Electromechanical Coefficient Research Articles

Giant Piezoelectric Effect Induced by Porosity in Inclined ZnO Thin Films

AbstractPiezoceramics have been the common choice for sensing applications, however their integration with other electronics is limited due to their large size. Also, environmental concerns have been limiting the use of ceramics due to their lead content, toxic for humans. Piezoelectric crystalline thin films have arisen as alternative materials offering compatibility with miniaturization and integrated processes, though their piezoelectric properties are low (d33 < 15 pC N−1) compared to ceramics (d33 > 300 pC N−1), hindering their applicability. Several methods have been studied aiming to improve the piezoelectric output of thin films, including doping or the less investigated inclusion of porosity. However, they all require complex techniques that increase the cost. In this work, a giant electromechanical d33 coefficient of 115.6 pC N−1 has been obtained inducing porosity in inclined ZnO thin films via oblique angle deposition, which is beyond record values reported for doped ZnO thin films and an order of magnitude higher than standard ZnO thin films (11.6 pC N−1). Morphology, composition, crystal structure, porosity, and piezoelectricity are reported for standard and inclined films. Finite element simulations have been carried out to investigate the performance of the piezoelectric‐enhanced thin films in an ultrasonic pulse‐echo setup.

Design of highly active and stable (K0.48Na0.48Li0.04)(Nb0.975Sb0.025)O3–(Bi0.5Na0.5)(Zr0.8Ti0.2)O3 lead–free piezoelectric ceramics by constructing rhombohedral–tetragonal phase boundaries at room temperature

Traditional piezoelectric materials cause serious environmental and health issues because of their lead–containing substances, and thus lead–free piezoelectric ceramics would have many applications. In this study, we successfully prepared the lead–free ceramics (1-x) (K0·48Na0·48Li0.04) (Nb0·975Sb0.025)O3–x (Bi0·5Na0.5) (Zr0·8Ti0.2)O3 ((1-x)KNLNS–xBNZT, x = 0, 0.005, 0.0075, 0.01, 0.015, 0.02 and 0.03) with rhombohedral–tetragonal (R–T) phase coexistence near room temperature, employing con–entional solid sintering. The minimum cell volume of the ceramics and R–T phase coexistence in them were achieved at a doping amount x = 0.01, which facilitated the optimal performance of the ceramics (d33∼467 pC/N ± 14 pC/N, Tc∼272 °C, εr∼1676, kp∼0.42, where d33: piezoelectric constant; Tc: Curie temperature; εr: dielectric constant; kp: electromechanical coefficient). The ceramics exhibited microstructures with high density and low porosity and had a maximum relative density of 95.68 %. At x = 0.01, the ceramics exhibited a uniformly distributed small domain structures with nanodomains, accounting for their high-voltage electrical properties. Because these stable and reliable piezoelectric (1-x)KNLNS–xBNZT ceramics exhibit excellent electrical performance, they can replace lead–based materials. The direct solid–phase sintering method provides prospects for the large–scale application of the lead–free piezoelectric ceramics.

High figure-of-merit A1-mode lamb wave resonators operating around 6 GHz based on the LiNbO3 thin film

The first asymmetric mode (A1 mode) lamb wave resonator (LWR) with a resonant frequency of 6 GHz based on Z-cut lithium niobate (LN) films is presented. An asymmetric electrode structure with different-sized electrode pads in the center and edged regions has been proposed, which can be used to optimize the distribution of the electric field and decrease acoustic impedance mismatch to improve the target mode. Experiment results reveal that LWRs with an asymmetric electrode structure can successfully enhance the A1 mode, achieving a high effective electromechanical coefficient ( keff2 ) of 26%, a quality factor (Q) of 1123, and an excellent figure-of-merit (FOM = keff2 ∙Q) of 262. It demonstrates that asymmetric electrode structure provides a new way to suppress the spurious modes for LWRs and shows a great application prospect in wide-bandwidth and low-loss filters used in the sub-6 G frequency range.

