Broadband Piezoelectric Energy Harvester Research Articles

A broadband and multiband magnetism-plucked rotary piezoelectric energy harvester

This study introduces a broadband and multiband piezoelectric energy harvester characterized by an E-shaped structure based on the rotational magnetic excitation. The piezoelectric oscillator is comprised of a trio of piezoelectric beams, which is like the letter 'E'. To elucidate the harvester's performance, this work employs both finite element analysis and experimental methods to explore the effects of pivotal parameters. Length ratio (Lr) and mass ratio (Mr) can influence the first two modes of vibration of the E-shaped oscillator. Lr = 1.0 and Mr = 3.0 are the critical points for mode transition of the E-shaped oscillator. Changing the added mass can reduce the gap between the resonance speed regions of the inner and outer beams, thus achieving the purpose of broadband. When piezoelectric patches are arranged in a "品" shape on the inner and outer beams, the total output power of a single oscillator can reach 5.33 mW, with the inner and outer beams contributing 4.01 mW and 1.32 mW respectively. Besides, when rotating magnets are two, a single piezoelectric oscillator can have 9 effective working regions. These can enhance the efficacy of energy harvesters, particularly in the realm of autonomous and self-powered systems.

Optimized multi-frequency nonlinear broadband piezoelectric energy harvester designs

Many electrical devices can be powered and operated by harvesting the wasted energy of the surroundings. This research aims to overcome the challenges of output power with a sharp peak, small bandwidth, and the huge dimensions of the piezoelectric energy harvesters relative to the output power. The aforementioned challenges motivated us to investigate the effect of nonlinearity in the shape (tapered and straight cross-section area) as well as the fixation method (the number of fastened ends) to determine the optimal design with high output power and wide working frequency. This research proposes a novel piezoelectric energy harvester array, where each beam is made up of three fixed beams that are joined together by a center mass. The proposed design produces an output power of 35 mW between 25 and 40 Hz. The output power of the proposed design is 3.24 times more than the conventional designs. The recommended approach is simulated utilizing finite element analysis FEA. Analytical and experimental methods validate the proposed FEA, which exhibits excellent agreement.

Electro-Mechanical Characterization and Modeling of a Broadband Piezoelectric Microgenerator Based on Lithium Niobate.

Vibration energy harvesting based on piezoelectric transducers is an attractive choice to replace single-use batteries in powering Wireless Sensor Nodes (WSNs). As of today, their widespread application is hindered due to low operational bandwidth and the conventional use of lead-based materials. The Restriction of Hazardous Substances legislation (RoHS) implemented in the European Union restricts the use of lead-based piezoelectric materials in future electronic devices. This paper investigates lithium niobate (LiNbO3) as a lead-free material for a high-performance broadband Piezoelectric Energy Harvester (PEH). A single-clamped, cantilever beam-based piezoelectric microgenerator with a mechanical footprint of 1 cm2, working at a low resonant frequency of 200 Hz, with a high piezoelectric coupling coefficient and broad bandwidth, was designed and microfabricated, and its performance was evaluated. The PEH device, with an acceleration of 1 g delivers a maximum output RMS power of nearly 35 μW/cm2 and a peak voltage of 6 V for an optimal load resistance at resonance. Thanks to a high squared piezoelectric electro-mechanical coupling coefficient (k2), the device offers a broadband operating frequency range above 10% of the central frequency. The Mason electro-mechanical equivalent circuit was derived, and a SPICE model of the device was compared with experimental results. Finally, the output voltage of the harvester was rectified to provide a DC output stored on a capacitor, and it was regulated and used to power an IoT node at an acceleration of as low as 0.5 g.

Research on piezoelectric vibration energy harvester for cutting part of roadheader

At present, coal mine tunneling technology is developing in the direction of intelligence and unmanned. The piezoelectric vibration energy harvester can convert the vibration energy generated by the cutting part of roadheader into electrical energy and realize the energy self-sufficiency of the low-power wireless sensor. In practical applications, the vibration frequency of the cutting part of roadheader is different, and the working condition is complex, resulting in the energy recovery efficiency of the vibration energy harvester is not ideal. In order to improve its adaptability and reliability, a separated excitation broadband piezoelectric vibration energy harvester is proposed in this paper.

Double defects in trampoline effect and Helmholtz coupled acoustic metamaterial for broadband piezoelectric energy harvesting

An acoustic metamaterial with double defects is proposed to widen bandwidth and improve energy collection. Defects can limit elastic waves to achieve energy localization. The introduction of defects in acoustical supermaterials can improve energy localization and amplify the effect, but single defects are easily limited by narrow bandwidth. Therefore, the bandwidth is broadened by adding double defects to the acoustic supermaterial. At the same time, the existence of double defect can influence the coupling effect of each other to a certain extent, which is helpful to the improvement of energy recovery. In order to further enhance the local resonance at the defect location, the trampoline effect and Helmholtz resonator are used to further enhance the energy recovery. Using finite element method (FEM) simulations, the comparison results show the double defect enhances energy recovery and broadens bandwidth of energy collection compared with single defect, and the maximum voltage output is about 0.86V under the effective sound pressure of 100dB.

