Transducers For Energy Harvesting Research Articles

A robust parametrically excited piezoelectric energy harvester with resonant attachment

Drawing inspiration from the enhancement of sensing capabilities in Micro-electro-Mechanical Systems (MEMS), the utilization of parametric resonance with nonlinear amplification features shows promise in vibration energy harvesting. However, harnessing parametric resonance for vibration energy harvesting presents several challenges. Initiating the resonant regime under low-energy conditions can be challenging, and the periodic modulation of system parameters requires additional time to accumulate the vibration amplitude. The range of modulation frequencies needs to trigger parametric resonance is notably narrow, especially when employing piezoelectric transducers for energy harvesting. To address these concerns, a parametrically excited piezoelectric energy harvester incorporating with a movable resonant attachment is proposed. The governing equations of this system were derived using the extended Hamilton principle and then numerically solved. Experimental testing was performed based on the design, and it displayed good agreement with numerical predictions. System parametric studies were carried out, revealing the mutual influence among critical system parameters. The findings demonstrate that the proposed device exhibited hardening dynamic responses and achieved more than a fivefold increase in overall bandwidth compared to a conventional parametrically excited counterpart.

Piezoelectric energy harvesting and synchronization of excited and modified Huygens's pendulums.

We consider a model of modified Huygens pendulums in order to be able to study the dynamics of such a system and carry out piezoelectric energy harvesting and the effects of phenomena encountered on this energy harvesting. The modifications made to the system here are the use of compound pendulums, a parametric force, and the addition of a piezoelectric transducer for energy harvesting. Thanks to the Lagrangian formalism, the governing equations were established and the numerical resolution was made using the fourth-order Runge-Kutta algorithm. We observed the presence of several types of synchronization (in-phase, anti-phase, quadrature-phase) and the existence of periodic, multi-periodic, or chaotic dynamics. Also, synchronization plays an important role in energy harvesting, in particular, in-phase synchronization, which promises much better performance than anti-phase synchronization. The effects of system parameters (amplitude and frequency of parametric force, stiffness coefficient, electromechanical coupling coefficient, etc.) are also studied on synchronization and energy harvesting. These results have applications in the manufacture of sensors and actuators, the power supply of electronic devices, and the manufacture of autonomous devices.

A High-Reliability Piezoelectric Tile Transducer for Converting Bridge Vibration to Electrical Energy for Smart Transportation.

Piezoelectric energy transducers offer great potential for converting the vibrations of pedestrian footsteps or cars moving on a bridge or road into electricity. However, existing piezoelectric energy-harvesting transducers are limited by their poor durability. In this paper, to enhance this durability, a piezoelectric energy transducer with a flexible piezoelectric sensor is fabricated in a tile protype with indirect touch points and a protective spring. The electrical output of the proposed transducer is examined as a function of pressure, frequency, displacement, and load resistance. The maximum output voltage and maximum output power obtained were 6.8 V and 4.5 mW, respectively, at a pressure of 70 kPa, a displacement of 2.5 mm, and a load resistance of 15 kΩ. The designed structure limits the risk of destroying the piezoelectric sensor during operation. The harvesting tile transducer can work properly even after 1000 cycles. Furthermore, to demonstrate its practical applications, the tile was placed on the floor of an overpass and a walking tunnel. Consequently, it was observed that the electrical energy harvested from the pedestrian footsteps could power an LED light fixture. The findings suggest that the proposed tile offers promise with respect to harvesting energy produced during transportation.

Modelling and Characterization Piezoelectric Transducer for Sound Wave Energy Harvesting

