Lead Zirconate Titanate Actuator Research Articles

Feasibility of Stress Wave-Based Debond Defect Detection for RCFSTs Considering the Influence of Randomly Distributed Circular Aggregates with Mesoscale Homogenization Methodology.

In order to efficiently investigate the effect of the mesoscale heterogeneity of a concrete core and the randomness of circular coarse aggregate distribution on the stress wave propagation procedure and the response of PZT sensors in traditional coupling mesoscale finite element models (CMFEMs), firstly, a mesoscale homogenization approach is introduced to establish coupling homogenization finite element models (CHFEMs) with circular coarse aggregates. CHFEMs of rectangular concrete-filled steel tube (RCFST) members include a surface-mounted piezoelectric lead zirconate titanate (PZT) actuator, PZT sensors at different measurement distances, a concrete core with mesoscale homogeneity. Secondly, the computation efficiency and accuracy of the proposed CHFEMs and the size effect of representative area elements (RAEs) on the stress wave field simulation results are investigated. The stress wave field simulation results indicate that the size of an RAE limitedly affects the stress wave fields. Thirdly, the responses of PZT sensors at different measurement distances of the CHFEMs under both sinusoidal and modulated signals are studied and compared with those of the corresponding CMFEMs. Finally, the effect of the mesoscale heterogeneity of a concrete core and the randomness of circular coarse aggregate distribution on the responses of PZT sensors in the time domain of the CHFEMs with and without debond defects is further investigated. The results show that the mesoscale heterogeneity of a concrete core and randomness of circular coarse aggregate distribution only have a certain influence on the response of PZT sensors that are close to the PZT actuator. Instead, the interface debond defects dominantly affect the response of each PZT sensor regardless of the measurement distance. This finding supports the feasibility of stress wave-based debond detection for RCFSTs where the concrete core is a heterogeneous material.

Finite Element Analysis and Fabrication of a 3 MHz Megasonic System for Semiconductor Cleaning

Megasonic cleaning has been used to clean contaminants from wafer surfaces in semiconductor production. This research developed a 3 MHz megasonic waveguide for cleaning processes in semiconductor industries. Firstly, a 1 MHz type was fabricated in aluminum (Al) and quartz, consisting of a lead zirconate titanate (PZT) actuator and a waveguide. A 3 MHz quartz waveguide was also fabricated based on the fabricated results, and its performance was tested. In the design process, finite element analysis was performed. As a result, the predicted value was 2.997 MHz, which agreed with the measured value of 2.995 MHz with a 0.1% error. Lastly, a particle removal efficiency (PRE) test was performed, and the results showed that 93.1% PRE was achieved at 8W power. Considering the acoustic pressure and the cleaning test results, the 3 MHz megasonic may help the removal of contaminants from wafer surfaces effectively.

Failure mechanism analysis and experimental study of lead zirconate titanate actuators in piezoelectric micro jetting valve

Piezoelectric ceramics have recently become one of the most common materials in electromechanical industries, especially in the microelectronic packaging industry. In a jetting dispenser, the presence of imbalanced stress-induced defects in such materials prevents them from providing high stability during the jetting dispensing process. In this work, lead zirconate titanate piezoelectric ceramics (PZT ceramics) were used to actuate the amplifying mechanism of the jetting dispenser. However, during the cyclic dispensing, several ceramics were found to be damaged. In order to figure out what actually caused the damage, analytical and experimental studies were carried out to acquire characteristics of PZT ceramics with damages, and simulation studies of overstress were also performed. Details of the damage characteristics in PZT ceramics are discussed in this paper. This work will improve the stability and life of the piezoelectric dispenser and further promote its wide application in various fields.

Arrangement of Live Human Cells through Acoustic Waves Generated by Piezoelectric Actuators for Tissue Engineering Applications

In this paper, the possibility to steer and confine live human cells by means of acoustic waves, such as flexural plate waves (FPWs), generated by piezoelectric actuators applied to non-piezoelectric substrates, has been explored. A device with two lead zirconate titanate (PZT) actuators with an interdigital transducer (IDT) screen-printed on an alumina (Al2O3) substrate has been fabricated and tested. The experimental results show that, by exciting the actuators at their resonant frequencies, FPW modes are generated in the substrate. By exploiting the device, arrangements of cells on lines at frequency-dependent distances have been obtained. To maintain the alignment after switching off the actuator, cells were entrapped in a fibrin clot that was cultured for several days, enabling the formation of cellular patterns.

