-vibration generation for de-icing system of aircraft

Utilizing piezoelectric actuators to micro-vibration generation for de-icing system of aircraft

High-Speed Cell Assembly with Piezo-Driven Two-Finger Microhand

In the past few decades, researchers have conducted extensive studies on cell micromanipulation methods. However, there has consistently been a lack of a micromanipulation system that excels in both precision and speed. Additionally, many of these methods rely on manual control, thus significantly reducing efficiency. In this paper, a robotized micromanipulation system employing a two-finger microhand is proposed. The microhand has a 3-DoF parallel mechanism driven by three piezoelectric actuators, enabling high-precision micromanipulation. Replacing the needle-tip end-effector with a hemispherical end-effector makes cell grasping easier and more stable. In addition, a vibration-based release method combined with gel coating is proposed to reduce the release difficulty caused by adhesion forces. Through multiple sets of experiments, we have determined the optimal grasping and releasing conditions while balancing precision, stability, and damage degree to cells. An automated cell assembly strategy based on microscopic visual feedback and pick-and-place path planning is proposed to achieve the robotized high-speed cell array. Hela cells were chosen as the operation objects, achieving a 95% success rate in grasping and a 97% success rate in releasing. A “T” letter array formed by cells was successfully assembled with an average grasp and release time of less than 0.8 s and an assembly accuracy of 4.5 μm for a single cell. This study holds significant implications for the fields of biology and medicine, presenting potential applications in tissue engineering.

Piezoelectric resonant ice protection systems – Part 1/2: Prediction of power requirement for de-icing a NACA 0024 leading edge

This paper proposes a numerical method to analyze the ice protection capability and predict the power requirements of a piezoelectric resonant de-icing system. The method is based on a coupled electro-mechanical finite element analysis which enables the fast computation of the modes of resonance of interest to de-ice curved surfaces and the estimation of the input voltage and current required for a given configuration (defined by its mode, actuator location, ice deposit, etc.). Eventually, the electric power to be supplied can be also assessed. The method is applied to a NACA 0024 leading edge equipped with piezoelectric actuators. First, two extension modes are analyzed and compared with respect to their efficiency and power requirements. Then, tests are carried out in an icing tunnel to verify the effectiveness of the piezoelectric ice protection system and the predictions of the maximal required power. The system allows de-icing the leading edge in less than 2 s for a glaze ice deposit.