Energy harvesting system is using ambient energy conversion in the environment. The environmental energy will be converted into usable electrical energy that can be used in controlling wireless electronic devices. The available mechanical vibration from the sound energy will then be converted to electrical energy by using a piezoelectric transducer. The size of the piezoelectric represents the surface area of the electrode on the piezoelectric model. A smaller size piezoelectric transducer is unable to produce a good vibration due to the smaller surface area. The bigger dimension of the piezoelectric model would be able to harvest more electrical energy output because the vibration from the bigger piezoelectric model which would able to produce more sound wave energy. The piezoelectric material Lead Zirconate Titanate (PZT-5H) vibration is focused on the resonance frequency at below 1 kHz with sound level decibel is between the range of 35-100 dB. This research is to concentrate on rectangular and trapezium-shaped cantilever. The trapezium shaped cantilever produces higher energy output due to its shape which has better in terms of stress and strain distribution. In addition, researchers have modelled and validated energy harvesters with different proof masses shapes. The improved piezoelectric vibrational energy harvester has a trapezoidal beam and an added triangular proof mass. The arrangement of the piezoelectric tested in parallel, series, combination series and parallel configuration to investigate the performance of the output power generated from the sound wave. The rectangular and trapezium shaped cantilever are resulted in a resonant frequency of 269.4 Hz and 269.88 Hz, respectively. The rectangular and trapezium shaped cantilever produced a maximum output voltage of 3.105 V and 3.635 V respectively. The piezoelectric output during the parallel array configuration, which is 5.636 V, 0.497 mA and 2.803 mW. The output power produced by parallel is 81 % higher than compare in series array configuration and 35.8 % higher than combination of series and parallel. Thus, the produced energy output 5 V would be able to apply at several low power supply applications such as mobile phones, power bank or wireless sensor networks (WSN).

Exploiting the voltage sensitivity of magnetostrictive transducer for energy harvesting and sensor applications

Magnetostrictive transducer, as a kind of high-efficiency transducer, has a broad application in the field of energy harvesting and sensor. However, the voltage generating performance of the transducer limits its application. This paper will endeavor to quantify the load-induced voltage of magnetostrictive transducer by developing a holistic theoretical model and deriving the corresponding analytical solution. On this basis, this paper proposed the concept of voltage sensitivity in transducer optimization, which could quantitatively analyze the normalized voltage generated by a unit excitation. Based on the theoretical simulation and experimental validation, the voltage sensitivities of magnetostrictive transducer under different mechanical loads are investigated. The parametric analysis will be conducted to further optimize the transducer structure to enhance its open-circuit and load voltage. The works of this paper could be instructive to guide magnetostrictive transducer design in sensing and energy harvesting applications.

Efficacy of singly curved thin piezo transducers for structural health monitoring and energy harvesting for RC structures

Piezoelectric materials have secured a significant place in the field of structural health monitoring (SHM) and energy harvesting over the past two decades. These materials are available in several forms and configurations, the efficacy of especially curved configurations is still unexplored. This article investigates, both experimentally and numerically, the potency of the curved configuration of the piezo transducers over the straight configuration when embedded in reinforced concrete (RC) structures for energy harvesting and SHM. The study consists of the comparative analysis of (a) open-circuit voltage generated across the piezo transducers; (b) the power developed under the impedance matching conditions; and (c) the potential of power storage into capacitors for both configurations. The article also experimentally examines the hitherto unexplored damage detection capability of the curved piezo transducers by the electro-mechanical impedance (EMI) technique. Results clearly demonstrate that curved piezo transducers exhibit better performance in comparison to straight configurations for both structural health monitoring and energy harvesting. A finite element (FE) analysis is also performed through a 3-D model of the real-life-sized RC beam with straight and curved piezo transducers embedded inside to evaluate the various parameters such as the angle of bend, the thickness, the number of elements and the position of placement of the curved transducers for energy harvesting. The FE simulations reveal an optimum range of the angle of bend as 130 to 160 degrees. There is a substantial impact of the increase in thickness of the transducers for energy harvesting in terms of its open-circuit voltage. The numerical analysis also suggests that the optimum position of placement of the piezo transducers is towards the top or bottom of the beam cross-section. The outcomes of the experimental and numerical investigations are very pivotal for the implementation of curved piezo transducers in real-life RC structures for improved energy harvesting and structural health monitoring.

A new approach to design electromagnetic transducers for wideband electrically-tuned vibration energy harvesting

This paper focuses on the opportunities offered by electrical tuning to widen the bandwidth of Vibration Energy Harvesters (VEH) based on electromagnetic conversion. The paper shows that some electromagnetic transducer topologies are more likely than others to take advantage of the wide bandwidth performance offered by electrical tuning. Using a general model including both a resonant electromagnetic VEH and a resistive-capacitive interface with electrical tuning, we highlight the parameters of interest influencing the bandwidth of the system. Based on these results, we develop an efficient optimization approach suitable for any electromagnetic transducer topology. The full optimization of different transducer topologies shows that the one that is based on variable reluctance is the best in terms of bandwidth-related performances.

