Performance Of Piezoelectric Energy Harvester Research Articles

Enhancing the Performance of Piezoelectric Wind Energy Harvester Using Curve-Shaped Attachments on the Bluff Body.

This paper presents a piezoelectric wind energy harvester that operates by a galloping mechanism with different shaped attachments attached to a bluff body. A comparison is made between harvesters that consist of different shaped attachments on a bluff body; these include triangular, circular, square, Y-shaped, and curve-shaped attachments. Simulation of the pressure field and the velocity field variation around the different shaped bluff bodies is performed and it is found that a high pressure difference creates a high lift force on the bluff body with curve-shaped attachments. A theoretical model based on a galloping mechanism is presented, which is verified by experiments. It is observed that the proposed harvester with curve-shaped attachments provides the best performance, where the harvester with a curve-shaped attachments provides the highest voltage and power output compared to the other shaped harvesters examined in this study. This paper provides a new concept for improving the power performance of the piezoelectric wind energy harvesters with modifications made on the bluff body.

PZT and PVDF piezoelectric transducers’ design implications on their efficiency and energy harvesting potential

Abstract Despite the intensive research carried out in the last two decades, the actual performance of piezoelectric energy harvesters needs significant improvement for widespread applicability. Custom designed experimental set-ups and methods can be applied for the evaluation of new piezoelectric energy harvesters or modified design versions of existing transducers, in terms of efficiency and specific power. In this context, two representative types of commercial cantilever piezoelectric transducers, made of PZT and PVDF material respectively, were tested in various combinations of aerodynamic and harmonic base excitation. A line type laser was used along with long exposure photography for the visualisation of the piezofilm’s mode shapes, tip deflection and the digitization of the elastic line at the oscillation extrema. The harvested power was measured at on-resonance conditions and studied relative to the excitation combinations and the mode shapes. Energy conversion efficiency, defined as the ratio of the electric-field energy accumulated by the supercapacitors, over the total elastic strain energy change of the material during the oscillations is measured and compared. Design improvements are proposed for both transducer types to extract and absorb higher amounts of energy and improve their bandwidth to match the available excitation source characteristics.

Experimental comparative analysis of hybrid energy harvesters exposed to flow-induced vibrations

In this study, hybrid energy harvesting based on electromagnetic induction (EM) and piezoelectric transduction (PZT) is experimentally investigated under different conditions of flow-induced vibrations. The energy harvesting performance of the system is examined when the electromagnetic and piezoelectric mechanisms are used both separately and simultaneously. In this regard, firstly, only electromagnetic induction harvesting structure is attached to a beam, and time-dependent voltage and displacement are experimentally investigated. Then, PZT has adhered to the beam, and voltage outputs are measured in both the PZT and EM circuits. The third scenario is based on removing the electromagnetic harvesting structure and only the piezoelectric energy harvesting performance is studied. The mentioned cases are investigated under different excitation circumstances, that is, distinct bluff-body geometries and flow velocities. While the square bluff-body geometry is connected to the structure, both PZT and EM harvested power are determined by considering different electrical load resistances. It is mainly revealed that the total energy amount is higher in the hybrid configuration. After determining the hybrid structure is the most effective, elements with different splitters geometry are attached to the bluff-body geometry of the harvesting structure. Finally, the vibration enhancement potential of these new types of splitters on the harvesting structure is experimentally investigated. For the solo electromagnetic harvester, the maximum power is obtained at an external load resistance value of 10 kΩ, while for the solo PZT harvester, the maximum power is observed at the resistance value of 330 kΩ. Among the three types of splitter geometries examined, the highest voltage was obtained from type-1 as 14.168 V.

