PZT Plate Research Articles

Electric field and vibration-assisted nanomolecule desorption and anti-biofouling for biosensor applications

A novel anti-fouling mechanism based on the combined effects of electric field and shear stress is reported. A lead zirconate titanate (PZT) composite is used to generate an electric field and an acoustic streaming shear stress that increase nanomolecule desorption. In vitro characterization showed that (1) 58 ± 5.5% and 39 ± 5.2% of adsorbed bovine serum albumin (BSA) proteins can be effectively removed from fired silver and titanium coated PZT plate, respectively; and (2) 43 ± 9.7% of the anti-mouse immunoglobulin G (IgG) can be effectively removed from a fired silver coated PZT plate. Theoretical calculations on protein-surface interactions (van der Waals (VDW), electrostatic, and hydrophobic) and shear stress describe the mechanism for protein desorption from model surfaces. We have shown that the applied electric potential is the major contributor in reducing the adhesive force between protein and surface, and the desorbed protein is taken away by acoustic streaming shear stress. We strongly believe that the present method offers the possibility of minimizing nanomolecule adsorption without further surface treatment.

Prediction of actuating displacement in a piezoelectric composite actuator with a thin sandwiched PZT plate by a finite element simulation

This paper presents the evaluation of a plate-type piezoelectric composite actuator (PCA) with a thin sandwiched plate having four kinds of lay-up configurations by analyzing the flexural displacement. For this, a three-dimensional finite element simulation considering the thermal deformation effect of PCA during manufacturing is conducted based on a thermal analogy model. The distribution of residual thermal stresses and the dome height caused by the mismatch in coefficient of thermal expansion (CTE) between the layers of PCA are predicted with the aid of a classical laminated plate theory (CLPT). Results of finite element analyses have revealed that the flexural displacement of PCA subjected to electric fields is considerably affected by the variation of lay-up configuration, the thickness of an embedded PZT wafer and boundary conditions. In particular, as the thickness of the PZT ceramic increases, the bending stiffness of PCA increases faster than the actuation distance does, which leads to the overall reduction in flexural displacement. It is therefore suggested that the electrically induced flexural displacement of unimorph-type PCA depends more on the bending stiffness than on the actuation distance.

Enhanced magnetoelectric effects in composite of piezoelectric ceramics, rare-earth iron alloys, and ultrasonic horn

A magnetoelectric (ME) composite consisting of a copper ultrasonic horn, a magnetostrictive Terfenol-D (TbxDy1−xFe2) plate, and multiple piezoelectric PZT [Pb(Zr1−xTix)O3] plates has been developed. The ultrasonic horn converges and amplifies the vibrating magnitude and drives PZT plates at wide bandwidth. The composite with multiple PZT plates electrically connected in series/parallel exhibits a 25 times higher ME voltage coefficient than the previous laminate composite of PZT and Terfenol-D plates. 100 times higher ME voltage coefficients can be obtained by using a silicon horn composite with a higher Q value of 104 and more PZT plates of ten electrically connected in series/parallel.

Three-Dimensional Free Vibration Analysis of Multiphase Piezocomposite Structures

Based on Hamilton’s principle, a three-dimensional semianalytical method for the analysis of free vibration of a structure composed of piezoelectric and elastic materials is developed. Computations of dynamical behavior including natural frequencies, and mode shapes are of interest. In this approach, the mechanical displacement and electric potential functions, in each region, are expressed as products of a three-dimensional (3D) base function and a 3D polynomial with unknown coefficients. The base functions over every domain are constructed with respect to the kinematical boundary conditions, geometry of the structure, and the geometry of that domain. These base functions satisfy the necessary continuities in the displacement field and electric potential at the interfaces, and at the same time accounting for possible discontinuities in their derivatives at the interfaces. The mode shapes will be decomposed in accordance to the presence of any symmetry plane. The robustness of the proposed approach is demonstrated through comparison with the finite element method as applied to the following problems: (1) A perforated thick plate made of piezoelectric and elastic layers and (2) an elastic plate containing a hole, whose exact solution is available. For the latter problem, the result of the present study is in good agreement with the exact solution. Also, an example of a thick PZT plate containing an elastic inclusion with a complex interface, and various types of boundary conditions is considered.