Active Elastomeric Composite Dense Array Stamp For Micro-transfer Printing

Micro-transfer printing is a powerful methodology for the manufacturing of 3D heterogeneously integrated micro-systems. This paper explores an active elastomeric composite dense array stamp which improves throughput while enabling local monitoring and control of the process. This dense array stamp is a scalable 4x4 geometry design with a multiplexed interconnection scheme, ensuring a small footprint. It consists of 16 individual stamps, each with a Lead Zirconate Titanate (PZT) actuator and a strain gauge sensor. Actuation and sensing characterization and closed-loop feedback control were established, and the dense array stamp performance was validated using selective pickup and place micro-transfer printing experiments.

Active shape control of an antenna reflector using piezoelectric actuators

The surface precision of an antenna reflector can be improved using the actuation of piezoelectric materials to obtain a high-performance space antenna. In this study, the active shape control of a reflector with piezoceramic (lead zirconate titanate) actuators assembled on ribs is proposed by theoretical and experimental approaches. A finite element model of the integrated reflector–actuator system is established using piezoelectric constitutive equations and the virtual work’s principle. For a desired shape, a closed-loop iterative shape control method based on the influence coefficient matrix model is developed, which resolves the issue of high-precision shape control of the antenna reflector in the presence of model errors. The shape controller based on the proposed closed-loop shape control method is implemented on a planar hexagonal reflector with 30 lead zirconate titanate actuators. Experimental results demonstrate that the closed-loop control is an effective way to improve the surface precision of the reflector considering uncertainties.

Numerical study on interface debonding detection mechanisms with 2D spectral element method for concrete-filled steel tube using embedded PZT sensor

Interface debonding detection approaches based on stress wave measurement for concrete-filled steel tube (CFST) members have received a great deal of attention in civil and infrastructural engineering societies. The development of efficient computing approaches to investigate the mechanisms of the interface debonding detection approaches and the effect of interface debonding on wave propagation within CFST members is critical. In this study, the wave propagation within the cross section of CFST members with and without interface debonding under a single point excitation force is simulated with a two-dimensional (2D) spectral element method (SEM) at first and that of CFST models coupled with a surface-mounted piezoelectric lead zirconate titanate (PZT) actuator and an embedded PZT sensor in the concrete core under continuous and sweep sinusoidal signals is simulated with the 2D SEM and a piezoelectric spectral element. The debonding defect is modeled by removing concrete elements between the steel tube and the concrete core. Results show that interface debonding affects the wave propagation process, the output potentials of the embedded PZT sensors as well as the displacement responses at different locations of CFST specimens obviously. Rayleigh damping identified from experiments is introduced to the SEM models to reflect wave attenuation in the coupled models. The effect of interface debonding on the amplitude, the Fourier spectra and the wavelet packet energy of stress waves are analyzed. For comparison, another numerical model in which the PZT actuator is not located near the interface debonding defect is studied numerically and the effect of the debonding defect on the response of the embedded PZT sensor is illustrated. SEM provides an efficient way to simulate stress wave propagation and to understand the mechanisms of interfacial debonding defect detection for CFSTs with PZT technique.

Piezoelectric‐driven self‐assembling micro air vehicle with bionic reciprocating wings

A 247 mg weight coin-size piezoelectric-driven micro air vehicle (MAV) with four symmetrical distributed bionic flexible wings is presented. The MAV is planar designed and monolithic fabricated via film printed circuit, graphic lasering and lamination process, and is able to be self-assembled by using shape memory polymer (SMP). The SMP can be heated by the flexible circuit and shrink at a large strain, resulting in the self-folding of hinges and self-assembly of MAV from 2D shape into 3D shape. The flexible four-bar mechanism converts the slight vibration of lead zirconate titanate (PZT) actuator into flexible wings’ reciprocation, thereby generating lift force. The response characteristics and motion behaviour of the MAV are experimentally tested. Results suggest that the prototype can be self-assembled to the designed position and achieve a 23.5° reciprocating angle at 134 Hz resonance frequency under 280 V driving signals.

