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Showing papers on "Bimorph published in 2013"


Journal ArticleDOI
TL;DR: In this article, the authors present electroelastic modeling, analytical and numerical solutions, and experimental validations of piezoelectric energy harvesting from broadband random vibrations, which can be used as a more accurate alternative to the existing single-degree-of-freedom solutions for broadband random vibration energy harvesting.
Abstract: We present electroelastic modeling, analytical and numerical solutions, and experimental validations of piezoelectric energy harvesting from broadband random vibrations. The modeling approach employed herein is based on a distributed-parameter electroelastic formulation to ensure that the effects of higher vibration modes are included, since broadband random vibrations, such as Gaussian white noise, might excite higher vibration modes. The goal is to predict the expected value of the power output and the mean-square shunted vibration response in terms of the given power spectral density (PSD) or time history of the random vibrational input. The analytical method is based on the PSD of random base excitation and distributed-parameter frequency response functions of the coupled voltage output and shunted vibration response. The first of the two numerical solution methods employs the Fourier series representation of the base acceleration history in an ordinary differential equation solver while the second method uses an Euler‐Maruyama scheme to directly solve the resulting electroelastic stochastic differential equations. The analytical and numerical simulations are compared with several experiments for a brass-reinforced PZT-5H bimorph under different random excitation levels. The simulations exhibit very good agreement with the experimental measurements for a range of resistive electrical boundary conditions and input PSD levels. It is also shown that lightly damped higher vibration modes can alter the expected power curve under broadband random excitation. Therefore, the distributed-parameter modeling and solutions presented herein can be used as a more accurate alternative to the existing single-degree-of-freedom solutions for broadband random vibration energy harvesting.

105 citations


Journal ArticleDOI
TL;DR: In this article, an impact-driven piezoelectric energy harvesting system mounted on a person's leg has been shown that the system has the potential for driving wearable devices.
Abstract: An impact-driven piezoelectric energy harvester from human motion is proposed in this paper. A high-frequency PZT-5A bimorph cantilever beam with attached proof mass at the free end was selected. A frequency up-conversion strategy was realized using impulse force generated by human motion. An aluminum prototype was attached to the leg of a person on a treadmill and measurements taken of the dissipated electric energy across multiple resistances over a range of walking speeds. The outer dimensions of this prototype are 90 mm × 40 mm × 24 mm. It has been shown that the average output voltage generated by the piezoelectric bimorph increases sequentially with a faster walking speed, the power varies with the external resistances and maximum levels occur at the optimal resistance, which is consistent with the simulation result. An open circuit voltage of 2.47 V and maximum average power of 51 μW can be achieved across a 20 kΩ external load resistance and 5 km h−1 walking speed. Experimental results reveal that the impact-driven piezoelectric energy harvesting system mounted on a person’s leg has the potential for driving wearable devices.

99 citations


Journal ArticleDOI
TL;DR: This paper investigates fish-like aquatic robotics using flexible bimorphs made of macro-fiber composite (MFC) piezoelectric laminates for carangiform locomotion as well as the development of a robotic fish prototype combining a microcontroller and a printed-circuit-board amplifier to generate high actuation voltage for untethered locomotion.
Abstract: This paper investigates fish-like aquatic robotics using flexible bimorphs made of macro-fiber composite (MFC) piezoelectric laminates for carangiform locomotion. In addition to noiseless and efficient actuation over a range of frequencies, geometric scalability, and simple design, bimorph propulsors made of MFCs offer a balance between the actuation force and velocity response for performance enhancement in bio-inspired swimming. The experimental component of the presented work focuses on the characterization of an elastically constrained MFC bimorph propulsor for thrust generation in quiescent water as well as the development of a robotic fish prototype combining a microcontroller and a printed-circuit-board amplifier to generate high actuation voltage for untethered locomotion. From the theoretical standpoint, a distributed-parameter electroelastic model including the hydrodynamic effects and actuator dynamics is coupled with the elongated-body theory for predicting the mean thrust in quiescent water. In-air and underwater experiments are performed to verify the incorporation of hydrodynamic effects in the linear actuation regime. For electroelastically nonlinear actuation levels, experimentally obtained underwater vibration response is coupled with the elongated-body theory to predict the thrust output. The measured mean thrust levels in quiescent water (on the order of ∼10 mN) compare favorably with thrust levels of biological fish. An untethered robotic fish prototype that employs a single bimorph fin (caudal fin) for straight swimming and turning motions is developed and tested in free locomotion. A swimming speed of 0.3 body-length/second (7.5 cm s−1 swimming speed for 24.3 cm body length) is achieved at 5 Hz for a non-optimized main body-propulsor bimorph combination under a moderate actuation voltage level.