Energy Harvesting Performance of a Novel Nonlinear Quad-Stable Piezoelectric Energy Harvester with Only One External Magnet

Nonlinear multi-stable piezoelectric energy harvesters show broadband frequency spectra and excellent energy harvesting performance, owing to their high output power related to inter-well transitions. However, existing quad-stable piezoelectric energy harvesters contain too many structural parameters, which makes the systems clumsy, and increases the difficulties of dynamic analysis and structural optimization. Herein, a nonlinear quad-stable piezoelectric energy harvester, with only one external magnet, is proposed based on the magnetic force characteristics between a ring magnet and a rectangular magnet. Under selected structural parameters, as the magnet spacing increases, the stability characteristic of the harvester changes from quad-stability to bi-stability, and then to mono-stability. The transformation of the stability characteristic results from the changes in the variation rate of the vertical magnetic force. Subsequently, under the filtered Gaussian white noise within the frequency range of 0–120 Hz, the energy harvesting performance of the harvester is simulated by the classic fourth-order Runge-Kutta method. Simulation results show that the performance of the harvester under the quad-stable structural parameters is better than that under the bi-stable structural parameters, independent of whether the excitation acceleration is small or large. This result is related to the potential well characteristics under the quad-stable and bi-stable structural parameters. More specifically, the potential well depths under the quad-stable and bi-stable structural parameters are almost the same, but the distance between the two outer potential wells under the quad-stable structural parameters is larger than that under the bi-stable structural parameters. Finally, a fabricated prototype is used to measure the experimental performance of the harvester. The experimental data and the estimated data share the same trend. This study provides a new conception and technical method for the design, optimization, and application of quad-stable piezoelectric energy harvesters.

Vibration Characteristics and Experimental Research of Combined Beam Tri-Stable Piezoelectric Energy Harvester.

Vibration energy harvesting technology is expected to solve the power supply and endurance problems of wireless sensor systems, realize the self-power supply of wireless sensor systems in coal mines, and promote the intelligent development of coal mine equipment. A combined beam tri-stable piezoelectric energy harvester (CTPEH) is designed by introducing magnetic force into the combined beam structure. In order to explore the vibration characteristics of CTPEH, a nonlinear magnetic model is obtained based on the magnetic dipole theory, and the dynamic equation of the system is established using the Lagrange theorem and Rayleigh–Ritz theory. The influence of the different magnet distances and excitation conditions on the static bifurcation characteristics and dynamic response characteristics of the system are analyzed by numerical simulation, and the simulation results are validated by the experiments. The research results show that the motion state of the CTPEH system has four transition forms from mono-stable to tri-stable with the change in magnet distance. The tri-stable system has three potential energy curves with different characteristic shapes. The appropriate starting excitation position and excitation frequency can make it easier for the system to realize a large-amplitude response state, thereby improving the output performance of the system. This research provides new ideas and methods for optimizing the performance of the combined beam piezoelectric energy harvester.

Design and performance of flexible polymeric piezoelectric energy harvesters for battery-less tyre sensors

A piezoelectric energy harvester for battery-less tyre sensors has been developed. It consists of two key elements: (a) a piezoelectric material—polyvinylidene difluoride (PVDF) film and (b) an electrode—a conductive elastomer filled with carbon black and single-wall carbon nanotubes (SWCNTs). It was designed as a flexible patch in a sandwich-like configuration, which can be mounted onto the inner liner of a tyre. The patch was fabricated by inserting a PVDF film in between two conductive elastomer sheets. The development started with improving the conductivity of the elastomer by adding 6 wt% of SWCNT masterbatch. The adhesion between the interfaces was improved through surface modification of the PVDF film by introducing oxygen functional groups via a plasma treatment and further modification with a thiocyanate silane. The successful surface modification of the PVDF film was affirmed by x-ray photoelectron spectroscopy. T-peel and fatigue tests showed durable and stable adhesion between PVDF and conductive elastomer, confirming that the silane can effectively bridge the two components. A glueing method is proposed to adhere the patch to the tyre inner liner compound. The harvester is estimated to sufficiently power a reference tyre sensor, producing 28 μW cm−2.

