Piezoelectric Energy Harvesting Devices Research Articles

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.

Design a low-frequency vibration energy harvesting device based on a square spiral beam local resonant phononic crystal

Self-powered miniature wireless sensors play a crucial role in Internet of Things technology. Harvesting low-frequency environmental vibrations to achieve self-powering of sensors is a current hot topic in research. In this study, a square spiral beam local resonant phononic crystal is designed for low-frequency vibrational energy harvesting. Initially, the bandgap and vibrational modes of an ideal phononic crystal at infinite period are analyzed by the finite element method; the possibility of using the structure to harvest vibrational energy is explored. Subsequently, a PnC plate model with a unit cell is built, and its vibrational modes are analyzed, verifying that it possesses similar vibrational properties. Following this, a piezoelectric vibration energy harvesting device is assembled and its energy harvesting performance is analyzed. Numerical simulations indicate that the designed device can achieve a maximum power density of 52.14 μW/cm2. Physical experiments validate the excellent energy harvesting performance of the device. The device offering a new option for designing self-powered devices for wireless miniature sensors.

Efficient energy harvesting enabled by large-area piezoelectric PVDF-based composite film enhanced by carbon nanotubes

Considerable attention has been drawn to the use of flexible piezoelectric energy harvesting devices for powering smart wearable technology. Herein, we employed a melt extrusion casting process to prepare large-area PVDF-based piezoelectric composite films and achieved continuous production. The films were prepared by adding 15 wt% lead zirconate titanate powder modified with a titanium coupling agent (PZT@UP15) and different content of carbon nanotubes (CNTs) exhibiting high conductivity into the PVDF matrix. The addition of CNTs in moderate amounts significantly enhanced the mechanical, dielectric, and piezoelectric properties of the composite films. Remarkably, the composite film containing 0.06 wt% CNTs achieved a d33 value of 28 pC/N, generated an open circuit voltage of 16.85 V, and a maximum power density of 0.46 μW/cm2 in the bending-releasing mode. Furthermore, the film exhibited relatively stable output performance even after 1500 cycles. The enhanced performances of the piezoelectric composite films can be attributed to the factors that the CNTs can effectively promote PVDF polarization by inducing dipole alignment and building an internal electric field, and further improve the piezoelectric performance and the electrostrictive performance. This work shows that the prepared piezoelectric composite film holds great potential as an energy harvesting device to provide power for wearable electronic devices.

Passively Tuning the Resonant Frequency of Kinetic Energy Harvesters Using Distributed Loaded Proof Mass

The inability to tune the frequency of MEMS vibration energy-harvesting devices is considered to be a major challenge which is limiting the use of these devices in real world applications. Previous attempts are either not compatible with microfabrication, have large footprints, or use complex tuning methods which consume power. This paper reports on a novel passive method of tuning the frequency by embedding solid microparticle masses into a stationary proof mass with an array of cavities. Altering the location, density, and volume of embedded solid filler will affect the resonant frequency, resulting in tuning capabilities. The experimental and computational validation of changing and tuning the frequency are demonstrated. The change in frequency is caused by varying the location of the particle filler in the proof mass to alter the center of gravity. The goal of this study was to experimentally and numerically validate the concept using macro-scale piezoelectric energy-harvesting devices, and to determine key parameters that affect the resolution and range of the frequency-tuning capabilities. The experimental results demonstrated that the range of the frequency tuning for the particular piezoelectric cantilever that was used was between 20.3 Hz and 49.1 Hz. Computational simulations gave similar results of 23.7 Hz to 49.4 Hz. However, the tuning range could be increased by altering the proof mass and cantilever design, which resulted in a tuning range from 144.6 Hz to 30.2 Hz. The resolution of tuning the frequency was <0.1 Hz.