Heart Energy Harvesting and Cardiac Bioelectronics: Technologies and Perspectives

Nanogenerators are a recently emerging technology which is able to cost-effectively harvest energy from renewable and clean energy sources at the micro/nano-scale. Their applications in the field of self-powered sensing systems and portable power supplying devices have been increasing in recent years. Wearable and implantable electromechanical/electrochemical transducers for energy harvesting represent a novel alternative to chemical batteries for low-power devices and to exploit the energy conveyed by human biomechanics. The human heart, in particular, is a compelling in vivo source of continuous biomechanical energy and is a natural battery which can power implantable or wearable medical devices. This review describes the recent advances in cardiac wearable/implantable soft and flexible devices and nanogenerators for energy harvesting (piezoelectric nanogenerators, triboelectric nanogenerators, biofuel cells, solar cells, etc.), as well as cardiovascular implantable electronic devices in a more general sense, as components of more complex self-sustainable bioelectronic systems for controlling irregular heartbeats or for interventional therapy for cardiac diseases. The main types of soft heart energy harvesters (HEHs) and heart bioelectronic systems (HBSs) are covered and classified, with a detailed presentation of state-of-the-art devices, and the advances in terms of materials choice, chemical functionalization, and design engineering are highlighted. In vivo bioelectronic cardiac interfaces are outlined as well as soft devices for in vitro cardiac models (patch and organoids). Cutting-edge 3D/4D bioprinting techniques of cardiac tissue are also mentioned. The technical challenges for the practical application and commercialization of soft HBSs are discussed at the end of this paper.

Design, modelling and testing of a compact piezoelectric transducer for railway track vibration energy harvesting

To enable wireless sensor networks to monitor rail infrastructures in real-time, a cost-effective power source is in need. This work presents the design, modelling and testing of a piezo stack energy harvester with frequency up-conversion mechanism for scavenging energy from railway track vibration. The proposed harvester is designed to meet railway track applications’ size, frequency, and stress requirements. A compact design integrating the inertial mass and the piezo stack transducer systems is used to enable the mechanical collision for realising the frequency up-conversion mechanism and ensure the size of the energy harvester is suitable for the limited space on the railway track. The frequency bandwidth of the energy harvester is broadened by utilizing the longitudinal and torsional oscillation of the designed plate springs which enable the system to have two adjacent natural frequencies. The mechanical transformer of the piezo stack transducer system is designed to achieve the required stress level under both the impact force caused by the collision motion and the inertial force generated by the random vibration of the rails. A finite element model (FEM) analysing the free vibration of the piezo stack transducer caused by the frequency up-conversion mechanism is developed to analyse the dynamic characteristics of the coupled system. Lab tests are carried out to validate the proposed FEM and evaluate the impact of different factors such as load resistance, acceleration, initial interval, plate spring, and pulse excitation on power generation. Experimental results show that the energy harvester has two resonant frequencies of 17 Hz and 20 Hz. The frequency up-conversion mechanism can convert this low-frequency vibration into the piezo stack transducer’s high resonant frequency vibration of 94 Hz. A maximum average power of 6.72 mW with a 1-mW-bandwidth of 15 Hz is obtained when actuated at 0.7 RMS g acceleration. • A piezo stack energy harvester for railway track vibration is designed, modelled and tested. • A compact design is proposed to enable the mechanical collision for realising the frequency up-conversion mechanism. • Two adjacent natural frequencies are achieved to broaden the frequency bandwidth. • The mechanical transformer is designed to achieve the required stress level under the impact force and inertial force. • A maximum average power of 6.72 mW with a 1-mW-bandwidth of 15 Hz is obtained when actuated at 0.7 RMS g acceleration.

Analytical and Experimental Investigation of a Curved Piezoelectric Energy Harvester.