Fabrication of an ultrathin lead zirconate titanate mirror device mounted on flexible substrate

We have developedultrathin MEMS mirror devices. The mirror device was driven by lead zirconate titanate (PZT) actuators. Because the thickness of the mirror device is 5.31 µm, the mirror device is flexible. The mirror device was mounted on a polyimide substrate by a mounting method that we have developed. After fabrication, we investigated the characteristics of the mirror device experimentally. The frequency of the resonant mode for scanning optical light was 10.4 kHz. Also, we conducted an experiment to confirm the flexibility of the mirror device. When the polyimide substrate was bent (radius of curvature was 125 mm), the mirror device can be actuated without breakage. Moreover, it was observed that the resonance frequency and mechanical angle of the mirror device were dependent on the radius of curvature of the flexible substrate. This fabrication and mounting technology is highly promising for the development of flexible hybrid electronic (FHE) devices.

Multi-Objective Topology Optimization of a Compliant Parallel Planar Mechanism under Combined Load Cases and Constraints

This paper focuses on a new type of configuration design of a compliant parallel mechanism (CPM) planar continuum structure and its characteristic analysis of vibration-inherent frequency for planar motion, which can suppress the impact of random vibration in ultra-precision positioning and manufacturing equipment and improve the inherent frequency response of the mechanism. Firstly, a vector-mapping isomorphism between the fully CPM and conventional isomorphic parallel mechanism was constructed with a kinematic differential Jacobian matrix. Then, the mathematical model of topology optimization was put forward considering the compromise programming on the static stiffness and mean vibration-inherent frequency of the mechanism as the design variable and the minimization of compliance as the objective function. A constraint of volume fraction was considered and multi-objective micro displacement mechanism topology optimization based on a prismatic-revolute-revolute (3-PRR) planar nano-positioning continuum structure was performed using the solid isotropic material with penalization (SIMP) technique, which combines the criteria of the optimization algorithm and the vector isomorphic mapping method. Multi-objective topology optimization of the continuum structure micro displacement mechanism was investigated and presented by optimizations with different initial rejection rates. The simulation results show that the stiffness and vibration suppression performance of the continuum structure were improved, whereas the positioning of differential kinematics characteristics of the 3-PRR micro displacement planar fully CPM and isomorphic prototype mechanism retain the same. The modal analysis also provides a rational configuration for the micro displacement mechanism dimensional design and its optimal modal parameters. The crossover oscillation in frequency response of the continuum structure was reduced and quickly converged in the optimization iterations. The performance of the optimized mechanism was verified by the experiments on a planar fully compliant micro displacement continuum structure based on Lead Zirconate Titanate (PZT) actuator.

Microwave generation with an inner-modulated laser and parallel Mach–Zehnder interferometers

Using an inner-frequency-modulated semiconductor laser, two parallel Mach–Zehnder delay-line interferometers and feedback control loop technique, we generate microwaves. The frequency of the Littrow-structure semiconductor laser is modified by a lead zirconate titanate actuator that covers a wideband modulating range. One long delay-line interferometer generates microwaves; the second short delay-line interferometer controls the linearity of the modulate laser and assures microwave stability by a feedback loop. Thus, this method, in theory, should produce more than one hundred GHz microwave. We experimentally generated 1.743 GHz to 5.134 GHz microwaves. This technology opens a new path for developments in microwave photonics.