Accurate finite element modeling of multilayered flexible piezoelectric energy harvesting devices with strong coupling of structure, piezoelectricity, and circuit

Multilayered flexible piezoelectric energy harvesting devices (FPEDs) are a new future harvesting technology which are highly flexible and lightweight than familiar cantilever piezoelectric energy harvesters. This mechanical vibration driven FPED is a strongly coupled multiphysics phenomena that involve complex natural three-way interaction among the composite piezoelectric structure, the electric charge accumulated in the piezoelectric material, and a controlling electrical circuit attached to it. Efficient and accurate computational solution approaches are essential for analyzing these mechanical vibration-driven FPEDs to capture the main physical aspect of the coupled phenomena and to accurately predict the output voltage. While there are some numerical models for simple familiar cantilever type piezoelectric energy harvester reported in the literature, a fully three-dimensional strongly coupled model for complex material distributed, complex geometry, and multilayered FPED involving strong coupling of structure, piezoelectricity, and circuit phenomena has not yet been developed. A partitioned iterative algorithm is developed using a hierarchical decomposition approach wherein the coupled three fields are solved separately and coupled through loop union integration techniques that provide an efficient and accurate simulation of FPEDs. The simulation results matched the experiment results very well. This study provides a basis for the natural extension of partitioned iterative finite element coupled algorithm to simulate the future piezoelectric energy harvesting technologies involving a strong coupling of structure, piezoelectricity, and circuit phenomenon.

Multi-functional piezoelectric nanogenerator based on relaxor ferroelectric materials (BSTO) and conductive fillers (MWCNTs) for self-powered memristor and optoelectronic devices

Nowadays self-charging memristors and photodetectors open the path for future research into energy-autonomous electronics which hold the promise of enabling exceptionally efficient applications in memory storage, small portable electronics, neuromorphic computing, and optoelectronics devices. Hence, in the recent era, much research work has been focused on the development of nanogenerators for technological applications. In this regard, the main aim of the present study is to develop a multi-functional piezoelectric nanogenerator based on relaxor ferroelectric materials having three-phase MWCNTs/BSTO/PVDF nanocomposites. BSTO and CNT fillers promote >80 % electroactive phase nucleation in PVDF, making it appropriate for piezoelectric energy harvesting devices. Incorporating conductive fillers (CNTs) and dielectric fillers (BSTO) into the PVDF matrix enhances the piezoelectric nanogenerator's dielectric, ferroelectric, and output performance. PENG based on an optimized BSTO-CNTs-PVDF composite (with 20 % BSTO and 0.20 % CNTs loading) produced an output power of 31.5 µW with a high open-circuit voltage of 42 V and a short-circuit current of 9 µA, it demonstrates enough capability to power up small portable electronic devices. This work can also be used for a realistic technique for generating self-powered memristors and photodetectors for extremely efficient memristive neural networks and optoelectronics devices. Demonstration of power generation of the prepared device by different activities is demonstrated.

Design, Multi-Perspective Computational Investigations, and Experimental Correlational Studies on Conventional and Advanced Design Profile Modified Hybrid Wells Turbines Patched with Piezoelectric Vibrational Energy Harvester Devices for Coastal Regions

This work primarily investigates the performance and structural integrity of the Wells turbines for power production in coastal locations and their associated unmanned vehicles. An innovative design procedure is imposed on the design stage of the Wells turbine and thus so seven different models are generated. In the first comprehensive investigation, these seven models underwent computational hydrodynamic analysis using ANSYS Fluent 17.2 for various coastal working environments such as hydro-fluid speeds of 0.34 m/s, 1.54 m/s, 12 m/s, and 23 m/s. After this primary investigation, the best-performing Wells turbine model has been imposed as the second comprehensive computational investigation for three unique design profiles. The imposed unique design profile is capable of enhancing the hydro-power by 15.19%. Two detailed, comprehensive investigations suggest the best Wells turbine for coastal location-based applications. Since the working environments are complicated, additional advanced computational investigations are also implemented on the best Wells turbine. The structural withstanding capability of this best Wells turbine model has been tested through coupled computational hydro-structural analysis for various lightweight materials. This best Wells turbine also enforces the vibrational failure factors such as modal and harmonic vibrational analyses. Finally, advanced and validated coupled engineering approaches are proposed as good methodology for coastal location-based hydropower applications.

Piezoelectric energy-harvesting devices for wearable self-powering system

Piezoelectric energy-harvesting devices for wearable self-powering system

Experimental study on power generation performances of a novel piezoelectric energy harvester

In this article, a new type of piezoelectric energy harvester device is proposed, which has good output performance and can scavenge a large amount of vibration energy at low frequency. By setting up the experimental platform and testing, the results show that the external resistance, the mass of the cantilever end, the excitation acceleration and the magnet distance have an impact on the device. When the mass of the end of the cantilever beam is 15 g and the acceleration is 0.5 g, the output power of the device is 5.2 mW, and the output performance is good.

