Piezoelectric Energy Conversion Research Articles

Magnetic Field Energy Harvesting with a Lead-Free Piezoelectric High Energy Conversion Material

This article presents a high-performance lead-free piezoelectric energy harvester (LPEH) system for magnetic field. It based on a Ba0.85Ca0.15Ti0.90Zr0.10O3 + CuO 0.3 wt% (BCTZC0.3) composite was fabricated by sintering at 1450 °C. The BCTZC0.3 composite, which has an enhanced high energy conversion constant (d33×g33), shows improved piezoelectric power-generation performance when compared with conventional piezoelectric energy harvesters. The BCTZC0.3-based LPEH produces instantaneous maximum power of 8.2 mW and an energy density of 107.9 mW/cm3 in a weak magnetic field of 250 μT. This system can be used to charge a capacitor and operate a wireless sensor network (WSN) system to provide temperature sensing and radio-frequency (RF) transmission in a 250 μT magnetic field. The proposed LPEH is a promising green-energy device for potentially self-powering WSN systems when applied.

Theoretical study on a novel piezoelectric ocean wave energy harvester driven by oscillating water column

ABSTRACT The wireless sensors offer the possibility of highly accurate salinity, temperature, or pollution detection for the ocean. Therefore, a novel self-powered piezoelectric wave energy harvester with a long service life was developed to replace the batteries in the sensors. A Pb(Zr,Ti)O3(PZT-5A) piezoelectric converter was applied to displace the traditional air turbine in this paper. The wave crest enters the chamber and compresses the entrapped air with oscillating water column (OWC). The outlet of piezoelectric patch deforms and output electric power when it is forced by the fluctuating air pressure. Based on the velocity potential and Green’s function method, theoretical analyses were conducted in the assumption of an incompressible fluid. A numerical OWC aerodynamic model was developed to verify the theoretical calculation based on the Reynolds-Averaged Navier-Stokes equations solver and Computational Fluid Dynamics (CFD) commercial software. The fluctuating air pressure was obtained in the chamber by numerical simulation. The pressure rose to 65 Pa when the ocean wave entered the air chamber with a daft of 0.3 m and a period of 1.8 s. Resultly, the piezoelectric harvester generates electric energy of J. This electric energy was used to evaluate the efficiency piezoelectric wave energy conversion system. Theoretical calculation results were consistent with that of the numerical simulation very well. This work testified their validity for the novel wave energy harvesting system.

A comprehensive review on the state-of-the-art of piezoelectric energy harvesting

The global energy crisis and environmental pollutions caused mainly by the increased consumption of nonrenewable energy sources prompted researchers to explore alternative energy technologies that can harvest energies available in the ambient environment. Mechanical energy is the most ubiquitous ambient energy that can be captured and converted into useful electric power. Piezoelectric transduction is the prominent mechanical energy harvesting mechanism owing to its high electromechanical coupling factor and piezoelectric coefficient compared to electrostatic, electromagnetic, and triboelectric transductions. Thus, piezoelectric energy harvesting has received the utmost interest by the scientific community. Advancements of micro and nanoscale materials and manufacturing processes have enabled the fabrication of piezoelectric generators with favorable features such as enhanced electromechanical coupling factor, piezoelectric coefficient, flexibility, stretch-ability, and integrate-ability for diverse applications. Besides that, miniature devices with lesser power demand are realized in the market with technological developments in the electronics industry. Thus, it is anticipated that in near future, many electronics will be powered by piezoelectric generators. This paper presents a comprehensive review on the state-of-the-art of piezoelectric energy harvesting. The piezoelectric energy conversion principles are delineated, and the working mechanisms and operational modes of piezoelectric generators are elucidated. Recent researches on the developments of inorganic, organic, composite, and bio-inspired natural piezoelectric materials are reviewed. The applications of piezoelectric energy harvesting at nano, micro, and mesoscale in diverse fields including transportation, structures, aerial applications, in water applications, smart systems, microfluidics, biomedicals, wearable and implantable electronics, and tissue regeneration are reviewed. The advancements, limitations, and potential improvements of the materials and applications of the piezoelectric energy harvesting technology are discussed. Briefly, this review presents the broad spectrum of piezoelectric materials for clean power supply to wireless electronics in diverse fields. This paper presents the state-of-the-art review of piezoelectric energy harvesting with a special focus on materials and applications. Piezoelectric energy conversion principles are delineated, and the working mechanisms and operational modes of piezoelectric generators are elucidated. Recent researches on the developments of inorganic, organic, composite, and bio-inspired natural piezoelectric materials are reviewed. The applications of piezoelectric energy harvesting at nano, micro and meso-scale in diverse fields are presented. The advancements, limitations, and improvements of the materials and applications of the piezoelectric energy harvesting technology are discussed. • Piezoelectric transduction is prominent energy harvesting mechanism. • Principles, structures, and operational modes are explained. • Inorganic, organic, ceramic, and bioinspired natural materials reviewed. • Broad range of applications are summarized.

