Browsing by Subject "Piezoelectricity"
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Item Piezoelectric properties of the new generation active matrix hybrid (micro-nano) composites(Elsevier B.V., 2014) Parali L.; Şabikoʇlu I.; Kurbanov M.A.A hybrid piezoelectric composite structure is obtained by addition of nano-sized BaTiO 3 , SiO 2 to the micro-sized PZT and polymers composition. Although the PZT material itself has excellent piezoelectric properties, PZT-based composite variety is limited. Piezoelectric properties of PZT materials can be varied with an acceptor or a donor added to the material. In addition, varieties of PZT-based sensors can be increased with doping polymers which have physical-mechanical, electrophysical, thermophysical and photoelectrical properties. The active matrix hybrid structure occurs when bringing together the unique piezoelectric properties of micro-sized PZT with electron trapping properties of nano-sized insulators (BaTiO 3 or SiO 2 ), and their piezoelectric, mechanic and electromechanic properties significantly change. In this study, the relationship between the piezoelectric constant and the coupling factor values of microstructure (PZT-PVDF) and the hybrid structure (PZT-PVDF-BaTiO 3 ) composite are compared. The d 33 value and the coupling factor of the hybrid structure have shown an average of 54 and 62% increase according to microstructure composite, respectively. In addition, the d 33 value and the coupling factor of the hybrid structure (PZT-HDPE-SiO 2 ) have exhibited about 68 and 52% increase according to microstructure composite (PZT-HDPE), respectively. © 2013 Elsevier B.V. All rights reserved.Item A digital measurement system based on laser displacement sensor for piezoelectric ceramic discs vibration characterization(Elsevier GmbH, 2016) Parali L.; Pechousek J.; Şabikoʇlu I.; Novak P.; Navarik J.; Vujtek M.This study describes the innovative design of a digital measurement system based on a laser displacement sensor (LDS) as a vibrometer which is capable to measure a dynamic displacement response dependence on a stimulated vibration. The frequency response of a piezoelectric ceramic disc is obtained by processing the input/output signals obtained from the function generator and digital oscilloscope (digitizer) cards driven by a personal computer. Resonant frequencies of vibration are achieved utilizing the swept-sine signal excitation following the peak values in the signal response measured by LDS. The analogue signal from LDS controller represents directly a mechanical vibration of a piezoceramic disc. The test measurement results indicate that the system can distinguish resonance frequencies of piezoelectric ceramic discs up to 40 kHz with the resolution 1 Hz. Piezoelectric coefficient d33 and its linearity along the excited voltage amplitudes have been calculated by the applied methods as a demonstration of a successful system concept. The results achieved are in compliance with the reference value declared by the manufacturer of the piezoceramic disc. © 2015 Elsevier GmbH. All rights reserved.Item An experimental study of a piezoelectrically actuated touch screen(Institute of Electrical and Electronics Engineers Inc., 2017) Sari G.; Akgül M.B.; Kirişken B.; Ak A.F.; Akiş A.A.An audiovisual feedback is used on touch screens in portable electronic devices. When these devices are used in noisy and distracting environments, suitable available feedback methods is severely inadequate and the availability of the device severely reduced. For these reasons, touch screen technology has become a popular recently. These panels used in many sectors such as watches, cars, mobile devices, aerospace. Touch screens, which provide tactile feedback to the user, are activated using solenoid actuators, coil-type actuators or vibration motors. The use of evolving piezoelectric vibrators has attracted considerable attention in recent years to obtain high-resolution tactile feedback. Their higher bandwidth helps create more user-perceivable haptic effects. In this work, we experimented to observe the effect of the piezo vibrator on the screen. As a result, the various types of tactile feedback functions will be developed on the