Search Results (572)

To address the structural complexity, limited detection sensitivity, and environmental susceptibility of the stable operating point in conventional fiber-optic current transformers for low-current detection, this study proposes a fiber-optic current transformer based on the coupling of an extrinsic Fabry–Perot interferometer (EFPI) and a lead zirconate titanate piezoelectric ceramic (PZT). In the proposed sensor, a toroidal magnetic core and an induction winding are used as the current pickup unit to convert the measured alternating current into an induced voltage. This induced voltage directly drives the PZT to generate axial displacement, causing periodic variations in the length of the air Fabry–Perot cavity formed between the fiber end face and the coated quartz diaphragm. As a result, the current signal is converted into an optical interference intensity signal. To prevent the static operating point from deviating from the optimal linear region during EFPI intensity demodulation, a DC-component-feedback-based operating point control method is proposed. By adjusting the driving voltage of the fiber Fabry–Perot tunable filter, the center wavelength of the incident narrowband demodulation light can track the optimal operating point of the interference spectrum, thereby improving the stability of the intensity demodulation process. Experimental results show that the fabricated sensor can generate a stable reflected interference spectrum and exhibits a relatively flat frequency response within the range of 0–7 kHz, indicating its potential for power-frequency current detection under the present laboratory conditions. When the measured current is 0.13 mA, the sensor can still produce a distinguishable sinusoidal output signal. When the measured current increases to 75 mA, obvious nonlinear distortion appears in the output signal, indicating that the sensor is approaching the boundary of its linear detection range. Within the linear operating region, the output peak-to-peak value shows good linearity with the measured current. The results indicate that the proposed EFPI-PZT fiber-optic current transformer has the advantages of a relatively simple structure, clear low-current response, and adjustable structural parameters, providing a reference for the miniaturized design and further development of new fiber-optic current sensors. Full article

As the foundational sensing element for AI-driven structural health monitoring systems, piezoelectric ceramic (PZT) is widely adopted in civil engineering to capture high-fidelity physical responses. Distinct from existing studies focusing on the actuation mode or static/quasi-static sensing conditions, this study specifically investigates the dynamic strain transfer behavior of surface-bonded PZT sensors in sensing mode by establishing a three-layer analytical model incorporating the adhesive shear lag effect, validated by finite element simulations. Accordingly, a dual-regime dynamic calibration strategy is proposed: employing a single sensitivity value for low-frequency global structural vibrations and frequency-dependent correction for high-frequency elastic wave applications. Parametric analyses on PZT thickness, adhesive thickness, and shear modulus quantitatively demonstrate that reducing PZT/adhesive thicknesses and increasing adhesive shear modulus extend the compensation-negligible frequency range (defined by a 10% strain ratio deviation threshold) and elevate the first-order longitudinal natural frequency; practical sensor fabrication guidelines are further derived from these findings. Additionally, the system’s first-order longitudinal natural frequency stabilizes when the host-to-PZT area ratio (A_s/A_p) exceeds a critical threshold. These findings provide a theoretical basis for the optimal design, dynamic calibration, and engineering application of bonded PZT sensors. Full article

Lead-free [(Ba_0.85Ca_0.15)_1−1.5xNd_x][(Zr_0.1Ti_0.9)_0.995Mn_0.005]O₃ (x mol% Nd/Mn BCZT, x = 0.05, 0.1, 0.5, 1 mol%) ceramics were prepared by the traditional solid-state reaction method, in which the synergistic effects of sintering temperature and Nd/Mn co-doping on the phase structure, microstructural evolution, and electrical properties were systematically investigated. All ceramics exhibit a pure perovskite structure, with the tetragonal (P4mm) phase dominating at room temperature as confirmed by the X-ray diffraction Rietveld refinement. The sintering temperature (1475–1520 °C) is found to be the primary factor governing densification and grain growth, with the relative density peaking at 91.7% for the x = 0.5 mol% sample sintered at 1505 °C. Within this optimized processing window, increasing the Nd content induces a gradual migration of the Curie temperature (T_C) toward lower temperatures, accompanied by enhanced relaxor behavior. A highlight of this work is the strategic balance between piezoelectric activity and mechanical quality factor through a “donor–acceptor” co-doping mechanism. Specifically, for the x = 0.5 mol% ceramics, an exceptionally high mechanical quality factor (Q_m = 424.5) is achieved for samples sintered at 1490 °C, which is proposed to be associated with the temperature-modulated formation of ${Mn}_{Ti}^{″}-V_O^{••}$ defect dipoles, while a peak inverse piezoelectric coefficient $d_{33}^{*}$ of 685.1 pm/V is maintained at a sintering temperature of 1520 °C. Full article

