Articoli di riviste: "P(VDF-TrFE) Piezoelectric polymer"

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P S, Lekshmi Priya, Biswaranjan Swain, Shailendra Rajput, Saubhagyalaxmi Behera e Sabyasachi Parida. "Advances in P(VDF-TrFE) Composites: A Methodical Review on Enhanced Properties and Emerging Electronics Applications". Condensed Matter 8, n. 4 (1 dicembre 2023): 105. http://dx.doi.org/10.3390/condmat8040105.

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Piezoelectric polymers are a class of material that belong to carbon–hydrogen-based organic materials with a long polymer chain. They fill the void where single crystals and ceramics fail to perform. This characteristic of piezoelectric polymers made them unique. Their piezoelectric stress constant is higher than ceramics and the piezoelectric strain is lower compared to ceramics. This study’s goal is to present the most recent information on poly(vinylidene fluoride) with trifluoroethylene P(VDF-TrFE), a major copolymer of poly(vinylidene fluoride) PVDF with piezoelectric, pyroelectric, and ferroelectric characteristics. The fabrication of P(VDF-TrFE) composites and their usage in a variety of applications, including in actuators, transducers, generators, and energy harvesting, are the primary topics of this work. The report provides an analysis of how the addition of fillers improves some of the features of P(VDF-TrFE). Commonly utilized polymer composite preparation techniques, including spinning, Langmuir–Blodgett (LB), solution casting, melt extrusion, and electrospinning are described, along with their effects on the pertinent characteristics of the polymer composite. A brief discussion on the literature related to different applications (such as bio-electronic devices, sensors and high energy-density piezoelectric generators, low mechanical damping, and easy voltage rectifiers of the polymer composite is also presented.

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He, Fu-An, Min-Ji Kim, Shui-Mei Chen, Yuen-Shing Wu, Kwok-Ho Lam, Helen Lai-Wa Chan e Jin-Tu Fan. "Tough and porous piezoelectric P(VDF-TrFE)/organosilicate composite membrane". High Performance Polymers 29, n. 2 (28 luglio 2016): 133–40. http://dx.doi.org/10.1177/0954008316631611.

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Novel P(VDF-TrFE)/organosilicate composite membrane was fabricated by electrospinning. The electrospun composite membrane containing as little as 2 wt% of organosilicate demonstrated significant improvements in strength, modulus, and toughness by about 103%, 45%, and 97%, respectively, when compared with those of electrospun pure P(VDF-TrFE) membrane, while maintaining high porosity and good breathability and piezoelectricity. We believe that such an organosilicate-reinforced durable, porous, and piezoelectric P(VDF-TrFE) membrane has huge advantages in various applications such as flexible sensors, wearable electronics, filter membrane, tissue engineering, battery separator, and polymer electrolyte.

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Jung, Eunyoung, Choon-Sang Park, Taeeun Hong e Heung-Sik Tae. "Structure and Dielectric Properties of Poly(vinylidenefluoride-co-trifluoroethylene) Copolymer Thin Films Using Atmospheric Pressure Plasma Deposition for Piezoelectric Nanogenerator". Nanomaterials 13, n. 10 (22 maggio 2023): 1698. http://dx.doi.org/10.3390/nano13101698.

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This study investigates the structural phase and dielectric properties of poly(vinylidenefluoride-co-trifluoroethylene) (P[VDF–TrFE]) thin films grown via atmospheric pressure (AP) plasma deposition using a mixed polymer solution comprising P[VDF–TrFE] polymer nano powder and dimethylformamide (DMF) liquid solvent. The length of the glass guide tube of the AP plasma deposition system is an important parameter in producing intense cloud-like plasma from the vaporization of DMF liquid solvent containing polymer nano powder. This intense cloud-like plasma for polymer deposition is observed in a glass guide tube of length 80 mm greater than the conventional case, thus uniformly depositing the P[VDF–TrFE] thin film with a thickness of 3 μm. The P[VDF–TrFE] thin films with excellent β-phase structural properties were coated under the optimum conditions at room temperature for 1 h. However, the P[VDF–TrFE] thin film had a very high DMF solvent component. The post-heating treatment was then performed on a hotplate in air for 3 h at post-heating temperatures of 140 °C, 160 °C, and 180 °C to remove DMF solvent and obtain pure piezoelectric P[VDF–TrFE] thin films. The optimal conditions for removing the DMF solvent while maintaining the β phases were also examined. The post-heated P[VDF–TrFE] thin films at 160 °C had a smooth surface with nanoparticles and crystalline peaks of β phases, as confirmed by the Fourier transform infrared spectroscopy and XRD analysis. The dielectric constant of the post-heated P[VDF–TrFE] thin film was measured to be 30 using an impedance analyzer at 10 kHz and is expected to be applied to electronic devices such as low-frequency piezoelectric nanogenerators.

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Wang, Aochen, Ming Hu, Liwei Zhou e Xiaoyong Qiang. "Self-Powered Well-Aligned P(VDF-TrFE) Piezoelectric Nanofiber Nanogenerator for Modulating an Exact Electrical Stimulation and Enhancing the Proliferation of Preosteoblasts". Nanomaterials 9, n. 3 (3 marzo 2019): 349. http://dx.doi.org/10.3390/nano9030349.

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Electric potential plays an indispensable role in tissue engineering and wound healing. Piezoelectric nanogenerators based on direct piezoelectric effects can be self-powered energy sources for electrical stimulation and have attracted extensive attention. However, the accuracy of piezoelectric stimuli on piezoelectric polymers membranes in vitro during the dynamic condition is rarely studied. Here, a self-powered tunable electrical stimulation system for assisting the proliferation of preosteoblasts was achieved by well-aligned P(VDF-TrFE) piezoelectric nanofiber membrane (NFM) both as a nanogenerator (NG) and as a scaffold. The effects of electrospinning and different post-treatments (annealing and poling) on the surface wettability, piezoelectric β phase, ferroelectric properties, and sensing performance of NFMs were evaluated here. The polarized P(VDF-TrFE) NFM offered an enhanced piezoelectric value (d31 of 22.88 pC/N) versus pristine P(VDF-TrFE) NFM (d31 of 0.03 pC/N) and exhibited good sensing performance. The maximum voltage and current output of the P(VDF-TrFE) piezoelectric nanofiber NGs reached −1.7 V and 41.5 nA, respectively. An accurate electrical response was obtained in real time under dynamic mechanical stimulation by immobilizing the NGs on the flexible bottom of the culture plate, thereby restoring the real scene of providing electrical stimulation to the cells in vitro. In addition, we simulated the interaction between the piezoelectric nanofiber NG and cells through an equivalent circuit model. To verify the feasibility of P(VDF-TrFE) nanofiber NGs as an exact electrical stimulation, the effects of different outputs of P(VDF-TrFE) nanofiber NGs on cell proliferation in vitro were compared. The study realized a significant enhancement of preosteoblasts proliferation. This work demonstrated the customizability of P(VDF-TrFE) piezoelectric nanofiber NG for self-powered electrical stimulation system application and suggested its significant potential application for tissue repair and regeneration.

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Budaev, Artem V., Ivanna N. Melnikovich, Vasily E. Melnichenko e Nikita A. Emelianov. "Atomic Force Microscopy of the Local Electrical Properties of Bilayer Polyaniline-Polystyrene/P(VDF-TrFE) Composite". Key Engineering Materials 899 (8 settembre 2021): 506–11. http://dx.doi.org/10.4028/www.scientific.net/kem.899.506.

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Atomic force microscopy techniques (conductive-AFM, I-V spectroscopy and PFM) were used for characterisation of the local electrical properties of bilayer polyaniline-polystyrene/P(VDF-TrFE) polymer nanocomposite. Observed hysteresis of current-voltage characteristics confirms its memristive properties. It was caused by the influence of the ferroelectric polarization of P(VDF-TrFE) layer, the domain structure of which was visualised by piezoelectric force microscopy on the transport of charge carriers at the interface.