Multi-interference local pressure modulation for improving performance of piezoelectric wind energy harvesters

Piezoelectric wind energy harvesters based on flow-induced vibration are attracting widespread attention because they can provide long-term sustainable power to wireless sensor network nodes. In order to improve the harvesting performance, this paper proposes a multi-interference local pressure modulation mechanism, and a three-plate multi-interference structure is applied for verification. Computational fluid simulations indicate that this three-plate multi-interference structure can effectively combine the double wake flow effect of the upstream double plates and the high-pressure feature in front of the downstream single plate. So that the local pressure of the fluid field can be effectively modulated to generate a significant lift force on the bluff body. Experiments show that this structure can promote the VIV(vortex-induced vibration)-based energy harvester to exhibit galloping vibration. Moreover, compared to the cases with only a single downstream plate or a double-plate upstream structure, lower cut-in wind speed and higher harvesting efficiency can be achieved by using the multi-interference structure. When the horizontal distance of the downstream plate, the horizontal and vertical offset distances of the upstream plates are set as 0.5D, 0.5D and 1.5D (D: windward width of the bluff body), respectively, the harvester can generate the highest output power of about 1.4 mW at a wind speed of 5 m/s. By introducing a spring–damper coupling mechanism, the synchronous movement of two side-by-side energy harvesters can be realized, thereby realizing the synchronous output of voltage and increasing the output power per unit volume.

Design and experiment of a low frequency non-contact rotary piezoelectric energy harvester excited by magnetic coupling

In this paper, a low frequency non-contact rotary piezoelectric energy harvester excited by magnetic coupling (L-PEH) was proposed. Through the coupling between the magnet inside the rotor driven by rotating motion and the magnet on the piezoelectric plate, the process of rotating motion transforming into electrical energy was realized. The purpose of this paper was to improve the output performance of piezoelectric energy harvester at low frequency by optimizing the magnetic field conditions, so the influence of the number of magnets and the arrangement of magnets on the output performance was studied in detail. A series of theories, simulations and experiments proved that the alternative magnet arrangement (mode 1) could optimize the output performance of the L-PEH. When the arrangement of magnets was mode 1 and the number of magnets was 2, the peak-to-peak voltage of rectangular and circular piezoelectric plates was 182.5 V and 4.4 V at 250r/min. Under the above optimal parameter variables, the L-PEH could generate the maximum output power of 140.45 mW. In addition, the output power generated by the prototype could fully meet the power consumption of low-power electronic equipment such as light-emitting-diodes (LEDs). In general, by changing the number and arrangement of magnets, i.e. optimizing the magnetic field conditions, L-PEH could effectively collect rotational energy and had a good application prospect in the power supply of micro electronic equipment.

Study of the Effect of the Segmentation Method on the Power Generation Performance of Rectangular Piezoelectric Energy Harvester

Since the piezoelectric energy harvester will generate strain zero point when it is bent, it will affect the power generation effect. In this paper, the strain zero point of the cantilever beam of the rectangular piezoelectric energy harvester is studied through theoretical analysis. The main analysis is the specific location of the strain zero point in the first-, second-, and third-order modes of the cantilever beam of the energy capturer. The results of the theoretical analysis are verified by experimenting with different segmentation methods of piezoelectric energy harvesters. The experimental results show that the piezoelectric energy harvester is segmented at 0.275 in the length direction of the piezoelectric ceramic in the second-order mode, and the output power is 5 times that of the nonsegmented state. In the third-order mode, the piezoelectric energy harvester is segmented at 0.16 and 0.61 in the length direction of the piezoelectric ceramic, and the output power is 5.83 times that of the nonsegmented state. The research in this paper provides new ideas and methods for improving the power generation capacity of piezoelectric energy harvesters.

Topology Optimization of Piezoelectric Energy Harvesters for Enhanced Open-Circuit Voltage Subjected to Harmonic Excitations.