Piezoelectric energy harvesters have traditionally taken the form of base excited cantilevers. However, there is a growing body of research into the use of curved piezoelectric transducers for energy harvesting. The novel contribution of this paper is an analytical model of a piezoelectric energy harvesting curved beam based on the dynamic stiffness method (DSM) and its application to predict the measured output of a novel design of energy harvester that uses commercial curved transducers (THUNDER TH-7R). The DSM predictions are also verified against results from commercial finite element (FE) software. The validated results illustrate the resonance shift and shunt damping arising from the electrical effect. The magnitude, phase, Nyquist plots, and resonance frequency shift estimates from DSM and FE are all in satisfactory agreement. However, DSM has the advantage of having significantly fewer elements and is sufficiently accurate for commercial curved transducers used in applications where beam-like vibration is the predominant mode of vibration.

Exploring energy harvesting and vibration mitigation in tall buildings accounting for wind and seismic loads

With the changing climate and the limited supply of fossil fuels available for global energy use, much research has been done to develop innovative methods of producing clean and renewable energy. Out of the various energy sources, wind forces can cause tall buildings to undergo significant vibrations presenting a potential source of clean and renewable energy for buildings and the power grid. To mitigate wind-induced vibrations in tall buildings, viscous dampers have been widely utilized, which, unlike tuned-mass dampers, are also effective in mitigating earthquake-induced vibrations. Contrary to conventional designs, this research explores the use of energy harvesting transducers, in place of viscous dampers, as a means of not only mitigating vibrations under extreme loading conditions (e.g. earthquakes), but also harvesting energy from wind induced vibrations during service conditions and converting it to electricity. This research demonstrates the often conflicting requirements for supplemental damping related to energy harvesting (EH) from wind loads under service conditions vs. vibration mitigation (VM) under extreme events (e.g., earthquakes). Specifically, this research shows that large damping is usually required for VM, whereas small or moderate damping is often required to maximize EH. In doing so, this research develops, and validates using test data, a nonlinear model for an electromagnetic EH transducer, quantifies the EH potential of a selected tall building as a function of the supplemental damping and wind speed showing that EH power generation can reach kWs (as opposed to W), and assesses the seismic performance of the same building as a function of the supplemental damping for two seismic hazard levels. The findings of this research will support future studies pursuing the concept of energy harvesting in structural design.

The Potential of Cylindrical Piezoelectric Transducers for High-Frequency Acoustic Energy Harvesting

The work presented in this paper studies the potential of cylindrical piezoelectric transducers for harvesting high-frequency acoustic energy. The cylinder was made of a modified PZT (lead zirconate titanate) and had the shape of a squared cylinder with a side length of 4 cm and a wall thickness of 1 mm. The study used open-circuit measurements to study the relationship between the sound wavelength and the cylinder size and its effect on the performance of energy harvesting. The cylinder was found to give the best performance at a frequency of 20 kHz. In addition to open-circuit measurements, closed-circuit measurements were performed to demonstrate the ability to dissipate energy harvested from 20 kHz sound waves across an electric load. The load was designed in a series of experimental steps that aimed at optimizing an impedance-matched energy harvester. Finally, the cylinder was tested at the optimized load conditions, and it was possible to harvest and store energy with a power of 67.6 μW and harvesting efficiency of 86.1%.

Development and application performance of road spring-type piezoelectric transducer for energy harvesting

Piezoelectric pavement energy transducers have attracted attention because they can directly convert mechanical energy into electric energy, thus enabling environmental protection, energy regeneration, and high energy output. However, existing piezoelectric transducers used in pavements made of piezoelectric ceramics are brittle and have short lives under long-term vehicle loading fatigue. In the present study, to raise the efficiency of energy harvesting, a new road piezoelectric transducer with a specified flexibility was designed and fabricated with two types of structures, plane and spring types, and their output performances were evaluated and compared. The test results showed that at the excitation frequency of 10 Hz and test displacement of 2 mm, the maximum output power of the spring piezoelectric energy harvester reached 14.183 mWmax for a matching resistance of 1 kΩ, and the output power was 2.24 times that of the plane piezoelectric energy harvester. Then, a fatigue test under an excitation frequency of 10 Hz and testing displacement of 2 mm was performed for the durability of the road spring-type piezoelectric transducer unit, and results showed that the piezoelectric transducer has a good durability and meets the general conditions for road engineering. Finally, the road spring-type piezoelectric energy harvester was tested on an actual road. When a pickup truck drove at a speed of 40 km h−1, the output power of the spring piezoelectric energy harvester reached a maximum of 592.77 mWmax for a matching resistance of 3 kΩ. Thus, this spring-type piezoelectric harvester can be ideally applied in road traffic.