95 citations


Journal ArticleDOI
TL;DR: In this article, a spectral finite element method for bimorph piezoelectric beam energy harvesters is developed based on the Timoshenko beam theory and the Euler-Bernoulli beam theory.
Abstract: Single-degree-of-freedom lumped parameter model, conventional finite element method, and distributed parameter model have been developed to design, analyze, and predict the performance of piezoelectric energy harvesters with reasonable accuracy. In this article, a spectral finite element method for bimorph piezoelectric beam energy harvesters is developed based on the Timoshenko beam theory and the Euler–Bernoulli beam theory. Linear piezoelectric constitutive and linear elastic stress/strain models are assumed. Both beam theories are considered in order to examine the validation and applicability of each beam theory for a range of harvester sizes. Using spectral finite element method, a minimum number of elements is required because accurate shape functions are derived using the coupled electromechanical governing equations. Numerical simulations are conducted and validated using existing experimental data from the literature. In addition, parametric studies are carried out to predict the performance of ...

75 citations


Journal ArticleDOI
TL;DR: In this paper, a novel energy harvesting cantilever array with magnetic tuning including three piezoelectric bimorphs is investigated theoretically and experimentally, with a good agreement between model and experiment.
Abstract: Power and bandwidth of piezoelectric harvesters can be increased by using multiple piezoelectric elements in one harvester. In this contribution, a novel energy harvesting cantilever array with magnetic tuning including three piezoelectric bimorphs is investigated theoretically and experimentally, with a good agreement between model and experiment. Other than harvester designs proposed before, this array is easy to manufacture and insensitive to manufacturing tolerances because its optimum operation frequency can be re-adjusted after fabrication. Using the superposition principle, the Butterworth-Van Dyke model and a mechanical lumped parameters model, the generated voltage and current are determined analytically. Formulas for calculating the power generated by array harvesters with an arbitrary number of piezoelectric elements connected in series or in parallel are derived. It is shown that optimum harvester design must take both the connected load and the operating frequency into account. Strategies for connecting multiple bimorphs to increase the maximum generated power and/or enhance the bandwidth compared to a single bimorph harvester are investigated. For bandwidth enhancement it is essential that individual rectifiers are used for the bimorphs. An example with three bimorphs shows that, depending on the chosen tuning strategy, the power is increased by about 340% or the bandwidth is increased by about 500%, compared to one single bimorph.

55 citations


Journal ArticleDOI
07 May 2013-Sensors
TL;DR: The dynamic characteristics of bending piezoelectric bimorphs actuators were theoretically and experimentally investigated for micro-gripping applications in terms of deflection along the length, transient response, and frequency response with varying driving voltages and driving signals.
Abstract: Piezoelectric bimorphs have been used as a micro-gripper in many applications, but the system might be complex and the response performance might not have been fully characterized. In this study the dynamic characteristics of bending piezoelectric bimorphs actuators were theoretically and experimentally investigated for micro-gripping applications in terms of deflection along the length, transient response, and frequency response with varying driving voltages and driving signals. In addition, the implementation of a parallel micro-gripper using bending piezoelectric bimorphs was presented. Both fingers were actuated separately to perform mini object handling. The bending piezoelectric bimorphs were fixed as cantilevers and individually driven using a high voltage amplifier and the bimorph deflection was measured using a non contact proximity sensor attached at the tip of one finger. The micro-gripper could perform precise micro-manipulation tasks and could handle objects down to 50 µm in size. This eliminates the need for external actuator extension of the microgripper as the grasping action was achieved directly with the piezoelectric bimorph, thus minimizing the weight and the complexity of the micro-gripper.

53 citations


Journal ArticleDOI
TL;DR: The developed model can be used to design more sensitive pMUTs or extract the flexural piezoelectric coefficient using pieZoelectrically actuated circular plates and matched well with the experimental measurements and the error ranged from 2.7-22% due to process variations across the wafer.