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Lam, Tu-Ngoc, Chia-Yin Ma, Po-Han Hsiao, Wen-Ching Ko, Yi-Jen Huang, Soo-Yeol Lee, Jayant Jain e E.-Wen Huang. "Tunable Mechanical and Electrical Properties of Coaxial Electrospun Composite Nanofibers of P(VDF-TrFE) and P(VDF-TrFE-CTFE)". International Journal of Molecular Sciences 22, n. 9 (28 aprile 2021): 4639. http://dx.doi.org/10.3390/ijms22094639.

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The coaxial core/shell composite electrospun nanofibers consisting of relaxor ferroelectric P(VDF-TrFE-CTFE) and ferroelectric P(VDF-TrFE) polymers are successfully tailored towards superior structural, mechanical, and electrical properties over the individual polymers. The core/shell-TrFE/CTFE membrane discloses a more prominent mechanical anisotropy between the revolving direction (RD) and cross direction (CD) associated with a higher tensile modulus of 26.9 MPa and good strength-ductility balance, beneficial from a better degree of nanofiber alignment, the increased density, and C-F bonding. The interfacial coupling between the terpolymer P(VDF-TrFE-CTFE) and copolymer P(VDF-TrFE) is responsible for comparable full-frequency dielectric responses between the core/shell-TrFE/CTFE and pristine terpolymer. Moreover, an impressive piezoelectric coefficient up to 50.5 pm/V is achieved in the core/shell-TrFE/CTFE composite structure. Our findings corroborate the promising approach of coaxial electrospinning in efficiently tuning mechanical and electrical performances of the electrospun core/shell composite nanofiber membranes-based electroactive polymers (EAPs) actuators as artificial muscle implants.

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Muthusamy, Lavanya, Balaadithya Uppalapati, Samee Azad, Manav Bava e Goutam Koley. "Self-Polarized P(VDF-TrFE)/Carbon Black Composite Piezoelectric Thin Film". Polymers 15, n. 20 (18 ottobre 2023): 4131. http://dx.doi.org/10.3390/polym15204131.

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Self-polarized energy harvesting materials have seen increasing research interest in recent years owing to their simple fabrication method and versatile application potential. In this study, we systematically investigated self-polarized P(VDF-TrFE)/carbon black (CB) composite thin films synthesized on flexible substrates, with the CB content varying from 0 to 0.6 wt.% in P(VDF-TrFE). The presence of –OH functional groups on carbon black significantly enhances its crystallinity, dipolar orientation, and piezoelectric performance. Multiple characterization techniques were used to investigate the crystalline quality, chemical structure, and morphology of the composite P(VDF-TrFE)/CB films, which indicated no significant changes in these parameters. However, some increase in surface roughness was observed when the CB content increased. With the application of an external force, the piezoelectrically generated voltage was found to systematically increase with higher CB content, reaching a maximum value at 0.6 wt.%, after which the sample exhibited low resistance. The piezoelectric voltage produced by the unpoled 0.6 wt.% CB composite film significantly exceeded the unpoled pure P(VDF-TrFE) film when subjected to the same applied strain. Furthermore, it exhibited exceptional stability in the piezoelectric voltage over time, exceeding the output voltage of the poled pure P(VDF-TrFE) film. Notably, P(VDF_TrFE)/CB composite-based devices can be used in energy harvesting and piezoelectric strain sensing to monitor human motions, which has the potential to positively impact the field of smart wearable devices.

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Hafner, Jonas, Marco Teuschel, Jürgen Schrattenholzer, Michael Schneider e Ulrich Schmid. "Optimized Batch Process for Organic MEMS Devices". Proceedings 2, n. 13 (28 novembre 2018): 904. http://dx.doi.org/10.3390/proceedings2130904.

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Recently, organic electromechanical transducers have attracted intense scientific and technological interest due to their unique mechanical flexibility and their piezoelectric properties. However, the fabrication of organic MEMS devices is challenging. For example, a lift-off process cannot be used on polymers, because of the solvent in photoresists. Here, we present a straightforward and low-cost batch process for organic MEMS devices using standard micromachining techniques. As organic material we used the ferroelectric (co-)polymer poly(vinylidene fluoride-trifluorethylene) (P(VDF-TrFE)). The integration of the polymer in a CMOS-compatible process was optimized in terms of deposition and patterning of the polymer and the corresponding metal layers. Micromachined devices, such as capacitors and cantilevers, were fabricated and analysed. The ferroelectric perfomance was evaluated by electrical and electromechanical measurements. Our first results indicate that the proposed fabrication process is reliable resulting in well-functioning organic MEMS devices. We measured as piezoelectric constant a d33 of −32 pm/V with our organic P(VDF-TrFE) capacitors.

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Singh, Deepa, Deepak Deepak e Ashish Garg. "An efficient route to fabricate fatigue-free P(VDF-TrFE) capacitors with enhanced piezoelectric and ferroelectric properties and excellent thermal stability for sensing and memory applications". Physical Chemistry Chemical Physics 19, n. 11 (2017): 7743–50. http://dx.doi.org/10.1039/c7cp00275k.

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Kim, Yong-Il, Dabin Kim, Jihun Jung, Sang-Woo Kim e Miso Kim. "Airflow-induced P(VDF-TrFE) fiber arrays for enhanced piezoelectric energy harvesting". APL Materials 10, n. 3 (1 marzo 2022): 031110. http://dx.doi.org/10.1063/5.0081257.

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Piezoelectricity, flexibility, light weight, and biocompatibility of piezoelectric polymer fibers are the desired attributes for energy harvesting and sensing in wearable and biomedical applications. However, the relatively insufficient piezoelectric performance of piezoelectric polymers remains an issue. Here, we demonstrate a considerable increase in P(VDF-TrFE) fiber alignment via electrospinning with a rapidly rotating collector, which substantially enhanced the piezoelectric performance of the fiber mat over a large area. Considering the relationship between the airflow induced near the collector surface and the rotating speed, the collectors with different geometries were systematically compared in terms of the degree of alignment, fiber morphology, and the resulting crystalline electroactive phases of the fibers produced by each collector. We found that the strong airflow induced by the rapid rotation of the modified drum collector contributes to the preferential fiber orientation by pulling and stretching over a large area, which led to an increase in the crystalline electroactive β-phase content responsible for piezoelectricity. As a result, a maximum voltage of 116.6 V and maximum output power of 13.6 µW were achieved using a flexible piezoelectric device comprising a large-area, highly aligned P(VDF-TrFE) fiber mat produced from a modified drum collector at a significantly high speed. This work provides a facile but powerful solution for the wide use of piezoelectric polymer fibers.

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El-Hami, Khalil, e Abdelkhalak El Hami. "Correlating Piezoelectric Polymer/Carbon Nanotubes Nanocomposite Strain Sensor with Reliability and Optimization Tools". Applied Mechanics and Materials 146 (dicembre 2011): 137–46. http://dx.doi.org/10.4028/www.scientific.net/amm.146.137.

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Carbon nanotubes with polymers offers great advantages in improving material for both mechanical and electrical nanostructures. Design and fabrication have to consider that a local change in each compound accounts to the total change of physical properties in nanocomposite materials. This paper presents two parts of study. A model of strain nanosensor has been developed by using the polyvinylidne fluoride and trifluoroethylene P(VDF-TrFE) copolymer and carbon nanotubes in sandwich nanostructure [P(VDF-TrFE)/SWCNTs/ P(VDF-TrFE)] as a new application in nanotechnology domain. The experimental strain sensing was about 10-4. On the other hand, reliability-based optimization is assessed for an efficient tool to consider this nanosensors nanodevice. We put emphasis on the combination of physical modeling and reliability based design optimization of nanomaterials. After investigation, we could make suggestions such as how to improve the reliability of nanodevices and nanosystems, and how to reduce cost and economic rates.

