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Sukumaran, Sunija. "Design and preparation of a micro-harvesting device made of hybrid SMA/Piezoelectric polymer composite". Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0140.
Pełny tekst źródłaSmall-scale energy harvesting to power self-powered electronic devices is tremendously increasing. In this regard, the ability to combine thermal and mechanical harvesting using smart materials pays more attention. We have presented the feasibility of using P(VDF-TrFE) piezoelectric polymer coupled with NiTi shape memory alloy (SMA) to harvest both mechanical and thermal energy in simple scalable devices. A novel multi-layered SMA-P(VDF-TrFE) composite was fabricated and carried out their electro-thermo-mechanical performance. We have designed and developed an experimental bench to perform the electro-thermomechanical characterization of the composite, allowing us to measure the piezoelectric response when it is subjected to periodic heating and cooling. Furthermore, we performed the finite element analysis of the SMA-Piezoelectric composite and simulated the main properties of SMA such as superelastic behavior, one-way shape memory effect, and two-way shape memory effect, to finally identify the overall effective electro-thermomechanical behavior of the SMA-piezoelectric polymer composite. Finally, in order to efficiently harvest the electric charge generated from the P(VDF-TrFE) film, we have studied and compared two types of integrated converters and determined the conditions for effective energy harvesting. These results are promising, which showing the feasibility of this multilayered composite to power small electronics such as wireless sensors, MEMS and biomedical devices in an autonomous way
Schulze, Robert. "Strukturintegrierbare Sensoren auf Basis piezoelektrischer Polymere". Doctoral thesis, Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-224135.
Pełny tekst źródłaThe presented work describes the development of sensors in a novel technology approach feasible for large-scale production. By using the multicomponent microinjection molding process, mechanical sensor structures out of (fiber-reinforced) polymers are joined with piezoelectric polymer transducers. The fabricated sensors can be processed further with hybrid manufacturing technologies and adapted for structure integration. This thesis introduces design methods and models for the preliminary calculation of the novel sensors, which are required for a technology qualification. Therefore, existing modelling approaches adapted and essentially extended for practical use. Design relevant parameters related to the technology like the elastic properties of the applied materials or the geometric dimensions of the manufactured sensor structures are characterized and the system and structure integration of the sensors is presented
Schulze, Robert. "Strukturintegrierbare Sensoren auf Basis piezoelektrischer Polymere". Doctoral thesis, Universitätsverlag der Technischen Universität Chemnitz, 2016. https://monarch.qucosa.de/id/qucosa%3A20688.
Pełny tekst źródłaThe presented work describes the development of sensors in a novel technology approach feasible for large-scale production. By using the multicomponent microinjection molding process, mechanical sensor structures out of (fiber-reinforced) polymers are joined with piezoelectric polymer transducers. The fabricated sensors can be processed further with hybrid manufacturing technologies and adapted for structure integration. This thesis introduces design methods and models for the preliminary calculation of the novel sensors, which are required for a technology qualification. Therefore, existing modelling approaches adapted and essentially extended for practical use. Design relevant parameters related to the technology like the elastic properties of the applied materials or the geometric dimensions of the manufactured sensor structures are characterized and the system and structure integration of the sensors is presented.
Della, Schiava Nellie. "Development of electrostrictive P(VDF-TrFE-CTFE) terpolymer for medical applications". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI112.
Pełny tekst źródłaIn the 21st century, cardiovascular diseases became a major cause of mortality, the first in the entire world, the second in France after cancers. Indeed, cardiovascular risk factors have been increasing significantly over the past decades and this phenomenon is ongoing today. These factors cause atherosclerosis and lead to coronary acute syndrome, heart attacks, cerebrovascular accident, renal insufficiency but also to peripheral arterial disease (PAOD) and arterial aneurysms. First line treatment of atherosclerosis, regardless of arterial territory concerned, is medical treatment. But, if despite best medical treatment, symptoms are important for patients, interventional treatment may be considered. For aneurysms and for PAOD, vascular surgery is possible. Vascular surgery can be divided into two categories: conventional open repair (COR) and endovascular techniques (ET). During the last ten years, ET became the first line treatment for most arterial injuries. ET has become the first line treatment because it allows a considerable reduction in surgical morbi-mortality and a great reduction in health costs
Gusarova, Elena. "Dispositifs souples pour la récupération d’énergie à base de matériaux organiques piezoélectriques P(VDF-TrFE) imprimés". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT139/document.