50 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated a tiny piezoelectric inertial motor with a self-moving slider that obtains bidirectional inertial motion when the saw tooth or the pulse type excitation signal is applied at resonant frequency.

44 citations


Journal ArticleDOI
TL;DR: The method used by SolMateS to determine the effective piezoelectric coefficient d31,eff of Pb(Zr,Ti)O3 (PZT) thin films from cantilever displacement measurements is described in this article.
Abstract: The method used by SolMateS to determine the effective piezoelectric coefficient d31,eff of Pb(Zr,Ti)O3 (PZT) thin films from cantilever displacement measurements is described. An example from a 48 cantilever dataset using different cantilever widths, lengths and crystal alignments is presented. It is shown that for the layer stack of our cantilevers, the multimorph model is more accurate compared to the bimorph model for the d31,eff determination. Corrections to the input parameters of the model are further applied in order to reduce the geometrical error of the cantilever that is caused by its design and processing, as well as correction to the measured tip displacement caused by resonance amplification. It is shown that after these corrections, the obtained d31,eff values are still up to 10% uncertain as the plate behavior and the non-constant radius of curvature of the cantilevers lead to inconsistent results. We conclude that quantitative determination of d31,eff from the cantilevers is highly subjective to misinterpretation of the models used and the measurement data. The true value of d31,eff was determined as −118.9 pm V−1.

43 citations


Journal ArticleDOI
TL;DR: In this article, a new post-CMOS-compatible piezoelectric thin/thick film technology was proposed that allows wafer-level integration of bulk PZT and PMN-PT on silicon substrates with precisely determined final film thickness of 5-100 μm while preserving the original material quality.
Abstract: In this paper, we present a new post-CMOS-compatible piezoelectric thin/thick film technology that allows wafer-level integration of bulk piezoelectric ceramics such as lead zirconium titanate (PZT) and lead magnesium niobate-lead titanate (PMN-PT) on silicon substrates with precisely determined final film thickness of 5-100 μm while preserving the original material quality. We bond commercially available bulk piezoelectric substrates to silicon using reliable and low-temperature (200°C) gold-indium (Au-In) diffusion bonding or parylene bonding. An enhanced fixed-abrasive lapping/polishing process thins the piezoelectric layer to the desired thickness with high precision and wafer-level uniformity (±0.5 μm). The fabricated films have bond interface shear strength of 1.5-4.5 MPa and average surface roughness of 43 nm, with bulk ferroelectric/piezoelectric properties preserved, such as remnant polarization (37.7 μC/cm2), coercive field (1.95 kV/mm), and effective longitudinal piezoelectric strain coefficients (140-840 pm/V). In addition, extensions of this process show the feasibility of fabricating bimorph layers via successive bonding/thinning, and of forming suspended structures on silicon via surface micromachining. The flexible process can easily be adapted for batch-mode silicon integration of a variety of other electroceramics.

37 citations


Journal ArticleDOI
TL;DR: In this paper, a model for non-linear magnetoelectric coupling was discussed for RF frequency doublers, and it was shown that NLME is strong in the absence of DC magnetic bias, when the frequency of h is tuned to half the frequency for bending oscillations, and when a PZT bimorph is used.
Abstract: Mechanical strain mediated non-linear magnetoelectric (NLME) coupling is studied in layered composites of ferromagnetic FeBSiC and piezoelectric lead zirconate titanate (PZT) bimorph. The NLME manifests as frequency doubling in the voltage response of the sample to an applied ac magnetic field. It is shown that NLME is strong (i) in the absence of DC magnetic bias, (ii) when the frequency of h is tuned to half the frequency for bending oscillations, and (iii) a PZT bimorph (instead of a single layer of PZT) is used. A model is discussed for the non-linear magnetoelectric coupling that is of interest for RF frequency doublers.

