Broadband Energy Harvesting Research Articles

Broadband energy harvesting by exploiting nonlinear oscillations around the second vibration mode of a rectangular piezoelectric bistable laminate

Recently bistable composite laminates have been investigated for broadband energy harvesting, by taking advantage of their nonlinear oscillations around the first vibration mode. However, it has been reported that the excitation acceleration needed for the desired large amplitude limit cycle oscillation is too high, if the first vibration mode is elevated to relative higher frequencies (60 Hz e.g.). This study investigates the feasibility of exploiting the nonlinear oscillations around the second vibration mode of a rectangular piezoelectric bistable laminate (RPBL), for broadband vibration energy harvesting at relative higher frequencies, but with relative low excitation acceleration. The proposed RPBL has three oscillation patterns around the second vibration mode, including single-well oscillation, chaotic intermittency oscillation and limit cycle oscillation. The broadband characteristics and the considerable energy conversion efficiency of the RPBL are demonstrated in experiments. The static nonlinearity and the dynamic responses of the RPBL are investigated by finite element method. Finite element analysis (FEA) reveals that the enhanced dynamic responses of the RPBL are due to its softening bending stiffness and the local snap through phenomenon. The FEA results coincide reasonably well with experimental results.

Numerical Investigations into the Effects of Multiple Parameters on Nonlinear Piezoelectric Vibration Energy Harvesters

It is very promising to improve the performance of piezoelectric vibration energy harvesters (PVEHs) using nonlinearities in energy harvesting applications. However it is almost impossible to analytically obtain their nonlinear dynamic behaviors. The goal of this paper is to investigate the relations among power outputs, vibration characteristics, and systematic nonlinearities by numerical analysis. A mathematical model of nonlinear PVEH is built by combining nonlinear damping, stiffness, and piezoelectric coupling coefficient. An iterative algorithm is proposed to solve the nonlinear model. Then the effects of these nonlinear parameters on the performance of the PVEH are studied deeply. The results demonstrate that the power output of a nonlinear PVEH will be overestimated or subestimated using a linear model. And nonlinearities can be used for broadband and low frequency vibration energy harvesting.

Development of a Broadband Triboelectric Energy Harvester With SU-8 Micropillars

This paper describes a broadband energy harvester working on the principle of contact electrification or triboelectric charging. Design and fabrication of the device have been discussed. The device uses contact and separation mechanism using a cantilever to generate triboelectric charges. This mechanism introduces nonlinearity in the cantilever, which results in broadband behavior of triboelectric energy harvester. The device uses SU-8 micropillar arrays to enhance the triboelectric charging. A study is conducted to study the effect of the micropillar sizes on the power output of devices. The devices were tested at different acceleration levels. The peak power output achieved is 0.91 μW at an acceleration of 1g. The amplitude limiter based design of the energy harvester enables broadening of operating bandwidth as the acceleration level increases. A maximum operating bandwidth of 22.05 Hz was observed at 1.4g increasing from an operating bandwidth of 9.43 Hz at 0.4g.

Broadband energy harvesting from coherence resonance of a piezoelectric bistable system and its experimental validation

Piezoelectric effect is an effective way of harvesting energy from the environmental broadband vibration. In this paper, we investigate the coherence resonance of a piezoelectric bistable vibration energy harvester theoretically and experimentally. The device is comprised of a cantilever beam with magnetic repulsive force. Firstly, the electromechanical coupled equation is derived based on the Euler-Bernoulli beam theory. Then, analyzing the potential shapes, we learn that when the system oscillates between the two potential wells, it will produce a large voltage generally. And the beam dynamic response under the random excitation is simulated by Euler-Maruyama method. The results of simulations and experiments show that there is a coherence resonance threshold in the Duffing type piezoelectric bistable energy harvester. When the standard deviation of the random excitation is less than the threshold, the motion state of the system will be trapped in a single potential well, which results in a low average output power. And when the excitation standard deviation is larger than the threshold, the system stochastic stability will change. The dynamic displacement and strain clearly show that the system can exhibit large oscillation between the two potential wells. Then, Kramers rate is used to explain the coherence resonance threshold of the bistable system under the broadband random excitation. The experimental results show that when the coherence resonance takes place, the beam will oscillate between the two potential wells more frequently, and the broadband vibration energy can be transformed into large amplitude narrow band low-frequency oscillation response, which can greatly improve the harvesting effectiveness of broadband vibration energy.