Piezoelectric Energy Harvester Based on LiNbO3 Thin Films.

This paper reports the results of the influence of the energy of laser pulses during laser ablation on the morphology and electro-physical properties of LiNbO3 nanocrystalline films. It is found that increasing laser pulse energy from 180 to 220 mJ results in the concentration of charge carriers in LiNbO3 films decreasing from 8.6 × 1015 to 1.0 × 1013 cm−3, with the mobility of charge carriers increasing from 0.43 to 17.4 cm2/(V·s). In addition, experimental studies of sublayer material effects on the geometric parameters of carbon nanotubes (CNTs) are performed. It is found that the material of the lower electrode has a significant effect on the formation of CNTs. CNTs obtained at the same growth time on a sample with a Cr sublayer have a smaller diameter and a longer length compared to samples with a V sublayer. Based on the obtained results, the architecture of the energy nanogenerator is proposed. The current generated by the nanogenerator is 18 nA under mechanical stress of 600 nN. The obtained piezoelectric nanogenerator parameters are used to estimate the parameters of the hybrid-carbon-nanostructures-based piezoelectric energy converter. Obtained results are promising for the development of efficient energy converters for alternative energy devices based on lead-free ferroelectric films.

Oxygen Pressure Influence on Properties of Nanocrystalline LiNbO3 Films Grown by Laser Ablation.

Energy conversion devices draw much attention due to their effective usage of energy and resulting decrease in CO2 emissions, which slows down the global warming processes. Fabrication of energy conversion devices based on ferroelectric and piezoelectric lead-free films is complicated due to the difficulties associated with insufficient elaboration of growth methods. Most ferroelectric and piezoelectric materials (LiNbO3, BaTiO3, etc.) are multi-component oxides, which significantly complicates their integration with micro- and nanoelectronic technology. This paper reports the effect of the oxygen pressure on the properties of nanocrystalline lithium niobate (LiNbO3) films grown by pulsed laser deposition on SiO2/Si structures. We theoretically investigated the mechanisms of LiNbO3 dissociation at various oxygen pressures. The results of x-ray photoelectron spectroscopy study have shown that conditions for the formation of LiNbO3 films are created only at an oxygen pressure of 1 × 10−2 Torr. At low residual pressure (1 × 10−5 Torr), a lack of oxygen in the formed films leads to the formation of niobium oxide (Nb2O5) clusters. The presented theoretical and experimental results provide an enhanced understanding of the nanocrystalline LiNbO3 films growth with target parameters using pulsed laser deposition for the implementation of piezoelectric and photoelectric energy converters.