Journal ArticleDOI
TL;DR: In this paper, the effects of ambient temperature on the level of harvesting energy from galloping oscillations of a bluff body are investigated and a nonlinear-distributed-parameter model is developed to determine variations in the onset speed of galloping and the harvested power when the ambient temperature is varied.
Abstract: The effects of ambient temperature on the level of harvesting energy from galloping oscillations of a bluff body are investigated. A nonlinear-distributed-parameter model is developed to determine variations in the onset speed of galloping and the level of the harvested power when the ambient temperature is varied. The considered harvester consists of a bimorph piezoelectric cantilever beam with a prismatic-structure tip mass. A modal analysis is performed to derive the exact mode shapes and natural frequencies of the beam‐structure system and their dependence on temperature variations. The quasi-steady representation is used to model the aerodynamic loads. The linear analysis shows that the temperature and the electrical load resistance affect the onset speed of galloping significantly. The nonlinear analysis shows that temperature variation affects the level of the harvested power. (Some figures may appear in colour only in the online journal)

Journal ArticleDOI
TL;DR: In this paper, three pairs of bimorph mirrors were re-polished at Thales-SESO to remove the junction effect and significantly improved beamline performance, and the results showed that the internal structure of the mirrors will retain their surface quality, and remain operational for many years.
Abstract: Bimorph mirrors are widely used by the X-ray, Laser, Space, and Astronomy communities to focus or collimate photon beams. Applying voltages to the embedded piezo ceramics enables the user to globally bend the optical substrate to a range of figures (including cylindrical, parabolic, and elliptical), and finely correct low spatial frequency errors, thus improving optical performance. Bimorph mirrors are employed on numerous synchrotron X-ray beamlines, including several at Diamond Light Source. However, many such beamlines were not achieving the desired size and shape of the reflected X-ray beam. Metrology data from ex-situ, slope measuring profilometry (using the Diamond-NOM) and in-situ, synchrotron X-ray “pencil-beam” scans, revealed sharp defects on the optical substrate directly above the locations at which the piezo ceramics are bonded together. This so-called “junction effect” has been observed on a variety of bimorph mirrors with different numbers of piezos, substrate length, and thickness. To repair this damage, three pairs of bimorph mirrors were re-polished at Thales-SESO. We review the re-polishing process, and show that it successfully removed the junction effect, and significantly improved beamline performance. Since the internal structure of the bimorph mirrors was not modified during re-polishing, it is hoped that the mirrors will retain their surface quality, and remain operational for many years. We also highlight the combination of super-polishing techniques with bimorph technology to create the “Ultimate” mirror, and discuss a next generation, bimorph mirror which is predicted not to suffer from the junction effect.

Journal ArticleDOI
TL;DR: In this article, a vibration based piezoelectric cantilever energy harvester was investigated as a power source by generating the electricity from two-dimensional ambient vibrations (less than 1g and 60 Hz) for mobile handsets, building automation, medical and defense applications.

Journal ArticleDOI
22 Mar 2013
TL;DR: In this article, a super-polished adaptive bimorph mirror has been developed, which provides variable focal distance and local figure control in the sub-nm range, and has the potential to generate distortion-free beams and enable dynamical focusing and wavefront control.
Abstract: A novel super-polished adaptive bimorph mirror has been developed, which provides variable focal distance and local figure control in the sub-nm range. The optic has the potential to generate distortion-free beams and enable dynamical focusing and wavefront control. We present results of this optic, including ex-situ characterisation of the surface topography using the Diamond-NOM, and in-situ investigation using synchrotron light at Diamond's B16 Test beamline. The wavefront properties of the mirror have also been studied using at-wavelength metrology methods based on X-ray speckle tracking.

Journal ArticleDOI
TL;DR: In this article, the giant magnetoelectric effect induced by the coupling of piezoelectrics and magnetic torque in piezo-bimorph/magnet composites has been investigated.
Abstract: The giant magnetoelectric (ME) effect induced by the coupling of piezoelectricity and magnetic torque in piezo-bimorph/magnet composites has been investigated. The relation between the ME voltage and the sample's geometry (thickness, length, width, etc.), materials parameters (piezoelectric coefficient, residual flux density, permittivity, etc.) was derived through the elasticity mechanics method. Our experimental results confirmed the theoretical prediction. A Pb(Zr 1− x Ti x )O 3 -bimorph/NdFeB sample with 500 pT sensitivity at 10 Hz was also constructed and showed a good linearity in the measurement range of nano to mili tesla. This research has provided a guide of designing better magnetoelectric devices with low cost and zero power consumption.