A multi-layered polydimethylsiloxane structure for application in low-excitation, broadband and low frequency energy harvesting

Vibrational kinetic energy is a promising energy source that can be harvested due to its abundance in daily life, especially from human motion. This low frequency vibration poses a challenge in achieving a small device that is practical and wearable. Further, the effective energy harvesting of a linear structure is very limited to a narrow range of frequencies around the resonance. These two limitations call for the development of wide bandwidth energy harvesters that can work at a wider low frequency range. Using low Young's modulus material is a common technique to achieve a low resonant frequency energy harvester. Nonlinear bistability is a potential solution for bandwidth broadening. In this paper, a broadband low frequency vibrational energy harvester using multi-layered soft polydimethylsiloxane (PDMS) will be presented. First, a multi-layered PDMS structure was created by sandwiching a thicker PDMS with two thinner pre-stressed PDMS films. After releasing the prestresses, the multi-layered PDMS structure can settle into two cylindrical configurations. An analytical model that can predict the shapes of this multi-layered structure has been developed using classical lamination theory along with Rayleigh–Ritz approximation technique. Through this model, PDMS shapes can be easily predicted by changing various parameters such as the ratio of side length to thickness, prestrain levels, and Young's modulus. A multi-layered PDMS structure has been further proposed to be used as a bistable energy harvester. The soft PDMS allows working frequencies of lower than 15Hz. The dynamic response of this harvester under small input excitation shows a softening spring system, before the strong nonlinear ‘snap through’ effect occurs. This softening spring system is able to broaden the bandwidth of the energy harvesting device.

Energy harvester array using piezoelectric circular diaphragm for rail vibration

Generating electric energy from mechanical vibration using a piezoelectric circular membrane array is presented in this paper. The electrical characteristics of the functional array consisted of three plates with varies tip masses are examined under dynamic conditions. With an optimal load resistor of 11 kΩ, an output power of 21.4 mW was generated from the array in parallel connection at 150 Hz under a pre-stress of 0.8 N and a vibration acceleration of 9.8 m/s2. Moreover, the broadband energy harvesting using this array still can be realized with different tip masses. Three obvious output power peaks can be obtained in a frequency spectra of 110 Hz to 260 Hz. The results show that using a piezoelectric circular diaphragm array can increase significantly the output of energy compared with the use of a single plate. And by optimizing combination of tip masses with piezoelectric elements in array, the frequency range can be tuned to meet the broadband vibration. This array may possibly be exploited to design the energy harvesting for practical applications such as future high speed rail.

Enhanced Multipeak Magnetoelectric Effects in Ferromagnetic/Ferroelectric Composite With H-Shaped Elastic Substrate

A magnetoelectric (ME) composite consisting of FeCuNbSiB foils, Terfenol-D plates, piezoelectric PZT plates, and an H-shaped elastic substrate has been developed. The H-shaped elastic substrate severs as the multipeak frequency determining element. Due to the coupling between the H-shaped elastic substrate beams, an enhancement in the multipeak ME effect can be obtained compared with the conventional composite using a rectangle elastic substrate. The ME coefficient of the composite with two PZT plates electrically connected in series reaches 58.2 V/cm·Oe, which is ~4 times higher than that of the ME composite with the rectangle structure. The multipeak ME effects, along with the giant ME coupling, can be used in multifunctional devices, such as broadband energy harvesters or magnetic field sensors.