A Design of mass-spring type piezoelectric energy harvesting

This study describes an experimental power generation system based on piezoelectric energy conversion for low power applications such as wireless sensor nodes. Piezoelectric transducers (PZTs) are especially suitable for energy harvesting from ambiance. A PZT is able to produce an open circuit voltage at hundreds volt level. But acquired current may be achieved at nano – micro scale. Therefore, PZT energy harvesters (PEH) have a very limited power generation capability. In order to generate higher output power, a series of PZT should be used in a PEH with proper electrical connection. In this paper, PEH is presented with a novel circuit topology for increase output power. The experimental system uses 20 diaphragm type PZTs with a 15 cm spring mounted at the center of each transducer. Necessary vibration is produced via a spring – mass structure of each PZT. Mass – spring structure is vibrated by the effect of wind. The maximum output power of the presented experimental generator for a nominal wind speed of 12 m/s is around 10.8 mJ. Results shows that proposed experimental generator is suitable for low power applications and output power of generator can be increased by using more PTZ is connected used circuit topology.

Design of a Unique Unimorph and Bimorph Cantilever Energy Harvesting System

Piezoelectric energy conversion has received considerable attention for vibration-to-electric energy conversion over the past decade. A typical piezoelectric energy harvester is a unimorph or a bimorph cantilever located on a vibrating host structure. This paper presents a comparison between unimorph and bimorph cantilever beam having a number of segmented PMN-PT piezo-elements on the input and output power. The numerical simulation was carried out by applying the finite element analysis (FEA) using COMSOL multi-physics software in order to predict output voltage and power over a frequency range of 60–200 Hz for the first resonant frequencies. The simulation results show maximum output voltage and power harvested of 7.38 V and 135.73 μW, respectively, by the unimorph piezoelectric energy harvester at resonant frequency value of 84 Hz with electromechanical coupling factor (ke) of 77.29%. These results highlight that the highest value of the output electrical power can be obtained when the piezoelectric element is attached on the top of a clamped end of a cantilever piezoelectric beam. Moreover, in an unimorph or bimorph cantilever beam system, increasing the number of piezoelectric elements results in a higher resonant frequency shift and significantly decreasing in the harvested power.

Development and performance of a piezoelectric energy conversion structure applied in pavement

This paper presents a multi-layer cantilever piezoelectric energy conversion structure for pavement, which avoids weakening the electrical output after the mass contact and realizes the coordinated vibration of each cantilever piezoelectric energy harvester and road driving. In order to ensure the structure meets the requirements of power generation and durability when applied in road engineering, based on the power generation theory of energy harvester, the structural parameters related to the electrical output magnitude are clarified. Based on the power generation performance and durability of energy conversion structure under typical road traffic characteristics, the optimal cantilever position and vibration amplitude are determined, which lay the foundation for the development and application of energy harvester in road field. The results indicate that the improved structure has the best power generation performance and durability with the condition of the distance from the piezoelectric material to the fixed end of 7 mm and the vibration amplitude of 4 mm under under typical road traffic conditions. The output voltage of the monolithic energy harvester at 5 Hz vibration frequency is 5.2 V, the output power can reach 3.14 mW, and the power density is 0.0063 mW/mm3. This power level and power density are significantly higher than other mechanisms. The structure will make it possible to co-vibrate with the driving, and the structural parameters avoid the misunderstandings of traditional designs that only the power generation performance is valued and the durability can be ignored, which make the structure can be used for collecting electric energy in pavement.

Preparation and characterization of flexible PVDF-HFP film for piezoelectric applications

We report on the preparation of electroactive β-phase in polyvinylidene fluoride hexafluoropropylene (PVDF-HFP) without any electrical poling treatment. The PVDF-HFP film with various mass fractions (wt%) of magnesium chloride hexahydrate salt (MgCh∼6H2O) was fabricated by a solution casting technique. The morphological, mechanical, structural and dielectric properties were investigated. Results founded that the PVDF-HFP composite films show a large number of micro-pores on the top surface as a sponge-like structure. The Young’s modulus and crystallinity values tend to be linearly decreased with the MgCh2⋗6H2O concentration leading to enhance flexibility. The largest β-phase fraction of 87.2% is found in the composite with 1 wt% MgCh2⋗6H2O filler. The obtained value is 4 times higher than the value of unfilled PVDF-HFP. Moreover, the maximum value of dielectric constant is about 19.2 at 10 Hz for 4 wt% MgCh2⋗6H2O filler. Therefore, the modified composites with the excellent flexibility, dielectric constant and β-phase may be a promising material for applications in the field of piezoelectric energy conversion.