Investigation of piezoelectric properties in manganese doped alkaline niobate-based lead-free piezoceramics

In this work, an attempt is made for improving the piezoelectric properties of a lead-free (Na[Formula: see text]K[Formula: see text]Li[Formula: see text](Nb[Formula: see text]V[Formula: see text]O3 ceramic system by doping manganese in it. The Rietveld analysis of XRD micrographs of the ceramics indicates the samples crystallizing into 99.86% of orthorhombic phase and very small traces of tetragonal phase around room temperature. The Curie temperature ([Formula: see text]) is hardly affected by the incorporation of Mn[Formula: see text] into the system. At the manganese concentration of 0.02[Formula: see text]wt.%, the ceramic system attains the peak values in its density, dielectric constant at room temperature ([Formula: see text]), planar electromechanical coefficient ([Formula: see text], piezoelectric coefficient ([Formula: see text]), and remnant polarization ([Formula: see text]). The optimum piezoelectric properties of [Formula: see text]% and [Formula: see text] pC/N are observed for this composition. The study reveals that the modification of (Na[Formula: see text]K[Formula: see text]Li[Formula: see text]) (Nb[Formula: see text]V[Formula: see text]O3 with an appropriate quantity of Mn[Formula: see text] can produce the desired changes in the crystallographic properties and densification so as to eventually improve its piezoelectric properties.

Closely Packed Stretchable Ultrasound Array Fabricated with Surface Charge Engineering for Contactless Gesture and Materials Detection.

Communication with hand gestures plays a significant role in human-computer interaction by providing an intuitive and natural way for humans to communicate with machines. Ultrasound-based devices have shown promising results in contactless hand gesture recognition without requiring physical contact. However, it is challenging to fabricate a densely packed wearable ultrasound array. Here, a stretchable ultrasound array is demonstrated with closely packed transducer elements fabricated using surface charge engineering between pre-charged 1-3 Lead Zirconate Titanate (PZT) composite and thin polyimide film without using a microscope. The array exhibits excellent ultrasound properties with a wide bandwidth (≈57.1%) and high electromechanical coefficient (≈0.75). The ultrasound array can decipher gestures up to 10cm in distance by using a contactless triboelectric module and identify materials from the time constant of the exponentially decaying impedance based on their triboelectric properties by utilizing the electrostatic induction phase. The newly proposed metric of the areal-time constant is material-specific and decreases monotonically from a highly positive human body (1.13 m2s) to negatively charged polydimethylsiloxane (PDMS) (0.02 m2s) in the triboelectric series. The capability of the closely packed ultrasound array to detect material along with hand gesture interpretation provides an additional dimension in the next-generation human-robot interaction.

Achievement of a giant electromechanical conversion coefficient in a molecule-based ferroelectric.

Molecule-based ferroelectrics are promising candidates for flexible self-powered power supplies (i.e., piezoelectric generators (PEGs)). Although the large electromechanical conversion coefficients (d 33 × g 33) of piezoelectrics are key to enhancing the performance of PEGs in their nonresonant states, it remains a great challenge to obtain molecule-based piezoelectrics with large d 33 × g 33. Here, we report a molecule-based ferroelectric [(CH3)3NCH2CH2Cl][GaBr4] (1) that exhibits the largest piezoelectric coefficient (∼454 pC N-1) and electromechanical conversion coefficient (4953.1 × 10-12 m2 N-1) among all known free-standing polycrystalline pellets. Notably, the PEG comprising 15 wt% 1 and polydimethylsiloxane (PDMS) achieves a power density of up to 120 μW cm-2, marking the highest reported power density for ferroelectric@PDMS PEGs to date.