Energy harvesting devices made of piezoelectric material are highly anticipated energy sources for power wireless sensors. Tremendous efforts have been made to improve the performance of piezoelectric energy harvesters (PEHs). Noticeably, topology optimization has shown an attractive potential to design PEHs with enhanced energy conversion efficiency. In this work, an alternative yet more practical design objective was considered, where the open-circuit voltage of PEHs is enhanced by topologically optimizing the through-thickness piezoelectric material distribution of plate-type PEHs subjected to harmonic excitations. Compared to the conventional efficiency-enhanced designs, the open-circuit voltage of PEHs can be evidently enhanced by the proposed method while with negligible sacrifice on the energy conversion efficiency. Numerical investigations show that the voltage cancellation effect due to inconsistent voltage phases can be effectively ameliorated by optimally distributed piezoelectric materials.

L-shape triple defects in a phononic crystal for broadband piezoelectric energy harvesting

This study proposes a phononic crystal (PnC) with triple defects in an L-shape arrangement for broadband piezoelectric energy harvesting (PEH). The incorporation of defects in PnCs has attracted significant attention in PEH fields owing to properties such as energy localization and amplification near the defect. Several studies have been conducted to enhance output electric power of PnC-based PEH systems with single defects. However, it is susceptible to the limitations of narrow bandwidth. Recently, double-defect-incorporated systems have been proposed to widen the PEH bandwidth via defect-band splitting. Nevertheless, the PEH performance rapidly decreases in the frequency range between the split defect bands. The limitations of single- and double-defect-incorporated systems can be resolved by the incorporation of the proposed design concept, called the L-shape triple defects in a PnC. The isolated single defect at the top vertex of the letter ‘L’ compensates for the limitations of double-defect-incorporated systems, whereas the double defects at the bottom vertices compensate for the limitations of the single-defect-incorporated systems. Hence, the proposed design can effectively confine and harvest elastic-wave energy over broadband frequencies while enhancing the application of single and double defects. The effectiveness of the proposed design concept is numerically validated using the finite element method. In the case of a circular hole-type PnC, it is verified that the PnC with L-shape triple defects broadens the bandwidth, and improves the output voltage and electric power compared with those of single- and double-defect-incorporated systems. This study expands the design space of defect-incorporated PnCs and might shed light on other engineering applications of the frequency detector and elastic wave power transfer.

Novel piezoelectric wind energy harvester based on coupled galloping phenomena with characterization and quantification of its dynamic behavior

In this study, a novel piezoelectric energy harvester is proposed based on coupled transverse and interference galloping to improve the energetic performance of the conventional transverse galloping-based piezoelectric energy harvester. To quantify the stochastic characteristics of the aerodynamic force under the coupled galloping effects, we developed a special approach that allowed us to successfully characterize the aerodynamic force obtained under a transient state and develop a set of coupled dynamic model system. An extensive investigation on the energetic state of the proposed system and its nonlinear behavior revealed the existence of an additional nonlinear damping mechanism. In particular, the associated nonlinear damping force was identified based on the energetic consideration of the proposed system. To the best knowledge of the authors, such a characterization process has not yet been reported. In addition, the dynamic model system was systematically designed by performing an eigen-analysis using the vector operator approach. Furthermore, a perturbation procedure was conducted to obtain the nonlinear limit-cycle behavior of the proposed system. The comparative analysis of the theoretical values derived using the proposed model system with those obtained from experiments revealed that they were consistent with each other, which validated the accuracy of the current modeling approach. When compared to the average electric power harvested from the conventional (transverse) galloping-based piezoelectric energy harvester, the proposed energy harvester generated 20 times more electric power.

Nanoampere‐Level Piezoelectric Energy Harvesting Performance of Lithography‐Free Centimeter‐Scale MoS2 Monolayer Film Generators (Small 24/2022)

Energy Harvesting In article number 2200184, Yong Soo Cho and co-workers successfully apply an interdigitated electrode for a centimeter-scale monolayer MoS2 film having preferred domain structure, without a complicated etching or e-beam lithography process. The fabricated device exhibits superior piezoelectric energy harvesting performance with 400.4 mV and 40.7 nA.

