Papers by Keyword: Piezoelectric

Abstract: The study explores the integration of additive manufacturing for the development of 4D-printed piezopolymer metamaterials, aiming to create dynamic, multifunctional structures capable of distributed sensing and energy harvesting. The focus is on Polyvinylidene fluoride (PVDF), a partially fluorinated polymer renowned for its strong electromechanical coupling, specifically within its polar β-phase. To harness these properties, three distinct experimental strategies were evaluated for integrating PVDF with conductive electrodes necessary for electrical poling: direct 3D printing with manually applied silver paste, printing directly onto pre-integrated aluminium foil substrates, and a novel chemical solvent-based deposition using a DMF/acetone mixture. While high-precision inkjet printing was initially tested for electrode deposition, it demonstrated significant limitations in scalability, throughput, and durability, particularly suffering from structural degradation during the post-poling silicon oil removal process. Consequently, the study advocates for a robust, hybrid multi-material extrusion platform. This approach will enable the simultaneous, monolithic deposition of structural PVDF thermoplastics and highly conductive thixotropic inks.

Abstract: Piezoelectric materials possess a special property to produce electricity from mechanical motion and are therefore it is suitable for green energy solutions. In our project, we fabricated a flexible piezoelectric device through a simple, non-vacuum process. We prepared the device by a solution casting process with a thin poly (vinylidene fluoride) (PVDF) film. Under mechanical stress, the device shows a clear electrical response, confirming its functionality. This indicates that piezoelectric materials can be fabricated to utilize as a low-cost, eco-friendly, and efficient means to harvest energy. This device can also be used as a sensor in robots and robot-related applications. This device can sense movement, which can be used in autonomous robots to sense movement, feed back, or even to harvest energy to power robotic sensors. In the future, we can improve the device performance by modifying the film thickness, using more efficient electrode materials, and making it stable to operate in different conditions.

Abstract: Polyvinylidene Fluoride (PVDF) and Lead Zirconate Titanate (PZT) thin-film sensors can be used to detect acoustic emissions, and their low thickness (28µm PVDF sensors available) allow them to be embedded (positioned within a laminate). However, the characteristics and sensitivity of these sensors within composite structures require further study. The attenuation curves of PZT, silver ink metallised PVDF and gold metallised PVDF sensors, when mounted using a variety of couplants such as ultrasonic gel, resin, silicone adhesive and thin double-sided adhesive tape, have been generated. Investigations also include positioning the sensor within the laminate, as opposed to on the surface, and monitoring the performance changes with respect to the through-thickness position. The sensors coupled using resin have shown to generally have the highest amplitude, with the highest being the PZT yielding 88 dB at 5cm. Initial comparisons of signal detection by the sensors with respect to fibre orientation have shown that signal travelling along the fibres generally has higher amplitude when compared to at 45^o. This research is the first step toward identifying the preferred sensor type and position within the structure for damage detection.

Abstract: Piezoelectric ceramics possess very high piezoelectric coefficients but lacks the conformability for using them in flexible devices, in high-resolution sensing devices that can be integrated to human skin and other such applications. This problem can be resolved by blending them in appropriate proportion with polymers which are intrinsically light weight, stable and flexible. In this paper polymer composites xPZT– (1-x) PVDF (x= 0, 0.025, 0.05, 0.10, 0.15, 0.20 and 0.25) were prepared by solution casting method and their dielectric and its mechanical properties were studied. Given that PZT has a very high dielectric value, the composite's dielectric constant grew as the filler concentration increased which shows better dipole alignment in the composite. With an increase in filler concentration, the composite loses flexibility and tensile strength. Due to their greater Young's modulus than pure PVDF film, the films with compositions x=0.025 and x=0.05 could have better piezoelectric characteristics.

Abstract: One of the traditional clean-energy harvesting solutions is through transducing different mechanical stresses into electrical energy. Generally, the acoustic-to-electric energy conversion of still needs more research investigations to be applicable. In our work, we are targeting to fabricate elastic nanofibers mats via electrospinning method to be used for acoustic harvesting/sensing applications. The targeted mechanically-elastic nanocomposite includes polyvinylidene fluoride (PVDF), which is one of the most famous organic piezo materials, with blended thermoplastic polyurethane (TPU). As TPU supports higher mechanical allowed breaking strain. Then, the synthesized mat has been used as a target for mechanical stresses with resulted piezosensitivity of 667±220 mV/N. Then, the nanofibers mat has been targeted against acoustic signals with different amplitude and frequencies. It has been observed that the synthesized mats can detect or harvest acoustic signals and convert them into output electric voltage. According to acoustic sound input, the synthesized electrospun nanofibers detect output voltage up to 300 mV with increased input audible amplitude and frequency up to 6 kHz, where the harvested voltage has a saturation behaviour beyond that audible frequency. That can open the track for using such nanocomposites in energy harvesting applications from disposable facemasks, filters, and music/noise in different opened and closed areas.

