Direct Piezoelectric Effect Research Articles

Köprü Yapısından Piezoelektrik Tabanlı Enerji Hasadının Sayısal Modellemesi

Bridges can be subjected to a variety of external loads that can lead to instability and cause vibrations. Fortunately, such vibrations can be a source of unlimited sustainable energy that may powers the devices used to monitor the bridges. A possible way to convert such vibrations is by utilizing the direct piezoelectric effect, a process known as piezoelectric based energy harvesting. The present study investigates piezoelectric energy harvesting from a bridge. A model of the bridge with mounted piezoelectric harvesters was developed under ANSYS APDL. Various scenarios with different moving loads were investigated in time and frequency domains. Moreover, the effect of the positions of the harvesters was also explored. Results confirmed that harvesting vibration energy from bridge systems is a promising source of energy. Also, it can be profitable if the harvesters are located near the maximum mode shape amplitude and they are designed in a way to make their natural frequency match the natural frequency of the moving loads.

Flexible ferroelectric wearable devices for medical applications.

SummaryWearable electronics are becoming increasingly important for medical applications as they have revolutionized the way physiological parameters are monitored. Ferroelectric materials show spontaneous polarization below the Curie temperature, which changes with electric field, temperature, and mechanical deformation. Therefore, they have been widely used in sensor and actuator applications. In addition, these materials can be used for conversion of human-body energy into electricity for powering wearable electronics. In this paper, we review the recent advances in flexible ferroelectric materials for wearable human energy harvesting and sensing. To meet the performance requirements for medical applications, the most suitable materials and manufacturing techniques are reviewed. The approaches used to enhance performance and achieve long-term sustainability and multi-functionality by integrating other active sensing mechanisms (e.g. triboelectric and piezoresistive effects) are discussed. Data processing and transmission as well as the contribution of wearable piezoelectric devices in early disease detection and monitoring vital signs are reviewed.

Geometry Investigation and Performance Optimization of a Single-Mass Piezoelectric 6-DOF IMU

This paper explores the fundamental steps towards the development of a 6-axis piezoelectric Inertial Measurement Unit (IMU). The main specification of the reported device is its ability to concurrently detect 3-axis acceleration and angular velocity using a single mass-based design. This work represents a detailed numerical analysis based on a finite element model. Experimental reported data are exploited to validate the FEM model in terms of acceleration detection which is ensured through the direct piezoelectric effect. The angular rate is detected thanks to the Coriolis effect by ensuring drive and sense modes. Using a Finite Element Analysis (FEA), light was shed on the different basic parameters that influence the sensor performance in order to present an optimized design. A detailed geometrical investigation of factors such as anchor position, optimized locations for sensing electrodes, proof-mass dimensions, PZT thickness, and operating frequency is illustrated. The 6-DOF sensor outputs are extracted in terms of the original and the optimized design. The amelioration rate of sensitivity is found to be up to 165% for linear acceleration, while for angular rate sensing, the lateral sensitivity is ameliorated by about 330% and is multiplied by around ten times in the normal axis. The optimized design exhibits a good acceleration sensitivity of 260mV/g in the lateral axis and 60.7mV/g in the z-axis. For angular rate sensing, the new design is more sensitive along the longitudinal axis than the lateral one. Sensitivity values are found to be 2.65µV/rad/s for both x-and y-axis, and 1.24V/rad/s for the z-axis.

Enhancement of electromechanical properties in (0–3) lead-free ferroelectric nanocomposites with multiphase coexistence

In this study, electromechanical responses of BiFeO3/BaTiO3 (BFO/BTO) (0–3) nanocomposites with different volume fractions of BFO nanoparticles are investigated using phase field model based on the Landau–Ginzburg theory. A rich phase coexistence, including tetragonal (T), orthorhombic (O), and rhombohedral (R) phases, is characteristically formed in the domain structure of the nanocomposite due to interactions between BFO nanoparticles and BTO matrix through their interfaces. In particular, the O and R phases emerged in the original T-BTO matrix arise from the disruption of long-range R phase in BFO nanoparticles and high strain near the interfaces. The coexistence of multiphases generates high densities of domain walls and triple junctions of multiphase domains, which make polarization field more susceptible to an external strain. As a result, an anomalously large piezoelectric response is found in the BFO/BTO (0–3) nanocomposites. We further demonstrate that the direct piezoelectric effect is strongly dependent on the volume fraction of constituent phases, suggesting a route for the rational design of polarization domains and piezoelectric effects.