Investigation of boundary flexibility on the performance of piezoelectric vibration energy harvesting beam systems by DTFM

The purpose of this paper is to investigate the effect of boundary flexibility on the performance of piezoelectric vibration energy harvester (PVEH) beam systems, which has not been studied comprehensively in the literature despite its importance. The coupled electromechanical equations of motion of a piezoelectric cantilever beam with a tip mass are established, with the base boundary constrained by translational and rotational springs. An exact closed-form solution of the frequency response function (FRF) of the PVEH is obtained by the distributed transfer function method (DTFM). The DTFM is a systematic powerful tool for the dynamic analysis of distributed parameter continua with non-classical boundary conditions, intermediate constraints, coupled fields, and non-proportional damping without adding much complexity to the solution formulation. Moreover, the DTFM computes the derivatives of the response, that is, the strains, which are required in the electromechanical coupling formulation, simultaneously without any differentiation. Numerical results showing the effects of boundary flexibility on energy harvesting efficiency are presented. A first-order rational function relating the boundary stiffness parameters and the harvesting efficiency is determined by nonlinear curve fitting of the calculated data. Physical insights and applicability of this analytical function for end-of-line quality check of the boundary of PVEH are discussed.

Wake galloping energy harvesting in heat exchange systems under the influence of ash deposition

Since the fluid flows in heat exchange systems contain hydrokinetic energies, flow-induced vibration (FIV) energy harvesting technology can be potentially applied to collect electrical energy. Different from the applications in traditional scenarios, cylinder bluff bodies implemented in the heat exchange systems will inevitably suffer from ash deposition. This study proposes a wake galloping energy harvester to be used in heat exchange systems and focuses on investigating the effects of different ash deposition types on the energy harvesting performance. According to different ash deposition types, bell-shaped and horn-shaped cylinder bluff bodies are designed to consider the ash deposition effect. Wind tunnel experiments are conducted to investigate the performance of the wake galloping piezoelectric energy harvester (PEH) with different upstream ash deposit cylinders, at various space distances and under different wind speeds. The experimental results reveal that compared to the horn-shaped cylinder, the bell-shaped cylinder is more beneficial for energy harvesting. Among all tested cases, the optimal configuration is determined: the upstream cylinder is attached by bell-shaped ash deposition; and the space ratio between the upstream and the downstream cylinders is 1.5. The threshold wind speed of the optimal configuration is reduced and the maximum voltage output is improved by over 111%. It is learned that the two types of upstream ash deposit cylinders can both cause the quenching phenomenon to deteriorate the performance of the energy harvester. Guidelines based on the experimental results are provided to avoid the occurrence of the quenching phenomenon. Computational fluid dynamics (CFD) studies are conducted to reveal the underlying mechanisms to explain the experimental results. The CFD results corroborate that different ash deposit cylinders produce different wake vortices and the flow pattern changes with the space distance, which determines the dynamic response of the downstream cylinder.

Nanoampere‐Level Piezoelectric Energy Harvesting Performance of Lithography‐Free Centimeter‐Scale MoS2 Monolayer Film Generators

2D transition-metal dichalcogenides have been reported to possess piezoelectricity due to their lack of inversion symmetry; thus, they are potentially applicable as electromechanical energy harvesters. Herein, the authors propose a lithography-free piezoelectric energy harvester composed of centimeter-scale MoS2 monolayer films with an interdigitated electrode pattern that is enabled only by the large scale of the film. High-quality large-scale synthesis of the monolayer films is conducted by low-pressure chemical vapor deposition with the assistance of an unprecedented Na2 S promoter. The extra sulfur supplied by Na2 S critically passivates the sulfur vacancies. The energy harvester having a large active area of ≈18.3mm2 demonstrates an unexpectedly high piezoelectric energy harvesting performance of ≈400.4mV and ≈40.7nA under a bending strain of 0.57%, with the careful adjustment of side electrodes along the zigzag atomic arrays in the two dominant domain structure. Nanoampere-level harvesting has not yet been reported with any 2D material-based harvester.

