Performance Of Piezoelectric Energy Harvester Research Articles

Enhanced performance of piezoelectric energy harvester through three serial vibrators

This paper presents a piezoelectric harvester array with three identical energy harvesting vibrators (EHVs) arranged in series along the water flow direction. Each EHV consists of a piezoelectric beam and an interference cylinder. Three serial EHVs are placed upright in the water channel. Prototypes of three EHVs are fabricated and experiments are conducted to explore the vibration response and harvesting performance. The experimental results demonstrated that three EHVs in the array show the obvious difference in excitation vibration and harvesting performance over single EHV. The lock-in frequency of three EHVs can be enhanced by the EHV array, and the speed bandwidth can be greatly broadened by accounting for 66.9%. The harvesting performance of upstream EHV (EHV-1) and downstream EHV (EHV-3) is significantly improved by the EHV array over single EHV. While, midstream EHV (EHV-2) shows an inhibitory effect to some extent. The overall harvesting performance in the EHV array can be increased by up to 36.23% compared with single EHV in certain spacing distances. The proposed EHV array shows the better harvesting ability over the previous harvesters. This work provides a comprehensive experimental guideline for further designing efficient harvester array used in low-speed water environment.

Lead-Free Bi3.15Nd0.85Ti3O12 Nanoplates Filler-Elastomeric Polymer Composite Films for Flexible Piezoelectric Energy Harvesting.

Nowadays, wearable and flexible nanogenerators are of great importance for portable personal electronics. A flexible piezoelectric energy harvester (f-PEH) based on Bi3.15Nd0.85Ti3O12 single crystalline nanoplates (BNdT NPs) and polydimethylsiloxane (PDMS) elastomeric polymer was fabricated, and high piezoelectric energy harvesting performance was achieved. The piezoelectric output performance is highly dependent on the mass ratio of the BNdT NPs in the PDMS matrix. The as-prepared f-PEH with 12.5 wt% BNdT NPs presents the highest output voltage of 10 V, a peak-peak short-circuit current of 1 μA, and a power of 1.92 μW under tapping mode of 6.5 N at 2.7 Hz, which can light up four commercial light emitting diodes without the energy storage process. The f-PEHs can be used to harvest daily life energy and generate a voltage of 2–6 V in harvesting the mechanical energy of mouse clicking or foot stepping. These results demonstrate the potential application of the lead-free BNdT NPs based f-PEHs in powering wearable electronics

Enhanced output performance of flexible piezoelectric energy harvester by using auxetic graphene films as electrodes

We demonstrate an effective approach to enhance the output performance of a flexible piezoelectric energy harvester by using flexible electrodes with negative Poisson's ratio (NPR). The relationship between open-circuit voltage and Poisson's ratio of electrodes is established theoretically by deriving the analytical expression. It reveals a continuous increasing trend in open-circuit voltage with the decrease in Poisson's ratio of the electrodes. Further, graphene-assembled macro-film (GAMF), an NPR material with excellent flexibility and high conductivity, is used as the electrodes to fabricate flexible piezoelectric energy harvesters. Compared with the energy harvesters using silver electrode, the harvesters made by GAMF electrodes, with an NPR of −0.39, achieve nearly 1.7-times enhancement in open-circuit voltage and 1.6-times in short-circuit current for output performance. The experimental results are highly consistent with the simulation results, indicating that the GAMF has great prospects in developing flexible piezoelectric energy harvesters with enhanced electrical output performance.

Investigation of Piezoelectric Energy Harvesting via Nonlinear Friction-Induced Vibration