Fabrication and characterizations of a monolithic PZT microstage

This paper reports on the fabrication and characterizations of a monolithic Pb(ZrTi)O3 (PZT) microstage with multi-degrees of freedom for high-precision positioning. The entire device is fabricated in a symmetrical arrangement from a PZT plate with a size of 15 × 15 × 0.8 mm3. Four actuation units with displacement amplification mechanisms are integrated in the structure. All the actuators can be driven individually which result in movements of a stage in different directions. The main fabrication steps include dicing, electroplating, lithography and laser machining. The performances of the displacement and the resonant frequencies of the microstage are simulated using a finite element method (FEM) with different dimensions. A prototype has been fabricated and evaluated. Comparisons between FEM simulation and experimental results are carried out.

High-efficiency piezoelectric single-phase uni-polar ultrasonic actuators with a notched PZT back disc

Disclosed herein is a high efficiency piezoelectric single phase uni-polar supersonic actuator which is composed of an upper back disc, a PZT plate an electrode, a lower back disc, a pivotal bolt and a fixing nut. The PZT plate and its electrode are interposed between the upper and the lower back discs, and the whole actuator unit is supported and fixed with the pivotal bolt and the nut combination by passing the bolt coaxially through the center of the actuator unit. The parametric output variation of the actuator is carried out by an asymmetrical structure due to varying number, size and location of notches, or a variety of notch and screw combination made on the upper back disc such that after the electrode is energized, the actuator produces an unbalanced periodic axial or transverse thrust force to drive a rotor installed on the pivotal bolt above the upper back disc. The maximum rotating speed of the rotor may reach up to above 3000 rpm.

Low voltage piezocomposite actuators based on PZT tubes and plates

Adaptive solutions based on piezoceramic actuators and sensors for noise reduction, vibration and shape control, micro positioning as well as health monitoring and health control gain in importance not only in automotive but also in mechanical engineering, machining and equipment industries. Commercially available multilayer actuators show high stiffness, high blocking force and short response time. But they are very fragile against non-axial loads, which is one reason of the limited use in mechanical engineering. Recently, the Fraunhofer IKTS developed anew generation of piezoceramic transducers, the so-called custom shape piezocomposites. which are based on PZT tubes and plates. The new actuators work in the d 31 -mode (contraction) and are especially failure tolerant against non-axial loads. They can easily be formed according to custom needs, which makes them suitable for integration in various structural components. Because the electric field is applied across the wall thickness of the PZT tubes or plates, the piezocomposite actuators can be driven at low operating voltages.

Piezoactuator-integrated monolithic microstage with six degrees of freedom

In comparison with miniature XY-stages in term of driving methods: electrostatic, electromagnetic and piezoelectric actuators, the piezoelectric actuators have high area efficiency but no machinability by conventional microfabrication techniques. In this paper we have proposed the novel fabrication method of a double-layered piezo-stack actuator made from a monolithic PZT plate based on a planar fabrication method, and integrated the actuators into an XYZ-stage with six degrees of freedom, i.e., X, Y, Z, θ x , θ y and θ z directions. The stacked piezoactuators were formed on both sides of the PZT plate. The double stacked-piezoactuators, which are arranged around the stage, can stretch in plane or bend to Z-direction. The fabrication method includes dicing, electroplating, and laser machining. After making grooves by dicing, metal electroplating was performed and buried Ni into the grooves, which was done on both sides of the PZT plate. After polishing the surface, metal electrodes were formed on an insulating photosensitive polyimide layer. Finally, the complete structure was defined by laser machining. The test results show that the X-direction displacement of the actuation arms was about 2 μm when 40 V was applied to both of double-layered piezo-stacked actuators. The Z-direction displacement of the actuation beam was about 2 μm when 40 V was only applied to one stacked actuator. These results show the possibility of the microstage with six degrees of freedom.

An optical method to assess electromechanical coupling in ferroelectric ceramics

A new technique is described, which allows the assessment of elastic and inelastic regions around a macroscopic defect in ferroelectric-ferroelastic ceramics. The accuracy and robustness of the method are demonstrated on a PZT plate with a centered hole subjected to uni-axial compressive stresses. From the electrical potential distribution on the sample surface, the mechanical response of the material is obtained at different load levels.