Piezoelectric power generation using vibrations from human heart

In past decades, energy harvesting using piezoelectric materials has offered various opportunities towards implementing self-powered electronic devices. In the direction of wearable devices, this paper is mainly focused towards charging the pacemaker device from human heart vibration using piezoelectric energy harvesting (PEH) technique. Here, a fan-folded piezoelectric energy harvesting (FF-PEH) device has been investigated to meet with the basic power requirement of pacemaker device. Initially, a simulation study has been conducted to observe the voltage-power-frequency response of FF-PEH using COMSOL Multiphysics version 5.4. Further, the behavior of FF-PEH has been optimized for variation in different materials used. It has been observed that by choosing PZT-5H, silicon and platinum as piezoelectric, substrate and rigid beam materials respectively, the FF-PEH device is capable to provide 10.19 μW power at 20 Hz resonant frequency.

Tailoring Triple Filler Systems for Improved Magneto-Mechanical Performance in Silicone Rubber Composites.

The demand for multi-functional elastomers is increasing, as they offer a range of desirable properties such as reinforcement, mechanical stretchability, magnetic sensitivity, strain sensing, and energy harvesting capabilities. The excellent durability of these composites is the key factor behind their promising multi-functionality. In this study, various composites based on multi-wall carbon nanotubes (MWCNT), clay minerals (MT-Clay), electrolyte iron particles (EIP), and their hybrids were used to fabricate these devices using silicone rubber as the elastomeric matrix. The mechanical performance of these composites was evaluated, with their compressive moduli, which was found to be 1.73 MPa for the control sample, 3.9 MPa for MWCNT composites at 3 per hundred parts of rubber (phr), 2.2 MPa for MT-Clay composites (8 phr), 3.2 MPa for EIP composites (80 phr), and 4.1 MPa for hybrid composites (80 phr). After evaluating the mechanical performance, the composites were assessed for industrial use based on their improved properties. The deviation from their experimental performance was studied using various theoretical models such as the Guth-Gold Smallwood model and the Halpin-Tsai model. Finally, a piezo-electric energy harvesting device was fabricated using the aforementioned composites, and their output voltages were measured. The MWCNT composites showed the highest output voltage of approximately 2 milli-volt (mV), indicating their potential for this application. Lastly, magnetic sensitivity and stress relaxation tests were performed on the hybrid and EIP composites, with the hybrid composite demonstrating better magnetic sensitivity and stress relaxation. Overall, this study provides guidance on achieving promising mechanical properties in such materials and their suitability for various applications, such as energy harvesting and magnetic sensitivity.

Nature-Driven Biocompatible Epidermal Electronic Skin for Real-Time Wireless Monitoring of Human Physiological Signals.

Wearable bioelectronic patches are creating a transformative effect in the health care industry for human physiological signal monitoring. However, the use of such patches is restricted due to the unavailability of a proper power source. Ideal biodevices should be thin, soft, robust, energy-efficient, and biocompatible. Here, we report development of a flexible, lightweight, and biocompatible electronic skin-cum-portable power source for wearable bioelectronics by using a processed chicken feather fiber. The device is fabricated with a novel, breathable composite of biowaste chicken feather and organic poly(vinylidene fluoride) (PVDF) polymer, where the chicken feather fiber constitutes the "microbones" of the PVDF, enhancing its piezoelectric phase content, biocompatibility, and crystallinity. Thanks to its outstanding pressure sensitivity, the fabricated electronic skin is used for the monitoring of different human physiological signals such as body motion, finger and joint bending, throat activities, and pulse rate with excellent sensitivity. A wireless system is developed to remotely receive the different physiological signals as captured by the electronic skin. We also explore the capabilities of the device as a power source for other small electronics. The piezoelectric energy harvesting device can harvest a maximum output voltage of ∼28 V and an area power density of 1.4 μW·cm-2 from the human finger imparting. The improved energy harvesting property of the device is related to the induced higher fraction of the electroactive phase in the composite. The easy process ability, natural biocompatibility, superior piezoelectric performance, high pressure sensitivity, and alignment toward wireless transmission of the captured data make the device a promising candidate for wearable bioelectronic patches and power sources.