In this work, piezoelectric energy harvesting (PEH) performance via friction-induced vibration (FIV) is studied numerically. A nonlinear two-degree-of-freedom friction system (mass-on-belt) with piezoelectric elements, which simultaneously considers the stick-slip motion, model coupling instability, separation, and reattachment between the mass and belt, is proposed. Both complex eigenvalue analyses and transient dynamic analysis of this nonlinear system are carried out. Results show that it is feasible to convert FIV energy to electrical energy when the friction system is operating in the unstable vibration region. There exists a critical friction coefficient (μc) for the system to generate FIV and output visible voltage. The friction coefficient plays a significant role in affecting the dynamics and PEH performance of the friction system. The friction system is able to generate stronger vibration and higher voltage in the case that both the kinetic friction coefficient and static friction coefficient are larger thanμc. Moreover, it is seen that the separation behavior between contact pair can result in overestimating or underestimating the vibration magnitude and output voltage amplitude, and the overestimate or underestimate phenomenon is determined by the located range of friction coefficient. Furthermore, it is confirmed that an appropriate value of external resistance is beneficial for the friction system to achieve the highest output voltage. The obtained results will be beneficial for the design of PEH device by means of FIV.

Multi-factors analysis on the energy harvesting performance of PEH under multiple-frequency excitation

The piezoelectric energy harvesters (PEHs) undergoing coupled bending-torsional vibrations were designed by crossbeam-offset and asymmetric mass, and the maximum output peak voltage at the first mode (Up-max1) and the minimum resonance frequency difference between the first and second modes (Δf0) were 81.5 V and 16.0 Hz chosen as the optimization objectives in the multi-factors analysis based on the orthogonal test method. The geometrical parameters including the crossbeam length, mass ratio, substrate thickness and primary beam length are correspondingly determined, before the PEHs were fabricated to investigate the optimum resistance and energy harvesting efficiency. The PEHs were constructed as the series connection structure, and the mechanical vibration experiments were performed to measure output peak voltage vs frequency curve. When the load resistance is applied from 47 to 1000 kΩ, all of the optimum resistances are about 470 kΩ for the PEHs with the offset ratio 1.23 and mass ratio 4. The errors are at the ranges of 5.0%–16.4% for Up-max and 1.1%–6.5% for f0, and the measurement reliability is acceptable. The sums of half-power bandwidths are regarded as the energy harvesting characteristic to evaluate the efficiency, and they are broaden by 133% and 180% for the PEHs with crossbeam-offset and asymmetric mass under multiple-frequency excitation. PEH undergoing coupled bending-torsion vibrations could harvest more electrical power at multiple resonance frequencies in nature environment.

Solvent-controlled crystalline beta-phase formation in electrospun P(VDF-TrFE) fibers for enhanced piezoelectric energy harvesting

Electrospun piezoelectric polymer fibers, which offer mechanical flexibility, light weight, and relatively low temperature processing, have emerged as a strong solution to shape-adaptive energy harvesting and sensing applications for smart electronics at multi-scales. In this work, we aim to enhance the electrospun fiber-based piezoelectric energy harvesting performance by elucidating the role of the solvent in crystallization kinetics and fiber formation during electrospinning as well as its influence on harvesting performance. Two key solvent characteristics, surface tension and evaporation rate, are found to play a role in determining uniform fiber formation with controllable diameters, degree of crystallization, and electroactive β-phase content, which are primarily responsible for the piezoelectric performance of the electrospun poly(vinylidene fluoride-trifluroethylene) P(VDF-TrFE). A substantial difference in the piezoelectric output performance is clearly observed depending on the choice of solvent. Indeed, N,N-dimethylformamide with a low evaporation rate enables piezoelectric output voltage generation of a thermally annealed P(VDF-TrFE) fiber-based device up to 139.5 V, while the device with as-spun fibers in the other solvent case, methyl ethyl ketone, yields a much lower voltage of 75.3 V. This study demonstrates that the tailoring capability of the solvent should be carefully considered together with other processing and operating conditions (e.g., thermal annealing, bending frequency, and electrical resistances) in order to realize enhanced piezoelectric energy harvesting performance of electrospun fibers for versatile potential applications.