Low frequency bending piezoelectric actuator with integrated ultrasonic NDE functionality

A bending piezoelectric actuator has been manufactured with a 250 μm thick PZT plate embedded in five layers of unidirectional fiber Kevlar epoxy. The selected orientation of the fibers produces a gradient of residual stresses in the composite that enhances bending actuation. By segmenting the electrodes, it is possible to launch an ultrasonic pulse in the actuator so that structural health monitoring of the actuator itself can be performed using pitch catch ultrasonic NDE during the low frequency actuation. Qualitative experimental results of fatigue tests and damage detection are presented.

Low frequency bending piezoelectric actuator with integrated ultrasonic NDE functionality

A bending piezoelectric actuator has been manufactured with a 250 μm thick PZT plate embedded in five layers of unidirectional fiber Kevlar epoxy. The selected orientation of the fibers produces a gradient of residual stresses in the composite that enhances bending actuation. By segmenting the electrodes, it is possible to launch an ultrasonic pulse in the actuator so that structural health monitoring of the actuator itself can be performed using pitch catch ultrasonic NDE during the low frequency actuation. Qualitative experimental results of fatigue tests and damage detection are presented.

Processing and Functional Evaluation of Titanium Thin Films for Biomimetic Micro Actuator

Titanium (Ti) thin films were created on glass and Pb(Zr, Ti)O3 (PZT) substrates using magnetic RF sputtering apparatus. Nano-indentation tests were carried out to study the influence of the Ti thin layer on piezoelectric properties. The piezoelectric properties of the PZT plate and a Ti sputtered one were also measured by laser Doppler vibrometer. Furthermore, some characteristics, such as crystalline structure, depth profiles, and surface roughness of the films were observed by means of an atomic force microscope (AFM). Main conclusions obtained in this study are summarized as follows: (1) From detailed observation and analytical results of AFM, the surface roughness, Ra, tends to increase as Ti film thickness increases. (2) Some of the mechanical properties, such as reduced modulus Er and hardness H obtained from nano-indentation tests, are significantly related to film thickness. (3) The validity of piezoelectric finite element analysis (ANASYS program) for deformation of a piezoelectric material was investigated. As a result, piezoelectric response properties are present in as-received PZT specimens and Ti-sputtered PZT specimens. Experimental and FE analytical results indicate that the piezoelectric coefficient is significantly influenced by Ti layer.

Parametric excitation of circular micromachined polycrystalline silicon disks

Center anchored polycrystalline silicon plates are parametrically excited using ultrasonic substrate motion generated by a lead zirconate titanate oxide (PZT) plate bonded to the silicon die. Parametric excitation is used to achieve large amplitude, greater than 100 nm, transverse plate vibrations in atmospheric pressure with sub-3 VPP drive on the PZT plate with corresponding surface velocities over 1.5 m/s. The preferred parametrically excited modes are observed to be “whispering gallery” plate modes with no radial nodal points. The possible nonlinear mechanisms are analyzed and the parametric excitation is explained with in-plane plate stresses due to the lateral plate anchor motion. The effect of in-plane stresses is modeled with von Kármán plate equations. Parametric instability is demonstrated with the use of nonlinear Floquet transition matrix.

A Piezoelectric Micromotor with a Stator of φ=1.6 mm and l=4 mm Using Bulk PZT

The smallest discrete piezoelectric ultrasonic motor using bulk ceramics was developed. We are proposing basically a two-part motor: stator and rotor. The stator of the present motor consists of a hollow metal brass tube with outer diameter of 1.6 mm, inner diameter of 0.8 mm and length of only 4 mm with 2 PZT plates bonded onto it. Owing to the asymmetrical stator surface, two degenerated orthogonal bending modes were slightly split, resulting in a wobbling motion. Thus, the motor can be driven by a single driving source. The rotor is a spring, which is basically different from previous designs, pressed at both ends to the stator by a pair of ferrules. Consequently, the length of the whole motor assembly was reduced significantly; a final motor length of only 5 mm was obtained. The working frequency under zero load was approximately 227–233 kHz. Although the size is small, relatively high power was obtained under an optimized load condition: torque of 0.06 mNm, maximum power of 3.2 mW with a speed of 118 rad/s, and maximum efficiency of 11% under 48 Vrms at 221 kHz.