Modeling and Simulation of Bow-Shaped Piezoelectric Energy Harvester

In recent years, new energy supply (energy self-sufficiency) technology which can replace the traditional battery supply has become a hot topic in global research field of microelectronic devices. A new low-frequency trapezoidal bow-shaped piezoelectric energy harvester (TBPEH) was proposed. The geometric model and finite element model (FEM) were built. The static analysis, modal analysis and harmonic response analysis of the TBPEH were discussed by using the Finite Element Analysis(FEA). Then traditional rectangular bow-shaped piezoelectric energy harvester(RBPEH) was compared with the new TBPEH. Simulation showed that the TBPEH could harvest energy more effectively than the RBPEH. The output voltage was increased by 135% with little change in resonant frequency, and indicator of the inhibition of side peak (SPI) which represented the capability of broad-band energy harvesting rose 11.2%. The TBPEH resonance frequency is 34.1Hz, which can be applied to the low frequency environment.

Investigation of contact electrification based broadband energy harvesting mechanism using elastic PDMS microstructures

Triboelectric energy harvesting has recently garnered a lot of interest because of its easy fabrication and high power output. Contact electrification depends on the chemical properties of contacting materials. Another important factor in contact electrification mechanism is surfaces’ elastic and topographical characteristics. One of the biggest limitations of resonant mechanism based devices is their narrow operating bandwidth. This paper presents a broadband mechanism which utilizes stiffness induced in the cantilever motion due to contact between two triboelectric surfaces. We have conducted experiments using polydimethylsiloxane (PDMS) micropad patterns to study the effect of micropad array configuration on the performance of triboelectric energy harvesting devices. The maximum power output measured from the device was observed to be 0.69 μW at an acceleration of 1 g. Due to the non-linearity introduced by contact separation mechanism, the bandwidth of the triboelectric energy harvester was observed to be increased by 63% at an acceleration level of 1 g. A hybrid energy harvesting mechanism has also been demonstrated by compounding the triboelectric energy harvester with a piezoelectric bimorph.

Multiple patch–based broadband piezoelectric energy harvesting on plate-based structures

Several engineering systems, such as aircraft structures, are composed of load-bearing thin plates that undergo vibrations and employ wireless health, usage, and condition monitoring components, which can be made self-powered using vibrational energy harvesting technologies. Integrated piezoelectric patches can be implemented for enabling self-powered sensors in the neighborhood of plate-based structures. In this work, coupled electroelastic modeling and experimental validations of broadband energy harvesting from structurally integrated piezoelectric patches on a rectangular thin plate are presented. A distributed-parameter electroelastic model for multiple patch–based energy harvesters attached on a thin plate is developed. Closed-form structural and electrical response expressions are derived for multiple vibration modes of a fully clamped thin plate for the series and parallel connection configurations of multiple patch–based energy harvesters. Experimental and analytical case studies are then compared for validating the analytical models of structurally integrated multiple patch–based energy harvesters. It is shown that analytical electroelastic frequency response functions exhibit very good agreement with the experimental frequency response function measurements for the series and parallel connection cases. In addition to offering an effective interface for energy harvesting from two-dimensional thin structures, series and parallel multiple patch–based energy harvester configurations yield effective broadband energy harvesting by combining the electrical outputs of harvester patches for multiple vibration modes.

Development of a broadband nonlinear two-degree-of-freedom piezoelectric energy harvester

Vibration energy harvesting using piezoelectric material has received great research interest in the recent years. One important concern for the development of piezoelectric energy harvesting is to broaden the operating bandwidth. Various techniques have been proposed for broadband energy harvesting, such as the resonance tuning approach, the frequency up-conversion technique, the multi-modal harvesting, and the nonlinear technique. A recently reported linear 2-degree-of-freedom harvester can achieve two close resonant frequencies both with significant power outputs, using its unique cantilever configuration. This article proposes to incorporate magnetic nonlinearity into the linear 2-degree-of-freedom system, aiming at further broadening its operating bandwidth. Experimental parametric study is carried out to investigate the behavior of such nonlinear 2-degree-of-freedom harvester. Among different configurations, an optimal configuration of the nonlinear 2-degree-of-freedom harvester is obtained to achieve significantly wider bandwidth. A lumped parameter model for such nonlinear 2-degree-of-freedom harvester is developed, and the results provide good validation for the experimental findings.