Piezoelectric energy harvesting from roadway deformation under various traffic flow conditions

Many laboratory tests and in situ measurements have been conducted to study piezoelectric energy harvesting from roadway deformation. However, the performance of piezoelectric energy harvesters under real traffic flow conditions is still unknown. In this study, an electromechanical model of piezoelectric energy harvesters with detailed parameters (including the geometric parameters, material parameters, and circuits) is established, and the influences of traffic flow conditions (i.e. traffic speed and traffic density) on the output power of piezoelectric energy harvesters are analyzed by employing a scaling law method and traffic flow theory. The results indicate that remarkable differences exist in the load patterns and the frequencies between the laboratory tests (or in situ measurements) and real traffic flow conditions. Because of these differences, the results (especially the output electric power and optimization design methods) of previous studies may be inapplicable for piezoelectric energy harvesters embedded in roadways. Considering the distinguishing features of the traffic load pattern, the optimization criteria to determine the geometric parameters and the intrinsic system parameter of piezoelectric energy harvesters are obtained, and the corresponding optimal output power densities of the piezoelectric energy harvesters are also quantitatively calibrated. These theoretical results may serve as guidelines for optimizing the design of piezoelectric energy harvesters embedded in roadways under different traffic flow conditions.

Parametric study and shape optimization of Piezoelectric Energy Harvesters by isogeometric analysis and kriging metamodeling

Piezo-electric energy harvesters (PEHs) are widely used to recycle waste vibrations for powering small electronic devices. In this work, the performance of PEHs of non-conventional shapes is studied with the aim to optimize their design. A PEH is modeled as a bimorph cantilever Kirchhoff-Love plate subjected to base acceleration. The shape is described by Non Uniform Rational B-Splines (NURBS), and the problem is solved by the isogeometric analysis (IGA). Accuracy of the IGA solutions is demonstrated on two benchmark problems. Then, we conduct a parametric study to investigate the effect of shape perturbations on the fundamental frequency, the peak amplitude of the frequency response function (FRF) and the peak amplitude of the FRF per unit of area. Next, we build the Kriging meta-model to obtain the boundary shapes that maximize the peak amplitude of the FRF and the peak amplitude of the FRF per unit of area for a target frequency. The optimization is performed for three cases: with a fixed tip mass, without a tip mass and with a tip mass being one of the design parameters.

Performance of beam-type piezoelectric vibration energy harvester based on ZnO film fabrication and improved energy harvesting circuit

We demonstrate a piezoelectric vibration energy harvester with the ZnO piezoelectric film and an improved synchronous electric charge extraction energy harvesting circuit on the basis of the beam-type mechanical structure, especially investigate its output performance in vibration harvesting and ability to generate charges. By establishing the theoretical model for each of vibration and circuit, the numerical results of voltage and power output are obtained. By fabricating the prototype of this harvester, the quality of the sputtered film is explored. Theoretical and experimental analyses are conducted in open-circuit and closed-circuit conditions, where the open-circuit mode refers to the voltage output in relation to the ZnO film and external excitation, and the power output of the closed-circuit mode is relevant to resistance. Experimental findings show good agreement with the theoretical ones, in the output tendency. It is observed that the properties of ZnO film achieve regularly direct proportion to output performance under different excitations. Furthermore, a maximum experimental power output of 4.5 mW in a resistance range of 3 kΩ–8 kΩ is achieved by using an improved synchronous electric charge extraction circuit. The result is not only more than three times the power output of classic circuit, but also can broaden the resistance to a large range of 5 kΩ under an identical maximum value of power output. In this study we demonstrate the fundamental mechanism of piezoelectric materials under multiple conditions and take an example to show the methods of fabricating and testing the ZnO film. Furthermore, it may contribute to a novel energy harvesting circuit with high output performance.

Research on piezoelectric vibration energy harvester with variable section circular beam

In order to reduce the natural frequency of the piezoelectric vibration energy harvester, improve performance of the piezoelectric vibration energy harvester, and meet the requirements of energy acquisition in the low-frequency vibration environment, a variable-section circular piezoelectric vibration energy harvester is presented. The dynamic model and electromechanical coupling model of variable-section circular piezoelectric vibration energy harvester are established. The main factors affecting the output performance of piezoelectric vibration energy harvester are analyzed. The structure parameters of piezoelectric vibration energy harvester are optimized by orthogonal experiment. An experimental platform is built to test output voltage and output power of piezoelectric vibration energy harvester. The experimental results show that when the number of energy harvester is 4 and the external load is 180KΩ, the parallel output power can reach 0.213mW, which can meet the requirements of micro-power device power supply.