Commercial lead zirconate titanate (PZT) ceramics are widely employed in electromechanical devices due to their excellent piezoelectric response and operational stability. This study investigates the influence of polarization temperature and time on the electromechanical performance of commercial Sparkler PZT-4 (Navy Type I) ceramics. Samples were compacted, sintered at 1230 °C, and polarized under temperatures ranging from 80 to 110 °C for 2, 8, and 15 min using a constant electric field of 3.0 kV/mm. Microstructural, physical, and crystallographic analyses confirmed the successful processing of the ceramics, yielding an apparent density of 7.68 g/cm³, relative density of 96.02%, and the predominance of the tetragonal Pb(Zr,Ti)O₃ perovskite phase. Electromechanical characterization revealed a strong dependence of the piezoelectric coefficient (d₃₃) and electromechanical coupling factor (K_p) on the polarization conditions. Maximum values of d₃₃ = 325.8 pC/N and K_p = 0.509 were obtained under elevated temperatures and longer polarization times. A phenomenological Avrami approach indicated faster apparent domain alignment at higher temperatures, while ANOVA and Tukey tests confirmed the significant influence of polarization parameters on the electromechanical response. The results identify favorable polarization conditions for commercial PZT-4 ceramics used in sensors, actuators, and ultrasonic transducers. Full article

Deep learning networks facilitate automated metal material/structural stress identification when employing the electromechanical impedance/admittance (EMI/EMA) of piezoelectric ceramic (PZT) transducers, while insufficient data quantity and low quality usually restrict the performance of data-driven deep networks. To address this problem, this paper innovatively proposed an original data enhancement method using the EMA generative adversarial network (EMAGAN) to overcome measurement data inefficiency and deficiency for deep learning-based stress identification, which is difficult to accomplish using the traditional EMA technique. In this method, a novel data-normalized algorithm was tuned to collaboratively foster the EMAGAN-based dataset generation. Then, the synthetic datasets incorporated with original ones were fed into an adaptively established one-dimensional convolutional neural network (1DCNN) for accurate stress prediction. A validating experiment was performed on an aluminum beam specimen subjected to uniaxial tensile load until failure, which was continuously monitored via two surface-bonded PZT transducers. The efficacy of the generated EMA datasets was evaluated through comparison with the raw ones in terms of statistical errors and deep learning-based aluminum structural stress identification. The results demonstrated that the EMAGAN generated high-accuracy EMA data which exceeded 380 times that of the normal collection method, and the EMAGAN paired with 1DCNN provides a promising way for EMA data-driven metal structural stress identification with high efficiency, intelligence and accuracy. Full article

Potassium sodium niobate (KNN) lead-free piezoelectric ceramics feature eco-friendliness and low density, coupled with superior high-frequency driving efficiency, albeit with inferior low-frequency performance. Conversely, Terfenol-D exhibits outstanding low-frequency driving capability but suffers from high density and poor high-frequency efficiency. This work proposes a ternary symmetric driving structure that integrates the complementary advantages of KNN and Terfenol-D, developing an underwater acoustic transducer with excellent lightweight design, low-frequency response, and broadband performance. The ternary symmetrically excited transducer maintains stable nodal planes across different operating frequencies and exhibits two distinct resonant frequencies. The vibration equation is analytically solved, and modal analysis is performed to clarify the evolution of the dual-resonance frequencies. A prototype transducer weighing 2.8 kg is fabricated and tested in an anechoic water tank. It delivers a maximum transmitting voltage response of 145 dB at 1.7 kHz with a broad operating bandwidth of 1–6 kHz. Compared with previously reported transducers, its weight is reduced by 26% to 93%. Benefiting from the double-ended radiation structure, the transducer yields a nearly omnidirectional radiation pattern. This ternary symmetrically excited transducer holds promising application prospects for underwater acoustic detection, communication, and navigation systems on unmanned underwater vehicle platforms. Full article