screen and compared. The best vibration functions depending on the settings are obtained through experiments. © 2017 IEEE.Item Vibration modelling of piezoelectric actuator (PEA) using Simulink software(Institute of Electrical and Electronics Engineers Inc., 2017) Parali L.; Sari A.This paper presents to define a vibration modelling of a PEA using MATLAB-Simulink software based on a single degree freedom mechanical model. The experimental vibration displacement values of PEA have been carried out utilizing the swept-sine signal excitation following the peak values in the signal response measured as contactless by the laser displacement sensor. Harmony between the mathematical modelling and experimental values have been observed from 96.6 to 81.4 % between excitation amplitudes of 0.5 and 3.0 V when the vibration modelling of PEA is normally taken into consideration with a linear working range. Therefore, obtained this vibration modelling could be used as training-testing tool for estimating vibration characterization of an actuator under any excitation voltages. © 2017 IEEE.Item Characterization of β-PVDF-based nanogenerators along with Fe2O3 NPs for piezoelectric energy harvesting(Springer, 2020) Zeyrek Ongun M.; Paralı L.; Oğuzlar S.; Pechousek J.β-phase polyvinylidene fluoride (PVDF) nanogenerators along with various concentrations (0.2, 0.4, 0.6, and 0.8 wt%) of iron oxide (Fe2O3) nanoparticles were produced using the electrospinning technique. The characterization of the free- and doped-nanogenerators was examined by X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and 57Fe Mössbauer spectroscopy, dielectric measurements, and piezoelectric effect analysis. All the analyses demonstrated that the structural transition in the specimens at doping ratios are above the critical concentration of 0.4% by wt. of Fe2O3 NPs in PVDF, superparamagnetic behavior of the iron oxide particles in the composite. Utilization of the β-PVDF along with Fe2O3 NPs (0.4 wt%) exhibited higher piezoelectric properties with respect to the free form and the other additive concentrations. Considering the piezoelectric properties of the nanogenerator, the output voltage of the β-PVDF in the presence of the 0.4 wt% of Fe2O3 NPs reaches up to 1.39 V by increasing the peak amplitude to almost 50% while the undoped β-PVDF nanogenerator reveals almost to 0.93 V at the same impact frequency (6–7 Hz). © 2020, Springer Science+Business Media, LLC, part of Springer Nature.Item Comparative evaluation of PVDF based piezoelectric nanogenerator (PNG) under various resistive loads for energy harvesting applications(Institute of Electrical and Electronics Engineers Inc., 2020) Parali L.; Koc M.; Sari A.Piezoelectric nanogenerator (PNG) is a type of sensor that converts mechanical energy to electrical energy by detecting small-scale physical deformation. In this study, to realize a PNG, firstly polyvinylidene difluoride (PVDF) based electrospun nanofiber film is produced through electrospinning system. The obtained nanofiber film was characterized by X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared spectroscopy (FTIR). After that, the PNG device was built as the capacitor by locating the PVDF electrospun nanofiber between two aluminum conductive plates and cabled. The piezoelectric energy harvesting analyses of the PNG was defined by taking measurements under various resistive loads. At a vibration frequency of 15 Hz, the effective voltage value of the PNG reached the maximum voltage of 62.6 mV under the resistive load of 750 KΩ while its electrical power was around 5.23 μ W under the same load. The PNG based energy harvesting system aims to obtain electrical energy from the natural vibrational sources for mobile microelectronics. © 2020 IEEE.Item Fabrication and vibrational energy harvesting characterization of flexible piezoelectric nanogenerator (PEN) based on PVDF/PZT(Elsevier Ltd, 2020) Koç M.; Paralı L.; Şan O.In this study, polyvinylidene difluoride (PVDF) is doped with different volume levels (10, 20, 30 vol %) of lead zirconate titanate (PZT), and neat PVDF (undoped) electrospun nanofibres are prepared by aligning them through the electrospinning process with a rotating drum collector. All