Piezoelectric Energy Harvesting Devices Research Articles

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.

Great new generation carbon microsphere-based composites: Facile synthesis, properties and their application in piezo-electric energy harvesting

In this work, new generation carbon microspheres (CMS) based rubber composites have been obtained for flexible electronics applications such as stretchable piezo-electric energy harvesting devices. The rubber matrix used was room-temperature-vulcanized silicone rubber (RTV-SR). Herein, the CMS was exploited as a source of reinforcement and conductive material for improving mechanical and electrical properties. For example, the compressive modulus was 2.1 MPa (virgin) and increased to as high as 3.3 MPa (5 phr CMS). Similarly, the Shore A hardness was 26 (virgin) and increased to 40 (5 phr CMS). The electrical properties were also influenced significantly with electro-chemical resistance of 22.05 kΩ (virgin) and decreased to 15.91 kΩ (5 phr CMS). CMS's XPS spectrum revealed a high carbon-to-oxygen atomic ratio (74.47 and 25.53 %). The carbon and oxygen-containing functional groups of CMS acted as a catalyst to improve interfacial interaction of the composites thereby leading to higher mechanical properties. These improved properties were explored in the real-time device and output voltage generation with high durability was tested. From measurements, it was found that the output voltage from the piezo-electric energy harvesting device was around 1.25 V and high durability of 0.5 million cycles was reported.

Study on vibration and power generation performance of percussive piezoelectric energy harvester device

In this paper, a percussive piezoelectric energy harvester device is proposed, which can better obtain the vibration energy in the low frequency. Through the construction of the experimental prototype and the experimental test, the results show that the output power is affected by the acceleration and the thickness of the percussive beam. When the free end mass of the piezoelectric beam is 3 g and the excitation frequency is 12.8 Hz, the maximum output power of the energy harvester is 316.8 μW. It is 2.3 times of the maximum output power of the energy harvester without mass.

Research on a novel non-linear magnetically coupled piezoelectric self-powered mouse

Based on the charging problem of wireless mouse, a magnetically coupled piezoelectric self-powered mouse is proposed in this paper. The piezoelectric self-powered mouse innovatively combines piezoelectric technology and scroll wheel structure into one. Moreover, the coupling in the structure deforms the piezoelectric element by magnetic force, avoiding damage to the piezoelectric element by direct contact. The introduction of non-linear forces improves the energy harvesting efficiency of the energy harvester. The distance between the piezoelectric cantilever beam and the rollers, and the number of magnets on the rollers are used as the study variables in this experiment. At a speed of 550 r/min, when the distance between the magnet attached to the free end of the piezoelectric cantilever beam and the mouse wheel is 17 mm and the number of magnets on the wheel is 4, the whole piezoelectric energy harvesting device has the maximum peak-to-peak voltage generated is 25.15 V. Through the design of the cantilever beam, greater deflection can be produced under the conditions of external force and size determination. The design of the structure is highly compatible with the actual mouse structure, which provides a great possibility to further combine the piezoelectric element with the mouse structure.

Dramatically enhanced energy harvesting capability in sandwich-structure modulated piezoelectric nanocomposites

Piezoelectric energy harvesting devices (PEHs) offer great potential for diverse electronic applications. However, it is still a great challenge to well combine appropriate mechanical strength and high output performance in composite-type PEHs. Herein, the sandwich-structured composite-type PEHs for high-output mechanical energy harvesting using piezoelectric Barium titanate nanoparticles and poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) copolymers matrix is reported. By intentionally modulating the distribution of piezoelectric nanoparticles in polymer matrix, a highest output of ∼60 V (open-circuit voltage), and ∼65 μW/cm3 (power density at load resistance of 50 MΩ), respectively, was obtained. Via mechanical property and energy harvesting capability quantification, the dramatically improved energy harvesting capability is determined to be stemmed from the stress-enforcement in embedded piezoelectric nanoparticles and optimized piezoelectric response. Besides, the device presents a sufficient mechanical durability, which endows it the ability for long time stable operation. This work sheds light on a universal strategy for fabricating high-performance composite-type PEHs by constructing a gradient distribution of piezoelectric active nanoparticles in polymer matrix.

Interaction integral approach for the Evaluation of Crack-front Singularities in a Solid Cantilever Beam under Magneto-Electro-Elastic loading using XFEM

In the piezoelectric energy harvesting devices, the most preferred is the cantilever beam orientation that can produce maximum deflection. Therefore, in this paper, three-dimensional fracture analysis of a cracked magneto-electro-elastic cantilever beam is studied using extended finite element methods (XFEM). The crack-front singularities like stress intensity factors (SIFs), electric displacement intensity factor (EDIF), and magnetic induction intensity factor (MIIF) are evaluated using the MEE interaction integral approach. The contour J-integral in domain form is solved with the asymptotic crack front fields as auxiliary fields using the Stroh formalism. The numerical results showed good agreement with the benchmark problem. Few case studies for the crack front singularities are presented using the proposed method. The results provided give useful guidance in the designing and manufacturing of smart devices.