Dielectric, piezoelectric and energy storage properties of Ca, Zr and Sn doped (Ba1-xCax)(Ti0.85+xZr0.02Sn0.13-x)O3 lead-free ceramics at MPB for 0.05 ≤ x ≤ 0.09

Lead-free piezoceramics based on the (Ba, Ca)(Zr, Ti)O3 (BCZT) system provide outstanding electromechanical characteristics for low-temperature actuation applications, however manufacturing temperatures are a little high. Here, we demonstrate how calcium doping can simultaneously enhance Ba(Zr, Ti, Sn)O3 piezoceramics' electromechanical strain response for the MPB composition(s) with formula (Ba1-xCax)(Ti0.85+xZr0.02Sn0.13-x)O3. The electromechanical, dielectric, and ferroelectric properties of the samples, which were created utilizing solid state synthesis techniques, were all investigated. The sample with the highest d*33 value, 748 pm/V for 0.26 kV/mm and 645 pm/V for 0.62 kV/mm, had 0.070 mol% Ca substituted on the perovskite lattice's A-site, which also demonstrated the best dielectric and piezoelectric performance in the composition range for 0.070 ≤ x ≤ 0.090. The ceramic with electromechanical coefficient (kp) = 44.6 % also displays the greatest values of large electrostrictive coefficients (Q33 ≈ 0.10 m4/C2) that also observed in these Ca, Zr and Sn doped Ba(Zr,Ti, Sn)O3 ceramics.

Structure Research of Resistance Shunt Type Piezoelectric Composite and Underwater Sound Absorption Performance Analysis

The high-efficiency sound absorption of underwater sound-absorbing materials under "low frequency" and "wide frequency" conditions has become a hot topic in current research. Underwater semi-active sound absorption can help to improve low frequency sound absorption performance by designing the structure of the piezoelectric composite and the shunt circuits, and it is also advantageous due to its simplicity, compactness, ease of installation, low cost, and high stability. In this paper, a kind of resistance shunt type piezoelectric composite is designed, and its underwater sound absorption performance is analyzed. Theoretical analytical formulas and finite element numerical calculation are used to calculate the electro-elastic constants of the piezoelectric composite. The theoretical model based on the Mason equivalent circuit and transfer matrix theory is used to calculate the sound absorption coefficient. Through the study of 0-3 and 1-3 composites used in the existing research work, it was found that the piezoelectric composite which is suitable for resistance shunt type underwater semi-active sound absorption should have a low longitudinal wave velocity and high electromechanical conversion coefficient. According to this design objective, the structure of the piezoelectric composite has been gradually modified, and finally it is determined that the sparse oblique 2-1-3 composite is an appropriate type of piezoelectric composite. Theoretical calculations and simulation experimental measurement verifies that when the inclination angle is 21 deg and the shunt resistance is 10 kOhm or the inclination angle is 24 deg and the shunt resistance is 10 kOhm, the sound absorption coefficient within the low frequency band 1--3~kHz can be significantly improved.

Convergence of alkaline earth and transition metal oxide nanotube properties toward the 2D slab limit, computational investigation for energy conversion implications

Nanoscale devices developed from low-dimensional materials (one and two-dimensional systems) have recently attracted great attention due to their critical applications in micro/nano electromechanics. However, the practical fabrication of 2D systems is often more challenging than that of their 1D counterparts. In the current investigation, the convergence of 1D nanotube properties toward the 2D slab limit has been verified and confirmed. In this regard, a variety of geometrical, electronic, and response (mechanical and piezoelectric) properties are computed for both zigzag (n,0) metal oxide MO (M = Be, Mg, Ca, Zn, Cd) nanotubes and MO 2D surfaces. The variation of such properties as a function of the tube index n (ranging from 6 to 48, corresponding to 24 to 192 atoms per cell, respectively) is highlighted. Additionally, the electronic and nuclear contributions to all aforementioned response properties have been discussed and analyzed. Interestingly, CdO (48,0) nanotube introduces considerable direct and converse piezoelectric constants: e11 = 6.04 |e|×bohr and d11 = 22.88 pm/V. These electromechanical coefficients converge well to the values of the 2D surface, while the response is entirely dominated by the ionic contribution, confirming the flexibility and softness. Such findings make these MO nanotubes good candidates for nanoscale energy conversion piezoelectric applications.