Lead-free piezoelectric ceramics have attracted substantial attention in environmental protection and energy storage applications due to their excellent performance. In this study, the Ba_1−xCa_xZr_0.1Ti_0.9−ySn_yO₃(BCZTS) lead-free piezoelectric ceramic system was synthesized. The effects of doping ratios of Ca and Sn, as well as sintering temperature, were systematically investigated on the phase structure, microstructure, and piezoelectric properties of BCZTS ceramics. The results showed that the Ba_0.88Ca_0.12Zr_0.1Ti_0.81Sn_0.09 ceramics synthesized with a Ca doping content of x = 12 mol% and a Sn doping content of y = 9 mol % had a homogeneous phase structure with an Orthorhombic–Tetragonal (O-T) morphotropic phase boundary (MPB) and uniform grain size. At a sintering temperature of 1300 °C, the ceramics achieved optimal piezoelectric performance, with a piezoelectric coefficient d₃₃ = 319 pC/N. These lead-free piezoelectric ceramics have superior properties compared to conventional lead-based piezoelectric ceramics in the local market, providing a novel and feasible way to replace lead-based ones in civilian applications. Full article

This study aims to demonstrate the feasibility of controlling particle size through a mathematical model in the design of industrially applicable ultrasonic spray nozzles by utilizing the vibrational characteristics of piezoelectric ceramics. A piezoelectric ceramic composition with a low sintering temperature and excellent thermal stability (Curie temperature above 300 °C) was developed and used as a ceramic vibrator. Furthermore, the resonance frequency and nozzle displacement were calculated using the COMSOL program and applied to a mathematical model to design an ultrasonic nozzle capable of producing a spray particle diameter of approximately 30 μm. The designed ultrasonic nozzle was fabricated, and its spray characteristics were analyzed. The consistency of the spray characteristics was examined by comparing them with the mathematical model based on changes in ultrasonic nozzle length, resonance frequency, and fluid viscosity. When the ultrasonic nozzle horn length was 22 mm, the resonance frequency was found to be 42.1 kHz, and at a flow rate of 65 mL/min. the average spray particle size was approximately 30–40 μm, indicating fine and uniform particles. In addition, it can be seen that as the length of the nozzle horn increases, the resonance frequency decreases, reducing the supply energy delivered to the liquid, and the particle size increases as shown in the mathematical analysis. The theoretical separation energy required to atomize pure water at a flow rate of 65 mL/min. is 2100 J, which was found to be greater than all energy loss occurring during the atomization process. However, it can be seen that as the length of the ultrasonic nozzle increases, the maximum atomization volume increases, and as viscosity increases, the energy required to separate a single atomized particle becomes greater. Full article

Polymer–ceramic piezoelectric composites are widely investigated to combine the high piezoelectric performance of ferroelectric ceramics with the flexibility and processability of electroactive polymers. However, achieving enhanced dielectric properties while preserving the intrinsic piezoelectric response of the polymer matrix remains challenging, particularly due to dielectric mismatch between the constituent phases and interfacial effects. In this work, barium titanate (BaTiO₃) loaded poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) nanocomposites were fabricated by solvent casting using polyvinylpyrrolidone (PVP) and polysorbate 80 (PS80) as dispersing agents, aiming to obtain polarizable materials capable of retaining high piezoelectric strain coefficient (d₃₃) values and potentially exploiting the opposite polarity of matrix and filler through tailored poling strategies. Morphological, crystallographic, structural, thermal, thermomechanical, dielectric, and piezoelectric characterizations were performed by SEM/EDXS, XRD, FTIR, DSC, TGA, DMTA, dielectric spectroscopy, and d₃₃ measurements. Both dispersants improved filler dispersion and film densification, increasing the crystalline fraction of the matrix, without altering the relative fraction of β-phase (up to 93%). PVP enabled moderate and stable permittivity enhancement with weak frequency dependence, whereas PS80 introduced an electrically active interfacial contribution that amplified low-frequency permittivity at high filler loadings but made the permittivity more frequency-dependent. The piezoelectric response (between −20 pC/N and −25 pC/N) remained predominantly governed by the polymer phase, suggesting limited polarization played by BaTiO₃. These results underlined the critical role of interfacial electrical properties in designing stable high-performance flexible PVDF-TrFE/BaTiO₃ composites. Full article