Elastic wave harvesting in piezoelectric-defect-introduced phononic crystal microplates

The localization of elastic wave at defect in phononic crystals (PnCs) has been applied to design piezoelectric energy harvesting (PEH) devices. However, the earlier researches were based on classical linear elasticity theory, which failed to predict the structural behavior at the micron scale. Based on a modified couple stress theory (MCST) and a mixed finite element method, the physics builder in COMSOL® Multiphysics is used to develop a novel interface that can capture the microstructure-dependent size effect and be applied in the simulation of a PnC-based PEH device. Size dependence of the newly developed model is demonstrated by three sets of models at different sizes. Numerical results show that when the size effect is considered in the model, the frequencies of the bandgap and defect bands increase with decreasing model size compared to the classical theory. Furthermore, the size reduction changes the internal stiffness ratio in the model, which affects the displacement amplitude, output voltage and output electrical power of the PEH device. Therefore, size effects are inevitable in micron-level models. These discoveries would help the design of small-scale PnC-based PEH devices for enhanced energy collection.

Scavenging energy from aeroelastic vibrations for hybrid stall control in a fixed-wing micro aerial vehicle

Scavenging energy from aeroelastic vibrations was considered for a self-powered hybrid passive-active stall control system intended to improve the aerodynamic performance of fixed-wing micro aerial vehicles without exhausting available batteries. It was found that the passive component of the system generates intense streamwise vortices, which give rise to vortex-induced vibrations. Measured frequency response functions indicated accelerations in a wing prototype up to 0.1 g at relatively low frequencies, when it was operated at simulated flight conditions in a wind tunnel. Aiming to use this resource for additional power, a piezoelectric energy harvesting device was installed inside the wing and tuned for resonant response. Two electromechanical modeling approaches for the piezoelectric harvester were investigated, namely, an analytical model and finite elements simulations. A comparison with experimental results has shown that the latter approach is better equipped to deal with advanced designs, yielding accurate predictions in the present study. Extracted power and generated voltage were quantified as a function of the electric loading resistance. The reported data demonstrated that the proof of concept was achieved, so that a lightweight, low-consumption actuator for the active component of the stall control system can be powered by the energy of structural vibrations.

Optimisation of a forced multi-beam piezoelectric energy harvester

A high-power multi-beam piezoelectric energy harvesting device is designed to meet the demands of the emerging technologies in Body Sensors Networks (BSNs), Wireless Sensors Networks (WSNs), the Internet of Things (IoT) and the Industrial Internet of Things (IIoTs). The proposed device utilises a plucking mechanism to excite the beams, organised in a comb-like structure. The harvester is presented in different length configurations and its performance is optimised to deliver the highest power under a given set of parameter values, constraints, and excitation characteristics. The unique feature of the device is that it can be tuned to any given frequency, although it demonstrates its superior performance in the frequency range of 2–50 Hz, delivering hundreds of mW. The device optimisation is conducted using a harmonic excitation, a harmonic excitation with random phase modulations, experimental vibration data collected using an internal combustion engine, and numerical data from simulations of out-of-plane oscillations of wind turbine blades. The paper proposes solutions to a number of challenges specific for multi-beam structures that have never been addressed before. It is demonstrated for the first time that the proposed harvester is able to meet the demands of relevant sensing applications.

Novel Rubber Composites Based on Copper Particles, Multi-Wall Carbon Nanotubes and Their Hybrid for Stretchable Devices.

New technologies are constantly addressed in the scientific community for updating novel stretchable devices, such as flexible electronics, electronic packaging, and piezo-electric energy-harvesting devices. The device promoted in the present work was found to generate promising ~6V and durability of >0.4 million cycles. This stretchable device was based on rubber composites. These rubber composites were developed by solution mixing of room temperature silicone rubber (RTV-SR) and nanofiller, such as multi-wall carbon nanotube (MWCNT) and micron-sized copper particles and their hybrid. The hybrid composite consists of 50:50 of both fillers. The mechanical stretchability and compressive modulus of the composites were studied in detail. For example, the compressive modulus was 1.82 MPa (virgin) and increased at 3 per hundred parts of rubber (phr) to 3.75 MPa (MWCNT), 2.2 MPa (copper particles) and 2.75 MPa (hybrid). Similarly, the stretching ability for the composites used in fabricating devices was 148% (virgin) and changes at 3 phr to 144% (MWCNT), 230% (copper particles) and 199% (hybrid). Hence, the hybrid composite was found suitable with optimum stiffness and robust stretching ability to be useful for stretching electronic devices explored in this work. These improved properties were tested for a real-time stretchable device, such as a piezoelectric energy-harvesting device and their improved voltage output and durability were reported. In the end, a series of experiments conducted were summarized and a discussion on the best candidate with higher properties useful for prospective applications was reported.