Current Achievements in Flexible Piezoelectric Nanogenerators Based on Barium Titanate

Harvesting ambient mechanical energy at the nanometric scale holds great promise for powering small electronics and achieving self-powered electronic devices. The current review is focused on kinetic energy harvesters, particularly on flexible piezoelectric nanogenerators (p-NGs) based on barium titanate (BaTiO3) nanomaterials. p-NGs based on nanotubes, nanowires, nanofibres, nanoplatelets, nanocubes or nanoparticles of BaTiO3 fabricated in vertical or lateral orientation, as well as mixed composite structures, are overviewed here. The achievable power output level is shown to depend on the fabrication method, processing parameters and potential application conditions. Therefore, the most widely studied aspects, such as influence of geometry/orientation, BaTiO3 content, poling process and other factors in the output performance of p-NGs, are discussed. The current standing of BaTiO3-based p-NGs as possible candidates for various applications is summarized, and the issues that need to be addressed for realization of practical piezoelectric energy harvesting devices are discussed.

Design and Modeling of a PVDF-TrFe Flexible Wind Energy Harvester

This study presents the simulation, experimentation, and design considerations of a Poly(vinylidene fluoride co-trifluoroethylene)/ Polyethylene Terephthalate (PVDF-TrFe / PET), laser-cut, flexible piezoelectric energy harvester. It is possible to obtain energy from the environment around autonomous sensor systems, which can then be used to power various equipment. This article investigates the actuation means of ambient vibration, which is a good candidate for using piezoelectric energy harvester (PEH) devices. The output voltage characteristics were analyzed in a wind test apparatus. Finite element modeling (FEM) was done for von Mises stress and modal analysis. Resonance frequency sweeps, quality factors, and damping ratios of the circular plate were given numerically. For a PVDF-TrFe piezoelectric layer thickness of 18 µm and 1.5 mm radius, a damping ratio of 0.117 and a quality factor of 4.284 was calculated. Vmax was calculated as 984 mV from the wind setup experiments and compared with the FEM outputs.

新型杂化金属硫氰化物压电体用于能量收集和动作传感

Hybrid organic-inorganic piezoelectrics have received considerable attention in recent years owing to their fascinating performance, facile synthesis, and mechanical flexibility. However, the reported systems usually contain toxic heavy metals or are unstable due to sensitive metal halide bonds in air. In this context, eco-friendly and stable hybrid materials with excellent piezoelectric properties are highly sought after. Here, a new stable zero-dimensional hybrid piezoelectric, [Me-V]3Mn(SCN)5 (Me-V, 1-methyl-[4,4′]-bipyridinium), based on a pseudo-halogen environmentally friendly anion of SCN− was synthesized. More importantly, the mechanical energy harvesting properties of its flexible composite films, [Me-V]3Mn(SCN)5/PBAT (PBAT, polybutylene adipate terephthalate), with a series of weight ratios (1, 5, 10, 15, and 20 wt%) of [Me-V]3Mn(SCN)5 are reported. Experimental results demonstrate that the 15 wt% [Me-V]3Mn-(SCN)5/PBAT devices present an exceptional performance in energy harvesting, which can produce a maximum output voltage of 18.49 V and a power density of 7.88 µW cm−2 under an applied force of only 0.03 MPa, catching up with those of the state-of-the-art piezoelectric energy harvesting devices. Meanwhile, a typical device was demonstrated to exhibit excellent mechanical durability under 5500 cycles and environmentally stable over 60 days. Furthermore, the devices also show good sensitivity in monitoring human body motions, including finger tapping, wrist and elbow bending, and foot stepping. This work proves that lead- and halide-free hybrid piezoelectrics can serve as eco-friendly materials for flexible sensing and energy harvesting.

A dual-cantilever based MEMS PZT thick-film energy harvester with enhanced internal resonance performance

In this paper, a multi-frequency vibrational piezoelectric energy harvester (PEH) with a dual-microcantilever coupled structure based on the internal resonance effect is proposed. The device consists of a low-frequency cantilever and a high-frequency cantilever with an integer multiple of resonant frequencies connected by a clamped–clamped coupling beam. The internal resonant PEH (IR-PEH) is prepared by the microelectromechanical systems piezoelectric thick-film process based on the flexible thin metal substrate. The output performance of the proposed PEH device is greatly improved by taking advantages of the internal coupling structure and the piezoelectric thick-film microfabrication process. Under the excitation acceleration of 2 g, the maximum power output of IR-PEH reaches 424.6 μW at 190 Hz and 108.8 μW at 365 Hz, which increases by 35% of the power output due to the internal resonance coupling comparing with the PEH without the coupling effect. The corresponding power densities of IR-PEH reach 6.3 and 1.6 mW/cm3, respectively. This IR-PEH configuration induces the competitive advantages of good performance, wide bandwidth, and small volume, which can be potentially employed as a power source for low power wireless sensing nodes.