The effect of fabric properties on the performance of a textile based ferroelectret generator toward human body energy harvesting

This paper reports the lamination of two thin fluorinated ethylene propylene (FEP) films onto the back and front surfaces of a conventional textile forming a sandwich structure which creates a textile-based ferroelectret. In this work, we study the effect of the physical properties and dimensions of the textile on the piezoelectric properties and energy harvesting performance of the ferroelectret. Five different fabrics with different thicknesses and Young’s modulus were used to form textile based ferroelectret harvesters. Thinner textiles result in increased piezoelectric properties of the fabricated FEP textile ferroelectret. The highest measured stable maximum piezoelectric coefficient d33 of 987 pC N−1 was achieved by the thinnest silk textile FEP ferroelectret. The energy harvester based on the FEP-silk textile ferroelectret generates a peak output power density of 2.26 µW cm−2. The textile ferroelectret can charge a 10 µF capacitor used to store the harvested energy to 3.2 V in 40 s. This corresponds to an average output power of 1.07 µW when subjected to compressive pressures of 30 kPa applied at a frequency of 1 Hz with a 90 MΩ loading resistance.

Use of half-cylinder obstacle for enhancing aeroelastic energy harvesting

ABSTRACT This study aims to improve the performance of the galloping-based piezoelectric energy harvester (GPEH) by benefiting from two half-cylinder obstacles. Two half-cylinder obstacles are employed to construct a variable cross-section tube which changes the airflow characteristics near the GPEH placed inside. The performance of the GPEH in the variable cross-section tube is tested by wind tunnel experiments. The experimental results demonstrate that compared with the traditional GPEH, the cut-in speed of the GPEH with the two half-cylinder obstacles at the downstream position −1.5D is reduced by 43.87%, from 2.23 m/s to 1.55 m/s. For the highest experimental wind speed of 4.29 m/s, the output voltage of the GPEH with the two half-cylinder obstacles is increased by 109.28%, from 4.31 V to 9.02 V. Moreover, the performance of the GPEH with the obstacles can be improved by appropriately increasing the obstacle curvature and reducing the throat width. The computational fluid dynamics (CFD) simulations are conducted to qualitatively interpret the experimental discoveries. The results demonstrated that the downstream area is beneficial to the GPEH, whereas the upstream area degrades the performance.

Evaluation of the pore morphologies for piezoelectric energy harvesting application

Piezoelectric energy harvesting has attracted significant attention in recent years due to their high-power density and potential applications for self-powered sensor networks. In comparison to dense piezoelectric ceramics, porous piezoelectric ceramics exhibit superiority due to an enhancement of piezoelectric energy harvesting figure of merit. This paper provides a detailed examination of the effect of pore morphology on the piezoelectric energy harvesting performance of porous barium calcium zirconate titanate 0.5Ba(Zr 0.2 Ti 0.8 )O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 (BCZT) ceramics. Three different pore morphologies of spherical, elliptical, and aligned lamellar pores were created via the burnt-out polymer spheres method and freeze casting. The relative permittivity decreased with increasing porosity volume fraction for all porous BCZT ceramics. Both experimental and simulation results demonstrate that porous BCZT ceramics with aligned lamellar pores exhibit a higher remanent polarization. The longitudinal d 33 piezoelectric charge coefficient decreased with increasing porosity volume fraction for the porous ceramics with three different pore morphologies; however, the rate of decrease in d 33 with porosity is slower for aligned lamellar pores, leading to the highest piezoelectric energy harvesting figure of merit. Moreover, the peak power density of porous BCZT ceramics with aligned lamellar pores is shown to reach up to 38 μW cm -2 when used as an energy harvester, which is significantly higher than that of porous BCZT ceramics with spherical or elliptical pores. This work is beneficial for the design and manufacture of porous ferroelectric materials in devices for piezoelectric energy harvesting applications.

Structure Optimization and Performance of Piezoelectric Energy Harvester for Improving Road Power Generation Effect

Structure Optimization and Performance of Piezoelectric Energy Harvester for Improving Road Power Generation Effect