Effect of Nd-doping on 0.95(K0.6Na0.4)NbO3-0.05(Bi0.5Na0.5)ZrO3 ceramics: Enhanced electrical properties and piezoelectric energy harvesting capability

Present work reports the influence of Nd-dopant on the structural, microstructural and di-/ferro-/piezo-electrical properties of lead-free binary piezoelectric perovskite system 0.95(K0.6Na0.4)NbO3-0.05(Bi0.5Na0.5)ZrO3 (abbreviated as KNN-BNZ). X-ray diffraction confirmed the formation of perovskite phase with coexisting tetragonal and rhombohedral phases for both the samples. The introduction of Nd3+ in KNN-BNZ resulted in reduced average grain size and curie phase transition temperature (from 347 °C to 294 °C at 1 kHz). Nd-doped KNN-BNZ ceramic showed enhanced piezoelectric response (d33 = 382 pC/N), well saturated P-E hysteresis loops (Ec = 15.27 kV/cm and Pr = 24.74 μC/cm2) with excellent fatigue stability and high pyroelectric coefficient (p ∼ 1418.4 μC/m2/oC). Based on the synthesized piezoceramics, piezoelectric energy harvesting devices were further fabricated and the open-circuit piezo-voltage from pure and Nd-doped KNN-BNZ based devices was measured to be 6.2 and 8.6 V, respectively. The obtained results highlight the candidature of Nd-doped KNN-BNZ ceramic for ferroelectric memory and mechanical vibration energy harvesting devices, as a substitute for lead based ferroelectric perovskites.

The optimal design of a piezoelectric energy harvester for smart pavements

The traffic environment contains tremendous mechanical energy due to the dynamic loads of moving vehicles which can be converted into electricity by using piezoelectric materials. Considering the road environmental characteristics, we propose here a piezoelectric energy harvester (PEH) consisting of piezoelectric ceramics that are encapsulated in epoxy resin filler between the MC nylon protective plates. As an illustration, periodic traffic loading is considered and is simulated by a controlled MTS loading, using which the effects of various system parameters on the efficiency of energy harvesting are examined. A theoretical electromechanical model is also developed to predict the energy harvesting behavior of the PEH device. The theoretical predictions agree very well with the experimental measurements, and they both suggest that various load, material, and circuit factors will have diverse effects on output power. To figure out the best collection of all factors and their simultaneous effect on the output performance, we also establish a simple and universal scaling law to reveal the underlying mechanism of the correlation between various systematic parameters. The normalized output power depends only on the normalized intrinsic impedance that consists of all material properties, geometrical, electrical circuit, and loading condition parameters. The optimization strategy may provide a useful tool to guide the design of the PEH device for enhancing the efficiency of energy harvesting by properly selecting the system parameters.

The Effects of A-site Doping on Crystal Structure, Microstructure and Electrical Properties of (Ba0.85Ca0.15) Zr0.1Ti0.9O3 Ceramics

(Ba0.85Ca0.15) Zr0.1Ti0.9O3 (BCZT) ceramics with donor (La3+ and Bi3+ ions) and acceptor (Na+ ions) doping at the A-site were fabricated in this study. The effects of crystal structure, microstructure, and chemical defects on all samples’ dielectric properties and piezoelectric coeffi cient (d33) were observed. Bi3+ ions decreased grain size, decreased phase transition temperature, and caused the diffuse dielectric spectrum, resulting in a low d33 value. Na+ ions induced abnormal grain growth, leading to enhancement in maximum dielectric constant; meanwhile, the phase transition temperature increased. The d33 value of Na-doped BCZT was comparable with BCZT ceramic. The addition of La3+ ions increased the phase transition temperature and decreased grain size. The d33 value of La-doped BCZT was lower than BCZT ceramic. The result suggested that BCZT, BCZT-Na, and BCZT-La ceramics could be alternative materials for piezoelectric energy harvesting devices.