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Li, Liao e Tjong. "Electrospun Polyvinylidene Fluoride-Based Fibrous Scaffolds with Piezoelectric Characteristics for Bone and Neural Tissue Engineering". Nanomaterials 9, n. 7 (30 giugno 2019): 952. http://dx.doi.org/10.3390/nano9070952.

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Polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE) with excellent piezoelectricity and good biocompatibility are attractive materials for making functional scaffolds for bone and neural tissue engineering applications. Electrospun PVDF and P(VDF-TrFE) scaffolds can produce electrical charges during mechanical deformation, which can provide necessary stimulation for repairing bone defects and damaged nerve cells. As such, these fibrous mats promote the adhesion, proliferation and differentiation of bone and neural cells on their surfaces. Furthermore, aligned PVDF and P(VDF-TrFE) fibrous mats can enhance neurite growth along the fiber orientation direction. These beneficial effects derive from the formation of electroactive, polar β-phase having piezoelectric properties. Polar β-phase can be induced in the PVDF fibers as a result of the polymer jet stretching and electrical poling during electrospinning. Moreover, the incorporation of TrFE monomer into PVDF can stabilize the β-phase without mechanical stretching or electrical poling. The main drawbacks of electrospinning process for making piezoelectric PVDF-based scaffolds are their small pore sizes and the use of highly toxic organic solvents. The small pore sizes prevent the infiltration of bone and neuronal cells into the scaffolds, leading to the formation of a single cell layer on the scaffold surfaces. Accordingly, modified electrospinning methods such as melt-electrospinning and near-field electrospinning have been explored by the researchers to tackle this issue. This article reviews recent development strategies, achievements and major challenges of electrospun PVDF and P(VDF-TrFE) scaffolds for tissue engineering applications.

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Yang, Jiang, Fan Xu, Hanxiao Jiang, Conghuan Wang, Xingjia Li, Xiuli Zhang e Guodong Zhu. "Piezoelectric enhancement of an electrospun AlN-doped P(VDF-TrFE) nanofiber membrane". Materials Chemistry Frontiers 5, n. 15 (2021): 5679–88. http://dx.doi.org/10.1039/d1qm00550b.

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A small amount of AlN doping induced a large piezoelectric enhancement of electrospun piezoelectric polymer nanofibers. A device was developed for mechanical energy harvesting and sensing of pulse, finger bending and multipoint recognition.

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Ummer, Rehana P., Raneesh B, Camille Thevenot, Didier Rouxel, Sabu Thomas e Nandakumar Kalarikkal. "Electric, magnetic, piezoelectric and magnetoelectric studies of phase pure (BiFeO3–NaNbO3)–(P(VDF-TrFE)) nanocomposite films prepared by spin coating". RSC Advances 6, n. 33 (2016): 28069–80. http://dx.doi.org/10.1039/c5ra24602d.

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(BiFeO₃–NaNbO₃)–(P(VDF-TrFE)) co-polymer thin films were fabricated by spin coating technique and their electric, magnetic, electromechanical and magnetoelectric properties were investigated.

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Kim, Dabin, Sooun Lee, Sangryun Lee, Yong-Il Kim, Sihyeon Kum, Sang-Woo Kim, Yunseok Kim, Seunghwa Ryu e Miso Kim. "Ambient Humidity-Induced Phase Separation for Electrospun Fiber Morphology Engineering Toward Piezoelectric Self-Powered Sensing". ECS Meeting Abstracts MA2022-02, n. 36 (9 ottobre 2022): 1299. http://dx.doi.org/10.1149/ma2022-02361299mtgabs.

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Electrospun polymeric piezoelectric fibers have a considerable potential for shape-adaptive mechanical energy harvesting and self-powered sensing in biomedical, wearable, and industrial applications. However, their unsatisfactory piezoelectric performance remains an issue to be overcome. While strategies for increasing the crystallinity of electroactive β phases have thus far been the major focus in realizing enhanced piezoelectric performance, tailoring the fiber morphology can also be a promising alternative. Herein, a design strategy that combines the nonsolvent-induced phase separation of a polymer/solvent/water ternary system and electrospinning for fabricating piezoelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE) fibers with surface porosity under ambient humidity is presented. Notably, electrospun P(VDF-TrFE) fibers with higher surface porosity outperform their smooth-surfaced counterparts with a higher β phase content in terms of output voltage and power generation. Theoretical and numerical studies also underpin the contribution of the structural porosity to the harvesting performance, which is attributable to local stress concentration and reduced dielectric constant due to the air in the pores. This porous fiber design can broaden the application prospects of shape-adaptive energy harvesting and self-powered sensing based on piezoelectric polymer fibers with enhanced voltage and power performance, as successfully demonstrated in this work by developing a communication system based on self-powered motion sensing.

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Botvin, Vladimir, Anastasia Fetisova, Yulia Mukhortova, Dmitry Wagner, Sergey Kazantsev, Maria Surmeneva, Andrei Kholkin e Roman Surmenev. "Effect of Fe3O4 Nanoparticles Modified by Citric and Oleic Acids on the Physicochemical and Magnetic Properties of Hybrid Electrospun P(VDF-TrFE) Scaffolds". Polymers 15, n. 14 (24 luglio 2023): 3135. http://dx.doi.org/10.3390/polym15143135.

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This study considers a fabrication of magnetoactive scaffolds based on a copolymer of vinylidene fluoride and trifluoroethylene (P(VDF-TrFE)) and 5, 10, and 15 wt.% of magnetite (Fe3O4) nanoparticles modified with citric (CA) and oleic (OA) acids by solution electrospinning. The synthesized Fe3O4-CA and Fe3O4-OA nanoparticles are similar in particle size and phase composition, but differ in zeta potential values and magnetic properties. Pure P(VDF-TrFE) scaffolds as well as composites with Fe3O4-CA and Fe3O4-OA nanoparticles demonstrate beads-free 1 μm fibers. According to scanning electron (SEM) and transmission electron (TEM) microscopy, fabricated P(VDF-TrFE) scaffolds filled with CA-modified Fe3O4 nanoparticles have a more homogeneous distribution of magnetic filler due to both the high stabilization ability of CA molecules and the affinity of Fe3O4-CA nanoparticles to the solvent used and P(VDF-TrFE) functional groups. The phase composition of pure and composite scaffolds includes a predominant piezoelectric β-phase, and a γ-phase, to a lesser extent. When adding Fe3O4-CA and Fe3O4-OA nanoparticles, there was no significant decrease in the degree of crystallinity of the P(VDF-TrFE), which, on the contrary, increased up to 76% in the case of composite scaffolds loaded with 15 wt.% of the magnetic fillers. Magnetic properties, mainly saturation magnetization (Ms), are in a good agreement with the content of Fe3O4 nanoparticles and show, among the known magnetoactive PVDF or P(VDF-TrFE) scaffolds, the highest Ms value, equal to 10.0 emu/g in the case of P(VDF-TrFE) composite with 15 wt.% of Fe3O4-CA nanoparticles.

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Marques-Almeida, Teresa, Vanessa F. Cardoso, Miguel Gama, Senentxu Lanceros-Mendez e Clarisse Ribeiro. "Patterned Piezoelectric Scaffolds for Osteogenic Differentiation". International Journal of Molecular Sciences 21, n. 21 (7 novembre 2020): 8352. http://dx.doi.org/10.3390/ijms21218352.