On exploiting the transition of nonlinear characteristics of a broadband piezoelectric energy harvester for tuning it to low and high-frequency applications

In this work, the applicability of nonlinear piezoelectric energy harvesters is demonstrated for high and low-frequency applications. An axially loaded piezoelectric patched beam model is derived considering in-plane stretching. The harvester setup is developed in the laboratory, and the energy-based numerical model is validated with experimental results. Optimum dimensions of the harvester are obtained. The broadband nature of the harvester is explored, considering nonlinear effects and axial loads on the harvester’s performance. The applicability of the proposed harvester is demonstrated meaningfully by exploiting bifurcation between hardening and softening types of non-linearity by adjusting axial loads with the help of a simple tunable harvester setup.

Hybrid magnetic coupling and impact enhanced low, adjustable and broadband piezoelectric vibration energy harvesting

Hybrid magnetic coupling and impact enhanced low, adjustable and broadband piezoelectric vibration energy harvesting

Design of multi-step zig-zag shaped piezoelectric energy harvesters for powering fetal heart rate monitoring system

The non-linear behavior of a broadband piezoelectric energy harvester with various configurations (single-layer, multi-layer and multi-step) in multimode operation is designed for powering fetal-heart rate monitoring medical device. In this research work the harvester has a zig-zag uniform structure with a dual-hold composition and three proof masses that improves the harvester’s operational bandwidth. The goal of this study is to find the maximum power generated from the harvester with lowest frequency and large bandwidth for enhancing the effectiveness of the device. The Multi-step energy harvester has proved to be more effective in comparison to single-layer and multi-layer harvesters, respectively.

A Novel Bird-Shape Broadband Piezoelectric Energy Harvester for Low Frequency Vibrations

This work presents a novel bird-shaped broadband piezoelectric energy harvester based on a two-DOF crossed beam for low-frequency environmental vibrations. The harvester features a cantilever mounted on a double-hinged beam, whose rotating motions effectively diminish its natural frequencies. Numerical simulation based on the finite element method is conducted to analyze the modal shapes and the harmonic response of the proposed harvester. Prototypes are fabricated and experiments are carried out by a testing system, whose results indicate a good agreement with the simulation. The multi-frequency energy harvesting is achieved at the first-, second-, and fifth-order resonances. In particular, the proposed harvester demonstrates the remarkable output characteristics of 9.53 mW and 1.83 mW at frequencies as low as 19.23 HZ and 45.38 Hz, which are superior to the majority of existing energy harvesters. Besides, the influences of key parameters on the harvesting performance are experimentally investigated to optimize the environmental adaptability of the harvester. This work provides a new perspective for efficiently harvesting the low-frequency vibration energy, which can be utilized for supplying power to electronic devices.

Multi-Objective Topology Optimization of a Broadband Piezoelectric Energy Harvester.

In recent years, topology optimization has proved itself to be state of the art in the design of mechanical structures. At the same time, energy harvesting has gained a lot of attention in research and industry. In this work, we present a novel topology optimization of a multi-resonant piezoelectric energy-harvester device. The goal is to develop a broadband design that can generate constant power output over a range of frequencies, thus enabling reliable operation under changing environmental conditions. To achieve this goal, topology optimization is implemented with a combined-objective function, which tackles both the frequency requirement and the power-output characteristic. The optimization suggests a promising design, with satisfactory frequency characteristics.

Mechanical Rectifier for Broadband Piezoelectric Vibration Energy Harvesting and Self-Adapting Synchronous Electric Charge Extraction

The synchronized switch interface circuit is believed to boost the piezoelectric power generation. The threshold voltage of electronic components causes rectification loss and delay of peak detection. This work reports a novel design of a mechanical rectification piezoelectric vibration energy harvester (MR-PVEH). Compact and low loss mechanical rectification is achieved by double switch with 5 electrodes contact at the cantilever tip. The switch as a mechanical stopper also contributes to broadband performance. The saturation voltage and response frequency range can be adjusted in modeling and simulation of nonlinear electromechanical coupling vibration. Self-adapting Mechanical rectification optimized synchronous electric charge extraction (M-OSECE) circuit is also proposed with less electronic components in this paper and shows an extra 60% increase in generated power than the traditional standard energy harvesting circuit (SEH) in test. This novel design gives a promising solution for self-adapting synchronous switching in broadband piezoelectric vibration energy harvesting.