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.

Advancements and applications of piezoelectric energy harvesters: A comprehensive review

This paper reviews current research on piezoelectric energy harvesting devices for low-frequency applications (0- 100Hz). It explores the challenge of optimizing energy output due to the high elastic moduli of piezoelectric materials. Key aspects contributing to harvester performance are discussed, aiming to minimize reliance on external power and maintenance for devices like wireless sensor networks. Optimizing geometry and dimensions of piezoelectric elements enhances energy conversion efficiency by matching vibration frequencies. Efficient energy management circuits are crucial for capturing and storing harvested energy effectively. These circuits must be capable of efficiently converting the AC output of the piezoelectric harvester into a stable DC voltage suitable for powering electronic devices or charging energy storage devices such as batteries or capacitors. In addition to material and design considerations, environmental factors such as temperature variations and humidity levels can significantly impact the performance of piezoelectric energy harvesters. Therefore, robust encapsulation techniques must be employed to protect the harvester from adverse environmental conditions while ensuring long-term reliability. Overall, this paper provides insights into the current challenges and advancements in the field of piezoelectric energy harvesting for low-frequency applications, offering valuable perspectives for future research and development efforts in this area.

Vibration Characteristics and Experimental Research of an Improved Bistable Piezoelectric Energy Harvester

Bistable piezoelectric energy harvester (BPEH) can remove mechanical energy waste, which is expected to realize the self-power supply of wireless sensors. To further improve the energy harvesting efficiency, we designed an improved bistable piezoelectric energy harvester (IBPEH). The restoring force model of the composing beam is acquired based on fitting experimental data, and the nonlinear magnetic model is obtained by using the magnetic dipole method. The electromechanical coupling dynamics model of the system is established based on Newton’s second law and Kirchhoff’s law. Based on the control variable method, the influences of excitation frequency and excitation amplitude on the vibration characteristics of IBPEH and BPEH are compared in simulation analysis. Moreover, the correctness of the theoretical analyses is verified by experiments. The results show that variations in the number of magnets and appropriate adjustments in their positions can broaden the operating frequency bandwidth of the bistable piezoelectric energy harvester, and realize large-amplitude periodic motion at lower excitation amplitudes. IBPEH can yield a higher voltage than BPEH under the same excitation conditions. This paper provides a theoretical basis for optimizing the potential well and further improving the electric energy harvest efficiency of the bistable piezoelectric energy harvester device.

Mechanical performance of composites reinforced with carbon black and different types of graphitic nanofillers for different applications

The piezo-electric energy harvesting devices based on rubber composites have attracted great attention in the field of flexible electronics. These devices have the ability to provide a voltage of ∼0.5 V when subjected to mechanical strain. In this work, carbon allotropes nanofillers were used to reinforce the room-temperature vulcanized silicone rubber (RTV-SR). The nanofillers added to the rubber matrix were found to improve the compressive modulus, tensile strength, fracture strain, and tensile modulus. For example, the compressive modulus was 1.29 MPa (Virgin) and improved to 1.4 MPa (graphene), 2.3 MPa (CB), 2.2 MPa (CB–graphite hybrid), 2.17 MPa (CB–Nano graphite hybrid), and finally 2.19 MPa (CB–graphene hybrid). Similarly, the fracture strain was 146% (Virgin) and improved to 149% (graphene), 156% (CB), 160% (CB–graphite hybrid), 151% (CB–Nano graphite hybrid), and lastly 178% (CB–graphene hybrid). Moreover, the effect of three different diameters of loading tips is used for voltage production. More areas of deformation during energy harvesting can be able to produce higher voltage output. For example, a 21 mm tip can produce higher energy output than 7 mm and 14 mm. In the end, it was found that formation of cracks in the electrode while repeated loading causes a reduction in voltage output.