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The morphological clues of scaffolds can determine cell behavior and, therefore, the patterning of electroactive polymers can be a suitable strategy for bone tissue engineering. In this way, this work reports on the influence of poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) electroactive micropatterned scaffolds on the proliferation and differentiation of bone cells. For that, micropatterned P(VDF-TrFE) scaffolds were produced by lithography in the form of arrays of lines and hexagons and then tested for cell proliferation and differentiation of pre-osteoblast cell line. Results show that more anisotropic surface microstructures promote bone differentiation without the need of further biochemical stimulation. Thus, the combination of specific patterns with the inherent electroactivity of materials provides a promising platform for bone regeneration.

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Han, Jin Kyu, Voon-Kean Wong, David Boon Kiang Lim, Percis Teena Christopher Subhodayam, Ping Luo e Kui Yao. "Environmental Robustness and Resilience of Direct-Write Ultrasonic Transducers Made from P(VDF-TrFE) Piezoelectric Coating". Sensors 23, n. 10 (12 maggio 2023): 4696. http://dx.doi.org/10.3390/s23104696.

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Conformability, lightweight, consistency and low cost due to batch fabrication in situ on host structures are the attractive advantages of ultrasonic transducers made of piezoelectric polymer coatings for structural health monitoring (SHM). However, knowledge about the environmental impacts of piezoelectric polymer ultrasonic transducers is lacking, limiting their widespread use for SHM in industries. The purpose of this work is to evaluate whether direct-write transducers (DWTs) fabricated from piezoelectric polymer coatings can withstand various natural environmental impacts. The ultrasonic signals of the DWTs and properties of the piezoelectric polymer coatings fabricated in situ on the test coupons were evaluated during and after exposure to various environmental conditions, including high and low temperatures, icing, rain, humidity, and the salt fog test. Our experimental results and analyses showed that it is promising for the DWTs made of piezoelectric P(VDF-TrFE) polymer coating with an appropriate protective layer to pass various operational conditions according to US standards.

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Terekhova, Yuliia S., Dmitry A. Kiselev e Alexander V. Solnyshkin. "Scanning probe microscopic study of P(VDF-TrFE) based ferroelectric nanocomposites". Modern Electronic Materials 7, n. 1 (30 marzo 2021): 11–16. http://dx.doi.org/10.3897/j.moem.7.1.73283.

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Ceramic and polymer based nanocomponents combine the properties of their constituents, e.g. flexibility, elasticity, polymer reprocessability, hardness typical of glass, wear resistance and high light refraction index. This helps improving many properties of the materials in comparison with the source components. Since recently researchers have been manifesting interest to the properties of complex composite compounds. This is primarily caused by the unique properties of their structures as compared with conventional materials having homogeneous composition. Secondly, this interest is caused by the fact that these compounds may prove to be much cheaper than homogeneous structures provided the physical properties of the composite in a preset range of parameters (temperature, applied field frequency etc.) are identical to those of the respective homogeneous materials. For example, polyvinyl idenfluoride (PVDF) type ferroelectric polymers and copolymers on its basis have found wide application for functional elements of various electromechanic devices in advanced electronics due to their relatively good piezoelectric and pyroelectric properties. The strong random polarization and the formation of polar non-centrosymmetric crystals provide for the high piezoelectric and pyroelectric activity in these crystals. Scanning probe microscopy has been used for study of ferroelectric nanocomposites having different compositions. The matrix specimen for study of local polarization switching at a nanoscale level was vinyl idenfluoride and trifluoroethylene P(VDF-TrFE) copolymer possessing sufficiently high crystallinity. The composite fillers were barium titanate BaTiO3 and deuterized triglycinsulfate DTGS ferroelectric powders and zirconate-titanate lead barium BPZT ceramic powder. We show these materials to show good promise for use in memory cells.

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He, Xiangyu, Jiaqi Lu, Feng Gao, Shurong Dong, Juan Li, Hao Jin e Jikui Luo. "Flexible Film Bulk Acoustic Wave Filter Based on Poly(vinylidene fluoride-trifluorethylene)". Polymers 16, n. 1 (3 gennaio 2024): 150. http://dx.doi.org/10.3390/polym16010150.

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Poly(vinylidene fluoride-trifluorethylene) (P(VDF-TrFE)) has promising potential applications in radio-frequency filters due to their excellent piezoelectric properties, flexibility, and stability. In this paper, a flexible film bulk acoustic wave filter is investigated based on P(VDF-TrFE) as piezoelectric film. A new method based on three-step annealing is developed to efficiently remove the porosity inside the P(VDF-TrFE) films so as to improve its properties. The obtained film achieved high β-phase content beyond 80% and a high piezoelectric coefficient of 27.75 pm/V. Based on the low porosity β-phase films, a flexible wide-band RF filter is designed, which consists of a bulk acoustic wave resonator and lumped inductor-capacitor elements as a hybrid configuration. The resonator sets the filter’s center frequency, while the lumped LC-based matching network extends the bandwidth and enhances out-of-band rejection. The testing results of the proposed wide-band filter show its good performance, with 12.5% fractional bandwidth and an insertion loss of 3.1 dB. To verify the possibility of folding and stacking the flexible bulk acoustic wave devices for high-density multi-filter integration in MIMO communication, bending tests of the filter are also conducted with the bending strain range up to 5500 με. The testing results show no noticeable performance degradation after four bending cycles. This work demonstrates the potential of β-phase P(VDF-TrFE) bulk acoustic wave filters to expand the scope of future flexible radio-frequency filter applications.

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Hu, Yian, Shunyao Huang, Yujia Gao, Jaeyeon Lee, Zhangsiyuan Jin, Geon-Hyoung An e Yuljae Cho. "Patchable Transparent Standalone Piezoelectric P(VDF-TrFE) Film for Radial Artery Pulse Detection". International Journal of Energy Research 2023 (24 novembre 2023): 1–12. http://dx.doi.org/10.1155/2023/2213988.

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Wearable or patchable biosensors have attracted tremendous attention due to their continuous health-monitoring capabilities. In particular, self-powered passive biosensors based on a piezoelectric nanogenerator (PENG) have demonstrated measurements of physiological signals from which cardiovascular information can be analyzed such as heart rate and blood pressure. However, challenges still remain with regard to both material and device aspects. For the effective and accurate measurement of extremely weak physiological signals, various methods have been introduced, including employment of inorganic lead-based piezoelectric materials and design of a complex material or device structure. In spite of their effectiveness in enhancing the piezoelectric output response, the introduced methods brought concomitant issues, such as toxicity and complexity. We present unique methods to produce a transparent standalone piezoelectric polymer film which can be directly transferred to any surface such as the human skin. Through a room temperature solvent vapor annealing process, we further enhance the crystallinity and a portion of the ferroelectric β-phase of the transparent standalone polymer film, resulting in an improved piezoelectric output response. Based on these two new methods introduced, we demonstrate a simple sandwich-structured, transparent, and patchable biosensor based on PENG for radial artery detection with significantly reduced complex manufacturing processes, providing great practical value.

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Zhou, Zhenji, Caiyin You, Yao Chen, Weimin Xia, Na Tian, Yun Li e ChuKai Wang. "Piezoelectric sensing performance of flexible P(VDF-TrFE)/PBDMS porous polymer materials". Organic Electronics 105 (giugno 2022): 106491. http://dx.doi.org/10.1016/j.orgel.2022.106491.

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Belovickis, Jaroslavas, Maksim Ivanov, Šarunas Svirskas, Vytautas Samulionis, Jūras Banys, Alexander V. Solnyshkin, Sergey A. Gavrilov, Kapiton N. Nekludov, Vladimir V. Shvartsman e Maxim V. Silibin. "Dielectric, Ferroelectric, and Piezoelectric Investigation of Polymer-Based P(VDF-TrFE) Composites". physica status solidi (b) 255, n. 3 (18 ottobre 2017): 1700196. http://dx.doi.org/10.1002/pssb.201700196.