Broadband Piezoelectric Energy Harvester Based on Coupling Resonance Frequency Tuning.

The bandwidth of piezoelectric energy harvesters (PEHs) can be broadened by resonance-based frequency tuning approaches, including mechanical tuning and electrical tuning. In this work, a new coupling tuning mechanism for regulating the near-open-circuit resonance frequency by changing the effective electrode coverage (EEC) is presented. A linear model of a bimorph piezoelectric cantilever with segmented electrodes is used to evaluate the power harvesting behavior near the open-circuit resonance frequency when EEC changes from 0 to 100%. According to the theoretical analysis, it is found that the variation of EEC brings about the change in coupling strength, which is positively associated with the near-open-circuit resonance frequency of PEH. Two cantilever PEHs with segmented electrodes based on PZT and PZT-PT are constructed for validation of the coupling tuning mechanism. The analytical and experimental results illustrate remarkable improvements in both bandwidth and average power through the coupling resonance frequency tuning method. In addition, adopting extraordinary piezoelectric single crystals and optimizing the proof mass and piezoelectric layer dimensions were theoretically shown to be effective methods for further improvement of bandwidth.

Design and Development of a Broadband Vibration Energy Harvester Suitable for Tractor Exhaust Cylinder Vibration

A large amount of vibration energy exists in the working environment of tractors. Therefore, the use of vibration energy harvesting technology to convert the vibration energy into electrical energy is a feasible way to supply power to low-power sensor equipment in agricultural machinery. Aiming at the problem in which the internal sensors of traditional tractors require built-in batteries or overlapping cables, this work proposes a broadband piezoelectric vibration energy harvester that could harvest the vibration energy from the tractor exhaust cylinder when the tractor is working. The vibration energy can be converted into electrical energy to power the air pressure sensor device. This experimental investigation shows that the energy harvester is composed of a folded piezoelectric energy harvester and a multi-source input synchronous electronic charge extraction circuit.The circuit has a high power density of 12,398 μW/(mm3·g2). Hence, it can convert vibration energy into a wide frequency range between 90-140 Hz and cause the air pressure sensor to operate.

On a nonlinear broadband piezoelectric energy harvester with a coupled beam array

A conventional energy harvester usually has narrow operational bandwidth, which makes it difficult to harvest energy with varying frequencies in the actual field. Herein, a nonlinear piezoelectric energy harvester with a coupled beam array is designed to broaden bandwidth and improve energy harvesting performance. The proposed harvester consists of a base, two elastic supports, and four piezoelectric beams with different natural frequencies. Due to the coupling effect caused by the two elastic supports, the four piezoelectric beams have large output voltages not only at their own natural frequencies, but also at the natural frequencies of other beams. Meanwhile, the two elastic supports enable the four piezoelectric beams to become nonlinear beams, which also contributes to operational bandwidth broadening. Next, the equivalent mass-spring-damping model and governing equations of the harvester are obtained, based on the lumped-parameter method. A strong coupling is found to occur when the equivalent stiffness of the elastic support is small. Subsequently, a fabricated prototype and an experiment platform are utilized to measure the energy harvesting performance of the harvester. Under 1 g up-sweep excitation, the average output power of the harvester from 40 Hz to 80 Hz is 144.2 % higher and the bandwidth is 93.3 % wider than those of the non-coupled multi-resonance harvester, which houses four beams separately. Finally, actual applicability of the proposed energy harvester is evaluated by operating a Bluetooth location tracking Internet of Things (IoT) device without a battery. Besides, the fabricated prototype is applied to the vehicle engine where the frequencies of vibration sources change rapidly with time and velocity. The field test argues that the harvester can be used in unstable or varying conditions, where a typical vibration energy harvester may not work efficiently, due to its limited operational bandwidth.

Soybean-inspired nanomaterial-based broadband piezoelectric energy harvester with local bistability

Bistable nonlinear energy harvesters are effective structures for scavenging broadband energy from frequency-varying vibration sources. The bistable characteristic of such structures is typically induced by introducing magnetic fields, prestress, and nonuniform geometries or fixtures. However, the complicated structures or single deformation modes of these structures limit their practical application. Inspired by the structure of soybean pods, a bionic metallic nanomaterial-based bistable piezoelectric energy harvester is developed in this study. The nanoplate substrate with a local bistable region mimics the configuration of a soybean pod. To the best of the authors’ knowledge, the local bistable configuration represents a novel energy harvesting strategy. The local bistable nanoplate is fabricated using a mature surface mechanical attrition treatment technique that generates a gradient nanostructure to enhance the mechanical properties of the bistable structure. The energy harvesting performance and nonlinear dynamic characteristics of the energy harvester are evaluated through frequency-sweep and fixed-frequency vibration tests and numerical simulations with a new two-step finite element (FE) model. The harvester characteristics in three vibration modes (single-well vibration (SV), intermittent cross-well vibration (ICV), and continuous cross-well vibration (CCV)) are discussed. The experimental and numerical results demonstrate that the voltage output and working bandwidth of the proposed harvester increase by five times in the ICV and CCV modes when the excitation acceleration increases from 0.5 g to 3.0 g. The bionic nanomaterial-based bistable piezoelectric energy harvester can be potentially used in various applications such as vehicle suspension systems, tires, and vehicle-bridge systems.