Piezoelectric energy conversion by lead-free perovskite BaTiO3 nanotube arrays fabricated using electrochemical anodization

Synthesis approaches for diverse morphologies of 1D piezoelectric ceramic nanomaterials are still challenging to investigate nanoscale properties and applications. In this work, we demonstrated a vertically grown barium titanate (BaTiO3; BT) nanotube (BT NT) arrays fabricated using optimized electrochemical anodization and hydrothermal reaction. The centimeter-scale synthesized BT NT arrays with a high aspect ratio of up to 300 showed the complete perovskite crystal structure and the notable piezoelectric coefficient of ~180 pm·V−1. A single BT NT-based piezoelectric device was fabricated on a flexible plastic substrate using a highly controlled focused ion beam-assisted method. The single BT NT device produced a piezoelectric voltage of ~150 mV and a current of ~3 nA when the NT was mechanically stimulated by bending and releasing, which are higher than previously reported values for 1D piezoelectric nanoscale materials. Finally, a flexible piezoelectric energy harvester (f-PEH) was achieved using vertically grown BT NT arrays with an elastomer as a vertically aligned nanocomposite; its generated maximum open-circuit voltage and short-circuit current were ~1.0 V and ~20 nA, respectively. The approach in this study can propose the vision for more advanced 1D piezoceramic nanomaterials and future piezoelectric nanodevices.

270-degree arc-shaped piezoelectric energy converter in uniflow fluid environment

Energy harvesting in uniflow fluid environment aims at ambient energy that can be used in water environment for monitor equipment. In this paper, we focus on coupling both bending vibration and torsional vibration to gain better power generation. A novel structure of energy converter(arc-shaped) was designed and manufactured. Meanwhile the influence of vibrator with and without a pelvic fin was tested. Mathematical analyse due to vibration phenomenon and experimental result are reported. The 270-degree arc-shaped ring size piezoelectric ceramic is verified capable of producing an effective voltage over 10 V with the power of 0.5 mW.

Development of the optimal bluff body for wind energy harvesting using the synergetic effect of coupled vortex induced vibration and galloping phenomena

This study mainly focuses on the development of a bluff body for an efficient wind energy harvesting through the combination of two typical flow-induced motions: Vortex-induced vibration (VIV), and galloping. We investigated, both theoretically and experimentally, the possibility of the synergetic effect of coupled VIV and galloping motions based on two types of widely applied cross-sectional shapes of a bluff body (circular and square cylinder). A series of D cross-sectional cylinders were designed and fabricated with varying cutting angles and afterbody lengths, and their dynamic responses were investigated over a practical wind speed range. A newly-designed bulb cross-sectional cylinder (15 × 10 bulb cylinder) is proposed as an optimally-shaped bluff body, which can maximize the synergetic effect of VIV and galloping through the dynamic coupling of these two phenomena. The proposed bluff body is then applied to a wind-based vibratory energy harvester (WBVEH) that uses a piezoelectric energy conversion mechanism, leading to a significant average power increase of 75% over the entire wind speed range of concern and a maximum power lift rate of 193% at a wind speed of approximately 2.95 m/s, compared to the reference square cross-sectional bluff body.