of the produced nanofibres are characterized by X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared spectroscopy (FTIR). The piezoelectric nanogenerator (PEN) devices are fabricated by placing the PVDF/PZT electrospun nanofibres as the dielectric material between two conductive plates. The vibrational energy harvesting analyses of the PEN are defined by taking measurements under various resistive loads. At 15 Hz excitation frequency, the maximum output power of PEN with PVDF+10 vol %PZT reaches 6.35 μW by increasing the power to 85% under a resistive load of 1MΩ, while the PEN with β-PVDF has the electrical power of 3.44 μW at the same load. The PEN based energy generation is a promising source of clean energy generation from mechanical vibrations for powering portable microelectronic applications without an external power supply. © 2020 Elsevier LtdItem Piezoelectric and magnetoelectric evaluations on PVDF/CoFe2O4based flexible nanogenerators for energy harvesting applications(Springer, 2022) Koç M.; Dönmez Ç.E.D.; Paralı L.; Sarı A.; Aktürk S.In this study, flexible PVDF/CoFe2O4based nanogenerators were fabricated using composite fibers which were prepared by combining polyvinylidene difluoride (PVDF) and cobalt ferrite (CoFe2O4) nanoparticles (NPs: ~16 nm diameter) at a concentration of 1, 3, 5, 7, and 10 wt%. All of the flexible PVDF/CoFe2O4 nanofibers were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The incorporation of CoFe2O4 NPs into the PVDF leads to the formation a rich electroactive β-phase in the composite structure. The piezoelectric properties of nanogenerators indicate that the nanogenerator based on the PVDF/CoFe2O4 fibers containing CoFe2O4 NPs at a concentration of 3 wt% has a greater power efficiency of 27.2% at 20 Hz compared to that of the nanogenerator with the pure PVDF fibers at 10 Hz, under the same resistive load of 2.5 MΩ. The results also show the magnetoelectric properties of the nanogenerator with PVDF + 10 wt% CoFe2O4 reached the highest voltage value of 18.87mV at the same load resistive load (2.5 MΩ) for a low-level magnetic field frequency of 50 Hz. The specially improved nanogenerators which have capability of producing electrical signals at the same time from mechanical and magnetic stimulations hold promise for the development of wearable electronics devices. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Piezoelectric and magnetoelectric properties of PVDF/NiFe2O4 based electrospun nanofibers for flexible piezoelectric nanogenerators(Elsevier B.V., 2022) Paralı L.; Demirci Dönmez Ç.E.; Koç M.; Aktürk S.In this study, flexible piezoelectric nanogenerators (PNGs) were fabricated using the composite fibers which were prepared by combining polyvinylidene difluoride (PVDF) and nickel ferrite (NiFe2O4) nanoparticles (NPs) at a concentration of 1, 3, 5, 7, and 10 wt%. The piezoelectric properties of PNG indicate that the PVDF/NiFe2O4 fibers containing NiFe2O4 NPs at a concentration of 10 wt% has a higher power efficiency of 5.4% at 20 Hz compared to that of the pure PVDF fibers at 10 Hz, under the same resistive load of 2.5 MΩ. The magnetoelectric properties of PNG show that the PNG with PVDF+7 wt%NiFe2O4 supplied the highest electrical power of 0.40 μW under a resistive load of 750KΩ while it reached a maximum voltage value of 17.50 mV at the same load resistive load for a low-level magnetic field of 50 Hz frequency. © 2022 Korean Physical SocietyItem Experimental Active Vibration Control of a Highly Flexible Composite Manipulator with Acceleration Feedback(Springer Science and Business Media Deutschland GmbH, 2022) Uyar M.; Malgaca L.; Lök Ş.