A graded metamaterial for broadband and high-capability piezoelectric energy harvesting

This work proposes a graded metamaterial-based energy harvester integrating the piezoelectric energy harvesting function targeting low-frequency ambient vibrations (<100 Hz). The harvester combines a graded metamaterial with beam-like resonators, piezoelectric patches, and a self-powered interface circuit for broadband and high-capability energy harvesting. Firstly, an integrated lumped parameter model is derived from both the mechanical and the electrical sides to determine the power performance of the proposed design. Secondly, thorough numerical simulations are carried out to optimize both the grading profile and wave field amplification, as well as to highlight the effects of spatial-frequency separation and the slow-wave phenomenon on energy harvesting performance and efficiency. Finally, experiments with realistic vibration sources validate the theoretical and numerical results from the mechanical and electrical sides. Particularly, the harvested power of the proposed design yields a five-fold increase with respect to conventional harvesting solutions based on single cantilever harvesters. Our results reveal that by bridging the advantages of graded metamaterials with the design targets of piezoelectric energy harvesting, the proposed design shows significant potential for realizing self-powered Internet of Things devices.

An innovative piezoelectric energy harvester inspired by a line tooth: design, dynamic model and broadband harvesting conditions

Piezoelectric energy harvesting is commonly considered to be a promising field of development for microelectronic devices due to its potential to address a variety of key supply problems. However, due to their geometric designs, traditional piezoelectric energy harvesters (PEHs) tend to only be able to cultivate energy from vibrations flowing in one direction. The results of PEHs only capable of harvesting mono-directional vibrations are that they suffer from narrow resonance frequency bands and low energy conversion efficiency. To overcome these difficulties, this paper proposes a PEH inspired by a line tooth (PEH-ILT) with the ability to collect three-dimensional stochastic vibrations. To do so, the PEH-ILT possesses a nonlinear geometric shape which can, in theory, be designed arbitrarily. An example PEH-ILT is illustrated in this paper as well corresponding nonlinear piezoelectric constitutive equations. The cylindrical spiral curve is inspired by the line tooth design and is intended to replicate a nonlinear electro-mechanical model and its electrical output. Furthermore, the PEH-ILT is evaluated in this study by interacting with the four basic vibrations such devices are expected to encounter. In addition, the broadband piezoelectric energy harvesting conditions of the PEH-ILT are parsed and determined through the Melnikov theory, providing a theoretical explanation to the broadband conditions of the harvester. And this study can lay the theoretical basis for practical applications.

A piezoelectric energy harvester for freight train condition monitoring system with the hybrid nonlinear mechanism

To improve operational safety and system reliability, real-time wireless health monitoring systems are necessary for freight trains. However, due to the lack of onboard power and space restrictions, monitoring sensors rely on batteries as power sources, which are not eco-friendly and involve high maintenance costs for battery replacement. Therefore, developing self-powered maintenance-free wireless monitoring sensors integrated with energy harvesting is in urgent demand. Here, we propose a compact ultralow-frequency and broadband piezoelectric energy harvester (UBPEH) that can be easily installed in the limited space of the axle box to effectively harvest bogie lateral vibrations. The T-shaped UBPEH employs magnetic interaction to soften the stiffness and strengthen the stopper operation in a low-frequency range. To predict and optimize the prototype, we establish the model of UBPEH by considering the displacement, inclination angle, and shape of the magnets. Theoretical and experimental results show that the prototyped UBPEH might operate in the range of 1–11 Hz, covering the representative frequencies of bogie vibrations on freight trains. An output power of 605 μW on a matched resistance of 200 kΩ under the acceleration of 11 Hz and 0.5 g (g = 9.8 m s−2) is achieved, and the harvested electric power can successfully drive typical commercial wireless Bluetooth sensors. Furthermore, the harvester possesses output stability and mechanical durability under actual service hours of freight trains. The results of this work pave the way to implement self-powered wireless condition monitoring on freight trains.

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.

Low-Frequency Broadband Piezoelectric Vibration Energy Harvester Based on Double L-shaped Beam Structures

Low-Frequency Broadband Piezoelectric Vibration Energy Harvester Based on Double L-shaped Beam Structures