Recent Progress in Hybridized Nanogenerators for Energy Scavenging.

SummaryAs the world's demand for alternative energy increases, the development of green energy harvesters becomes ever more important. As a result, the creation of triboelectric (TENG), piezoelectric (PENG), and pyroelectric nanogenerators, electromagnetic generators (EMG), solar cells, and electrochemical cells is attracting interest in an effort to convert mechanical, thermal, magnetic, solar, and chemical energy into electricity. In order to take advantage of the ambient energies from our surrounding environment, the design of hybridized generator units that can simultaneously scavenge energy in a variety of forms continues to develop. These systems are being considered to satisfy the energy needs of a range of electronic devices and adapt to a variety of working environments. This review demonstrates the latest progress in hybridized nanogenerators in accordance with their structure, operating principle, and applications. These studies demonstrate new approaches to developing hybrid techniques and novel assemblies for efficiently harvesting environmental energy from a number of sources.

A parametric analysis of the nonlinear dynamics of bistable vibration-based piezoelectric energy harvesters

Piezoelectric materials exhibit electromechanical coupling properties and have been gained importance over the last few decades due to their broad range of applications. Vibration-based energy harvesting systems have been proposed using the direct piezoelectric effect by converting mechanical into electrical energy. Although the great relevance of these systems, performance enhancement strategies are essential to improve the applicability of these system and have been studied substantially. This work addresses a numerical investigation of the influence of cubic polynomial nonlinearities in energy harvesting systems considering a bistable structure subjected to harmonic excitation. A deep parametric analysis is carried out employing nonlinear dynamics tools. Results show complex dynamical behaviors associated with the trigger of inter-well motion. Electrical power output and efficiency are monitored in order to evaluate the configurations associated with best system performances.

Triboelectric and Piezoelectric Nanogenerators for Future Soft Robots and Machines.

SummaryThe triboelectric nanogenerator (TENG) and piezoelectric nanogenerator (PENG) are two recently developed technologies for effective harvesting of ambient mechanical energy for the creation of self-powered systems. The advantages of TENGs and PENGs which include large open-circuit output voltage, low cost, ease of fabrication, and high conversion efficiency enable their application as new flexible sensors, wearable devices, soft robotics, and machines. This perspective provides an overview of the current state of the art in triboelectric and piezoelectric devices that are used as self-powered sensors and energy harvesters for soft robots and machines; hybrid approaches that combine the advantages of both mechanisms are also discussed. To improve system performance and efficiency, the potential of providing self-powered soft systems with a degree of multifunctionality is investigated. This includes optical sensing, transparency, self-healing, water resistance, photo-luminescence, or an ability to operate in hostile environments such as low temperature, high humidity, or high strain/stretch. Finally, areas for future research directions are identified.

Piezoelectricity in the proteinogenic amino acid L-leucine: A novel piezoactive bioelectret

Here, we report the growth of bioelectret crystal films of L-leucine on conductive substrates and detail the first quantitative measurements of the direct piezoelectric effect in this proteinogenic amino acid. Through extensive electromechanical characterisation, we demonstrate that L-leucine is a promising candidate material for use in non-toxic, biocompatible and biodegradable energy harvesting and sensing devices. The data presented here is among, if not the, largest set of quasi-static, longitudinal piezoelectric measurements on crystalline films of a proteinogenic amino acid to date. We substantiate these measurements using a combination of density functional theory calculations and optical microscopy. Our data provides a further example of the enormous unexploited potential of amino acids and similar biological materials in flexible energy harvesting applications. Their combination of sizeable piezoelectric strain constants and extremely low elastic and dielectric constants makes them ideal as biocompatible replacements for toxic, expensive inorganic piezoelectric materials.

Ferroelectricity in Si-Doped Hafnia: Probing Challenges in Absence of Screening Charges.