A piezodriven XY-microstage for multiprobe nanorecording

The properties of electrostatic, electromagnetic and piezoelectric actuators used for XY-microstage are compared to indicate high area efficiency but no good machinability of piezoelectric actuator, so that a novel planer fabrication method of the piezodriven XY-microstage with one PZT plate has been proposed. This fabrication method includes three processes, dicing, electroplating, femtosecond laser machining and so no. A parallelogram mechanism with flexure hinges, lever mechanisms and piezoelectrical actuators has been designed to make XY-displacement in monolayer plane structure. The area efficiency and volume efficiency of piezodriven XY-microstage are very higher than electrostaticdriven and electromagneticdriven one. The relationship of displacement characteristics with the sizes of parallelogram mechanism has been tested with the several principium prototypes fabricated by femtosecond laser machining of single nickel plate and assembly of PZT actuator. The test results show that the flexure hinges the shorter, the accuracy of the XY-displacement the better. Thirty micrometer displacement and 50% and above area efficiency have been obtained in the principium prototype.

バイオマイクロアクチュエータ用チタン薄膜材料の創製と機能評価

Titanium (Ti) thin films were created on glass and Pb(Zr–Ti)O3 (PZT) substrates using magnetic RF sputtering apparatus. Nano-indentation tests were carried out to study the influence of the Ti thin layer on piezoelectric properties. The piezoelectric properties of the PZT plate and a Ti sputtered one were also measured by laser Doppler vibrometer. Furthermore, some characteristics, such as crystalline structure, depth profiles, and surface roughness of the films were observed by means of an atomic force microscope (AFM). Main conclusions obtained in this study are summarized as follows: (1) From detailed observation and analytical results of AFM, the surface roughness, Ra, tends to increase as Ti film thickness is increased. (2) Several mechanical properties, such as reduced modulus Er and hardness H obtained from nano-indentation tests, are significantly related to film thickness. (3) Piezoelectric response properties are present in as-received PZT specimens and Ti-sputtered PZT specimens. Experimental and FE analytical results indicate that the piezoelectric coefficient is significantly influenced by Ti layer.

Development of a bi-directional valve-less silicon micro pump controlled by driving waveform

A new bi-directional valve-less silicon micro pump was proposed based on an analysis using an equivalent circuit model, and the performance of the fabricated pump was studied. The flow direction of the pump can be controlled by changing a driving waveform applied to a PZT plate fixed on a diaphragm. The feasibility of this new bi-directional pumping principle was verified by experiments. The pump generated maximum flow rates of 393 nl/s for forward direction and 323 nl/s for backward direction and maximum pumping pressures of 11.0 kPa for forward direction and 9.9 kPa for backward direction.

Fiber-grating sensor using dynamic PZT modulation

In this paper we propose a new sensor based on a periodically modulated fiber grating. The fiber grating is fixed on a PZT plate, which is modulated by an alternating voltage. In order to measure strains, we only use an oscilloscope and a single-mode-laser source to measure the change of the reflected-light pulse period. Comparing with the original method of strain measurement that using an optical spectrum analyzer and a broadband light source to measure the wavelength shift of reflected power peak, this method is much simpler and has lower cost. Our research results show that two methods are equivalent, and theoretical analysis well consists with experimental results.

Electron emission type infrared imaging sensor using ferroelectric thin plate

We propose a novel electron emission type infrared light sensor, which is constructed with a PZT ceramics plate and an Al electrode. A quartz plate separated the Al electrode and a PZT plate. The distance between the Al electrode and the PZT plate kept about 10µm. The PZT plate acts as an infrared light detector and a cathode electrode. The Al electrode is an anode. As the PZT plate was irradiated by infrared light in a vacuum chamber, an anode current was observed, and the anode current was lineally proportional to the incident infrared light power. From these fundamental experiments, the principle of this sensor was confirmed. Using this principle, we fabricated prototype infrared imager. This imager was constructed with the PZT photocathode, a multichannel plate and a fluorescent substrate. An infrared light source was successively taken by this imager.

Smart actuator with magneto-elastic strain sensor

We proposed a smart actuator using magneto-elastic strain sensor. This actuator was cantilever-shape and composed by the strain sensor, a PZT plate and feedback system. In this smart actuator, a touching force at the free end was kept constant if the end was displaced. The smart actuator was sensitive for the touching force of less than 1 mN.