Layout Optimization Design of Two Vortex Induced Piezoelectric Energy Converters (VIPECs) Using the Combined Kriging Surrogate Model and Particle Swarm Optimization Method

The layout configuration of Vortex Induced Piezoelectric Energy Converters (VIPECs) is essential to improve its overall performance. Based on the formations of migrating geese, the configuration is characterized by two nondimensionalized layout parameters. A number of sampled points for different configurations are simulated with the two-dimensional Computation Fluid Dynamics (CFD) method. The influence of layout configurations on VIPECs’ lift force and wake structure is investigated and the generated open circuit output voltage is obtained through the derived output voltage equation. The response surface model of the output voltage of both the leading VIPEC and the following VIPEC and their summation are established using the Kriging surrogate model based on the obtained simulation results. Then, optimal layout parameters are found through the Particle Swarm Optimization (PSO) algorithm, and its predicted result is compared with that of the CFD simulation. The simulation and optimization results reveal that the output voltage is not always consistent with the lift force on the plate. When VIPECs are placed in parallel with a certain spacing, their overall performance increases. The summation of output voltage is predicted to improve by approximately 63.7% compared to two single VIPECs when they are placed at the optimal layout parameters.

Strain generation and energy-conversion mechanisms in lead-based and lead-free piezoceramics

Abstract

Durable, efficient, and flexible piezoelectric nanogenerator from electrospun PANi/HNT/PVDF blend nanocomposite

Currently, there is considerable research focus on portable, lightweight, shock‐resistant, and inexpensive wearable devices that are ideally powered by harvesting abundant mechanical or vibration energy, making battery or related wiring superfluous. In this study, piezoelectric nanogenerator was electrospun from PANi (polyaniline)/HNT (halloysite nanotube)/PVDF (poly[vinylidene fluoride]) blend nanocomposite. Polymorphism, crystallinity and morphology of the nanogenerator were explored in detail. HNT and PANi acted as a nucleating agent and conductive filler, respectively in PVDF; their synergism helps improve the piezoelectric performance of PVDF. The piezoelectric performance of the nanogenerator patch was studied under various external mechanical stresses, such as pressure, tapping, and impact. A maximum voltage output of approximately 7.2 V was generated by the nanogenerator under impact. The nanogenerator patch attached to human arm exhibited not only excellent piezoelectric response during arm movements, but, also proved to be flexible, highly sensitive and durable. This nanogenerator could possibly be used in wearable piezoelectric energy conversion application for self‐powered devices. POLYM. COMPOS., 40:1663–1675, 2019. © 2018 Society of Plastics Engineers

All-Organic High-Performance Piezoelectric Nanogenerator with Multilayer Assembled Electrospun Nanofiber Mats for Self-Powered Multifunctional Sensors

Rapid development of wearable electronics, piezoelectric nanogenerator (PNG), has been paid a special attention because of its sustainable and accessible energy generation. In this context, we present a simple yet highly efficient design strategy to enhance the output performance of an all-organic PNG (OPNG) based on multilayer assembled electrospun poly(vinylidene fluoride) (PVDF) nanofiber (NF) mats where vapor-phase polymerized poly(3,4-ethylenedioxythiophene)-coated PVDF NFs are assembled as electrodes and neat PVDF NFs are utilized as an active component. In addition to the multilayer assembly, electrode compatibility and durability remain a challenging task to mitigate the primary requirements of wearable electronics. A multilayer networked three-dimensional structure integrated with a compatible electrode thereby provides enhanced output voltage and current (e.g., open-circuit voltage, Voc ≈ 48 V, and short-circuit current, Isc ≈ 6 μA, upon 8.3 kPa of the applied stress amplitude) with superior piezoelectric energy conversion efficiency of 66% compared to the single-mat device. Besides, OPNG also shows ultrasensitivity toward human movements such as foot strikes and walking. The weight measurement mapping is critically explored by principal component analysis that may have enormous applications in medical diagnosis to smart packaging industries. More importantly, fatigue test under continuous mechanical impact (over 6 months) shows great promise as a robust wearable mechanical energy harvester.