Analysis and experiment of magnetic excitation cantilever-type piezoelectric energy harvesters for rotational motion

In order to solve the problem that when the piezoelectric cantilever generator captures the low-frequency vibration, the structural resonance frequency bandwidth is small and the generating capacity cannot be fully developed. A magnetic excitation cantilever-type piezoelectric energy harvester for rotational motion was presented in this paper. Energy harvesting capability of resonant harvesting structures, such as piezoelectric cantilever beams, can be improved by utilizing coupled oscillations that generate favorable strain mode distribution. The theoretical analysis and simulation analysis of the working state of the piezoelectric energy harvester is performed. The power generation performance of magnetic excitation cantilever-type piezoelectric energy harvester under different environmental excitations was tested by experimental methods. The experimental results show that the magnetic excitation cantilever-type piezoelectric energy harvester has the best power generation performance when the rotational speed is 150 r min−1, the installation angle of the piezoelectric cantilever is 60°, the distance between the mass magnet and the excitation magnet is 8 mm, and the number of excitation magnets is 6. The maximum open-circuit voltage of the magnetic excitation cantilever-type piezoelectric energy harvester is 38.49 V. When the load resistance is 40 KΩ, the magnetic excitation cantilever-type piezoelectric energy harvester has a voltage of 24.84 V and an average power of 15.425 mW. Piezoelectric energy harvesting is an attractive technique for the potential powering of wireless sensors and low power devices.

Investigation upon the performance of piezoelectric energy harvester with elastic extensions

Piezoelectric vibration energy harvesters have attracted much attention due to its potential to replace currently popular batteries and to provide an sustainable power sources. Many researchers have proposed ways to increase the performance of piezoelectric energy harvesters like bandwidth, working frequency and output performance. Here in this contribution, we propose the method of using elastic extensions to tune the performance of a piezoelectric energy harvester. Mathematical model of the proposed device is derived and analyzed. Numerical simulations are done to investigate the influences of the derived parameters, like length ratio λl, bending stiffness ratio λB, and line density ratio λm. Results show that the elastic extension does change the motion of the proposed device and help tune the performance of piezoelectric energy harvesters.

Porous sandwich structures based on BaZrTiO3–BaCaTiO3 ceramics for piezoelectric energy harvesting

Abstract In this study, porous sandwich structures based on barium zirconate titanate–barium calcium titanate (BZT–BCT) ceramics are investigated for energy harvesting applications. To improve the piezoelectric energy harvesting performance, porous sandwich structures based on the BZT–BCT ceramics produced by the tape casting method are designed to be optimum materials with high piezoelectric charge coefficient and low dielectric constant. The dense and porous layer are made of BZT–BCT ceramic sheets and a mixture of BZT–BCT ceramic and polyvinylidene fluoride (PVDF), respectively. Here, the PVDF is a sacrificial material that is volatilized in the burnout process, which results in the formation of pores within the microstructure. Depending on the volume fraction of the porous layer, the BZT–BCT ceramics are manufactured in proportions ranging from 0% to 100 vol%. The 20 vol% of the porous layer exhibits the highest figure of merit (FOM) of 4.53 p.m.2/N. When the volume fraction of the porous layer exceeds 20 vol%, the FOM sharply decreases. The stored energy is calculated by measuring the output voltage on the external capacitor (1 μF) through the full-bridge circuit connected to the specimen. The energy density is calculated by dividing the stored energy by the sample area. The sample with a 20 vol% of the porous layer has an energy density of 7.29 μJ/cm2, which is the highest value attained.