Journal ArticleDOI
TL;DR: In this paper, a 1.2mm-diameter gold-silicon bimorph varifocal micromirror (VFM) has been designed and investigated for imaging applications.
Abstract: A 1.2-mm-diameter gold-silicon bimorph varifocal micromirror (VFM) has been designed and investigated for imaging applications. Several prototypes have been fabricated in a 10-μm-thick single-crystal silicon-on-insulator material. Controlled variation of the radius of curvature using electrothermal and optothermal actuation has been demonstrated. A finite-element-based simulation of the device behavior has been undertaken. Experimental characterization has shown that the device focusing power varied from an initial 87 dioptre to 69 dioptre by applying dc electrical power of 33 mW and produced a focusing power value of 59 dioptre when optothermally actuated with a normally incident laser beam of 488-nm wavelength and 43 mW. When electrothermally driven, the mechanical rise and fall times of the device were measured as 130 and 120 ms, respectively. Experimental and theoretical analyses using Zernike coefficients show that, throughout the actuation range, the aberration of the VFM is mainly a small defocus term, with negligible higher order aberrations. A compact active imaging system incorporating the VFM has been also demonstrated. This system was capable of focusing several objects located along the optical axis with a maximum tracking range of 134 mm.

Proceedings ArticleDOI
07 Jan 2013
TL;DR: In this paper, the authors compared the performance of a servo-actuated and a morphing-actuation-based control surface design with a single servo actuator and showed that the servoactuated aircraft exhibited velocity deficits during doublet maneuvers, while the morphing actuation negligibly decreased velocity.
Abstract: ‡‡ A novel morphing control surface design employing piezoelectric Macro Fiber Composite (MFC) actuators is compared to a servo-actuated system. The comprehensive comparison including aerodynamics, size, weight, power, bandwidth, and reliability has been extended to include flight test comparisons. Flight agility and control response of the morphing-actuated and servo-actuated configurations were quantified through state measurement during identical automated maneuvers. The morphing actuation scheme demonstrated superior response times and a fully controllable vehicle, but was unable to match the magnitude of roll and pitch rates attained by the servo-actuated baseline aircraft. The servo-actuated aircraft exhibited velocity deficits during doublet maneuvers, while the morphing actuation negligibly decreased velocity, demonstrating lower drag and more efficient production of control forces and moments. Reliability cycle testing of an MFC bimorph achieved 1 million cycles without failure and minimal degradation in performance.

Patent
20 Nov 2013
TL;DR: In this article, a piezoelectric ceramic flapping-wing-type robot is described, where the robot body support frame, robot wings, a driver, a driving electric cable, a transmission amplifying mechanism and driving feet are used to enable the robot to fly.
Abstract: The invention discloses a piezoelectric ceramic flapping-wing-type robot. The piezoelectric ceramic flapping-wing-type robot comprises a robot body support frame, robot wings, a piezoelectric driver, a driving electric cable, a transmission amplifying mechanism and driving feet, wherein the robot wings are based on a bionic design and are similar to a dipster hoverfly in shape; when the robot walks on land, a piezoelectric ceramic sheet is selected as the piezoelectric driver, and the piezoelectric ceramic sheet and a single-bent-end transmission amplifying mechanism form the driving feet; the driving electric cable inputs two common grounding sine wave signals for respectively driving the two driving feet, and the robot is driven to do controllable plane motion by utilizing a resonant oscillation principle. When the robot flies in the sky, the driving feet are taken down; a piezoelectric ceramic bimorph element is used as the piezoelectric driver to input a driving voltage signal; by a four-connecting-rod transmission mechanism, the oscillation is amplified and is converted into flapping of wings, thereby driving the robot body to fly. The robot is simple, light and convenient, and has certain adaptability to the environment.