Dramatic Amplification of the Flexoelectric Effect in Snapping Surfaces

Abstract Flexoelectricity exists in all inhomogeneously deformed dielectric materials and is of great interest in engineering science, especially in microelectromechanical systems. However, the flexoelectricity is relatively small compared to the commonly known piezoelectricity. How to produce a considerably large flexoelectric effect and how to apply the effect to a large scale have concerned people for a long time. In this paper, we creatively amplify the flexoelectric effect without decreasing the structure scale by harnessing the electromechanical instability—the snap-through instability—of a curved dielectric plate subjected to a concentrated load. We formulate the electrostatic energy of the system and obtain the governing equations by taking the first variation of the free energy. In the analysis, we find that the thickness of the plate and the initial configuration affect the onset of the snap-through. Beyond that, we notice that flexoelectricity can lower the critical load of the snap-through instability. Importantly, we find that a large flexoelectricity can be generated by harnessing the instability. For a dielectric plate with thickness 2 × 10−7 m, the effective electromechanical coefficient is equal to 35 pC/N in the beginning; however, by using the instability, the effective coefficient can be increased to as high as 740 pC/N, which is 21 times higher after the instability. In the end, we tune the electromechanical behaviors by designing the curved plate’s thickness and configuration. This paper contributes to our understanding of the amplification of flexoelectric effects by harnessing snapping surfaces.

THE INFLUENCE OF EXTERNAL FACTORS ON THE ACCURACY AND RELIABILITY OF THE DETERMINATION OF ULTRA-LOW POWER ELECTRIC FIELDS

The article presents the results of an experimental study of the influence of temperature, relative humidity of the surrounding environment, as well as the coefficient of electromechanical action on the process of determining ultra-low power electric fields. The analysis of the obtained results made it possible to establish the most rational conditions for determining the force (electrical tension) and energy (distribution of surface charge and electric capacity) parameters of such fields with higher accuracy and reliability. The paper proposes an experimental experiment to establish the accuracy and reliability of power and energy parameters for determining electric fields under conditions of changes in climatic factors and the electromechanical coefficient, the implementation of which took place on a measuring stand developed with the participation of the authors. The main element of such a measuring stand is an automatic device for determining, collecting and processing information on the distribution of power and energy parameters of the electric field under the sensitive element of the measuring transducer. The results obtained as a result of the experimental research made it possible to establish that the coefficient of electromechanical influence has a decisive influence on the accuracy of measuring electric fields of ultra-low power. It is shown that an increase in the coefficient of electromechanical influence from 38 pN/V (silicon <111>) to 190 pN/V (PZT-8 piezoelectric ceramics) leads to an increase in the relative error of electric field determination by 4.7%. It was established that reducing the temperature to 20 °C while maintaining the relative humidity from 38 % to 74 % leads to a decrease in the relative error by 1.5-2.2 %. At the same time, a decrease in temperature with a simultaneous decrease in relative humidity leads to an increase in the reliability of the determination of electric fields (so, the probability of error-free measurement of power and energy parameters of electric fields increases by 18 %). A comparison of the results obtained by the proposed method with the results obtained by atomic force microscopy method (in the mode of measuring the leakage currents from the working areas of the investigated surfaces) was carried out, which showed a strong positive correlation between these results, which confirms the objectivity of the proposed method and the adequacy of the obtained results. The conclusions and analyzed data obtained in the article based on the results of experimental studies can be used to create a system of automatic error correction and instability determination of power and energy parameters of ultra-low power electric fields, taking into account limiting external influences.