Abstract: The present study discusses the fabrication of non-lead ceramic/polymer composites employing (Na_1/2Bi_1/2)TiO₃ (NBT) ceramic powder as a filler and poly(vinylidene fluoride); PVDF as a polymer matrix. The NBT (volume fraction, ϕ = 1) ceramics were synthesized using the conventional mixed-oxide method followed by the high-energy ball milling method whereas (1-ϕ)PVDF/ϕ(Na_1/2Bi_1/2)TiO₃; 0 ≤ ϕ ≤ 0.3 composites were prepared from a melt-mixing process. It was observed that the real and imaginary parts of dielectric permittivity, ac conductivity, and longitudinal piezoelectric charge coefficient increase with the increase in NBT-content. Different dielectric mixing models were presented to determine the effective complex permittivity of the composites. Five dielectric mixture equations have been chosen to test the acceptability of experimental data. It was revealed that theoretical models as given by Bruggman, Rother-Lichtenecker, and modified Rother-Lichtenecker show good agreement with the experimental results of filler-concentration dependent alteration of effective relative permittivity and loss factor of the PVDF/NBT composite. A mathematical model of first-order exponential growth has also been proposed, which fitted excellently the experimental data (r² > 0.998).

Abstract: The structure, microstructure, Fourier transformed infrared spectra, dielectric, and impact generated energy harvesting characteristics of x(Ba_0.7Ca_0.3)TiO₃–(1-x)Ba (Zr_0.2Ti_0.8)O₃; x = 0, 0.5, and 1.0 synthesized using solid-state reaction method are discussed in this work. The X-ray diffraction (XRD) process was used to examine the forming of a single-phase compound. The Rietveld refinements of XRD data were used in FullProf software to determine crystal symmetry, lattice parameters, and space groups. A scanning electron microscope was taken into use to examine the surface morphology of all of the samples. The samples' phase transition temperature was observed to lie between-10°C and 87°C, shifting toward the higher temperature side as x increased. In the case of x = 0.5, two-phase transitions were discovered at 22°C and 70°C. The value of impact generated output voltage and electrical energy increases as applied mechanical energy increases. The findings of this study point to the possibility of using 0.5(Ba_0.7Ca_0.3)TiO₃–0.5Ba (Zr_0.2Ti_0.8)O₃ ceramic for energy harvesting and sensing purposes.

Abstract: The microstructure, energy dispersive X-ray spectra, and field dependent polarization and electrostrictive strain characteristics of x(Ba_0.7Ca_0.3)TiO₃–(1-x)Ba (Zr_0.2Ti_0.8)O₃; x = 0, 0.5, and 1.0 synthesised using solid-state reaction process are discussed in this work. The X-ray diffraction process and scanning electron microscope were, respectively taken into use to examine the forming of single-phase compound and the surface morphology as well as elemental analyses of all of the samples. The grains sizes were found to lie between 3–12 μm and was largest for x = 0.5. The value of piezoelectric coefficient, converse piezoelectric effect (strain maximum to peak electric field), and electrostrictive coefficient were found to be the highest for x = 0.5 sample. Ba_0.85Ca_0.15Zr_0.10Ti_0.90O₃ was shown to be a potential lead-free electrostriction material for industrial applications, particularly in positioning actuators, based on field-dependent polarisation and strain experiments at ambient temperature.

Abstract: Study of smart functionally graded (FG) beam made of carbon nanotube (CNT) reinforced composites combined with piezoelectric material is carried out. Material parameters of the beam are supposed to vary along its thickness following extended rule of mixture. Finite element model is developed for the functionally graded CNT reinforced beam combined with piezoelectric material using ANSYS software. Numerical results are evaluated using different boundary conditions. Computed results revealed that piezoelectric layer of smart FG beam efficiently controls the bending deformations of the presently studied smart CNT reinforced functionally graded beams. Results are also presented considering various material profiles for the grading of FG beams. It is observed that X type profile distribution considering CNT volume fraction of 0.28 provides minimum bending deflection of the presently studied smart FGCNT reinforced composite beams for the activated as well as inactivated piezoelectric material

Abstract: Pb (Zr_0.35Ti_0.65)_1-xSn_xO₃ (PZST) piezoelectric ceramics with ABO₃ perovskite structure were synthesized using Solid state reaction technique. The piezoelectric, ferroelectric and dielectric behavior of PZST piezoceramics was studied systematically by varying the amount of Sn at fixed Zr/Ti ratio. It was found that sample containing Sn= 0.26 exhibit maximum piezoelectric coefficient of 324 pC/N and minimum tangent loss of 0.009. Decrease in tetragonality and Curie Temperature (Tc) was observed with the increase of Sn content. The polarization–electric field hysteresis loops for all compositions were studied and it was observed that the sample containing Sn= 0.26 exhibit maximum polarization of 0.3C/m². The synthesized PZST compositions can be utilized for Pressure sensors and maritime SONAR applications. Keywords: Piezoelectric, PZST ceramics, ferroelectric, Domains