Performance comparisons of piezoelectric energy harvesters under different stochastic noises

Harvesting energy utilizing the electromechanical coupling mechanism of piezoelectric materials in a noise environment has become important for developing applicable micropower generators. Although a variety of configurations have been proposed to harvest ambient vibration energy driven by deterministic excitations and the energy conversion efficiency of classical one degree of freedom piezoelectric energy harvesters with a purely resistive circuit has been analyzed systematically, crucial questions still remain on how to design system parameters to maximize the performance under different ambient noises. Here, combining the moment method of random processes theory and the energy balance equation, we explore the performance of piezoelectric energy harvesters with and without an inductor excited by Gaussian white noise, exponential correlation noise, and bounded noise, respectively. The exact closed-form expressions of the mean square voltage, averaged output power, and efficiency are presented, and the effects of dimensionless system parameters and noise parameters on the performance metrics are illustrated in detail. Monte Carlo simulations are performed to validate the analytical predictions. The expressions given in this paper are useful in comparing the two types of piezoelectric energy harvesters under different ambient excitations and provide a key to design optimized harvesters operating in a more suitable environment.

Parametrical Investigation of Piezoelectric Energy Harvesting via Friction-Induced Vibration

In this work, piezoelectric energy harvesting performance via friction-induced vibration is investigated numerically. A one-degree-of-freedom friction system with a piezoelectric element is proposed, to study the piezoelectric energy harvesting via friction-induced stick-slip vibration. Subsequently, a two-degree-of-freedom friction system with two piezoelectric elements is proposed, to investigate the piezoelectric energy harvesting via model coupling vibration. Results show that regardless of the friction systems, it is feasible to convert friction-induced vibration energy to electrical energy when the friction system is operating in the unstable vibration region. Parametrical analysis indicates that for the one-degree-of-freedom friction system, when the normal load increases from 5 N to 30 N, the stick-slip motion becomes more intense, and the friction system will generate more electric energy. While for the two-degree-of-freedom friction system, with the normal load increase from 20 N to 120 N, there is a critical normal load value for the generation of the strongest vibration and the highest voltage output. When the velocity of the belt increases from 0.5 m/s to 2 m/s, the amplitudes of vibration and output voltage become larger. While with the velocity further increasing, the stick-slip motion and generated electric energy disappear. For both friction systems, the external electric resistance has no effect on the dynamic behaviour of the friction system; however, it can modify the output voltage amplitudes within limits. It is also found that when the force factor of piezoelectric element increases from 3.1 × 10−5 N/V to 3.1 × 10−3 N/V, the vibration and harvested energy gradually increase. When the force factor further increases to 3.1 × 10−2 N/V, the vibration reduces drastically and the corresponding output voltages reduce significantly, which proves that a piezoelectric element with an appropriated force factor can give the highest harvested energy and conversion efficiency.

Research on Output Characteristics of Double-Ended Fixed Beam Piezoelectric Energy Harvester Under Random Excitation

By use of the concept of impedance, this paper establishes a random energy harvester output model of double-ended fixed beam piezoelectric energy harvester under random White Gaussian noise excitation, which is based on the discussion of the output characteristics influenced by changing vibration beam shape and piezoelectric sheet length under random excitation, while improving piezoelectric structure of double-ended fixed beam piezoelectric energy harvester. It also deduces the output voltage, current and power of energy harvester with Fokker–Planck equation, which are verified by Monte Carlo simulation and experimental testing. It can be found that improving vibration beam shape can reduce resonant frequency and increase average output power of the system. The optimal value of piezoelectric sheet length can be different corresponding to different structures, which proves that double-ended fixed beam piezoelectric energy harvester under random White Gaussian noise excitation can achieve maximum output with optimal piezoelectric sheet length. In addition, in order to further improve the output performance of piezoelectric energy harvester under random excitation, it is necessary to increase the acceleration spectral density under random excitation and set an optimal value of the piezoelectric loading resistance, which is more suitable for energy harvester applied under random low-frequency environment.