Magnetic circuit optimization design and thermal analysis of the giant magnetostrictive transducer

A giant magnetostrictive transducer was studied. The dynamic simulation analysis of the transducer was carried out, the influence of the magnetic block and the magnetic cylinder on the vibration performance of the transducer was studied, and the temperature rise of the transducer during the operation was simulated and calculated. The impedance and output amplitude of the developed transducer were tested experimentally. The results show that the axial magnetic field intensity of the Terfenol-D rod increased and then decreased, and the output amplitude increased and then decreased slightly with the increase of the thickness of the magnetic cylinder. As the thickness of the magnetic block increased, the axial magnetic field intensity of the rod increased, and the output amplitude of the transducer also increased. Compared with the transducer without magnetic cylinder, the transducer with magnetic cylinder has larger electromechanical conversion coefficient, and output amplitude, but the temperature was higher after working for the same time.

Research on a stacked high-sensitivity hydroacoustic transducer

PurposeIsland attack and defense, emergency rescue, scientific research, civilian fisheries and other fields are inseparable from timely, high-quality underwater communications. However light and other electromagnetic waves are severely attenuated in water, acoustic is currently the only energy carrier that can transmit signals over long distances in water. However, the complex water environment and serious interference bring serious challenges to underwater activities using underwater acoustic sensors-hydroacoustic transducers. Thus, this paper aims to develop a class of high reception sensitivity hydroacoustic transducer structures to provide research and utilization ideas for related scholars.Design/methodology/approachThe electromechanical coupling coefficient is improved by converting the thickness vibration mode of the piezoelectric ceramic into the longitudinal vibration mode of the piezoelectric pillars array, and no polymer is added between the piezoelectric pillars array to reduce lateral coupling as well as internal friction, which can thus reduce the energy losses. Radial stacking in parallel can also enhance the charge generated through the positive piezoelectric effect. The optimal parameters of the structure are determined by equivalent circuit method and finite element analysis, and a hydroacoustic transducer of this structure is fabricated finally.FindingsAccording to the standard test procedure, the hydroacoustic transducer was tested in water. The tests show that the conductance curve of the stacked high-sensitivity hydroacoustic transducer tested in the air is in good agreement with the simulation results. The resonant frequency is about 118 kHz, and the receiver sensitivity is −166 dB. The stacked material hydroacoustic transducer is in the high-frequency range and has a much higher sensitivity (−166 dB) than many types of hydroacoustic transducers fabricated by piezoelectric ceramic (less than −200 dB).Research limitations/implicationsAlthough the stacked high-sensitivity hydroacoustic transducer that the authors have fabricated has a performance improvement, it has a limitation. The hollow design of the pillar arrays increases the reception stress on each pillar, and the imposed pressure comes from water also increases simultaneously, so the depth of water that the stacked high-sensitivity hydroacoustic transducer can operate in may be slightly shallower than that made of a pure piezoelectric ceramic block or a piezoelectric ceramic material with polymer added. This will be a problem to be solved in a future deployment.Practical implicationsWhether it is marine scientific research or in various fields such as civil recreation and fishing, hydroacoustic communication and necessary underwater exploration are indispensable for acoustic waves. The hydroacoustic transducer is the sensor that sends and receives sound waves, so a lot of water equipment, such as yachts, sonar buoys, and so on, cannot be separated from the hydroacoustic transducer. In addition, the complexity of the water environment also requires a good performance of the hydroacoustic transducer to facilitate the convenience and effectiveness of subsequent signal processing. Therefore, hydroacoustic transducers have great market and commercial value.Social implicationsHydroacoustic transducers are not only of great commercial value but also have a significant impact on the military as well as on people’s livelihood. As we all know, in the area of submarine communication and underwater exploration, sonar is the main force. The performance of the hydroacoustic transducer directly affects the performance of the hydroacoustic signal processing system, and ultimately directly determines the success or failure of the mission. In addition, the large-scale replacement of hydroacoustic transducers on equipment requires the concerted efforts of a large number of practitioners, such as material scientists, structural scientists, mathematicians and so on. Therefore, the rise of hydroacoustic transducers has given rise to a large number of learning positions as well as employment positions.Originality/valueTo enhance the reception sensitivity of the hydroacoustic transducer, the authors have optimized the existing hydroacoustic transducer materials and structures to propose a stacked sensitive element, which can effectively enhance the electromechanical conversion coefficient of the piezoelectric material. Furthermore, the authors have manufactured a hydroacoustic transducer using the proposed stacked sensitive element. The test results of the hydroacoustic transducer also show that the designed stacked sensitive element is of great help to enhance the reception sensitivity of the hydroacoustic transducer.