The ability to develop ferroelectric materials using binary oxides is critical to enable novel low-power, high-density non-volatile memory and fast switching logic. The discovery of ferroelectricity in hafnia-based thin films, has focused the hopes of the community on this class of materials to overcome the existing problems of perovskite-based integrated ferroelectrics. However, both the control of ferroelectricity in doped-HfO2 and the direct characterization at the nanoscale of ferroelectric phenomena, are increasingly difficult to achieve. The main limitations are imposed by the inherent intertwining of ferroelectric and dielectric properties, the role of strain, interfaces and electric field-mediated phase, and polarization changes. In this work, using Si-doped HfO2 as a material system, we performed a correlative study with four scanning probe techniques for the local sensing of intrinsic ferroelectricity on the oxide surface. Putting each technique in perspective, we demonstrated that different origins of spatially resolved contrast can be obtained, thus highlighting possible crosstalk not originated by a genuine ferroelectric response. By leveraging the strength of each method, we showed how intrinsic processes in ultrathin dielectrics, i.e., electronic leakage, existence and generation of energy states, charge trapping (de-trapping) phenomena, and electrochemical effects, can influence the sensed response. We then proceeded to initiate hysteresis loops by means of tip-induced spectroscopic cycling (i.e., “wake-up”), thus observing the onset of oxide degradation processes associated with this step. Finally, direct piezoelectric effects were studied using the high pressure resulting from the probe’s confinement, noticing the absence of a net time-invariant piezo-generated charge. Our results are critical in providing a general framework of interpretation for multiple nanoscale processes impacting ferroelectricity in doped-hafnia and strategies for sensing it.

A Block Diagram of Electromagnetoelastic Actuator for Control Systems in Nanoscience and Nanotechnology

The block diagram and the transfer functions of the electromagnetoelastic actuator are received for control systems in nanoscience and nanotechnology. The block diagram of the electromagnetoelastic actuator is reflected the transformation of electrical energy into mechanical energy, in contrast to Cady’s and Mason’s electrical equivalent circuits of piezotransducer. The electromagnetoelasticity equation and the second order linear ordinary differential equation with boundary conditions are solved for calculations the block diagram of the electromagnetoelastic actuator. The block diagram of the piezoactuator is obtained with using the reverse and direct piezoelectric effects. The back electromotive force is determined from the direct piezoelectric effect equation. The transfer functions of the piezoactuators are obtained for control systems in nanoscience and nanotechnology.

An evaluation method for direct piezoelectric coefficients of thin films using both-ends-hinge-supported unimoprh beams

We have developed a new method for measuring the direct piezoelectric effect of piezoelectric thin films, consisting of both-ends-hinge-supported unimorph beams (BUBs). This method can determine the precise direct transverse piezoelectric coefficient e31,f of arbitrary piezoelectric films by measuring the displacement and the output voltage between the electrodes of the BUBs. We formulated the e31,f values based on the flexure basic formula, and a constitutive equation of electromagnetic field for the BUBs, including measuring systems such as oscilloscopes, which have an arbitrary input impedance. In this study, we were able to obtain a piezoelectric coefficient of a lead zirconate titanate (PZT) thin film on a Si substrate of e31,f = 4.7 Cm−2, regardless of the input impedance of the measurement instrument. Using this method, we then measured the temperature characteristics of e31,f for the PZT thin film. We clearly observed the increase of e31,f , and the relative dielectric constant, with an increase in temperature. We obtained a temperature gradient for of a = 0.01 Cm−2K−1, a value which is in good agreement with previous research. We also measured the time dependences of the e31,f after polling piezoelecric films. The e31,f value decreased over time, and we were able to obtain a logarithmic time gradient for normalized e31,f of p = −0.01, a value consistent with the results of previous studies.