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24

Terekhova, Yu S., D. A. Kiselev e A. V. Solnyshkin. "Study of ferroelectric nanocomposites based on P(VDF-TrFE) by scanning probe microscopy". Izvestiya Vysshikh Uchebnykh Zavedenii. Materialy Elektronnoi Tekhniki = Materials of Electronics Engineering 24, n. 2 (30 agosto 2021): 71–78. http://dx.doi.org/10.17073/1609-3577-2021-2-71-78.

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Abstract (sommario):

Ceramic and polymer based nanocomponents combine the properties of their constituents, e.g. flexibility, elasticity, polymer reprocessability, hardness typical of glass, wear resistance and high light refraction index. This helps improving many properties of the materials in comparison with the source components. Since recently researchers have been manifesting interest to the properties of complex composite compounds. This is primarily caused by the unique properties of their structures as compared with conventional materials having homogeneous composition. Secondly, this interest is caused by the fact that these compounds may prove to be much cheaper than homogeneous structures provided the physical properties of the composite in a preset range of parameters (temperature, applied field frequency etc.) are identical to those of the respective homogeneous materials. For example, polyvinyl idenfluoride (PVDF) type ferroelectric polymers and copolymers on its basis have found wide application for functional elements of various electromechanic devices in advanced electronics due to their relatively good piezoelectric and pyroelectric properties. The strong random polarization and the formation of polar non-centrosymmetric crystals provide for the high piezoelectric and pyroelectric activity in these crystals. Scanning probe microscopy has been used for study of ferroelectric nanocomposites having different compositions. The matrix specimen for study of local polarization switching at a nanoscale level was vinyl idenfluoride and trifluoroethylene P(VDF-TrFE) copolymer possessing sufficiently high crystallinity. The composite fillers were barium titanate BaTiO3 and deuterized triglycinsulfate DTGS ferroelectric powders and zirconate-titanate lead barium BPZT ceramic powder. We show these materials to show good promise for use in memory cells.

25

Silibin, Maxim, Dmitry Karpinsky, Vladimir Bystrov, Dzmitry Zhaludkevich, Marina Bazarova, P. Mirzadeh Vaghefi, P. A. A. P. Marques, Budhendra Singh e Igor Bdikin. "Preparation, Stability and Local Piezoelectrical Properties of P(VDF-TrFE)/Graphene Oxide Composite Fibers". C 5, n. 3 (13 agosto 2019): 48. http://dx.doi.org/10.3390/c5030048.

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The unprecedented attributes such as biocompatibility and flexibility of macromolecular piezoelectric polymer has triggered an immense interested in scientific society for their potential exploitation in implantable electronic devices. In the present article, a theoretical and experimental investigation is done to explore the polarization behavior of composite fibers based on copolymer poly-trifluoroethylene P(VDF-TrFE) and graphene oxide (GO) with varying composition of the components is explored for its possible application in bioelectronic devices. Electromechanical properties of the PVDF/GO nanofibers were investigated using piezoresponse force microscopy (PFM) method. The switching behavior, charge states, and piezoelectric response of the fibers were found to depend on the concentration of GO up to 20%. Theoretical models of PVDF chains, interacting with Graphene/GO layers has been used to explore the evolution of piezoresponse in the composite fibers. In order to compute piezoelectric coefficients, the behavior of composite in electrical fields has been modeled using software HyperChem. The experimental results are qualitatively correlated with a computed theoretical model.

26

Schellin, R., G. Hess, R. Kressman e P. Wassmuth. "Corona-poled piezoelectric polymer layers of P(VDF/TrFE) for micromachined silicon microphones". Journal of Micromechanics and Microengineering 5, n. 2 (1 giugno 1995): 106–8. http://dx.doi.org/10.1088/0960-1317/5/2/012.

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27

Chang, Wen-Chi, An-Bang Wang, Chih-Kung Lee, Han-Lung Chen, Wen-Ching Ko e Chih-Ting Lin. "Photoconductive Piezoelectric Polymer Made From a Composite of P(VDF-TrFE) and TiOPc". Ferroelectrics 446, n. 1 (gennaio 2013): 9–17. http://dx.doi.org/10.1080/00150193.2013.820974.

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28

Ranjan, Abhishek, Chengxiang Peng, Sanat Wagle, Frank Melandsø e Anowarul Habib. "High-Frequency Acoustic Imaging Using Adhesive-Free Polymer Transducer". Polymers 13, n. 9 (30 aprile 2021): 1462. http://dx.doi.org/10.3390/polym13091462.

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Abstract (sommario):

The piezoelectric polymer PVDF and its copolymers have a long history as transducer materials for medical and biological applications. An efficient use of these polymers can potentially both lower the production cost and offer an environment-friendly alternative for medical transducers which today is dominated by piezoelectric ceramics containing lead. The main goal of the current work has been to compare the image quality of a low-cost in-house transducers made from the copolymer P(VDF-TrFE) to a commercial PVDF transducer. Several test objects were explored with the transducers used in a scanning acoustic microscope, including a human articular cartilage sample, a coin surface, and an etched metal film with fine line structures. To evaluate the image quality, C- and B-scan images were obtained from the recorded time series, and compared in terms of resolution, SNR, point-spread function, and depth imaging capability. The investigation is believed to provide useful information about both the strengths and limitations of low-cost polymer transducers.

29

Wang, Aochen, Ming Hu, Liwei Zhou e Xiaoyong Qiang. "Self-Powered Wearable Pressure Sensors with Enhanced Piezoelectric Properties of Aligned P(VDF-TrFE)/MWCNT Composites for Monitoring Human Physiological and Muscle Motion Signs". Nanomaterials 8, n. 12 (7 dicembre 2018): 1021. http://dx.doi.org/10.3390/nano8121021.

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Self-powered operation, flexibility, excellent mechanical properties, and ultra-high sensitivity are highly desired properties for pressure sensors in human health monitoring and anthropomorphic robotic systems. Piezoelectric pressure sensors, with enhanced electromechanical performance to effectively distinguish multiple mechanical stimuli (including pressing, stretching, bending, and twisting), have attracted interest to precisely acquire the weak signals of the human body. In this work, we prepared a poly(vinylidene fluoride-trifluoroethylene)/ multi-walled carbon nanotube (P(VDF-TrFE)/MWCNT) composite by an electrospinning process and stretched it to achieve alignment of the polymer chains. The composite membrane demonstrated excellent piezoelectricy, favorable mechanical strength, and high sensitivity. The piezoelectric coefficient d33 value was approximately 50 pm/V, the Young’s modulus was ~0.986 GPa, and the sensitivity was ~540 mV/N. The resulting composite membrane was employed as a piezoelectric pressure sensor to monitor small physiological signals including pulse, breath, and small motions of muscle and joints such as swallowing, chewing, and finger and wrist movements. Moderate doping with carbon nanotubes had a positive impact on the formation of the β phase of the piezoelectric device, and the piezoelectric pressure sensor has the potential for application in health care systems and smart wearable devices.

30

Schulze, Robert, Michael Heinrich, Patryk Nossol, Roman Forke, Martynas Sborikas, Alexander Tsapkolenko, Detlef Billep, Michael Wegener, Lothar Kroll e Thomas Gessner. "Piezoelectric P(VDF-TrFE) transducers assembled with micro injection molded polymers". Sensors and Actuators A: Physical 208 (febbraio 2014): 159–65. http://dx.doi.org/10.1016/j.sna.2013.12.032.

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31

Oh, Sharon Roslyn, Kui Yao, Lei Zhang e Francis Eng Hock Tay. "Asymmetric electrode design for significant performance enhancement of piezoelectric P(VDF-TrFE) polymer microcantilevers". Smart Materials and Structures 24, n. 4 (10 marzo 2015): 045035. http://dx.doi.org/10.1088/0964-1726/24/4/045035.