Young’s modulus and ferroelectric property of BaTiO3 films formed by aerosol deposition in consideration of residual stress and film thickness

Film thickening by aerosol deposition (AD) is effective for the fabrication of self-sustained piezoelectric energy harvesting devices. Here we investigated the properties, microstructure, and residual stresses of BaTiO3 films deposited by AD at different film thicknesses. The Young’s modulus measured by the nanoindentation test showed no thickness dependence; however, it increased from approximately 130– 160 GPa with annealing. Ferroelectric hysteresis curves showed that the increase in film thickness facilitated polarization switching. The microstructure of the films showed no significant changes with the film thickness, while the results of X-ray diffraction and finite element analysis of thermal stress showed that the residual stress after annealing depended on the film thickness. The energy harvesting performance of the BaTiO3 films deposited by AD may increase owing to the residual stress, rather than the increase in the film thickness.

Broadband characteristics of high-performance energy-harvesting phononic crystals with point defect

As an artificial periodic material, phononic crystals (PnCs) are suitable for energy harvesting from vibration and noise environments of equipments. A two-dimensional (2D) PnC with a point defect is presented to design a piezoelectric energy-harvesting (PEH) device. Using finite element (FE) simulations, bandwidth and electric power of the initial supercell using the PnC are obtained but do not attain the optimal performance. Therefore, five geometric parameters are considered to perform the numerical experiment using a five-factor and seven-level experimental design. The two relationships between the five geometric parameters and PnCs bandwidth, the five geometric parameters, and output power are finally obtained. The two functional relationships are regarded as a unified objective function to further optimize five geometric parameters. The optimized PnC-based PEH device will achieve better output power within broadband. It is expected to be used to design PEH devices to achieve better output power in wider bandwidth.

A self-protective piezoelectric-piezoresistive dual-mode device with superior dynamic-static mechanoresponse and energy harvesting performance enabled by flextensional transduction

Dual-mode pressure sensors capable to perceive various external dynamic and static mechanical stimulus are constantly required to develop wearable electronics and smart subhuman robots. However, most sensors can hardly exhibit robust and reliable highly sensitive response to dynamic and static mechanical stimulus coming from rough or cuspidal surfaces. Here, we report a self-protective piezoelectric-piezoresistive dual-mode pressure sensor based on elastic cylinder induced flextensional transduction due to the positive Poisson effect. The cylindric design allows the transition from normal force to lateral expansion force, avoiding direct contact with rough or cuspidal surfaces and endowing the sensor with self-protective characteristic. Surprisingly, the flextensional transduction can give rise to more than 10 times amplification of the normal force to lateral expansion force, contributing to significantly enhanced sensitivity of the piezoresistive and piezoelectric response. Meanwhile, the open circuit voltage, short circuit current and power density of the device can reach up to 200 V, 8 μA and ~82 μW/cm2, enlightening people to design high-performance piezoelectric energy harvesting devices. In addition, the dual-mode device exhibits great potentials for dynamic-static pressure detection and sports evaluation. The proposed flextensional transduction strategy provides people great inspirations to design self-protective sensing devices with dynamic-static mechanoresponse for more complex application scenarios.

Soft Composites Filled with Iron Oxide and Graphite Nanoplatelets under Static and Cyclic Strain for Different Industrial Applications.

Simultaneously exhibiting both a magnetic response and piezoelectric energy harvesting in magneto-rheological elastomers (MREs) is a win–win situation in a soft (hardness below 65) composite-based device. In the present work, composites based on iron oxide (Fe2O3) were prepared and exhibited a magnetic response; other composites based on the electrically conductive reinforcing nanofiller, graphite nanoplatelets (GNP), were also prepared and exhibited energy generation. A piezoelectric energy-harvesting device based on composites exhibited an impressive voltage of ~10 V and demonstrated a high durability of 0.5 million cycles. These nanofillers were added in room temperature vulcanized silicone rubber (RTV-SR) and their magnetic response and piezoelectric energy generation were studied both in single and hybrid form. The hybrid composite consisted of 10 per hundred parts of rubber (phr) of Fe2O3 and 10 phr of GNP. The experimental data show that the compressive modulus of the composites was 1.71 MPa (virgin), 2.73 (GNP), 2.65 MPa (Fe2O3), and 3.54 MPa (hybrid). Similarly, the fracture strain of the composites was 89% (virgin), 109% (GNP), 105% (Fe2O3), 133% (hybrid). Moreover, cyclic multi-hysteresis tests show that the hybrid composites exhibiting higher mechanical properties had the shortcoming of showing higher dissipation losses. In the end, this work demonstrates a rubber composite that provides an energy-harvesting device with an impressive voltage, high durability, and MREs with high magnetic sensitivity.