Wave propagation simulation and its wavelet package analysis for debonding detection of circular CFST members

In order to investigate the interface debonding defects detection mechanism between steel tube and concrete core of concrete-filled steel tubes (CFSTs), multi-physical fields coupling finite element models constituted of a surface mounted Piezoceramic Lead Zirconate Titanate (PZT) actuator, an embedded PZT sensor and a circular cross section of CFST column are established. The stress wave initiation and propagation induced by the PZT actuator under sinusoidal and sweep frequency excitations are simulated with a two dimensional (2D) plain strain analysis and the difference of stress wave fields close to the interface debonding defect and within the cross section of the CFST members without and with debonding defects are compared in time domain. The linearity and stability of the embedded PZT response under sinusoidal signals with different frequencies and amplitudes are validated. The relationship between the amplitudes of stress wave and the measurement distances in a healthy CFST cross section is also studied. Meanwhile, the responses of PZT sensor under both sinusoidal and sweep frequency excitations are compared and the influence of debonding defect depth and length on the output voltage is also illustrated. The results show the output voltage signal amplitude and head wave arriving time are affected significantly by debonding defects. Moreover, the measurement of PZT sensor is sensitive to the initiation of interface debonding defects. Furthermore, wavelet packet analysis on the voltage signal under sweep frequency excitations is carried out and a normalized wavelet packet energy index (NWPEI) is defined to identify the interfacial debonding. The value of NWPEI attenuates with the increase in the dimension of debonding defects. The results help understand the debonding defects detection mechanism for circular CFST members with PZT technique.

Microfluidic fluorescence-activated cell sorting (μFACS) chip with integrated piezoelectric actuators for low-cost mammalian cell enrichment

A low-cost, microfluidic fluorescence-activated cell sorting (μFACS) microchip integrated with two piezoelectric lead–zirconate–titanate actuators was demonstrated for automated, high-performance mammalian cell analysis and enrichment. In this PDMS–glass device, cells were hydrodynamically focused into a single file line in the lateral direction by two sheath flows, and then interrogated with a forward scattering and confocal fluorescent detection system. The selected cells were displaced transversely into a collection channel by two piezoelectric actuators that worked in a pull–push relay manner with a minimal switching time of ~0.8 ms. High detection throughput (~2500 cells/s), high sorting rate (~1250 cells/s), and high sorting efficiency (~98%) were successfully achieved on the μFACS system. Six cell mixture samples containing 22.87% of GFP-expressing HeLa cells were consecutively analyzed and sorted on the chip, revealing a stable sorting efficiency of 97.7 ± 0.93%. In addition, cell mixtures containing 37.65 and 3.36% GFP HeLa cells were effectively enriched up to 83.82 and 78.51%, respectively, on the microchip, and an enrichment factor of 105 for the low-purity (3.36%) sample was successfully obtained. This fully enclosed, disposable microfluidic chip provides an automated platform for low-cost fluorescence-based cell detection and enrichment, and is attractive to applications where cross-contamination between runs and aerosol hazard are the primary concerns.

Surgical Grasping Forceps With Enhanced Sensorimotor Capability via the Stochastic Resonance Effect

Haptic information is crucial in the execution of precise dexterous manipulations. Laparoscopic surgery, a type of minimally invasive surgery, requires that the surgeon senses force information about tissue through forceps, because he or she cannot touch the organs directly. We propose the concept of surgical grasping forceps with enhanced sensorimotor capability based on attaching a vibrator to the forceps’ grip by evoking a stochastic resonance (SR) effect. To apply appropriate vibrations, a summing network of FitzHugh–Nagumo neurons was built to investigate the system's response when white noise was applied to each of the four types of tactile receptor. The relation among the tactile sensitivity, noise intensity, and amplitude of input signal is discussed by the simulation with the neural network composed of different tactile receptors. The simulation results revealed that the working range of the SR effect is extended by taking advantage of having multiple receptors with different characteristics in skins. It was also found that improved tactile sensitivity could be obtained even without a strict set of vibration intensity values. Based on the findings from the simulation, we developed surgical forceps with sensorimotor-enhancing capability taking advantage of the SR effect. The forceps are equipped with a lead zirconate titanate actuator at the grip as a vibration source. We conducted touch testing, texture discrimination testing, and tumor detection testing to verify their improved tactile sensitivity. The experiments conducted with the proposed forceps showed that maintaining the noise intensity within the optimal range could improve tactile sensitivity, and confirmed the usefulness of the SR application for medical devices.