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32

Hafner, Jonas, Marco Teuschel, Davide Disnan, Michael Schneider e Ulrich Schmid. "Large bias-induced piezoelectric response in the ferroelectric polymer P(VDF-TrFE) for MEMS resonators". Materials Research Letters 9, n. 4 (17 gennaio 2021): 195–203. http://dx.doi.org/10.1080/21663831.2020.1868593.

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33

Aleksandrova, Mariya, Tsvetozar Tsanev, Berek Kadikoff, Dimiter Alexandrov, Krasimir Nedelchev e Ivan Kralov. "Piezoelectric Elements with PVDF–TrFE/MWCNT-Aligned Composite Nanowires for Energy Harvesting Applications". Crystals 13, n. 12 (23 novembre 2023): 1626. http://dx.doi.org/10.3390/cryst13121626.

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Abstract (sommario):

A self-sustainable power supply function with flexibility, mechanical stability, and lightweight quality is among the required properties for pressure sensors and other low-power-consuming electronics and wearable devices. In this work, a poly(vinylidene fluoride-trifluoroethylene)/multi-walled carbon nanotube (P(VDF–TrFE)/MWCNT) composite was prepared to increase the electrical conductivity of the piezoelectric polymer and, thus, improve its electrical power generation capabilities. It was soaked by injection molding through an anodic aluminum oxide membrane to align vertically with the dipoles and exclude the possibility of dipole moment quenching. The composite membrane-type element exhibited an excellent piezoelectric coefficient d33 of 42 pC/N at a frequency of 50 Hz and an applied force intensity of 10 N, while the sensitivity was ~375 µV/g, which is favorable for self-powered pressure sensor application. The resulting composite element was utilized to generate the piezoelectric signal and to investigate the dependence of the electromechanical behavior on the surface roughness, morphology, and contact interface resistance.

34

Kaval, William G., Robert A. Lake e Ronald A. Coutu. "PVDF-TrFE Electroactive Polymer Mechanical-to-Electrical Energy Harvesting Experimental Bimorph Structure". MRS Advances 2, n. 56 (2017): 3441–46. http://dx.doi.org/10.1557/adv.2017.397.

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ABSTRACTResearch of electrostrictive polymers has generated new opportunities for harvesting energy from the surrounding environment and converting it into usable electrical energy. Electroactive polymer (EAP) research is one of the new opportunities for harvesting energy from the natural environment and converting it into usable electrical energy. Piezoelectric ceramic based energy harvesting devices tend to be unsuitable for low-frequency mechanical excitations such as human movement. Organic polymers are typically softer and more flexible therefore translated electrical energy output is considerably higher under the same mechanical force. In addition, cantilever geometry is one of the most used structures in piezoelectric energy harvesters, especially for mechanical energy harvesting from vibrations. In order to further lower the resonance frequency of the cantilever microstructure, a proof mass can be attached to the free end of the cantilever. Mechanical analysis of an experimental bimorph structure was provided and led to key design rules for post-processing steps to control the performance of the energy harvester. In this work, methods of materials processing and the mechanical to electrical conversion of vibrational energy into usable energy were investigated. Materials such as polyvinyledenedifluoridetetra-fluoroethylene P(VDF-TrFE) copolymer films (1um thick or less) were evaluated and presented a large relative permittivity and greater piezoelectric β-phase without stretching. Further investigations will be used to identify suitable micro-electromechanical systems (MEMs) structures given specific types of low-frequency mechanical excitations (10-100Hz).

35

Pourbafrani, Mehdi, Sara Azimi, Narges Yaghoobi Nia, Mahmoud Zendehdel e Mohammad Mahdi Abolhasani. "The Effect of Electrospinning Parameters on Piezoelectric PVDF-TrFE Nanofibers: Experimental and Simulation Study". Energies 16, n. 1 (21 dicembre 2022): 37. http://dx.doi.org/10.3390/en16010037.

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Polyvinylidene fluoride and its copolymers can be used as active materials for energy harvesting and environmental sensing. Energy harvesting is one of the most recent research techniques for producing stable electrical energy from mechanical sources. Polyvinylidene fluoride–trifluoroethylene (PVDF-TrFE) is applicable for sensors and self-powered devices such as medical implants and wearable electronic devices. The preparation of electrospun P(VDF-TrFE) nanofibers is of great interest for the fabrication of sensors and self-powered devices, nanogenerators, and sensors. In this regard, it is necessary to investigate the effects of various parameters on the morphology and piezoelectric output voltage of such nanofibers. In this study, we have examined the effect of concentration and feed rate on the nanofiber diameter. It has been found that by increasing the concentration and feed rate of the polymer solution, the diameter of the nanofibers increases. The experimental results and the finite element method (FEM) simulation have also shown consistency; when the nanofiber diameter increases, the output voltage of the nanofibers decreases. This behavior can be related to the strain reduction in the deformed nanofibers.

36

Parangusan, Hemalatha, Jolly Bhadra e Noora Al-Thani. "Flexible piezoelectric nanogenerator based on [P(VDF-HFP)]/ PANI-ZnS electrospun nanofibers for electrical energy harvesting". Journal of Materials Science: Materials in Electronics 32, n. 5 (19 febbraio 2021): 6358–68. http://dx.doi.org/10.1007/s10854-021-05352-4.

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Abstract Over the past decade, piezoelectric nanogenerator have attracted much attention to harvest mechanical energy from abundant resources in nature. Here, the ZnS microspheres is prepared by hydrothermal method and core-shell structured PANI/ZnS microspheres are synthesized by in situ polymerization method and then used as filler for the preparation of flexible [P(VDF-HFP)] based piezoelectric nanogenerator. The flexible P(VDF-HFP)/PANI-ZnS piezoelectric nanogenerator is prepared by Electrospinning technique. The core-shell PANI/ZnS composite improves the content of electroactive phase in [P(VDF-HFP)] and significantly improves the interfacial polarization between the PANI/ZnS particles and polymer matrix. Among all the samples, [P(VDF-HFP)]/2 wt% PANI-ZnS composite nanofibers exhibited the high piezoelectric peak-to-peak output voltage of 3 V compared with the neat [P(VDF-HFP)] (~ 120 mV). In addition, the high dielectric constant is observed for the [P(VDF-HFP)]/2 wt% PANI-ZnS composite nanofibers. These results implies that the fabricated flexible and efficient piezoelectric nanogenerator can be utilized for energy harvesting system.

37

B, Chandar Shekar, Sulana Sundari, Sunnitha S e Sharmila C. "ARATION AND CHARACTERIZATION POLY (VINYLIDENE FLUORIDE-TRIFLUOROETHYLENE) COPOLYMER THIN FILMS FOR ORGANIC FERROELECTRIC FIELD EFFECT THIN FILM TRANSISTORS." Kongunadu Research Journal 2, n. 1 (30 giugno 2015): 7–10. http://dx.doi.org/10.26524/krj56.

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Polyvinylidene fluoride (PVDF) and Trifluoroethylene ((TrFE) are potential polymers which are used in acoustic transducers and electromechanical actuators because of their inherent piezoelectric response, as heat sensors because of their inherent pyroelectric response and as dielectric layer in organic thin filmtransistors. In the present study thin films of copolymer Poly(vinylidene fluoride-trifluoroethylene) were prepared by spin coating method for two different concentrations 2% to 8% and for various spin speeds from 2000 RPM to 5000 RPM. A P-type Si wafer was used as a substrate to deposit P(VDF-TrFE) thin films. 2-butanone was used as a solvent to prepare P(VDF-TrFE) solution. To study the annealing effect, the films were annealed for three different temperatures 50°C, 100° C and 175° C. Ellipsometry was used to measure the thickness of the films. The identification of the films prepared was done by using FTIR spectrophotometer. The structure of the films was studied by using small angle XRD. The morphology of the coated surface was investigated using SEM. It is observed that the thickness of the film coated depends on concentration, spin speed and annealing temperature. The XRD spectrum indicated the amorphous nature with crystallites of very low dimension. SEM micrographs also conforms the predominantly amorphous nature of the film surface. The observed smooth surface with amorphous structure indicated that these films could be used as dielectric layer in organic ferroelectric field effect thin film transistors.