Journal ArticleDOI
TL;DR: An electric circuit model for a clamped circular bimorph piezoelectric micromachined ultrasonic transducer (pMUT) was developed for the first time and could provide more insight into the design, optimization, and characterization of pMUTs and allow for performance comparison with their cMUT counterparts.
Abstract: An electric circuit model for a clamped circular bimorph piezoelectric micromachined ultrasonic transducer (pMUT) was developed for the first time. The pMUT consisted of two piezoelectric layers sandwiched between three thin electrodes. The top and bottom electrodes were separated into central and annular electrodes by a small gap. While the middle electrode was grounded, the central and annular electrodes were biased with two independent voltage sources. The strain mismatch between the piezoelectric layers caused the plate to vibrate and transmit a pressure wave, whereas the received echo generated electric charges resulting from plate deformation. The clamped pMUT plate was separated into a circular and an annular plate, and the respective electromechanical transformation matrices were derived. The force and velocity vectors were properly selected using Hamilton's principle and the necessary boundary conditions were invoked. The electromechanical transformation matrix for the clamped circular pMUT was deduced using simple matrix manipulation techniques. The pMUT performance under three biasing schemes was elaborated: 1) central electrode only, 2) central and annular electrodes with voltages of the same magnitude and polarity, and 3) central and annular electrodes with voltages of the same magnitude and opposite polarity. The circuit parameters of the pMUT were extracted for each biasing scheme, including the transformer ratio, the clamped electric impedance, and the open-circuit mechanical impedance. Each pMUT scheme was characterized under different acoustic loadings using the theoretically developed model, which was verified with finite element modeling (FEM) simulation. The electrode size was optimized to maximize the electromechanical transformer ratio. As such, the developed model could provide more insight into the design, optimization, and characterization of pMUTs and allow for performance comparison with their cMUT counterparts.

Journal ArticleDOI
TL;DR: A power harvester with adjustable frequency, which consists of a hinged¿hinged piezoelectric bimorph and a concentrated mass, is studied by the precise electric field method (PEFM), taking into account a distribution of the electric field over the thickness.
Abstract: A power harvester with adjustable frequency, which consists of a hinged?hinged piezoelectric bimorph and a concentrated mass, is studied by the precise electric field method (PEFM), taking into account a distribution of the electric field over the thickness. Usually, using the equivalent electric field method (EEFM), the electric field is approximated as a constant value in the piezoelectric layer. Charge on the upper electrode (UEC) of the bimorph is often assumed as output charge. However, different output charge can be obtained by integrating on electric displacement over the electrode with different thickness coordinates. Therefore, an average charge (AC) on thickness is often assumed as the output value. This method is denoted EEFM AC. The flexural vibration of the bimorph is calculated by the three methods and their results are compared. Numerical results illustrate that EEFM UEC overestimates resonant frequency, output power, and efficiency. EEFM AC can accurately calculate the output power and efficiency, but underestimates resonant frequency. The performance of the harvester, which depends on concentrated mass weight, position, and circuit load, is analyzed using PEFM. The resonant frequency can be modulated 924 Hz by moving the concentrated mass along the bimorph. This feature suggests that the natural frequency of the harvester can be adjusted conveniently to adapt to frequency fluctuation of the ambient vibration.

Proceedings ArticleDOI
21 Jul 2013
TL;DR: In this article, a PZT bimorph technology for integrated chip-scale in-plane nano-motion actuators is demonstrated, where the actuators are micro-machined to define beams by laser-cutting through a pZT-4 plate while also defining arbitrary 2D electrode patterns on top and bottom surface of the beams by using a commercial laser cutting tool.
Abstract: We demonstrate a PZT bimorph technology for integrated chip-scale in-plane nano-motion actuators. Bulk PZT actuators are micro-machined to define beams by laser-cutting through a PZT-4 plate while also defining arbitrary 2D electrode patterns on top and bottom surface of the beams by using a commercial laser cutting tool with backside alignment capability. Lateral actuators that are 5, 10 and 20 mm long, 0.45 mm wide, and 0.5 mm thick were characterized with single and dual side laser patterned electrodes. The in-plane bimorph displacements are in the range of 0.02 to 0.64 microns/volt. The out of plane displacement sensitivity of these actuators were simulated to be ~ 100's ppm/V compared to the desired in plane actuation. We also report doubling of the actuator tip displacement for the same applied voltages in the dual side electrode actuators, when compared to the single sided actuators.