Design and Testing of Cantilevered PVDF Energy Harvester Based on the Coanda Effect

Low-flow air has been attracted many researchers which can be transformed into electric energy by the piezoelectric materials. A flow amplifier device can be used to increase the performance of piezoelectric energy harvester excited by low-flow air. The Coanda effect theory has been analyzed based on the fast-moving air. To analyze the effect of the amplifier device and verify the feasibility of the proposed cantilevered PVDF energy harvester, we employed finite element simulation to analyze the flow distribution of the amplified flow air. Then the stress and potential distribution of PVDF film have been analyzed. A prototype of the cantilevered PVDF energy harvester is tested with different variables such as input air flow, pressure and cycle time. The test results show that the output voltage increases with increasing input air flow. The output voltage decreases slightly with increasing input cycle time. The peak voltage decreases as the distance between the prototype and the excitation source increases. Importantly, the output voltage for the amplified airflow is about three-times that of the non-amplified air flow. The maximal output voltage and power are 12.80 V and 19.89 μW at the pressure of 0.2 MPa and a flow rate of 200 L/min, respectively.

Nano-ZnO decorated ZnSnO3 as efficient fillers in PVDF matrixes: toward simultaneous enhancement of energy storage density and efficiency and improved energy harvesting activity.

Here, we report the effect of ZnO decoration on ZnSnO3fillers on the dielectric property, energy storage behaviour and mechanical energy harvesting performance of PVDF matrixes. More enhanced dielectric constant and reduction in dielectric loss were achieved in PVDF-ZnO@ZnSnO3 (PVDF-ZNZS) films than in PVDF-ZnSnO3 (PVDF-ZS) films for the same concentration of filler loading. Similarly, PVDF-ZNZS films showed simultaneous enhancement in electrical energy storage density and storage efficiency compared to PVDF-ZS composites. As all the constituent materials (PVDF, ZnSnO3 and ZnO) were piezoelectric, the resulting composite film showed improved piezoelectric energy harvesting performance too. After rectification, the output ac voltage was used to charge a 10 μF capacitor up to ∼5 V dc which was further used to light up some LEDs. Furthermore, in order to exhibit improved sensitive output, a hybrid piezo-tribo nanogenerator was fabricated which was demonstrated as a motion sensor, a weight sensor and a human body movement sensor as part of a real life application.

A tri-stable energy harvester in rotational motion: Modeling, theoretical analyses and experiments

This paper originally investigates the performance of a tri-stable piezoelectric energy harvester (TPEH) in rotational motion, aiming to solve the challenging issue of power supply for wireless sensors. Based on the Lagrange equation, the related theoretical model with the consideration of the effect of rotational motion is originally derived to describe its dynamic response and energy harvesting performance. In addition, the perturbation method is used to theoretically describe the TPEH for the oscillations around both non-zero and zero stable equilibrium positions. The numerical simulations and case studies are carried out to investigate the influence of the Kc coefficient on the dynamic response of the TPEH. More importantly, the corresponding experiments under different constant rotational speeds are performed to validate the energy harvesting enhancement of the presented TPEH and the accuracy of its theoretical model. It is experimentally verified that the TPEH can efficiently harvest energy in the wide rotational speed range (240–440 rpm), and the proposed theoretical model is suitable for the TPEH. Overall, the energy harvesting enhancement of the TPEH in rotational motion are verified, and the accuracy of the presented theoretical model is also experimentally validated.

Enhanced performance of piezoelectric wind energy harvester by a curved plate

Piezoelectric wind energy harvesting is a promising strategy for developing self-powered small electromechanical systems. In this paper, a curved-plate bluff body is studied for enhancing the performance of piezoelectric wind energy harvester based on galloping phenomenon. The proposed curved-plate bluff body seems to have more design flexibility and the possibility of improving aerodynamic performance. A lumped parameter theoretical model is given and verified by experiments. The numerical research has shown that the curved-plate bluff body can obtain high lift and negative pressure in the inner circulation, which are the key drivers for the vibration of the piezoelectric beam based on galloping phenomenon. Experimental results show that the piezoelectric wind energy harvester with the curved-plate bluff body (WEHC) can generate higher output voltage than the conventional cross-section (square, regular-triangle, and D-shaped) bluff bodies, and has a lower cut-in wind speed. When an external load resistance of 820 KΩ is connected and the arc length is 45 mm, the piezoelectric wind energy harvester with curved-plate bluff body generates an average power of 35.6 μW.