38

Liu, Y. Z., H. Zhang, J. X. Yu, Z. Y. Huang, C. Wang e Y. Sun. "Ferroelectric P(VDF-TrFE)/POSS nanocomposite films: compatibility, piezoelectricity, energy harvesting performance, and mechanical and atomic oxygen erosion". RSC Advances 10, n. 29 (2020): 17377–86. http://dx.doi.org/10.1039/d0ra01769h.

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39

Fares, Hoda, Yahya Abbass, Maurizio Valle e Lucia Seminara. "Validation of Screen-Printed Electronic Skin Based on Piezoelectric Polymer Sensors". Sensors 20, n. 4 (20 febbraio 2020): 1160. http://dx.doi.org/10.3390/s20041160.

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Abstract (sommario):

This paper proposes a validation method of the fabrication technology of a screen-printed electronic skin based on polyvinylidene fluoride-trifluoroethylene P(VDF-TrFE) piezoelectric polymer sensors. This required researchers to insure, through non-direct sensor characterization, that printed sensors were working as expected. For that, we adapted an existing model to non-destructively extract sensor behavior in pure compression (i.e., the d33 piezocoefficient) by indentation tests over the skin surface. Different skin patches, designed to sensorize a glove and a prosthetic hand (11 skin patches, 104 sensors), have been tested. Reproducibility of the sensor response and its dependence upon sensor position on the fabrication substrate were examined, highlighting the drawbacks of employing large A3-sized substrates. The average value of d33 for all sensors was measured at incremental preloads (1–3 N). A systematic decrease has been checked for patches located at positions not affected by substrate shrinkage. In turn, sensor reproducibility and d33 adherence to literature values validated the e-skin fabrication technology. To extend the predictable behavior to all skin patches and thus increase the number of working sensors, the size of the fabrication substrate is to be decreased in future skin fabrication. The tests also demonstrated the efficiency of the proposed method to characterize embedded sensors which are no more accessible for direct validation.

40

Xia, Weimin, Zhuo Xu, Qiuping Zhang, Zhicheng Zhang e Yuanqing Chen. "Dependence of dielectric, ferroelectric, and piezoelectric properties on crystalline properties of p(VDF-co -TrFE) copolymers". Journal of Polymer Science Part B: Polymer Physics 50, n. 18 (30 luglio 2012): 1271–76. http://dx.doi.org/10.1002/polb.23125.

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41

Roggero, Aurélien, Eric Dantras e Colette Lacabanne. "Poling influence on the mechanical properties and molecular mobility of highly piezoelectric P(VDF-TrFE) copolymer". Journal of Polymer Science Part B: Polymer Physics 55, n. 18 (26 giugno 2017): 1414–22. http://dx.doi.org/10.1002/polb.24396.

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42

Wong, Voon-Kean, Sarbudeen Mohamed Rabeek, Szu Cheng Lai, Marilyne Philibert, David Boon Kiang Lim, Shuting Chen, Muthusamy Kumarasamy Raja e Kui Yao. "Active Ultrasonic Structural Health Monitoring Enabled by Piezoelectric Direct-Write Transducers and Edge Computing Process". Sensors 22, n. 15 (30 luglio 2022): 5724. http://dx.doi.org/10.3390/s22155724.

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Abstract (sommario):

While the active ultrasonic method is an attractive structural health monitoring (SHM) technology, many practical issues such as weight of transducers and cables, energy consumption, reliability and cost of implementation are restraining its application. To overcome these challenges, an active ultrasonic SHM technology enabled by a direct-write transducer (DWT) array and edge computing process is proposed in this work. The operation feasibility of the monitoring function is demonstrated with Lamb wave excited and detected by a linear DWT array fabricated in situ from piezoelectric P(VDF-TrFE) polymer coating on an aluminum alloy plate with a simulated defect. The DWT array features lightweight, small profile, high conformability, and implementation scalability, whilst the edge-computing circuit dedicatedly designed for the active ultrasonic SHM is able to perform signal processing at the sensor nodes before wirelessly transmitting the data to a remote host device. The successful implementation of edge-computing processes is able to greatly decrease the amount of data to be transferred by 331 times and decrease the total energy consumption for the wireless module by 224 times. The results and analyses show that the combination of the piezoelectric DWT and edge-computing process provides a promising technical solution for realizing practical wireless active ultrasonic SHM system.

43

Shin, Ju Hwan (Jay), Derek K. Messer, Metin Örnek, Steven F. Son e Min Zhou. "Dielectric breakdown driven by flexoelectric and piezoelectric charge generation as hotspot ignition mechanism in aluminized fluoropolymer films". Journal of Applied Physics 132, n. 8 (28 agosto 2022): 085101. http://dx.doi.org/10.1063/5.0099321.

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Using multiphysics simulations and experiments, we demonstrate that dielectric breakdown due to electric charge accumulation can lead to sufficient hotspot development leading to the initiation of chemical reactions in P(VDF-TrFE)/nAl films comprising a poly(vinylidene fluoride-co-trifluoroethylene) binder and nano-aluminum particles. The electric field ( E-field) development in the material is driven by the flexoelectric and piezoelectric responses of the polymer binder to mechanical loading. A two-step sequential multi-timescale and multi-physics framework for explicit microscale computational simulations of experiments is developed and used. First, the mechanically driven E-field development is analyzed using a fully coupled mechanical–electrostatic model over the microsecond timescale. Subsequently, the transient dielectric breakdown process is analyzed using a thermal–electrodynamic model over the nanosecond timescale. The temperature field resulting from the breakdown is analyzed to establish the hotspot conditions for the onset of self-sustained chemical reactions. The results demonstrate that temperatures well above the ignition temperatures can be generated. Both experiments and analyses show that flexoelectricity plays a primary role and piezoelectricity plays a secondary role. In particular, the time to ignition and the time to pre-ignition reactions of poled films (possessing both piezoelectricity and flexoelectricity) are ∼10% shorter than those of unpoled films (possessing only flexoelectricity).

44

Thevenot, Camille, Didier Rouxel, Sunija Sukumaran, Sawsen Rouabah, Brice Vincent, Samir Chatbouri e Tarak Ben Zineb. "Plasticized P( VDF‐TrFE ): A new flexible piezoelectric material with an easier polarization process, promising for biomedical applications". Journal of Applied Polymer Science 138, n. 20 (7 gennaio 2021): 50420. http://dx.doi.org/10.1002/app.50420.

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45

V M, Ashwini Chavan, Shireesha G e Ambika M R. "A Succinct Review on Piezoelectric Characteristics of PVDF and its Copolymer PVDF-HFP". ECS Transactions 107, n. 1 (24 aprile 2022): 10623–30. http://dx.doi.org/10.1149/10701.10623ecst.

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Abstract (sommario):

Researchers are making attempts to develop a lightweight, shock resistance, portable, wireless sensors, and flexible wearable electronic devices. Piezoelectric nanogenerators are those which are used to convert mechanical into electrical energy and vice versa, which in turn meets the requirement of low-powered electronic gadgets. PVDF (Poly vinylidene difluoride) is found to be one of the versatile polymeric materials with intriguing characteristics and many technological applications. In recent days, Polyvinylidene difluoride and its copolymers like P(VDF-trifluoroethylene) and P(VDF-tetrafluoroethylene) are being explored extensively in order to produce energy harvesting devices. The present study deals with recent trends in the processing techniques of piezoelectric materials PVDF-HFP with different nano fillers in order to enhance its efficiency. This article may inspire several researchers to fabricate polymer composites of PVDF-HFP with different additives, which finds applications in several fields like shoe pad nanogenerator, biomedical, smart scaffolds, spin valve devices, and hybrid generators.