Low power energy harvesting systems: State of the art and future challenges

Recent works on self-charging power technologies mainly focused on the low energy harvesting component, while its integration with the energy storage system was usually not further evaluated or discussed. This was addressed in the present work by providing a comprehensive state-of-the-art review on different types of energy storage used for self-sufficient or self-sustainable power units to meet the power demands of low power devices such as wearable devices, wireless sensor networks, portable electronics, and LED lights within the range of 4.8 mW–13 W. The paper presents the relevant scientific studies and recent developments on incorporating low energy harvesting with energy storage and power management systems. Recent advances on seven types of low energy harvesting technologies or transducers and eight types of micro/small-scale energy storage systems from farads to amps were examined to assess the integrated design's overall efficiency. The study focused on the design, distribution management networks, efficiency, compatibility with other components, costs, and environmental impact of self-sustainable power unit. To effectively assess the most suitable energy storage for the self-charging power unit, assessing its technical characteristics, economical, and environmental impact is discussed. Finally, the review identified the challenges and further research that must be carried out to achieve a more sustainable and stable integrated technology, moving from the proof of concept or laboratory to actual applications.

Finite Element Analysis of Lead-Free Ceramic Based Cymbal Transducer for Energy Harvesting

In this paper, the stress behaviour and power generation of cymbal bimorph transducer of different piezoelectric ceramics are studied. Comparison of stress, deformation and power is done between different materials cymbal bimorph transducer. The cymbal bimorph design is made on Solidworks, and simulation is carried out on ANSYS 18.0. In this design, the substrate thickness is varied. Its both end surface is bonded to the piezoelectric layers of 0.50 mm thickness and further piezoelectric layers bonded to endcaps. A 100 N of the load is applied at the apex of end caps. The lead-free ceramics and lead-based ceramic are used as a piezoelectric material in the design. The stress and power are calculated for different values of thickness of the substrate, and comparison is made among them. After having a comparison it is found that both types of ceramics can be used, but there are some conditions which prioritise lead-free ceramic over lead-based ceramic.

PVDF-BaTiO3 Nanocomposite Inkjet Inks with Enhanced β-Phase Crystallinity for Printed Electronics.

Polyvinylidene difluoride (PVDF) and its copolymers are promising electroactive polymers showing outstanding ferroelectric, piezoelectric, and pyroelectric properties in comparison with other organic materials. They have shown promise for applications in flexible sensors, energy-harvesting transducers, electronic skins, and flexible memories due to their biocompatibility, high chemical stability, bending and stretching abilities. PVDF can crystallize at five different phases of α, β, γ, δ, and ε; however, ferro-, piezo-, and pyroelectric properties of this polymer only originate from polar phases of β and γ. In this research, we reported fabrication of PVDF inkjet inks with enhanced β-phase crystallinity by incorporating barium titanate nanoparticles (BaTiO3). BaTiO3 not only acts as a nucleating agent to induce β-phase crystallinity, but it also improves the electric properties of PVDF through synergistic a ferroelectric polarization effect. PVDF-BaTiO3 nanocomposite inkjet inks with different BaTiO3 concentrations were prepared by wet ball milling coupled with bath ultrasonication. It was observed that the sample with 5 w% of BaTiO3 had the highest β-phase crystallinity, while in higher ratios overall crystallinity deteriorated progressively, leading to more amorphous structures.

Flexible Piezoelectric Transducers for Energy Harvesting and Sensing from Human Kinematics

This study reports flexible nanocomposite-based piezoelectric nanogenerators (PENGs) fabricated by dispersing various piezoelectric nanoparticles (BaTiO3, ZnO, and PZT) and graphene nanopowder in a silicone matrix. The results indicated that the PZT-based composites showed superior performance in comparison to other ceramics. Subsequently, practical application of PENGs was demonstrated by developing a fully functioning shoe-insole nanogenerator (SING). The SING generated high open-circuit voltage (∼27 V), short-circuit current (429.23 μA), and power density (402 mW/m2) under real-time human walking. Moreover, a facile and inexpensive fabrication method for efficient, skin-friendly, and highly stretchable biomechanical piezoelectric sensors is also proposed. In this regard, multiwall carbon nanotubes/silicone composite stretchable electrodes were prepared to be compatible with the sensors. The electrodes displayed stability even under high uniaxial elongation (100%), and the fabricated sensors responded effectively to almost every joint movement. The results suggested that the fabricated PENGs can be potentially used as self-powered biomechanical energy harvesters/sensors in wearable electronics, haptic sensing, or internet of human-related applications.