Textured Lead-Free Piezoelectric Ceramics for Flexible Energy Harvesters

A lead-free (K,Na)NbO3-based piezoelectric ceramic is textured along the (001) direction using the NaNbO3 (NN) seeds. The composition 0.96(K0.5Na0.5)(Nb0.965Sb0.035)O3-0.01CaZrO3-0.03(Bi0.5K0.5)HfO3 (KNN) is found to provide an excellent combination of electromechanical coefficients at room temperature. The textured composition with 5 wt % NN template (KNN-5NN) exhibits considerably improved electromechanical coefficients, d33 ∼ 590 pC/N, k31 ∼ 0.46, and d31 ∼ 215 ×10-12 C/N, at room temperature. A flexible piezoelectric energy harvester (F-PEH) is fabricated using the textured KNN-5NN ceramic and tested under cyclic force. F-PEH exhibits enhanced output voltage (Voc ∼ 25 V), current (I ∼ 0.4 μA), and power density (PD ∼ 5.5 mW/m2) (RL of 10 MΩ) in the off-resonance frequency regime. In comparison to the random ceramic KNN-0NN-based F-PEH (Voc ∼ 8 V and I ∼ 0.1 μA), the textured F-PEH significantly outperformed energy harvesting capability due to the large figure-of-merit value (d31 × g31) ∼ 3354 ×10-15 m3/J. This work provides a methodology for texturing lead-free materials and further implementing them in flexible energy harvesting devices and sensors.

Physical properties of Sm2O3 added Pb(Ni1/3Nb2/3) O3–Pb(Zr0.32Ti0.68)O3 system ceramics for piezoelectric speaker application

In this article, to develop the composition ceramics for the application of single-layer piezoelectric speaker, Pb(Ni1/3Nb2/3)0.5(Zr0.32Ti0.68)0.5O3 co-doped with Ta2O5 and Sm2O3 were manufactured and then their dielectric and piezoelectric properties were investigated. At the 0.4 wt% Ta2O5 and 0.0 wt% Sm2O3 added composition ceramics, excellent physical properties were also appeared, respectively: the dielectric constant (ε r) of 6778, piezoelectric charge constant (d33) of 1027 [pC/N], electromechanical coefficient (k p) of 0.67 and curie temperature of 155 [°C]. These values were suitable for the device application such as ultrasonic tooth cleaner and piezoelectric speakers.

Multi-objective optimisation of technical wind turbines parameters based on multi-physical models

This paper presents a decision tool for the optimisation of wind turbine technical parameters, using a multiphysical model of the power system. This includes a multiphysical modelling of aerodynamical, mechanical and electromechanical system behaviours. The aerodynamics is based on a blade element momentum model. A mass model of wind turbines components is also used in this paper. The optimisation is performed with NSGA-II algorithm which may choose technical parameters (blade length, transmission ratio or electro-mechanical coefficient in this example) to maximise performances indicators (in this example the output electrical power and the wind turbine mass). The results provide a wide range of solutions that are the best compromises between the performances indicators chosen. The diversity in terms of parameters allows great latitude in the design of wind turbine.

Dynamical response and vibrational resonance of a tri-stable energy harvester interfaced with a standard rectifier circuit.