46

Yang, Tzu-Chuan, Yi-Pei Jiang, Ting-Han Lin, Shih-Hsuan Chen, Ching-Mei Ho, Ming-Chung Wu e Jer-Chyi Wang. "N-butylamine-modified graphite nanoflakes blended in ferroelectric P(VDF-TrFE) copolymers for piezoelectric nanogenerators with high power generation efficiency". European Polymer Journal 159 (ottobre 2021): 110754. http://dx.doi.org/10.1016/j.eurpolymj.2021.110754.

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47

Wang, Kainan, Thomas Godfroid, Damien Robert e André Preumont. "Electrostrictive PVDF-TrFE Thin Film Actuators for the Control of Adaptive Thin Shell Reflectors". Actuators 9, n. 3 (17 luglio 2020): 53. http://dx.doi.org/10.3390/act9030053.

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This paper presents the technology to control the shape of thin polymer doubly curved shell structures with a unimorph layer of strain actuators to achieve high quality, light-weight, foldable space reflectors. The selected active material is PVDF-TrFE deposited by spin coating; it is electrostrictive, isotropic and enjoys an excellent piezoelectric coefficient d 31 ≃ 15 pC/N when properly annealed, but has a nonlinear, quadratic behavior. The strain actuation is controlled by an array of segmented electrodes. The purpose of this study is to evaluate the material properties achieved in the manufacturing process. A simple, unidirectional model of electrostrictive material is considered and the material constants (electrostrictive constant Q 33 , piezoelectric constant d 31 , spontaneous polarization P s and poling strain S P ) are estimated from various static and dynamic experiments. The final part of the paper illustrates the control authority on a small demonstrator with seven independent electrodes and compares the experimental results with numerical finite element simulations.

48

Thuau, Damien. "(Invited) Organic Thin Films Transistors: From Mechanical to Biochemical Sensors". ECS Meeting Abstracts MA2022-02, n. 35 (9 ottobre 2022): 1287. http://dx.doi.org/10.1149/ma2022-02351287mtgabs.

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Interest in organic electronic materials, and in particular their potential for low-cost fabrication over large areas, led to the development of organic field-effect transistors (OFETs). The potential of OFETs has been demonstrated in a variety of applications, including pixel drivers for displays, bionic skin, wearable electronics and sensitive chemical sensors that can operate in aqueous environments. OFETs use conjugated, semiconducting small molecules and polymers and offer an alternative to inorganic devices for applications in which facile processing on different substrates and tunable electronic properties are required. The flexibility requirement implies either performance stability towards deformation, or conversely, detectable response to the deformation itself. The knowledge of the electromechanical response of organic semiconductors to external stresses is therefore not only interesting from a fundamental point of view, but also necessary for the development of real world applications. To this end, this presentation highlights the importance of the choice of functional materials (organic semiconductors and dielectrics) as well as the relationship structure/properties in transistors based sensors. Organic semiconductors (OSCs) are promising transducer materials when applied in OFETs taking advantage of their electrical properties that highly depend on the morphology of the semiconducting film. The effects of a high-performance p-type organic semiconductor, namely dinaphtho [2,3-b:2,3-f] thieno [3,2–b] thiophene (DNTT) thickness on its piezoresistive sensitivity are presented. A critical thickness corresponding to the appearance of charge carriers percolation paths in the material can tune the gauge factors (GFs) by a factor 10. In addition, single crystal OSC are regarded as promising electroactive materials for strain sensing application. Herein this talk, we will present how strain induces simultaneous mobility changes along all three axes, and that in some cases the response is higher along directions orthogonal to the mechanical deformation. These variations cannot be explained by the modulation of intermolecular distances, but only by a more complex molecular reorganisation, which is particularly enhanced, in terms of response, by p-stacking and herringbone stacking. This microscopic knowledge of the relation between structural and mobility variations is essential for the interpretation of electromechanical measurements for crystalline organic semiconductors, and for the rational design of electronic devices. Alternatively, this talk will highlight how the use of an active gate dielectric layer such as poly(vinylidenefluoride/trifluoroethylene) (P(VDF-TrFE)) piezoelectric polymer can lead to highly efficient electro-mechanical sensitivity. In such case, the sensing mechanism of the electro-mechanical transducer originates from the piezoelectric material itself, which affects the electrical behavior of the transistor as signature of a mechanical event. The second part of this talk will focus on another kind of TFT based sensor, namely the organic electrochemical transistors (OECTs) which have found recently applications in chemical and biological sensing and interfacing and neuromorphic computing. OECT rely on ions that are injected from the electrolyte into polymer-based mixed conductors, thereby changing its doping state and hence its conductivity. While great progress has been achieved, organic mixed conductors frequently experience significant volumetric changes during ion uptake/rejection, i.e., during doping/ de-doping and charging/discharging. Although ion dynamics may be enhanced in expanded networks, these volumetric changes can have undesirable consequences, e.g., negatively affecting hole/electron conduction and severely shortening device lifetime. New materials able to transport ions and electrons/holes and that exhibits low swelling will be presented, expanding the materials-design toolbox for the creation of low-swelling soft mixed conductors with tailored properties and applications in bioelectronics and beyond.

49

Tian, Li, Jing Sun, Yanping Li e Xiang Hua Zhang. "Pyroelectric response in the Langmuir–Blodgett fabricated artificial polymer multilayers". Modern Physics Letters B 33, n. 11 (18 aprile 2019): 1950137. http://dx.doi.org/10.1142/s0217984919501379.

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Abstract (sommario):

Ferroelectric poly(vinylidenefluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer, poly(vinylidenefluoride-trifluoroethylene-chlorofloroethlene) [P(VDF-TrFE-CFE)] terpolymer and P(VDF-TrFE)/P(VDF-TrFE-CFE) multilayers were fabricated by Langmuir–Blodgett (LB) technique. The microstructure, ferroelectric and pyroelectric properties of these films were investigated. In [Formula: see text] multilayer, an enhancement of pyroelectric performance was observed compared with [Formula: see text] multilayer and P(VDF-TrFE-CFE) film. The results indicate that the internal electric field due to polarization mismatch has a dominating contribution from the view of electrostatic coupling.

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Yu, Zhentao, Feng Gao, Xiangyu He, Hao Jin, Shurong Dong, Zhen Cao e Jikui Luo. "Flexible Film Bulk Acoustic Resonator Based on Low-Porosity β-Phase P(VDF-TrFE) Film for Human Vital Signs Monitoring". Sensors 23, n. 4 (14 febbraio 2023): 2136. http://dx.doi.org/10.3390/s23042136.

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Abstract (sommario):

P(VDF-TrFE) is a promising material for flexible acoustic devices owing to its good piezoelectric performance and excellent stretchability. However, the high density of internal pores and large surface roughness of the conventional P(VDF-TrFE) results in a high propagation attenuation for acoustic waves, which limits its use in flexible acoustic devices. In this paper, a novel method based on two-step annealing is proposed to effectively remove the pores inside the P(VDF-TrFE) film and reduce its surface roughness. The obtained P(VDF-TrFE) film possesses excellent characteristics, including a high breakdown strength of >300 kV/mm, a high-purity β-phase content of more than 80%, and high piezoelectric coefficients (d33) of 42 pm/V. Based on the low-porosity β-phase P(VDF-TrFE) film, we fabricated flexible film bulk acoustic resonators (FBARs) which exhibit high sharp resonance peaks. The pressure sensor was made by sandwiching the FBARs with two PDMS microneedle patches. Heartbeat and respiration rate monitoring were achieved using the pressure sensor. This work demonstrates the feasibility of high-performance flexible piezoelectric acoustic resonators based on low-porosity P(VDF-TrFE) films, which could see wider applications in the wearable sensors for both physical and chemical sensing.

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