Printable piezoelectric materials are emerging as a cornerstone of next-generation sensing, actuation, and energy harvesting technologies, driven by the need for lightweight, flexible, and digitally manufactured transducers. Conventional ceramic piezoelectrics offer exceptional electromechanical performance but require high-temperature sintering and exhibit intrinsic brittleness, limiting their integration with soft or unconventional substrates. Polymeric piezoelectrics, in contrast, provide mechanical compliance and low-temperature processability yet suffer from lower crystallinity, reduced piezoelectric coefficients, and limited thermal stability. These contrasting characteristics have catalyzed the development of functional piezoelectric inks—ceramic, polymeric, and hybrid formulations engineered for additive manufacturing techniques such as direct ink writing, stereolithography, screen printing, and inkjet printing. This review systematically examines the material compositions, dispersion chemistries, printing requirements, thermal treatment pathways, and poling strategies that govern the performance of printed piezoelectric transducers. By comparing ceramic-based, polymer-based, and hybrid systems, we reveal the fundamental trade-offs between printability, crystallinity, mechanical compliance, and electromechanical response, and map how these trade-offs shape device design across wearable electronics, soft robotics, and structural health monitoring. Finally, we highlight emerging approaches—including surface functionalization, low-temperature crystallization, liquid-phase sintering, and engineered ceramic–polymer interfaces—that offer promising routes to bridge the gap between printability and high piezoelectric performance. Full article

Resonant electromechanical de-icing uses piezoelectric actuators to generate stresses high enough to fracture and shed ice, offering an energy-efficient alternative to conventional systems. This work focuses on prestressed piezoelectric actuators composed of a ceramic stack clamped between two brackets, addressing limitations of previous designs such as mechanical losses and screw fatigue. A new architecture is proposed, featuring a variable-cross-section screw that concentrates deformation in a thinned central region and brackets bonded to the structure to reduce losses. An analytical sizing method is developed using multi-beam longitudinal vibration modelling and two de-icing criteria, including a newly introduced one. The analysis shows how actuator geometry and modal shapes influence de-icing performance, required voltage, and mechanical stresses, highlighting key trade-offs. A dedicated prototype is designed and experimentally tested, with results in good agreement with the analytical predictions. Full article

To address the need for high electrical insulation, strong immunity to electromagnetic interference, and miniaturized AC electrical-signal detection in complex electromagnetic environments, we propose and experimentally demonstrate a fiber-optic sensor based on a piezoelectric ceramic (PZT)-driven ring tapered-fiber resonator. The applied AC excitation is converted into periodic mechanical deformation through the inverse piezoelectric effect of the PZT, and the resulting strain modulates the resonator response, enabling optical demodulation of the input frequency and amplitude. A comprehensive figure of merit was introduced to optimize the tapered-fiber geometry, yielding an optimal waist diameter of approximately 10 μm. The sensor can effectively distinguish both single- and dual-frequency AC signals. Over the range of 50–500 Hz, the demodulated frequency agrees closely with the input frequency, with a linear fitting coefficient of 0.9999. At a fixed driving frequency of 250 Hz, the amplitude of the characteristic spectral peak increases nearly linearly with the input voltage amplitude, with a fitting coefficient of 0.9945. The device also exhibits good stability over 30–150 °C and during 70 h of continuous operation. With its simple structure, low cost, and strong immunity to electromagnetic interference, this sensor provides a practical solution for AC electrical-signal detection in complex environments. Full article