Lamb-wave-based two-dimensional areal scan damage imaging using reverse-time migration with a normalized zero-lag cross-correlation imaging condition

This article presents a two-dimensional, non-contact, areal scanning system to image and quantify multiple sites of damage in isotropic plates using reverse-time migration with a normalized zero-lag cross-correlation imaging condition. The hybrid system composed of a single piezoelectric actuator mounted onto the structure and a laser Doppler vibrometer for two-dimensional scan. The laser Doppler vibrometer scanned a region in the vicinity of the lead zirconate titanate actuator to capture the scattered wavefield introduced by the damage. The proposed damage imaging technique takes into account the amplitude, phase, and all the frequency content of the single-mode Lamb waves propagating in the plate; thus, the size of multiple sites of damage can be imaged without bias, regardless of the damage locations. Damage image quality was used as a metric to compare two-dimensional areal scans and linear scans as well as to compare the proposed method with existing imaging conditions. The experimental results show that the two-dimensional reverse-time migration/normalized zero-lag cross-correlation technique is capable of imaging and quantification of multiple damage sites in an aluminum plate using a single lead zirconate titanate actuator and a nearby, areal laser Doppler vibrometer scan.

Design and Fabrication of an Ultrasonic Waveguide for Microchip Cooling Applications

1. Introduction Ultrasound is generated by a piezoelectric actuator and a waveguide, which can amplify the sub-micro displacement from electrical energy. It has been widely used in semiconductor cleaning, and one of challenging application area of the ultrasound is semiconductor chip including central processing unit (CPU) cooling, which can be performed by wave energy [1-3]. Previous researches were investigated, and main focuses of those studies were about exploring the methods of increasing passive cooling effect by enhancing the convective heat transfer coefficient. But in this research, an ultrasonic waveguide for microchip cooling that is operated by 40 kHz operating frequency, was designed and fabricated for active cooling. To develop the waveguide, finite element analysis using ANSYS software was processed. First, anti-resonance frequency for a piezoelectric actuator was predicted, the result was compared with the experimental result. Then the waveguide was fabricated, and impedance characteristics were measured and compared. Next, predicted anti-resonance frequency for the ultrasonic waveguide was compared with the experimental value. Finally, the application area of the developed ultrasonic waveguide to microchip cooling is discussed. 2. Design and fabrication of the ultrasonic waveguide For the generation of the ultrasound, the 40 kHz ultrasonic waveguide for microchip cooling is mainly composed of two parts, the ultrasonic unit and the electric generator. The fabricated ultrasonic waveguide system is shown in Fig. 1. The waveguide has a cylindrically shaped aluminium (Al) waveguide with a lead zirconate titanate (PZT) actuator attached on the top. In the waveguide, there are a resonator and stacks that can refrigerate. For the actuation, power is supplied to the PZT actuator, and the actuator vibrates. Subsequently, the displacement is transferred through the waveguide to the resonator part for cooling. To design the ultrasonic waveguide, FEM analysis using Ansys (Commercial FEM software) was performed. Firstly, the PZT actuator was modeled with the analysis tool. For the analysis, it was modelled axis-symmetrically and the nodes of the top and bottom electrodes were coupled to apply voltages. To obtain a solution, series of calculations were performed from 30.0 kHz through 40.0 kHz. As a result, the highest impedance value was 34.8 kHz, which was decided as a design frequency. Secondly, the waveguide with the PZT actuator was modelled. After analysis, the highest impedance value was 39.4 kHz as shown in Fig. 2. For the prediction of the displacement, analysis was performed using the same analysis model. The PZT actuator and the waveguide were modeled. And modal analysis was performed and structural motion could be predicted. As a result, displacements at the operating frequency of 39.4 kHz is shown in Fig. 3. 3. Experiments Based on the analysis results, ultrasonic waveguide was fabricated. And the peak frequency value of impedance was measured to be 34.7 kHz of the PZT alone and 39.8 kHz of the system, which agreed well with predicted value with 0.3% and 1.0% error, as shown in Fig 4 for the waveguide. 4. Conclusion In this paper, the design and fabrication processes of an ultrasonic waveguide for microchip cooling that is operated by 40 kHz operating frequency were explained. In the development stage, finite element analysis using ANSYS software was performed to design the waveguide. So the predicted anti-resonance frequency for a piezoelectric actuator was 34.8 kHz, which was in good agreement with the experimental result of 34.7 kHz with 0.3% error. The waveguide was manufactured, and impedance characteristics were measured and compared. The predicted anti-resonance frequency for the ultrasonic waveguide was 39.4 kHz, which coincided with the experimental value of 39.8 with 1.0% error. Based on these results, it is thought that the developed ultrasonic waveguide will be applicable in microchip cooling.