İ.; Can S.V.In this study, vibration control of a single-link flexible smart composite manipulator (FSCM) is experimentally studied. The experimental system includes a real-time data acquisition control card, accelerometer, amplifier, servo motor, and driver. The FSCM is an epoxy-glass composite manipulator with the piezoelectric actuator and has the orientation of [0/90] lay-up. Modal analysis is experimentally conducted to find the natural frequencies by applying a chirp signal to the piezoelectric actuator. Natural frequencies are found by taking the Fast Fourier Transform (FFT) in MATLAB. Triangular motion profiles are used to drive the FSCM. Motion parameters are found by utilizing the natural frequencies of the system for different deceleration times (tdec). with different deceleration times (tdec). Residual vibrations are suppressed by using PID control with acceleration feedback. The acceleration signals at the tip point are measured by utilizing the accelerometer. The controller gains are determined with the trial and error method. Experimental residual vibration results are presented for the active control. It is observed that the suppression of vibration amplitudes further increases with active control. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.Item Fabrication and Characterization of High Performance PVDF-based flexible piezoelectric nanogenerators using PMN-xPT (x:30, 32.5, and 35) particles(Elsevier Ltd, 2023) Paralı L.; Koç M.; Akça E.Flexible piezoelectric nanogenerators based on polyvinylidene difluoride (PVDF) and lead magnesium niobate-lead titanate Pb(Mg1/3Nb2/3)O3–PbTiO3(PMN-xPT compositions for x between 30 and 35) particles with various filler ratios from 10 to 30 vol% were fabricated through the electrospinning method. The phase and microstructural characterizations revealed that the homogenous and continuous fiber-shaped composite structure with good interfacial interaction between the PMN-PT particles and the PVDF matrix was achieved. It was found that the diameter of the neat PVDF fibers was approximately 354 nm, whereas the PVDF/PMN-35PT fibers with ceramic particle concentrations of 10, 20, and 30 vol% had average diameters of 317, 249, and 163 nm, respectively. The piezoelectric performance tests indicated that the 30 vol%PVDF/PMN-35PT nanogenerator had a 3 times greater electrical power efficiency (10.59 μW) at 20 Hz compared to that of the pure PVDF nanogenerator (3.56 μW) at 15 Hz under the same resistance load of 1 MΩ. All in all, the incorporation of PMNT-PT particles into the PVDF appears to be a good approach for the fabrication of high-performance flexible piezoelectric nanogenerator applications for biomechanical energy harvesting of devices converting the mechanical movements of organs such as cardiac and lung into electrical energy. © 2023 Elsevier Ltd and Techna Group S.r.l.Item The piezoelectric response of electrospun PVDF/PZT incorporated with pristine graphene nanoplatelets for mechanical energy harvesting(Springer, 2024) Paralı L.; Tatardar F.; Koç M.; Sarı A.; Moradi R.Flexible nanogenerators based on electrospun piezoelectric polyvinylidene fluoride (PVDF)/lead zirconium titanate (PZT) incorporated with unmodified graphene nanoplatelets (GNP) were fabricated via the electrospinning method. The microstructural and phase characterizations demonstrated a continuous and homogeneous fiber-shaped composite structure with good interfacial interaction between the GNP and the PVDF/PZT matrix. It was found that the diameter of the PVDF/PZT fibers was on average 270 nm, while the PVDF/PZT/GNP fiber with GNP content of 1.5wt.% had a diameter of approximately 236 nm. The piezoelectric performance evaluations of all nanogenerator devices indicated that the PVDF/PZT/GNP with GNP content of 1.5wt.% nanogenerator had an almost 6 times higher electrical output (8.68 µW) compared to that of the PVDF/PZT-based nanogenerator (1.51 µW) at 20 Hz within the same resistance of 2.5 MΩ. Considering its simple and low-cost fabrication technology, high performance, and stable electrical power efficiency, the introduced flexible nanogenerator based on the PVDF/PZT/GNP offers a promising capability of powering portable and wearable electronics. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item The output performance evaluations of multilayered piezoelectric nanogenerators based on the PVDF-HFP/PMN-35PT using various layer-by-layer assembly techniques(Springer, 2024) Paralı L.Multilayered Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and lead magnesium niobate lead titanate Pb (Mg1/3Nb2/3) O3–PbTiO3 (PMN-35PT) composition-based piezoelectric nanogenerators (PNGs) were fabricated as series, parallel, and combined series-parallel connections using various layer-by-layer assembly techniques. Supporting the theoretical approaches with experimental results shows that the fabricated four-layered PNG with parallel connections (4L-P) reached an open-circuit voltage of 0.4 V (VRMS) and a maximum electrical power of 0.3 µW (PRMS) by drawing a current (IRMS) of 1.46 µA under a resistive load of 140.2 KΩ. Increasing the capacitance and decreasing the impedance with the fabrication of the four-layer PNG by connecting the layers in parallel connection with the support of the impedance matching process led to an increase in electrical output. With the use of an impedance matching system, the piezoelectric performance tests revealed that the 4L-P-based PNG had a 6.7 times greater electrical power efficiency (72.92 µW) at the vibrational frequency of 20 Hz compared to that of the single-layered PNG (10.82 µW). Furthermore, the multilayer PNG was successfully used as a wearable sensor for the monitoring of human body motions in real time on an IOT (Internet of Things) platform. © The Author(s) 2024.Item The piezoelectric properties of three-phase electrospun PVDF/PZT/Multiwalled Carbone Nanotube composites for energy harvesting applications(Elsevier Ltd, 2024) Koç M.; Tatardar F.; Musayeva N.N.; Guluzade S.; Sarı A.; Paralı L.In this study, the piezoelectric nanogenerators (PENs) based on the PVDF (polyvinylidene fluoride)/PZT (lead zirconate titanate, the particle size of <1 µm) incorporated with MWCNT (Multiwalled Carbone Nanotube, Outer diameter: 10 nm, Inner diameter: 4.5 nm, and Length: 3–6 µm) were produced using the electrospinning method. An β-phase content of 96.56 % in PVDF electrospun composites was arrived at due to the synergistic effect of the PZT ceramics and the MWCNT nanoparticles. The experimental results showed that a PVDF/PZT/0.7 wt%MWCNT composite with a thickness of 145 μm based on the PEN had an electrical power efficiency (0.16 μW) approximately 1.3 times higher at a vibrational frequency of 20 Hz under a resistive load of 46 KΩ as compared to that of the PEN based on the PVDF/PZT composite (0.12 μW). The PVDF/PZT/MWCNT-based PENs have promising potential for flexible energy transmission and structural health monitoring. © 2024 Elsevier B.V.Item Impacts of using a piezo-mounted elastic fin energy harvester on the power production and heat transfer control in a ventilated cavity during turbulent forced convection(Elsevier Ltd, 2024) Selimefendigil F.; Altammar H.; Oztop H.F.Piezo-electric energy harvesters (PE-EH) are used in a variety of engineering applications due to their simplicity, ease of installation, compact structure, higher power density, and lower cost. In this study, a novel elastic PE-EH fin assembly within a ventilated cavity is proposed for thermal management and power production during forced convection in turbulent flow regimes by using finite element method with ALE. Impacts of Reynolds number (Re between 10,000 and 50,000), opening ratio (OR between 0.5 and 2), fin vertical placement (yf between −0.3H and 0.3H), and inlet port horizontal position (xi between 0 and 0.6H) on the characteristics of generated power and convective heat transfer are numerically assessed. Higher deflection of the elastic fin assembly and vortex size reduction at the fin tip are the outcomes of higher Re and OR values. The average Nu rises by about 135% for Re values between Re = 10,000 and Re = 30,000 but reduces by 55% between Re = 30,000 and Re = 50,000. Cooling performance is improved by 165% when OR variation is taken into account, going from the lowest value of OR to OR = 1.5. For generated power, the enhancement factors are 290 and 81 when values of Re and OR are raised from their lowest to highest levels. For cooling performance and generated power, the corresponding improvement factors are 6.94 and 2.5, respectively, from the lowest to the maximum value of the vertical position. Inlet and outlet port locations closer to the middle of the top and bottom wall provides the highest power generation from the PE-EH. There are 121% and 41% variations of generated power when inlet and outlet port locations are varied. An artificial neural network is used to assess the power generated by the PE-EH device using a three-input, one-output system. © 2024 Elsevier Ltd