Efficiency improving of NEMS solar cell using piezoelectric nanowires

This paper presents a new structure of solar cells based on NEMS (Nano Electro Mechanical System) technology to eliminate dependence of cell to band gap energy and improve efficiency. In this paper, the process of converting solar energy to electrical energy using NEMS solar cell, which is able to convert the thermal to mechanical energy and then to electrical energy by changing the temperature and using direct piezoelectric effect, is investigated. Thus, unlike photovoltaic cells, these cells have ability to absorb the full spectrum of the sun’s radiation. Energy conversion is such that at first a two-layer cantilever with different thermal expansion coefficient (Al aluminum and SiO2 Silicon Oxide) is diverted by solar energy absorption, thus the solar energy is converted to mechanical energy. This structure is capable to receive heat energy from all spectrum of solar radiations. The mechanical oscillation of PZT (Lead Zirconate Titanate) nanowires, which are perpendicular to cantilever beams, is converted to electrical energy. The electrical voltage produced by the proposed structure is an alternating voltage with amplitude of 0.9 volts. Also, the efficiency of this proposed cell, which was introduced at first time and does not have a similar sample, is 40% which shows improved performance and much smaller size compared to previous works.

Time-resolved open-circuit conductive atomic force microscopy for direct electromechanical characterisation

Studying nanomaterial piezoelectricity and triboelectricity is attractive for energy and sensing applications. However, quantitative characterisation of electromechanical effects in nanomaterials is challenging due to practical limitations and possible combination of effects, resulting in contradicting reports at times. When it comes to piezoelectricity at the nanoscale, piezoresponse force microscopy (PFM) is the default characterisation tool. In PFM the converse piezoelectric effect is measured - the conversion from electrical signal to mechanical response. However, there is an underlying desire to measure the direct piezoelectric effect - conversion of mechanical deformation to an electrical signal. This corresponds to energy harvesting and sensing. Here we present time-resolved open-circuit conductive atomic force microscopy (cAFM) as a new methodology to carry out direct electromechanical characterisation. We show, both theoretically and experimentally, that the standard short-circuit cAFM mode is inadequate for piezoelectric characterisation, and that resulting measurements are governed by competing mechanisms. We apply the new methodology to nanowires of GaAs, an important semiconductor, with relatively low piezoelectric coefficients. The results suggest that time-resolved operation distinguishes between triboelectric and piezoelectric signals, and that by measuring the open-circuit voltage rather than short-circuit current, the new methodology allows quantitative characterisation of the vertical piezoelectric coefficient. The result for GaAs nanowires, ∼ 1–3 pm V−1, is in good agreement with existing knowledge and theory. This method represents a significant advance in understanding the coexistence of different electromechanical effects, and in quantitative piezoelectric nanoscale characterisation. The easy implementation will enable better understanding of electromechanics at the nanoscale.

Piezoelectric Energy Harvesting Solutions: A Review.

The goal of this paper is to review current methods of energy harvesting, while focusing on piezoelectric energy harvesting. The piezoelectric energy harvesting technique is based on the materials’ property of generating an electric field when a mechanical force is applied. This phenomenon is known as the direct piezoelectric effect. Piezoelectric transducers can be of different shapes and materials, making them suitable for a multitude of applications. To optimize the use of piezoelectric devices in applications, a model is needed to observe the behavior in the time and frequency domain. In addition to different aspects of piezoelectric modeling, this paper also presents several circuits used to maximize the energy harvested.

Test, modeling, and analysis of air-coupled ultrasonic transducer based on piezoelectret film

Piezoelectrets, a new type of electromechanical transducer material with low acoustic impedance and high piezoelectric d33 and g33 coefficients, are promising candidates for developing high-performance air-coupled ultrasonic transducers. In this work, we design polypropylene-piezoelectret-film based air-coupled transducers (ACTs) with two different structures and investigate the influence of boundary conditions of the film with experimental measurement, electromechanical equivalent circuit modeling (EECM), and finite element analysis (FEA) for both inverse and direct piezoelectric effects. The experimental data are in great agreement with the results of EECM and FEA. The resonant frequency of the ACT with a free-front-clamped-back (FFCB) film is about half of that of the device with a free-front-free-back (FFFB) film, the response peak of the FFCB device is higher than that of the FFFB device, and the −3dB bandwidth of the former is much narrower than that of the latter. The results show that the experimental measurements can be predicted by EECM and FEA, which can provide the basis for the development of high-performance air-coupled ultrasonic transducers based on piezoelectret films.