(Invited) Piezoelectric Peptide-Based Energy Harvesters

Nanoscale energy harvester holds promise for the development of self-powered nanosystems, while molecular self-assembly of bio-inspired materials has attracted much research effort in recent years. Here we report the controlled growth of vertically aligned FF peptide microrods and their application in nanogenerators. The peptide has recently been demonstrated as a sustainable and smart material for piezoelectric energy conversion. Utilizing both piezoelectric and triboelectric effects is of significant research interest due to their complementary energy conversion mechanisms. We discovered a simple and efficient approach to integrate the piezoelectric nanogenerator with triboelectric nanogenerator. The stacking one layer atop the piezoelectric peptide-based nanogenerator to form the single-electrode triboelectric nanogenerator eliminate the needed extra electrode and complicated connection found in other devices. The energy conversion process is simplified and improved. This work demonstrated the first biomaterial-based hybrid nanogenerator and significantly advanced the study of smart biomaterials. Our work can enable new applications of bio-inspired materials in areas such as energy harvesting and storage, electromechanical sensing and actuation, drug delivery, as well as fundamental studies of FF-based structures.

Lead iodide nanosheets for piezoelectric energy conversion and strain sensing

Flexible piezoelectric devices are attractive for energy conversion and strain sensing applications, including in the area of wearable electronics and self-powered sensors. Here, we report a piezoelectric nanogenerator/strain sensor based on lead (II) iodide (PbI2) nanosheets with the shape of two-dimensional (2D) structures, of which the piezoelectricity is not affected by the number of layers. A typical 2D piezoelectric device fabricated with 3 layers PbI2 nanosheets has recorded peak values of open-circuit voltage, short-circuit current and loading power as 29.4 mV, 20 pA, and 0.12 pW, respectively, and also possess good charging and integration capabilities. Moreover, these devices can be applied as self-powered strain sensors, with high sensitivity and excellent stability. As such, this study provides new knowledge and strategy for flexible energy harvesting or strain sensing devices based on 2D structures.

Design and CFD Simulations of a Vortex-Induced Piezoelectric Energy Converter (VIPEC) for Underwater Environment

A novel vortex-induced piezoelectric energy converter (VIPEC) is presented in this paper to harvest ocean kinetic energy in the underwater environment. The converter consists of a circular cylinder, a pivoted plate attached to the tail of the cylinder, several piezoelectric patches and a storage circuit. Vortex-induced pressure difference acts on the plate and drives the plate to squeeze piezo patches to convert fluid dynamic energy into electric energy. The output voltage is derived from the piezoelectric constitutive equation with fluid forces. In order to evaluate the performance of the VIPEC, two-dimensional computational fluid dynamics (CFD) simulations based on the Reynolds averaged Navier–Stokes (RANS) equation and the shear stress transport (SST) k- ω turbulence model are conducted. The CFD method is firstly verified for different grid resolutions and time steps, and then validated using simulation and experimental data. The influences of the plate length and flow velocity on the wake structure, the driving force and the performance of the VIPEC are investigated. The results reveal that different parameters reach their peaks at different plate lengths, and the converter has a maximal output voltage of 2.3 mV in a specified condition and the maximal power density reaches 0.035 μ W/m 3 with a resistance load of 10 M Ω . The influence of the simulated subcritical Reynolds number on the driving force is not noticeable. The simulation results also demonstrate the feasibility of this device.

Mathematical modelling of energy harvesting in piezo embedded electric vehicle tyres together with self-health assessment of suspension system

This paper proposes embedding piezoelectric material inside the electric vehicle (EV) tyres. The paper focuses on two aspects: one pertains to the mathematical modelling of energy harvesting through piezoelectric energy conversion inside the tyre, and the other to collecting and processing the mechanical stress data obtained from the embedded piezoelectric material. The electrical energy generated due to mechanical strain of the piezoelectric material is utilised to charge the battery. Concurrently the material stress-strain data generated by, and collected from the piezoelectric material, is used to extract valuable real-time information. This information is used for condition based maintenance of tyres and suspension system that includes remaining useful life of tyres, uneven or excessive tyre wear, need for wheel balancing, suspension system health assessment, and wheel alignment. Thus, the proposed system will not only reduce the driving range anxiety, it will also enhance vehicle health and safety and lead to concomitant savings.