Investigation of large signal properties of quasi-static lead zirconate titanate actuators at elevated temperature

Quasi-static multilayer piezoelectric actuators are finding more and more applications, for example, in the field of aerospace; however, their properties are still not fully characterised, in particular at a high temperature. The present study targets the full characterisation of both soft-doped and hard-doped lead zirconate titanate (PZT) up to 200°C. A simple set of tests and test results are presented, focusing particularly on dielectric losses and creep effect. Dielectric losses were found to decrease with the increasing field for soft-doped PZT, while they tend to increase for hard-doped PZT. The interpretation is that soft-doped PZT has less hysteresis at high field. The creep behaviour is also significantly different. While soft-doped PZT follows a logarithmic model with low and stable creep rates, hard-doped PZT exhibits non-logarithmic creep with increasing or decreasing rates depending on the temperature. This behaviour is attributed to the generation of additional poling in the material.

Linear and Nonlinear Analysis of Piezoelectric Based Vibration Absorber with Acceleration Feedback

In the present paper, analysis of a single degree of freedom spring-mass-damper primary system with a piezoelectric based dynamic vibration absorber (DVA) is carried out. The proposed DVA model consisting of a lead zirconate titanate (PZT) actuator which is connected in series with a spring. The analysis is done in two section by considering a static force and a harmonic force acting on the primary system respectively. In the first section linear stiffness is considered in the primary mass and in the second section cubic nonlinear stiffness along with the linear stiffness is considered. The voltage applied to the stack PZT actuator is considered to be proportional to the acceleration of the primary mass. Method of multiple scales (MMS) is used to obtain the system response in the nonlinear analysis and compared with linear analysis. For linear system optimum system parameters of the absorber are obtained using fixed point theory of optimization and Routh's stability criterion is used for stability analysis. Primary resonance condition is studied in the nonlinear analysis. In the proposed model as a spring is connected in series with PZT actuator for which force developed by the absorber to suppress the vibration of the primary system is not solely depend upon the voltage, so one can use small voltage to reduce the vibration of primary system.

Sine-modulated wavelength-independent full-range complex spectral optical coherence tomography with an ultra-broadband light source

We present a full-range complex spectral domain optical coherence tomography with an ultra-broadband light source based on sinusoidal modulation. For the sinusoidal modulation strategy, a lead zirconate titanate stack actuator is employed to achieve the sinusoidal vibration of a mirror and therefore to get a series of spectral interferogram with different phase delays. The purpose of this strategy is to get higher performance complex-conjugate artifact elimination. Bessel separation of the signal sequence at each wavelength of the spectrometer was used to reconstruct the real and imaginary components of interference fringes; however, the sinusoidal modulation method is independent of light source wavelength. The experimental results demonstrated that the method had an excellent performance in a complex-conjugate suppression of 50 dB for a full width at half maximum bandwidth of 236 nm, and it has better anti-artifact ability and more flexible range in phase shifting than the conventional wavelength-dependent phase-shifting method on a full-range complex spectral optical coherence tomography system. Furthermore, the effect of the hysteresis error of lead zirconate titanate actuators on the performance of complex-conjugate artifact elimination was investigated and the solution of lead zirconate titanate positioning performance for both conventional phase-shifting and sine-modulation methods was suggested.

High bandwidth frequency lock of a rigid tunable optical cavity.

In this paper, we present a high bandwidth frequency lock of a rigid tunable Fabry Perot cavity based on a set of lead zirconate titanate (PZT) actuators. The cavity spacer was specifically designed such that the frequency of the first resonance of the whole assembly under PZT excitation is above 35kHz, thus allowing a servo-loop bandwidth of 13kHz. It is demonstrated that no significant noise is added by the cavity to the output beam with respect to the input beam over the servo-loop bandwidth. This cavity can be used as a pre-mode cleaner in interferometric gravitational wave detectors such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo.