Showing papers on "Bimorph published in 2009"
TL;DR: In this paper, a closed-form analytical solution for a unimorph cantilever under base excitation based on the Euler-Bernoulli beam assumptions is presented, and the performance of the bimorph device is analyzed extensively for the short circuit and open circuit resonance frequency excitations.
Abstract: Piezoelectric transduction has received great attention for vibration-to-electric energy conversion over the last five years. A typical piezoelectric energy harvester is a unimorph or a bimorph cantilever located on a vibrating host structure, to generate electrical energy from base excitations. Several authors have investigated modeling of cantilevered piezoelectric energy harvesters under base excitation. The existing mathematical modeling approaches range from elementary single-degree-of-freedom models to approximate distributed parameter solutions in the sense of Rayleigh–Ritz discretization as well as analytical solution attempts with certain simplifications. Recently, the authors have presented the closed-form analytical solution for a unimorph cantilever under base excitation based on the Euler–Bernoulli beam assumptions. In this paper, the analytical solution is applied to bimorph cantilever configurations with series and parallel connections of piezoceramic layers. The base excitation is assumed to be translation in the transverse direction with a superimposed small rotation. The closed-form steady state response expressions are obtained for harmonic excitations at arbitrary frequencies, which are then reduced to simple but accurate single-mode expressions for modal excitations. The electromechanical frequency response functions (FRFs) that relate the voltage output and vibration response to translational and rotational base accelerations are identified from the multi-mode and single-mode solutions. Experimental validation of the single-mode coupled voltage output and vibration response expressions is presented for a bimorph cantilever with a tip mass. It is observed that the closed-form single-mode FRFs obtained from the analytical solution can successfully predict the coupled system dynamics for a wide range of electrical load resistance. The performance of the bimorph device is analyzed extensively for the short circuit and open circuit resonance frequency excitations and the accuracy of the model is shown in all cases.
1,187 citations
TL;DR: In this article, an electromechanically coupled finite element (FE) plate model is presented for predicting the electrical power output of piezoelectric energy harvester plates.
270 citations
TL;DR: In this article, the authors reported the implementation of ultrathin (100 nm) aluminum nitride (AlN) piezoelectric layers for the fabrication of vertically deflecting nanoactuators.
Abstract: This letter reports the implementation of ultrathin (100 nm) aluminum nitride (AlN) piezoelectric layers for the fabrication of vertically deflecting nanoactuators. The films exhibit an average piezoelectric coefficient (d31∼−1.9 pC/N), which is comparable to its microscale counterpart. This allows vertical deflections as large as 40 nm from 18 μm long and 350 nm thick multilayer cantilever bimorph beams with 2 V actuation. Furthermore, in-plane stress and stress gradients have been simultaneously controlled. The films exhibit leakage currents lower than 2 nA/cm2 at 1 V, and have an average relative dielectric constant of approximately 9.2 (as in thicker films). These material characteristics and actuation results make the AlN nanofilms ideal candidates for the realization of nanoelectromechanical switches for low power logic applications.
152 citations
TL;DR: In this paper, the authors quantify the influence of each operational parameter and its relative impact on thermal performance of piezoelectric fans and find that the performance of the fans is maximized at a particular value of the gap between the fan tip and the heated surface.
121 citations
01 Dec 2009
TL;DR: In this article, a simple step-by-step procedure is presented to design the cantilever beam based energy harvester by incorporating piezoelectric material at maximum stress points in first and second resonance modes.
Abstract: This chapter provides the introductory information on piezoelectric energy harvesting covering various aspects such as modeling, selection of materials, vibration harvesting device design using bulk and MEMS approach, and energy harvesting circuits. All these characteristics are illustrated through selective examples. A simple step-by-step procedure is presented to design the cantilever beam based energy harvester by incorporating piezoelectric material at maximum stress points in first and second resonance modes. Suitable piezoelectric material for vibration energy harvesting is characterized by the large magnitude of product of the piezoelectric voltage constant (g) and the piezoelectric strain constant (d) given as (d· g). The condition for obtaining large magnitude of d·g has been shown to be as |d| =en, where e is the permittivity of the material and n is a material parameter having lower limit of 0.5. The material can be in the form of polycrystalline ceramics, textured ceramics, thin films, and polymers. A brief coverage of various material systems is provided in all these categories. Using these materials different transducer structures can be fabricated depending upon the desired frequency and vibration amplitude such as multilayer, MFC, bimorph, amplified piezoelectric actuator, QuickPack, rainbow, cymbal, and moonie. The concept of multimodal energy harvesting is introduced at the end of the chapter. This concept provides the opportunity for further enhancement of power density by combining two different energy-harvesting schemes in one system such that one assists the other.
79 citations
TL;DR: A self-sensing method dedicated to free uni- and bimorph piezocantilevers but can also be adapted to other piezoactuator types, which has the ability to keep displacement information for long-term periods and in the reduction in signal noise.
Abstract: Piezoelectric meso- and microactuator systems required for manipulation or assembly of microscale objects demand reliable force and/or displacement information. Available sensors are prone to dimension restrictions or precision limitation. Self-sensing method, based on the electric charge measurement, may represent a solution in terms of cost-effectiveness and integration, the actuator performing simultaneously as its own sensor. This paper presents a self-sensing method dedicated to free uni- and bimorph piezocantilevers but can also be adapted to other piezoactuator types. The integrated electric current, used to convert the charge, can be compensated against piezoelectric material nonlinearities to provide accurate displacement information. The advantages relative to existing self-sensing methods consist in the ability to keep this displacement information for long-term periods (more than a thousand seconds) and in the reduction in signal noise. After introductive issues related to the method the base principle allowing the estimation of tip displacement is presented. Then, the identification procedure of the estimator parameters is depicted and representative experimental results are shown. Finally, a series of aspects related to electronic circuits are discussed, useful for successful system implementation.
74 citations
TL;DR: In this paper, the performance study of a novel principle of a piezoelectric flow pump is presented, which is based on the use of a bimorph PIE actuator inserted in fluid (water).
Abstract: Flow pumps have been developed for classical applications in Engineering, and are important instruments in areas such as Biology and Medicine. Among applications for this kind of device we notice blood pump and chemical reagents dosage in Bioengineering. Furthermore, they have recently emerged as a viable thermal management solution for cooling applications in small-scale electronic devices. This work presents the performance study of a novel principle of a piezoelectric flow pump which is based on the use of a bimorph piezoelectric actuator inserted in fluid (water). Piezoelectric actuators have some advantages over classical devices, such as lower noise generation and ease of miniaturization. The main objective is the characterization of this piezoelectric pump principle through computational simulations (using finite element software), and experimental tests through a manufactured prototype. Computational data, such as flow rate and pressure curves, have also been compared with experimental results for validation purposes.
58 citations
TL;DR: In this paper, a general analytical solution for the transient analysis of a magneto-electro-elastic bimorph beam is obtained based on the Timoshenko beam theory and on the assumption that the electric and magnetic fields can be treated as steady.
Abstract: Based on the Timoshenko beam theory and on the assumption that the electric and magnetic fields can be treated as steady, since elastic waves propagate very slowly with respect to electromagnetic ones, a general analytical solution for the transient analysis of a magneto-electro-elastic bimorph beam is obtained. General magneto-electric boundary conditions can be applied on the top and bottom surfaces of the beam, allowing us to study the response of the bilayer structure to electromagnetic stimuli. The model reveals that the magneto-electric loads enter the solution as an equivalent external bending moment per unit length and as time-dependent mechanical boundary conditions through the definition of the bending moment. Moreover, the influences of the electro-mechanic, magneto-mechanic and electromagnetic coupling on the stiffness of the bimorph stem from the computation of the beam equivalent stiffness constants. Free and forced vibration analyses of both multiphase and laminated magneto-electro-elastic composite beams are carried out to check the effectiveness and reliability of the proposed analytic solution.
52 citations
TL;DR: A planate conducting polymer actuator based on polypyrrole (PPy) and two types of acids, such as p -phenol sulfonic acid and dodecylbenzene sulfonic acids, by electrodeposition was proposed in this paper.
Abstract: In this study, we propose a planate actuator which can transform only its central part locally. We have developed a planate conducting polymer actuator based on polypyrrole (PPy) and two types of acids, such as p -phenol sulfonic acid and dodecylbenzene sulfonic acid, by electrodeposition. Its structure was patterned bimorph structure with anion-driven, cation-driven and bimorph layers. The planate conducting polymer actuator could deform only its central part locally. Moreover, we introduce a micro-pump that operates by planate conducting polymer actuator as the drive source. The water level in the flow channel of micro-pump shows the reciprocating motion measuring ±2 mm in accordance with the oscillation of the bimorph conducting polymer actuator which was approximately 28 μl/min. The oscillating volume can be controlled by the application of electrochemical potential and its scan rate applied to the actuator.
39 citations
TL;DR: In this article, the authors examined the possibility of constructing deformable mirrors for adaptive optics with a large number of degrees of freedom from silicon wafers with bimorph piezoelectric actuation.
Abstract: This paper examines the possibility of constructing deformable mirrors for adaptive optics with a large number of degrees of freedom from silicon wafers with bimorph piezoelectric actuation. The mirror may be used on its own, or as a segment of a larger mirror. The typical size of one segment is 100 to 200 mm; the production process relies on silicon wafers and thick film piezoelectric material deposition technology; it is able to lead to an actuation pitch of the order of 5 mm, and the manufacturing costs appear to grow only slowly with the number of degrees of freedom in the adaptive optics.
36 citations
TL;DR: A number of concepts are demonstrated including the focusing and defocusing action of an azo-LCN membrane, laser beam steering from a bimorph azo -LCN/metal cantilever, and surface initiated bending and blocking of a parallel propagating laser beam.
Abstract: Optically deformable membranes and cantilevers based on azobenzene liquid crystal polymer networks (azo-LCN) are demonstrated in the context of dynamic optical systems. Large modulations in laser beam propagation direction or amplitude directed by laser-induced changes in material shape are demonstrated. These macroscopic shape changes are induced by local changes to the liquid crystalline order induced by photoisomerization processes. We demonstrate herein a number of concepts including the focusing and defocusing action of an azo-LCN membrane, laser beam steering from a bimorph azo-LCN/metal cantilever, and surface initiated bending and blocking of a parallel propagating laser beam. High speed and large angle deformations of an incident or reference beam is demonstrated when coupled into suitable optical architectures. The concepts under discussion appear to be highly practical for a number of applications due to the significant nonlinearity and photosensitivity of azo-LCN materials.
TL;DR: In this article, a two-axis gimbal-less micromirror optimized for large-angle circumferential scanning applications is presented, which consists of novel folded bimorph electrothermal actuators, flexural springs, and a mirror plate coated with a high-reflective Cr/Au thin film.
Abstract: In this paper, we present the design, simulation, fabrication, and characterization of a two-axis gimbal-less micromirror optimized for large-angle circumferential scanning applications. The single-crystal silicon micromirror consists of novel folded bimorph electrothermal actuators, flexural springs, and a mirror plate coated with a high-reflective Cr/Au thin film. A modified silicon-on-insulator microelectromechanical system process has been applied on the micromirror fabrication. The single-wafer process is based on deep reactive ion etching in order to achieve high fill factor as well as small outline of the micromirror chip. A new mechanical design of bimorph actuators is developed to further increase the mechanical deflection. Both theoretical and experimental results demonstrate that the micromirror can provide a uniform mechanical deflection up to ~9deg with multichannel driving voltages of less than 2.3 V to any angle in full 360deg circumference.
TL;DR: It is shown that the time constant of the probe can be reduced by reducing its quality factor and/or increasing its resonance frequency to reduce the scan error in tapping mode AFM.
Abstract: We adjust the transient dynamics of a piezoactuated bimorph atomic force microscopy (AFM) probe using a state feedback controller. This approach enables us to adjust the quality factor and the resonance frequency of the probe simultaneously. First, we first investigate the effect of feedback gains on dynamic response of the probe and then show that the time constant of the probe can be reduced by reducing its quality factor and/or increasing its resonance frequency to reduce the scan error in tapping mode AFM.
TL;DR: A new read-out technique based on the change in the electric current flowing through the bimorph and the contact pad has been employed, replacing the conventional cumbersome piezoresistive method or tedious optical alignment.
Abstract: The combination of design and subsequent fabrication of organic/inorganic nanostructures creates an effective way to combine the favorable traits of both to achieve a desired device performance. We demonstrate a miniature electrical read-out, and a sensitive temperature sensor/switch, based on a ZnO nanobelt/plasma-polymerized benzonitrile bimorph structure. A new read-out technique based on the change in the electric current flowing through the bimorph and the contact pad has been employed, replacing the conventional cumbersome piezoresistive method or tedious optical alignment. The thermal sensor demonstrated here has great prospects for thermal switching and triggered detection owing to the relative ease in the fabrication of arrays and the direct electrical read-out.
07 Jun 2009
TL;DR: In this article, a slot antenna with an embedded temperature sensor for remote sensing in harsh environment applications is presented, where the returned signal's frequency is modulated by the loaded capacitance formed by an array of MEMS bimorph (metal-dielectric) cantilevers.
Abstract: In this paper we present a new slot antenna with an embedded temperature sensor for remote sensing in harsh environment applications. When the antenna is illuminated with a plane wave it returns a signal. The returned signal's frequency is modulated by the loaded capacitance formed by an array of MEMS bimorph (metal-dielectric) cantilevers. The MEMS cantilevers deflect downwards when the temperature is changed from 20°C to 300°C. As a result, the resonant frequency of the slot is linearly tuned from 19.45 to 19.30 GHz. The design yields a totally passive and integrated antenna/sensor. The MEMS fabrication is inherently robust, does not suffer from the creep or fatigue problems of traditional bimorph temperature sensors, and has a very high manufacturing yield, even in an academic clean room environment.
TL;DR: In this paper, a control system using distributed bimorph actuators was designed to eliminate any detrimental vibration of the membrane mirror. But, the performance of the active system was not evaluated.
Abstract: The future of space satellite technology lies in ultra-large mirrors and radar apertures for significant improvements in imaging and communication bandwidths. The availability of optical-quality membranes drives a parallel effort for structural models that can capture the dominant dynamics of large, ultra-flexible satellite payloads. Unfortunately, the inherent flexibility of membrane mirrors wreaks havoc with the payload's on-orbit stability and maneuverability. One possible means of controlling these undesirable dynamics is by embedding active piezoelectric ceramics near the boundary of the membrane mirror. In doing so, active feedback control can be used to eliminate detrimental vibration, perform static shape control, and evaluate the health of the structure. The overall motivation of the present work is to design a control system using distributed bimorph actuators to eliminate any detrimental vibration of the membrane mirror. As a basis for this study, a piezoceramic wafer was attached in a bimorph configuration near the boundary of a tensioned rectangular membrane sample. A finite element model of the system was developed to capture the relevant system dynamics from 0 to 300 Hz. The finite element model was compared against experimental results, and fair agreement found. Using the validated finite element models, structural control using linear quadratic regulator control techniques was then used to numerically demonstrate effective vibration control. Typical results show that less than 12 V of actuation voltage is required to eliminate detrimental vibration of the membrane samples in less than 15 ms. The functional gains of the active system are also derived and presented. These spatially descriptive control terms dictate favorable regions within the membrane domain for placing sensors and can be used as a design guideline for structural control applications. The results of the present work demonstrate that thin plate theory is an appropriate modeling medium for capturing the relevant system dynamics of an active membrane mirror and can be used effectively to set the framework for the closed-loop vibration control architecture.
TL;DR: In this paper, constitutive equations of transparent lead lanthanum zirconate titanate (PLZT) materials poling along thickness direction or with 0-3 polarization are presented.
TL;DR: In this article, the magnetically and elastically tunable, flexural resonant mode in the bimorph FeNi36% (invar)/polyvinylidene fluoride clamped bilayer has been investigated by Doppler laser spectroscopy.
Abstract: In this letter, we report a method for a tunable magnetic field sensor based on the magnetoelastic coupling properties of a magnetoelastic/piezoelectric laminated composite structure. The magnetically and elastically tunable, flexural resonant mode in the bimorph FeNi36% (invar)/polyvinylidene fluoride clamped bilayer has been investigated by Doppler laser spectroscopy. Here we demonstrate that this bimorph structure can be used for low-frequency contactless detection of magnetic field fluctuation and magnetic field monitoring.
01 Oct 2009
TL;DR: In this paper, an inherently robust wireless capacitive MEMS temperature sensor capable of operating to 300°C is presented. The heart of the sensor is an array of bimorph (metal-dielectric) cantilevers whose deflections are sensed by a array of appropriately placed electrodes.
Abstract: Presented is an inherently-robust wireless capacitive MEMS temperature sensor capable of operating to 300°C. The heart of the sensor is an array of bimorph (metal-dielectric) cantilevers whose deflections are sensed by an array of appropriatelyplaced electrodes. The key advantages of this configuration are the following. First, its dielectric layer is SiO 2 thermally-grown at 1,100°C as opposed to conventional low-temperature PECVD or sputtered films. Second, the lack of a sensing surface directly beneath the movable structures renders stiction nearly impossible. Third, the fringing-field sensing results in constant sensitivity throughout the entire temperature range. Fourth, the employed passive approach is immune to high-temperature reliability issues faced by active devices. Furthermore, the fabrication yield is over 99%, even in an academic cleanroom (Birck Nanotechnology Center at Purdue University). When configured with an inductor and wirelessly interrogated, the measured resonant frequency has a linear shift from 206 MHz at room temperature to 199 MHz at 300°C.
Patent•
07 Apr 2009TL;DR: In this paper, a bimorph type piezoelectric element is configured such that the stretching axis (39) and the other stretching axis(40) are intersected at an angle of 90 degrees.
Abstract: A piezoelectric element including a piezoelectric sheet, which exhibits piezoelectricity when it is stretched, such as a polylactic acid, has a problem in that the piezoelectric sheet tends to tear along a stretching direction. For example, when a bimorph type piezoelectric element (31) is to be configured, the stretching axis (39) of one piezoelectric sheet (32) and the stretching axis (40) of the other piezoelectric sheet (33) are oriented in different directions from each other. Preferably, the one stretching axis (39) and the other stretching axis (40) are intersected at an angle of 90 degrees.
TL;DR: In this article, an analytical model, a finite element analysis and measured results for a planar, parallel and symmetrical piezoelectric bimorph structure are presented.
Abstract: In this work, an analytical model, a finite element analysis and measured results for a planar, parallel and symmetrical piezoelectric bimorph structure are presented. The bimorph consists of two rectangular piezoelectric strips that are connected back-to-back on a thin metallic centre electrode. The bimorph is intended to be used as a millinewton range force sensor with dynamic excitation. The bimorph is modelled with a static, analytical expression for generated charge, voltage, displacement and force that correspond to the deflection of a freely oscillating piezoelectric bimorph. Also, a case where the movement of the bimorph is blocked is analyzed. A circuit that is used to actuate the bimorph is presented, as well as the measured results from the actuator and the sensor side of the bimorph in both free oscillation and blocked cases. The measurement results show a reasonably good agreement with the analytical model and very good agreement with the FEM model. Force sensor setup and a way to measure the force inflicted on the bimorph are also presented, as well as the force response of the bimorph against a commercial piezoresistive force sensor.
Patent•
09 Jan 2009TL;DR: In this article, an electrode (17) formed on opposing main surfaces of a piezoelectric sheet (12, 13) having a predetermined stretching axis and made of a chiral polymer is divided into four electrode portions (E1 to E4) by a plurality of dividing lines (21a, 21b, 22a, 22b) extending in a radiation direction.
Abstract: When a piezoelectric speaker, which has a bimorph structure, for example, and is configured by using a piezoelectric sheet having a predetermined stretching axis and made of a chiral polymer, is fixed on a whole circumference, an appropriate vibration is hindered, so that it cannot function as a speaker. An electrode (17) formed on opposing main surfaces of a piezoelectric sheet (12, 13) having a predetermined stretching axis and made of a chiral polymer is divided into four electrode portions (E1 to E4) by a plurality of dividing lines (21a, 21b, 22a, 22b) extending in a radiation direction. The four electrode portions (E1 to E4) are distributed along the outer peripheral portion except for the central portion of a vibration region 15. Voltage is applied to the respective four electrode portions (E1 to E4) in such a manner that electric field vectors generated in the thickness direction of the piezoelectric sheet (12, 13) direct in opposite directions between the adjacent ones of four sheet portions of the piezoelectric sheet (12, 13) to which voltage is applied by the electrode portions (E1 to E4).
TL;DR: In this paper, a novel tunable microwave filter with tuning range of 13.8 GHz to 18.2 GHz fabricated using a standard silicon foundry process based on low resistivity silicon substrate is reported.
Abstract: A novel tunable microwave filter with tuning range of 13.8 GHz to 18.2 GHz fabricated using a standard silicon foundry process based on lowresistivity silicon substrate is reported. The filter effect has been realized by integrating two interdigitated comb capacitors with a straight line inductor. The tuning effect has been achieved by varying the capacitance value of the capacitors with a bimorph MEMS actuator. The structure in whole, measuring 1.5 mm × 3.3 mm, allows 27.5% continuous tuning and insertion loss ranging from 3.4 to 6 dB. The driving voltage ranges from 0 V to 0.36 V.
TL;DR: Several adaptive-optics techniques, based on the active modification of the optical properties of the laser cavity, were used to significantly reduce the time-to-full-brightness of solid-state lasers.
Abstract: Several adaptive-optics techniques, based on the active modification of the optical properties of the laser cavity, were used to significantly reduce the time-to-full-brightness of solid-state lasers. Resonator re-configuration was achieved using a mechanical translation stage and both multi- and single-element deformable bimorph mirrors. Using these techniques the effects of thermally induced distortion in Nd:YLF and Nd:YAG lasers can be minimized and the warm-up time reduced by a factor of 3-6.
TL;DR: A multi-walled carbon nanotube (MWNT) bimorph nanoactuator has been modeled, fabricated and characterized and the measured values agreed well with the prediction based on the model.
Abstract: A multi-walled carbon nanotube (MWNT) bimorph nanoactuator has been modeled, fabricated and characterized. A thin aluminum film was uniformly deposited on the sidewalls of MWNTs using a pulsed laser deposition method to create the bimorph nanostructure. For a temperature change from 290 to 690 K with measured dimensions of 100 +/- 20 nm for the MWNT diameter, 40 +/- 10 nm for the Al thickness, and 5.2 +/- 0.5 microm for the bimorph length, the measured deflection was 550 +/- 200 nm, which was in good agreement with the calculation. The actuation force was measured using a lateral force microscopy technique, and the measured values agreed well with the prediction based on the model. The nanoactuator generated a microN force at its tip.
21 Jun 2009
TL;DR: In this article, the first implementation of ultra thin (100 nm) Aluminum Nitride (AlN) piezoelectric layers for the fabrication of vertically deflecting nano-actuators was reported.
Abstract: This paper reports the first implementation of ultra thin (100 nm) Aluminum Nitride (AlN) piezoelectric layers for the fabrication of vertically deflecting nano-actuators. An average piezoelectric coefficient (d 31 ∼ − 1.9 pC/N) that is comparable to its microscale counterpart has been demonstrated in nanoscale thin AlN films. Vertical deflections as large as 40 nm have been obtained in 18 µm long and 350 nm thick cantilever beams under bimorph actuation with 2 V. Furthermore, in-plane stress and stress gradients have been simultaneously controlled. Leakage current lower than 2 nA/cm2 at 1 V has been recorded and an average relative dielectric constant of approximately 9.2 (as in thicker films) has been measured. These material characteristics and preliminary actuation results make the AlN nano-films ideal candidates for the realization of nanoelectromechanical switches for low power logic applications.
TL;DR: In this article, the authors used Finite Element Analysis with thermal analogy technique to numerically reproduce the force-displacement relationship of an ionic polymer-metal composite (IPMC) actuator.
01 Jan 2009
TL;DR: In this article, the amplitude-wise correction of the existing lumped parameter piezoelectric energy harvester model for base excitation was discussed, and coupled distributed parameter modeling of unimorph and bimorph cantilevers under persistent base excitations was presented.
Abstract: This chapter investigates electromechanical modeling of cantilevered piezoelectric energy harvesters excited by persistent base motions. The modeling approaches are divided here into two sections as lumped parameter modeling and distributed parameter modeling. The first section discusses the amplitude-wise correction of the existing lumped parameter piezoelectric energy harvester model for base excitation. For cantilevers operating in the transverse and longitudinal vibration modes, it is shown that the conventional base excitation expression used in the existing lumped parameter models may yield highly inaccurate results in predicting the vibration response of the structure. Dimensionless correction factors are derived to improve the predictions of the coupled lumped parameter piezoelectric energy harvester model. The second section of this chapter presents coupled distributed parameter modeling of unimorph and bimorph cantilevers under persistent base excitations for piezoelectric energy harvesting. Closed-form solutions are obtained by considering all vibration modes and the formal representation of the direct and converse piezoelectric effects. Steady state electrical and mechanical response expressions are derived for arbitrary frequency excitations. These multi-mode solutions are then reduced to single-mode solutions for excitations around the modal frequencies. Finally, the analytical expressions derived here are validated experimentally for a cantilevered bimorph with a proof mass.
Proceedings Article•
01 Apr 2009TL;DR: In this article, a preliminary analysis of the energy scavenger configuration is proposed by investigating the performance of microsystems based on the electrostatic coupling and testing the power scavenged by a capacitive microscavenger, with out-of-plane gap closing layout.
Abstract: Electromechanical conversion of mechanical vibration into electrical energy looks very attractive for industrial applications recently proposed and involving wireless sensors networks. A preliminary analysis of the energy scavenger configuration is proposed by investigating the performance of microsystems based on the electrostatic coupling and testing the power scavenged by a capacitive microscavenger, with out-of-plane gap closing layout. This study includes some key features of the mechatronic design of the energy scavenger. Some strategies for tuning the MEMS resonance frequency on the exciting vibration are investigated. An original procedure based on the static electro-mechanical coupling is introduced. A parametric modeling of the microscavenger is performed and experimentally validated. This investigation allows comparing the performance of the energy harvesting strategy to the configuration with in-plane motion of electrostatic benders and to the performance of bimorph piezoelectric transducers.
TL;DR: In this article, a dimensionally gradient magnetoelectric (ME) sensor that demonstrates high performance over a wide frequency range and a magnetic dc bias operating in the longitudinal transversal mode is presented.
Abstract: We report results on a dimensionally gradient magnetoelectric (ME) sensor that demonstrates high performance over a wide frequency range and a magnetic dc bias operating in the longitudinal-transversal mode. The design of the sensor is based on a piezoelectric bimorph structure and utilizes a laminate configuration with Pb(Zn1/3Nb2/3)0.2(Zr0.5Ti0.5)0.8O3 and Metglas as material layers. The wide-band behavior was characterized by a flat ME response over a wide range of magnetic dc biases corresponding to 60–215 Oe and frequencies corresponding to 7–22 kHz. By using tip mass, the wide-band frequency response was shifted to a lower frequency range of 5–14 kHz. The results show that the operating frequency range of the sensor can be easily shifted by changing the tip mass at the end of the composite.