Broadband energy harvesting via magnetic coupling between two movable magnets

Harvesting energy from ambient mechanical vibrations by the piezoelectric effect has been proposed for powering microelectromechanical systems and replacing batteries that have a finite life span. A conventional piezoelectric energy harvester (PEH) is usually designed as a linear resonator, and suffers from a narrow operating bandwidth. To achieve broadband energy harvesting, in this paper we introduce a concept and describe the realization of a novel nonlinear PEH. The proposed PEH consists of a primary piezoelectric cantilever beam coupled to an auxiliary piezoelectric cantilever beam through two movable magnets. For predicting the nonlinear response from the proposed PEH, lumped parameter models are established for the two beams. Both simulation and experiment reveal that for the primary beam, the introduction of magnetic coupling can expand the operating bandwidth as well as improve the output voltage. For the auxiliary beam, the magnitude of the output voltage is slightly reduced, but additional output is observed at off-resonance frequencies. Therefore, broadband energy harvesting can be obtained from both the primary beam and the auxiliary beam.

Design and analysis of a connected broadband multi-piezoelectric-bimorph- beam energy harvester.

The rapid growth of remote, wireless, and microelectromechanical system (MEMS) devices over the past decades has motivated the development of a self-powered system that can replace traditional electrochemical batteries. Piezoelectric energy harvesters are ideal for capturing energy from mechanical vibrations in the ambient environment. Numerous studies have been made of this application of piezoelectric energy conversion; however, the narrow frequency operation band has limited its application to generate useful power. In this paper, a broadband energy harvester with an array/matrix of piezoelectric bimorphs connected by springs has been designed and analyzed based on the 1-D piezoelectric beam equations. The predicted result shows that the operational frequency band can be enlarged significantly by carefully adjusting the small end masses, length of the beam and spring stiffness. An optimal selection of the load impedance to realize the maximum power output is discussed. The results provide an important foundation for future broadband energy harvester design.

Chaos in the fractionally damped broadband piezoelectric energy generator

Piezoelectric materials play a significant role in harvesting ambient vibration energy. Due to their inherent characteristics and electromechanical interaction, the system damping for piezoelectric energy harvesting can be adequately characterized by fractional calculus. This paper introduces the fractional model for magnetically coupling broadband energy harvesters under low-frequency excitation and investigates their nonlinear dynamic characteristics. The effects of fractional-order damping, excitation amplitude, and frequency on dynamic behaviors are proposed using the phase trajectory, power spectrum, Poincare map, and bifurcation diagram. The numerical analysis shows that the fractionally damped energy harvesting system exhibits chaos, periodic motion, chaos and periodic motion in turn when the fractional order changes from 0.2 to 1.5. The period doubling route to chaos and the inverse period doubling route from chaos to periodic motion can be clearly observed. It is also demonstrated numerically and experimentally that the magnetically coupling piezoelectric energy harvester possesses the usable frequency bandwidth over a wide range of low-frequency excitation. Both high-energy chaotic attractors and large-amplitude periodic response with inter-well oscillators dominate these broadband energy harvesting.

Simulative verification of a novel semi-active broadband energy harvester

Abstract. This paper presents a semi-active broadband vibrational-energy harvesting system. Based on a non-resonant rotational generator, electronic circuitry was used to overcome the physical start-up restrictions. Due to the functional design it remains an energy harvester suitable for battery-less devices. For the first time a vibrational energy harvester is presented that allows standardization and thus higher volume production. A system layout, simulation, and measurement data will be shown.