Methods for the Integration of New Architectural Nanostructures with MEMS Systems for Sensors and Harvester Devices

Introduction This work is addressing the development of new, improved piezomaterials and devices with the goal to build high efficiency energy microharvesters as alternative sources of sustainable energy, and resonant piezo sensors for bio and chemical sensing. Integration of piezolayers in MEMS devices is the key issue of the successful harvester and sensors fabrication. An integrable piezomaterial appeared as a stringent need of our days in answering the environmental problems such as climate change, having as consequence the need to decrease the non-renewable fuels consumption.Piezoelectric MEMS have been an attractive technology for the generation of a small amount of energy from the vibrations and movements of the environment. This technology can eliminate the replacement of chemical batteries or complex cables from microsensors / microsystems, bringing us closer to autonomous sensor systems and networks. To achieve this, a fully assembled energy piezoelectric micro generator should be able to provide approximately 200 µW of continuous power from ambient vibration and its cost should be low enough for large-scale manufacturing.On the other hand, a piezolayer integrated into a resonant device like a thin silicon membrane working at high frequency would be a very good solution for sensitive chemo and biosensors dedicated to environment monitoring. Device structure We are focusing on the structure of a MEMS harvester which demonstrates the technology of new piezolayers with high piezocoefficients. The harvester includes a MEMS device based on an array of released silicon micrometric structures (cantilevers, bridges) electrically connected together for increasing the power density. Each MEMS structure was covered with a thick piezoelectric film having the role of converting mechanical energy into electrical energy (direct piezoelectric effect). The best piezoelectric film known until now is PZT. Replacing PZT films with lead-free ones (for environment protection) was one of our main goals.For this purpose, we prepared on the one hand PZT thin film (deposited by Pulsed Laser Deposition) and on the other hand ZnO-based structures, and we studied comparatively their piezoelectric properties. It was found that the piezoelectric coefficients d33 for both type of films are similar. Preparation Method of the complex structure based on ZnO A new approach was to obtain a sample of stack layer consisting of hierarchical PMMA / CuO NSs / ZnO NWs / ZnO seed layer (as shown in the figure below). Fig.1 Stack layer of PMMA / CuO NSs / ZnO NWs / ZnO seed layerThe structures consist of a ZnO seed layer deposited by the Sol-Gel method, over which a ZnO film was hydrothermally grown. Vertically ZnO nano wires (NWs) were formed after this step. One layer of nanostructured (NS) CuO was deposited on the ZnO-NWs and on top two layers of poly (methyl methacrylate) (PMMA) were added.The results highlight the influence of the thickness of the ZnO seed layer on the distribution and density of the nanowires grown by hydrothermal synthesis. Also, the temperature chosen for annealing plays a major role in the formation of well-aligned and strongly oriented ZnO NWs along the c axis, a role confirmed by the SEM and TEM images The piezoelectric response of this compound was highly dependent on the substrate. For this purpose, we used simple flexible metal substrate, such as Ti, and silicon substrates with several layers, lithographically patterned, as Pt/Ti/SiO2/Si or Au/Ti/SiO2/Si. In the case of silicon substrate, the MEMS test structures needed to be thinned up to 10 microns and this was done by back side DRIE etching of silicon wafer. Results and Conclusion The thickness of the substrate contributes to the mechanical deformation of the entire structure and therefore a piezoelectric response is generated. All films were characterized (structurally, morphologically), compared and optimized in order to obtain the best piezoelectric response (evaluated by the d 33 parameter). To verify the stability of the results, the piezoelectric measurements were repeated daily, for one week.We concluded that the best piezofilm without lead, able to be integrated and technological compatible with a MEMS device is a stack layer consisting of PMMA / CuO NSs / ZnO NWs / ZnO seed layer Acknowledgements: The financial support of the project PN-III-P1-1.2-PCCDI-2017-0419 and EU (ERDF) and Romanian Government for the research infrastructure under POS-CCE O 2.2.1 project INFRANANOCHEM – No. 19/01.03.2009 is gratefully acknowledged. Figure 1

Nonlinear electromechanical coupling in ferroelectric materials: large deformation and hysteresis