Journal ArticleDOI
TL;DR: In this article, a resonantly driven piezoelectric gas pump with annular bimorph as the driver is presented, and the working principle of the novel pump is analyzed, the vibration mechanics model was determined, and displacement amplified theory was studied.
Abstract: Piezoelectric pumps have the potential to be used in a variety of applications, such as in air circulation and compression. However, piezoelectric membrane pumps do not have enough driving capacity, and the heat induced during the direct contact between the driving part and the gas medium cannot be dissipated smoothly. When the gas is blocked, the piezoelectric vibrator generates heat quickly, which may eventually lead to damage. Resonantly driven piezoelectric stack pumps have high performance but no price advantage. In this situation, a novel, resonantly driven piezoelectric gas pump with annular bimorph as the driver is presented. In the study, the working principle of the novel pump was analyzed, the vibration mechanics model was determined, and the displacement amplified theory was studied. The outcome indicates that the displacement amplification factor is related with the original displacement provided by the piezoelectric bimorph. In addition, the displacement amplification effect is related to the stiffness of the spring lamination, adjustment spring, and piezoelectric vibrator, as well as to the systematic damping factor and the driving frequency. The experimental prototypes of the proposed pump were designed, and the displacement amplification effect and gas output performance were measured. At 70 V of sinusoidal AC driving voltage, the improved pump amplified the piezoelectric vibrator displacement by 4.2 times, the maximum gas output flow rate reached 1685 ml/min, and the temperature of the bimorph remained normal after 2000 hours of operation when the gas medium was blocked.

Journal ArticleDOI
TL;DR: In this article, a laterally-driven piezoelectric bimorph micro electro mechanical systems actuator with high aspect-ratio (AR) lead?zirconate?titanate (PZT) structures is presented.
Abstract: This paper reports on the fabrication and characterization of a novel laterally-driven piezoelectric bimorph micro electro mechanical systems actuator with high aspect-ratio (AR) lead?zirconate?titanate (PZT) structures. The PZT structures (AR=8) sandwiched with Pt sidewall electrodes were fabricated by a nanocomposite sol?gel process with micromachined silicon templates. A single-cantilever-type lateral bimorph actuator was successfully fabricated, and no initial vertical bending was observed, even on a 500??m long actuator. A lateral displacement of 10??m was obtained in bimorph actuation at driving voltages of?+25?V/?5?V. Then the piezoelectric property of the PZT structure was characterized from the actuator's performance. The lateral piezoelectric actuator has a variety of potential applications as a replacement for electrostatic comb drive actuators occupying a large area.

Journal ArticleDOI
TL;DR: The results show that the notable advantage of the AFM is that dynamic process of the sample with large dimensions can be easily investigated and could provide a way to study a sample in real time under the given experimental condition, such as under an external electric field, on a heating stage, or in a liquid cell.
Abstract: A piezoelectric bimorph-based scanner operating in tip-scan mode for high speed atomic force microscope (AFM) is first presented. The free end of the bimorph is used for fixing an AFM cantilever probe and the other one is mounted on the AFM head. The sample is placed on the top of a piezoelectric tube scanner. High speed scan is performed with the bimorph that vibrates at the resonant frequency, while slow scanning is carried out by the tube scanner. The design and performance of the scanner is discussed and given in detailed. Combined with a commercially available data acquisition system, a high speed AFM has been built successfully. By real-time observing the deformation of the pores on the surface of a commercial piezoelectric lead zirconate titanate (PZT-5) ceramics under electric field, the dynamic imaging capability of the AFM is demonstrated. The results show that the notable advantage of the AFM is that dynamic process of the sample with large dimensions can be easily investigated. In addition, this design could provide a way to study a sample in real time under the given experimental condition, such as under an external electric field, on a heating stage, or in a liquid cell.

Journal ArticleDOI
TL;DR: The frequency bandwidth through which energy can be harvested is roughly doubled when compared with conventional beam bimorph energy harvesters operating with flexural motion in one direction and one resonance only.
Abstract: We propose a new structure for piezoelectric energy harvesters. It consists of an elastic beam with two pairs of piezoelectric films operating with the fundamental flexural modes in perpendicular directions. A one-dimensional model is developed and used to analyze the proposed structure. The output power density is calculated and examined. Results show that, with simultaneous flexural motions in two perpendicular directions, the output power has two peaks close to each other resulting from the two fundamental flexural resonances. The distance between the two peaks can be adjusted through design to make the two peaks merge into one wide peak. Hence, the frequency bandwidth through which energy can be harvested is roughly doubled when compared with conventional beam bimorph energy harvesters operating with flexural motion in one direction and one resonance only.