This paper investigates the dynamical response and vibrational resonance (VR) of a piecewise electromechanically coupled tri-stable energy harvester (TEH), which is driven by dual-frequency harmonic excitations. To achieve a stable DC output, the TEH is interfaced with a standard rectifier circuit. Using the harmonic balance method combined with the separation of fast and slow variables, a steady-state response together with the analytical expressions of displacement and harvested power is derived. The multi-solution feature in the amplitude-frequency response is observed and can improve the harvesting performance of the TEH under a low-frequency environment. There is an optimal time constant ratio and electromechanical coupled coefficient to maximize the harvested DC power. Meanwhile, the VR phenomenon of the TEH is explored through the response amplitude of the low-frequency input signal, which implies that an appropriate combination can induce the occurrence of VR and improve the rectified voltage. Similarly, the nonlinear stiffness coefficients can be adjusted by changing the magnet distance to induce the appearance of VR. The theoretical solutions are well supported by numerical simulation and experimental verification. Specifically, the theoretical analysis and experimental evidence illustrate that the harvested power under the VR effect is much higher than that without VR.

Microstructural features and complex electromechanical parameters of Pb0.95Sr0.05Ti0.47Zr0.53O3 + 1% Nb2O5 porous piezoceramics

In this article, a correlation between microstructure and properties for porous piezoceramics of the composition Pb0.95Sr0.05Ti0.47Zr0.53O3 + 1% Nb2O5 was studied in detail. Experimental samples of porous piezoceramics were obtained using a modified method of burning-out a pore former. Porosity dependences of dielectric, elastic, piezoelectric, and electromechanical coefficients of the porous ceramics in the relative porosity range 0–50% were measured and analyzed. It was revealed that the microstructural features of porous piezoceramics defined the character of the porosity dependences of the dielectric, piezoelectric, and electromechanical properties of porous piezoelectric ceramics.

Extraction of Electromechanical Coefficients from Capacitance–Voltage Measurements of Unannealed Solution‐Processed KNN Thin Films: Effects of Frequency and Electrostatic and Mechanical Deformation

A solution‐processed piezoceramic thin‐film MπM parallel‐plate capacitor structure to determine electromechanical coefficient using capacitance–voltage measurements is demonstrated. Electrical loading is applied to the capacitor to stimulate out‐of‐plane longitudinal and transverse elongation. The piezoelectric coefficient (d 33) is estimated using the spatial deviation of thin‐film dimensions as a function of the applied electric field. The results are validated using finite element method‐based modeling and compared with several measurements in literature, including piezoresponse force microscopy‐based measurements, which are generally considered unreliable due to strong electrostatic interactions between the tip‐cantilever, and the charged sample surface, wherein such artifacts result in the overestimation of the electromechanical response of the material under investigation.

Performance Assessment and Comparison of Two Piezoelectric Energy Harvesters Developed for Pavement Application: Case Study

To advance the development of piezoelectric energy harvesters, this study designed and manufactured bridge-unit-based and pile-unit-based piezoelectric devices. An indoor material testing system and accelerated pavement test equipment were used to test the electrical performance, mechanical performance, and electromechanical coupling performance of the devices. The results showed that the elastic modulus of the pile structure device was relatively higher than that of the bridge structure device. However, the elastic modulus of the two devices should be improved to avoid attenuation in the service performance and fatigue life caused by the stiffness difference. Furthermore, the electromechanical conversion coefficients of the two devices were smaller than 10% and insensitive to the load magnitude and load frequency. Moreover, the two devices can harvest 3.4 mW and 2.6 mW under the wheel load simulated by the one-third scale model mobile load simulator, thus meeting the supply requirements of low-power sensors. The elastic modulus, electromechanical conversion coefficients, and electric performance of the pile structure device were more reliable than those of the bridge structure device, indicating a better application prospect in road engineering.