In this study, the sintering behavior and electrical properties of 0.7Pb(Zr_0.46Ti_0.54)O₃ (PZT)–0.1Pb(Zn₁/₃Nb₂/₃)O₃ (PZN)–0.2Pb(Ni₁/₃Nb₂/₃)O₃ (PNN) piezoelectric ceramics with different Pb(Fe₂/₃W₁/₃)O₃ (PFW) doping contents were investigated to obtain a formulation that can be co-fired with silver (Ag) electrodes below 900 °C for multilayer ceramics. PFW was introduced as a sintering aid, which effectively reduced the sintering temperature of the ceramics from 1200 °C to 850 °C. The sample with x = 0.12 exhibited the largest average grain size of 1.72 μm, achieving excellent comprehensive properties with piezoelectric constant (d₃₃) = 477 pC/N, planar electromechanical coupling factor (k_p) = 0.68, dielectric loss tangent (tanδ) = 0.0154, and relative density of 98.2%. Furthermore, the feasibility of fabricating piezoelectric actuators based on this optimized composition was verified. Multilayer piezoelectric devices were prepared via screen printing combined with a carbon-based sacrificial layer method. No obvious interdiffusion was observed at the interface between the Ag internal electrodes and the ceramic matrix. The 9-layer device attained a high d₃₃ = 1470 pC/N and produced a large displacement of 5.5 μm (corresponding to a strain = 1.83%) with a voltage of 500 V. The thickness of the multilayer piezoelectric film was approximately 0.3 mm. Through this, the feasibility of manufacturing a multilayered actuator with an Ag electrode was confirmed through the composition of 0.58PZT–0.1PZN–0.2PNN–0.12PFW. Full article

Piezoelectric sensors are widely used for force and vibration monitoring in both rigid and flexible structures, yet their performance can be significantly affected by how they are integrated into the host material. Challenges such as limited sensitivity, inconsistent signal transmission, and delays in response remain particularly relevant in flexible components produced by additive manufacturing. Addressing these limitations requires a better understanding of how integration strategies influence sensor behavior. This study presents preliminary experimental results on the performance of commercial piezoelectric ceramic (PZT) sensors embedded in flexible structures fabricated by additive manufacturing (3D printing). Although the current investigation did not assess variability from mass production, repeated testing of each specimen was performed to reduce this potential error. Filaflex Foamy 95A polyurethane (TPU) samples were produced using Fused Filament Fabrication (FFF) technology in two configurations: with and without a cavity for sensor fitting. A minimum of seven valid compression tests, at each condition, were performed, with ten loading and unloading cycles up to 1000 N of force, using an indentation rate of 0.5 mm/s. In most tests, the two configurations showed different peak amplitudes throughout the cycles. Samples with the sensor embedded in the cavity consistently reached peak signal amplitudes more rapidly. In contrast, samples with the sensor positioned on the material surface without a fitting exhibited similar results across all tests and demonstrated a broader signal distribution over time. These findings indicate that the sensor-integration strategy is the primary factor influencing dynamic force transfer, impact sensitivity, piezoelectric response time, and maximum signal magnitude. Full article

Piezoelectric biomaterials have attracted considerable interest in osteochondral tissue engineering owing to their inherent ability to produce electrical signals in response to mechanical stimuli without external power, thereby closely mimicking the physiological electrical microenvironment required for tissue regeneration. This review comprehensively summarizes recent insights into biological piezoelectricity from the molecular to the macroscopic level, highlighting its interplay with streaming potentials and its regulatory roles in bone and cartilage regeneration. We critically analyze recent advances in major piezoelectric material systems, including ceramics, polymers, and composite scaffolds, with emphasis on their structural characteristics, bioactive performance, and suitability for tissue-specific repair. Among them, polymer-based composite and hybrid piezoelectric scaffolds appear particularly promising for the development of flexible, high-performance osteochondral repair platforms, as they offer a more favorable balance between mechanical compliance, electromechanical output, and biological adaptability. Despite encouraging preclinical findings, significant challenges remain, including biocompatibility, controlled degradation kinetics, and the precise modulation of electrical cues for specific biological contexts. To address these barriers, future research should focus on optimizing scaffold design, integrating responsive and multimodal stimulation strategies, and establishing standardized protocols for preclinical evaluation and clinical translation. Overall, piezoelectric biomaterials hold substantial potential for the development of innovative regenerative therapies for complex osteochondral defects. Full article