Manufacture and Characterisation of Piezoelectric Broadband Energy Harvesters Based on Asymmetric Bistable Laminates

Manufacture and Characterisation of Piezoelectric Broadband Energy Harvesters Based on Asymmetric Bistable Laminates

Manufacture and Characterisation of Piezoelectric Broadband Energy Harvesters Based on Asymmetric Bistable Laminates

Piezoelectric energy harvesters that convert mechanical vibration into electrical energy are potential power sources for systems such as autonomous wireless sensor networks or safety monitoring devices. However, ambient vibrations generally exhibit multiple time-dependent frequencies, which can include components at relatively low frequencies. This can make typical linear systems inefficient or unsuitable; particularly if the resonant frequency of the device differs from the frequency range of the vibrations it is attempting to harvest. To broaden the frequency response of energy harvesters researchers have introduced elastic non-linearities; for example by designing bistable harvesters with two energy wells. Methods employed to induce bistability include magnetic interactions, axial loading, and buckling of hinge-like components. An alternative method has been recently considered where a piezoelectric element is attached to bistable laminate plates with an asymmetric stacking sequence to induce large amplitude oscillations. Such harvesting composite structures have been shown to exhibit high levels of power extraction over a wide range of frequencies. In this paper we manufacture and characterise the energy harvesting capability of bistable asymmetric laminates coupled to piezoelectric materials. Cantilever configurations are explored and harvested power levels as a function of load impedance, vibration frequency and amplitude assessed. Harvested power levels, natural frequencies and mode shapes are compared with linear cantilevers of similar geometry with a symmetrical stacking sequence to assess the benefits of using bistable laminate configurations. doi:10.12783/issn. 2168-4286/2.3/Kim

Self-tuning behavior of a clamped-clamped beam with sliding proof mass for broadband energy harvesting

Real world systems rarely vibrate at a single resonance frequency and the frequencies drift over time. Tunable devices exist, but generally need additional energy to achieve frequency adaptation. This means that the benefits in power output from this tuning need to be large enough to power the mechanism itself. Passively self-tuning systems go into resonance without requiring active control. This paper focuses on a passively self-tuning system with a proof mass that can slide freely along a clamped-clamped beam. Under external vibration, the slider moves along the beam until the system goes into resonance. A proof-of-concept design is introduced using either a copper or a steel beam and a 3D-printed ABS thermoplastic proof mass. Successful self-tuning is demonstrated in both cases. The frequencies range from 80 – 140 Hz at accelerations as low as 0.007 g rms. Results show the resonance of the beam and the position of the slider along the beam with time. Furthermore, the dynamic magnification and the proof mass position at resonance are discussed, together with the inherent non-linearities of double-clamped beam resonators. The findings support the hypothesis that the effect of the ratio between proof mass and beam mass outweighs the Duffing spring stiffening effects.

Integrated bistable generator for wideband energy harvesting with optimized synchronous electric charge extraction circuit

Bistable generators have been proposed as potential solutions to the challenge of variable vibration frequencies. In the authors' previous works, a specific BSM (Buckled-Spring-Mass) harvester architecture has been suggested. It presents some properties of interests: simplicity, compactness and wide bandwidth. Using a normalized model of the BSM generator for design and optimization at different scales, this paper presents a new integrated BSM bistable generator design with the OSECE (Optimized Synchronous Electric Charge Extraction) technique which is used for broadband energy harvesting. The experimental results obtained from an initial prototype device show that the BSM generator with the OSECE circuit exhibits better performance for low coupling cases or reverse sweep excitations. This is also confirmed by simulations for the proposed integrated generator. Good applications prospective is expected for the bistable generator with the nonlinear OSECE circuit.

A general mass law for broadband energy harvesting

Abstract It is well known that the power absorbed by a linear oscillator when excited by white noise base acceleration depends only on the mass of the oscillator and the spectral density of the base motion. This places an upper bound on the energy that can be harvested from a linear oscillator under broadband excitation, regardless of the stiffness of the system or the damping factor. It is shown here that the same result applies to any multi-degree-of-freedom nonlinear system that is subjected to white noise base acceleration: for a given spectral density of base motion the total power absorbed is proportional to the total mass of the system. The only restriction to this result is that the internal forces are assumed to be a function of the instantaneous value of the state vector. The result is derived analytically by several different approaches, and numerical results are presented for an example two-degree-of-freedom-system with various combinations of linear and nonlinear damping and stiffness.