Proceedings ArticleDOI
16 Sep 2013
TL;DR: In this article, an artificial hair cell (AHC) piezoelectric sensor inspired by the hair cells found in the mammalian cochlea was used to detect sound pressure levels ranging from 20 μPa to 20 Pa (0 to 120 dB).
Abstract: The inner hair cells (IHC’s) and outer hair cells (OHC’s) in the cochlea are vital components in the process of hearing. The IHC’s are responsible for converting sound-induced vibration into electrical signals. The OHC’s produce forces that amplify these vibrations and therefore enhance the electrical signals produced by the IHC’s. The resulting “cochlear amplifier” produces a nonlinear amplification which gives the ear its ability to detect sound pressure levels ranging from 20 μPa to 20 Pa (0 to 120 dB).This paper presents the modeling and testing of an artificial hair cell (AHC) piezoelectric sensor inspired by the hair cells found in the mammalian ear. The sensor is a bimorph cantilever beam consisting of a sensing piezoceramic element and an actuating piezoceramic element bonded to a brass substrate. The sensing element is used to detect the mechanical motion of the beam. Output feedback control can be used to send a voltage signal to the actuating element and alter the frequency response of the beam. A control law, which modifies the linear damping term of the first mode and introduces cubic damping, is used to create a closed-loop system perched at a Hopf bifurcation. The result is a system that produces a nonlinear amplification of the beam’s mechanical response in a manner which mimics the nonlinear behavior of the mammalian cochlea. This active sensor is studied under base acceleration and the initial test results are compared to a finite element model. Simulations of the closed-loop system are examined for the system with a single mode and for the system with multiple modes.Copyright © 2013 by ASME

Journal ArticleDOI
04 Dec 2013
TL;DR: In this article, a new way of manufacturing efficient vibration energy harvesters using thick films of piezoelectrics is described, based on the thinning of high-density bulk Lead Zirconate Titanate (PZT) ceramic substrates, which enables the realization of thick layers (10-100 μm).
Abstract: This paper describes a new way of manufacturing efficient vibration energy harvesters using thick films of piezoelectrics. The presented fabrication process is based on the thinning of high-density bulk Lead Zirconate Titanate (PZT) ceramic substrates, which enables the realization of thick layers (10–100 μm). Using this fabrication approach, we prepared two types of cantilever-based vibration energy scavengers (unimorph and bimorph) operating at very low frequency (~15 Hz) with a 50 μm PZT final thickness. Given that under a harmonic 10 mg vibration the harvested mean power was 1.3 μW and 3 μW respectively, these devices rank among the best ever-reported vibration energy scavengers according to commonly accepted figures of merit. The presented fabrication approach is therefore believed to be a good candidate for the manufacturing of highly efficient piezoelectric energy scavengers operating at very low frequency.

Journal ArticleDOI
TL;DR: In this paper, a piezoelectric pseudo-bimorph actuator was proposed, which is made of only one single plate with interdigitated electrodes on both sides and polarized alternately in longitudinal direction.
Abstract: We report a piezoelectric pseudo-bimorph actuator, which is made of only one single plate with interdigitated electrodes on both sides and polarized alternately in longitudinal direction. Like a bimorph actuator, it can also produce a large bending actuation based on anti-symmetrically longitudinal piezoelectric d33 strain effect under an applied electric field. The presented pseudo-bimorph actuator shows much better temperature stability than conventional piezoelectric bimorph actuators from room temperature to the depolarization temperature of the material due to lacking of interface strain loss.

Proceedings ArticleDOI
07 Apr 2013
TL;DR: This paper presents the reliability study of an S-shaped bimorph MEMS mirror, which shows that after a 100 million cycles of scanning, the maximum drift was less than 0.01°.
Abstract: MEMS devices based on bimorphs are affected by several effects including creep, stress, and fracture in bimorph structures. In this paper, we present the reliability study of an S-shaped bimorph MEMS mirror. The following tests are performed: 100 million cycle scanning, vibration, and isothermal holding. Only 0.4% scan angle change was observed after experiencing a 6-axis, 20g vibration. A maximum 0.7% change was measured after the MEMS mirror gone through an isothermal holding for 10 hours at 150°C. After a 100 million cycles of scanning, the maximum drift was less than 0.01°.