Smart materials respond to external stimuli, e.g., electric fields, which enables their use as sensors and actuators. The electromechanical coupling of the direct and converse piezoelectric effects, for instance, is used for both actuation and sensing in diverse engineering applications. The response of ferroelectric materials depends on their state of remanent polarization and the presence of an external electric field. To extend the operational range of sensors and actuators, an accurate understanding of the evolution of the material’s state of polarization is imperative, which requires both physical and geometric nonlinearities to be taken into account. Moreover, polymeric smart materials like PVDF allow significantly larger deformation as compared to conventional piezoelectric ceramics. The electromechanical coupling in piezoelectric materials manifests in ferroelectric and ferroelastic hystereses, which are related to both reversible and irreversible processes. Focusing on the latter, we transfer phenomenological models for domain switching in ferroelectric materials to the geometrically nonlinear regime. For this purpose, we follow related concepts of geometrically nonlinear elastoplasticity, where the concept of a multiplicative decomposition of the deformation gradient plays a key role. Accordingly, an additional deformation path that describes the evolution of the poled state from the unpoled referential configuration is introduced. The constitutive response of the material to mechanical and electrical loads is discussed, and dissipative internal forces that drive the evolution of the remanent polarization are derived within a thermodynamical framework and the principle of maximum dissipation.

Control problems for energy harvester model and interpolation in Hardy space

AbstractThree control problems for the system of two coupled differential equations governing the dynamics of an energy harvesting model are studied. The system consists of the equation of an Euler–Bernoulli beam model and the equation representing the Kirchhoff's electric circuit law. Both equations contain coupling terms representing the inverse and direct piezoelectric effects. The system is reformulated as a single evolution equation in the state space of 3‐component functions. The control is introduced as a separable forcing term on the right‐hand side of the operator equation. The first control problem deals with an explicit construction of that steers an initial state to zero on a time interval [0, T]. The second control problem deals with the construction of such that the voltage output is equal to some given function (with being given as well). The third control problem deals with an explicit construction of both the force profile, , and the control, , which generate the desired voltage output . Interpolation theory in the Hardy space of analytic functions is used in the solution of the second and third problems.

Piezoelectricity in the Intervertebral disc

Lower back pain is a major global health challenge that can often be caused by degeneration of the Intervertebral Disc (IVD). While IVD biomechanics are a key factor in the degenerative cycle, many mechanotransduction pathways remain unknown, in particular the electro-mechanical coupling in the loaded tissue. However, despite evidence for a role in the mechanically-induced remodelling of similar tissue, piezoelectricity has been overlooked in the IVD. In this study, we investigate the piezoelectric properties of the Annulus Fibrosus (AF) and the Nucleus Pulposus (NP) by measuring the direct piezoelectric effect of mechanically-induced electrical potential change. To verify these findings, we conducted Piezoresponse Force Microscopy (PFM) to measure the inverse effect of electrically-induced deformation. We demonstrate that, for the first time, piezoelectricity is generated throughout the IVD. Piezoelectric effects were greater in the AF than the NP, owing to the organised collagen networks present. However, the piezoresponse found in the NP indicates piezoelectric properties of non-collagenous proteins that have not yet been studied. The voltage generated by longitudinal piezoelectricity in-vivo has been calculated to be ~1 nV locally, indicating that piezoelectric effects may directly affect cell alignment in the AF and may work in conjunction with streaming potentials throughout the IVD. In summary, we have highlighted an intricate electro-mechanical coupling that appears to have distinct physiological roles in the AF and NP. Further study is required to elucidate the cell response and determine the potential role of piezoelectric effects in regeneration and preventative measures from degeneration.

Synthesis and experimental investigation of PZT nanocomposite films

In this paper, synthesis of nanocomposite and experimental investigation of three samples of nanocomposite films are presented. The aim of this research is to determine influence of the PZT particle concentration in nanocomposite on the surface morphology, qualitative and quantitative chemical composition ant direct piezoelectric effect. The specimens were prepared by mixing the PZT nanopowder with PMMA in three different proportions: 85% of PZT and 15% of binder; 90% of PZT and 10% of binder; 95% of PZT and 5% of binder. Surface morphology and qualitative and quantitative chemical composition were evaluated using scanning electron microscope, which is equipped with the Energy Dispersive X-Ray Spectrometer. Electrical response of the pulse-excited specimens is also presented.