Design and Implementation of an IoT-Oriented Strain Smart Sensor with Exploratory Capabilities on Energy Harvesting and Magnetorheological Elastomer Transducers

This work designed and implemented a new low-cost, Internet of Things-oriented, wireless smart sensor prototype to measure mechanical strain. The research effort explores the use of smart materials as transducers, e.g., a magnetorheological elastomer as an electrical-resistance sensor, and a cantilever beam with piezoelectric sensors to harvest energy from vibrations. The study includes subsequent and validated results with a magnetorheological elastomer transducer that contained multiwall carbon nanotubes with iron particles, generated voltage tests from an energy-harvesting system that functions with an array of piezoelectric sensors embedded in a rubber-based cantilever beam, wireless communication to send data from the sensor’s central processing unit towards a website that displays and stores the handled data, and an integrated manufactured prototype. Experiments showed that electrical-resistivity variation versus measured strain, and the voltage-generation capability from vibrations have the potential to be employed in smart sensors that could be integrated into commercial solutions to measure strain in automotive and aircraft systems, and civil structures. The reported experiments included cloud-computing capabilities towards a potential Internet of Things application of the smart sensor in the context of monitoring automotive-chassis vibrations and airfoil damage for further analysis and diagnostics, and in general structural-health-monitoring applications.

Surface energy layers investigation of intelligent magnetoelectrothermoelastic nanoplates through a vibration analysis

Intelligent materials such as magnetoelectrothermoelastic (METE) nanoplates offer great potential to supply more efficient energy harvesting devices, transducers, sensors, and actuators. In this study, the influences of slanted angle of the METE nanoplate and orthotropic angle of Pasternak foundation on the magnitude of surface energy layers are investigated through a vibrational analysis. The nanoplate is exposed to outer thermal, electric, magnetic and in-plane loadings. For modeling the plate’s nonlocal behavior and surface stresses, the governing equations are constructed based on Hamilton’s principle. Galerkin method is implemented to solve the equilibrium motions, and also for the authenticity of the solution, the equations are resolved by the Navier’s method. Obtained results are deemed useful for the mechanical analysis and design of nano-/microelectromechanical system nanostructures constructed from the METE materials. The numerical examples indicated that after a particular value of slanted angle of the nanoplate, α ≥ 80, the magnitude of surface energy layers in the vibration behavior becomes opposite to the case when the slanted angles are 0° < α < 80°. In addition, the value of the slanted angle of the nanoplate can cause the harmonic responses of the vibration due to the orthotropic angle of Pasternak foundation to shift in harmony with the slanted angle degree.

Fabrication and performance of Tile transducers for piezoelectric energy harvesting

In recent years, pavement piezoelectric energy harvesting has become one of the most promising road energy harvesting system clean energy sources. However, it is difficult for existing piezoelectric transducer structures to meet road power generation requirements. In this study, ceramic grinding and polishing techniques were used to make curved piezoelectric ceramic units with controllable curvatures. A new type of Tile transducer for roadway applications was developed in combination with an elastic metal base. Under the action of traffic load, the Tile transducer was subject to both vertical stress and a horizontal tearing force. Laboratory tests were performed on Tile transducers with simply supported and fixed boundary conditions, and the effects of concentrated and uniformly distributed loads on energy harvesting efficiency were analyzed. When the excitation frequency was 6 Hz and the load was 0.7 MPa, the output power of the Plane transducer was 0.23 mW, while that of the Tile transducer was 24.5 times as large at 5.65 mW. The ultimate compressive yield strength of a single Tile transducer could reach 2.18 kN, and the load limit was 1.5 kN at an excitation frequency of 10 Hz. This meets traffic load requirements. The open circuit voltage peak did not decrease substantially when 360 000 cyclic loading processes were performed. This indicated that Tile transducer structural performance was stable and that the transducer was durable. Based on the test results, an effective Tile transducer packaging method is proposed for application in road power generation systems.