Pełny tekst źródłaThis work aims to study innovative solutions for energy harvesting applicable toautonomous wireless sensors for IoT (Internet of Things). It is focused on flexiblepiezoelectric composite materials and a multi-physical approach. The objective is to harvestenergy via strain-induced phenomena from both mechanical and thermal sources, andparticularly sources neglected so far (slow and low). The main idea is the hybridization ofdifferent functional materials with the core of the system being screen printed piezo/pyroelectricmicrogenerators, mandatory to generate electrical charges. The originality of thiswork is to realize large area flexible energy harvesting systems by using ink-basedpiezoelectric copolymers of polyvinylidene fluoride P(VDF-TrFE). This material is veryflexible and durable which makes it attractive for applications in systems with complexshapes. Another benefit of P(VDF-TrFE) is that it does not need to be pre-stretched as PVDFand it is now available in inks for printable electronics which can simplify and reduce theprice of the fabrication process.We first describe the fabrication process of the screen printed P(VDF-TrFE)microgenerators, followed by ferroelectric and piezoelectric characterizations. For thispurpose we have developed optimized methods in open-circuit conditions adapted for flexiblesystems tested and validated on commercial bulk PVDF. The last step was to realize a lowprofile thermal flexible energy harvester prototype (no radiator). It was done by hybridizationof the fabricated microgenerators and foils of shape memory NiTi-based alloy, which is afunctional material sensitive to a given temperature threshold.The key outcomes of this work are: 1) the successful deposition of multilayers ofP(VDF-TrFE) and organic PEDOT:PSS electrode, 2) dielectric, ferroelectric and directpiezoelectric constants reported as a function of film thickness, and 3) the g31 direct voltagecoefficient, measured for the first time, and showing the record value of 0.15 V·m/N. Also,we have demonstrated that in open-circuit conditions, the microgenerators can produce auseful strain-induced voltage of 10 V with an energy density close to 500 μJ/cm3, these valuesbeing limited by the experimental set-up.The concept of thermal energy harvesting composite based on thin film screen printedP(VDF-TrFE) microgenerators was realized and demonstrated to be effective. We concludewith a functional prototype of flexible energy harvester, able to detect non-continuous slowthermal events and producing 37 V (corresponding to 95 μJ) at 65 ºC
Ganesan, Lakshmi Meena. "Coupling of the electrical, mechanical and optical response in polymer/liquid-crystal composites". Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2010/4157/.
Pełny tekst źródłaMikrometer-große, in eine Polymermatrix eingebettete Flüssigkristall-Tröpfchen können als elektro-optische Lichtventile fungieren, da die Ausrichtung der Flüssigkristalle durch ein externes elektrisches Feld verändert werden kann. Wird nun ein ferroelektrisches Polymer als Matrix verwendet, so kann das durch den piezoelektrischen Effekt erzeugte und von der äußeren mechanischen Spannung abhängige elektrische Feld den Flüssigkristall ausrichten. Solche Materialien können daher als piezo-optische Lichtventile eingesetzt werden. Im Rahmen dieser Arbeit wurden PDLCs (polymer-dispersed liquid crystals) durch Einbettung von nematischen Flüssigkristallen in Poly(Vinylidenefluoride-Trifluorethylene) (P(VDF-TrFE)) erzeugt. Die Wechselwirkungen an der Grenzfläche zwischen Flüssigkristall und Polymer wurden mittels dielektrischer Spektroskopie untersucht. Im dielektrischen Spektrum des reinen P(VDF-TrFE) wurden zwei Dispersions-Regionen beobachtet, welche vom Glasübergang und einer Ladungsträgerrelaxation des Polymers herrühren. PDLC Folien mit unterschiedlichen Anteilen von Flüssigkristall-Tröpfchen (10 bzw. 60 Gewichtsprozente) zeigten beim Anlegen eines elektrischen Wechselfelds zusatzliche Relaxationseffekte, welche der Bewegung der eingebetteten Flüssigkristall-Moleküle zugeordnet werden konnten. Durch die Einlagerung der Flüssigkristall-Moleküle weist die Struktur eine Relaxation auf, die gegenüber vergleichbaren Prozessen im reinen Flüssigkristall deutlich verlangsamt ist. Des weiteren wurde das elektrooptische und piezo-optische Verhalten der mit 10 und 60 Gewichtsprozent Flüssigkristall geladenen Folien untersucht. Die Lichtstreuung hängt dabei ab von der Fehlanpassung der Brechungsindizes von Polymermatrix und Flüssigkristallen sowie von den Wechselwirkungen der Polymerdipole mit den Flüssigkristall-Molekülen an der Tröpfchenoberfläche. Es konnte erstmalig gezeigt werden, dass die Lichtdurchlässigkeit der PDLC-Folien durch eine externe mechanische Spannung gesteuert werden kann. Dieser Effekt macht das piezo-optische PDLC-Material für die Verwendung in Optik- und Sensoranwendungen interessant. Im Vergleich mit unpolaren Wirtspolymeren zeigen polare Wirtsmaterialien eine deutlich stärkere Wechselwirkung zwischen den Flüssigkristall-Molekülen an der Polymer/Flüssigkristall-Grenzfläche, welche den elektrooptischen Effekt beeinflusst und so die maximale transmissions änderung reduziert.
Nguyen, Van Son. "Élaboration de films nanocomposites hybrides P(VDF-TrFE)/nanocristaux, et intégration dans des dispositifs microstructurés". Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0075/document.
Pełny tekst źródłaThe objective of this work is to develop flexible organic/inorganic hybrid materials for application in microsystems. This study included the preparation and characterization of nanocomposites based on ferroelectric polymer matrix P(VDF-TrFE), potential materials for applications based on thin films on substrates, and different types of nanoparticles: ZnO, LiNbO3 (piezoelectric) and Al2O3 (non-piezoelectric). The protocols of the ultrasonic dispersion of nanoparticles in solvents and polymeric solutions are optimized, allowing dispersing quite homogeneously clusters of nanocrystals in the matrix copolymer. Films of controlled thickness between 0.1 µm and 100 µm were fabricated by spin-coating and doctor blade coating with surface quality suitable for micro-technologies. Morphology and crystallinity of P(VDF-TrFE) are preserved in the presence of up to 10 wt.% of nanoparticles. Thus nanocomposites keep high piezoelectric properties and show an increased up to 30% of the mechanical properties for 10 wt.% ZnO or Al2O3. In addition, the increase in elastic constant with decreasing cluster size of nanoparticles was observed. Nanocomposite films on substrates or free-standing filled up to 10 wt.% were successfully polarized by corona without contact. Specific procedures for preparing microdevices by photolithography on nanocomposite polymer films, while keeping piezoelectric activities of materials, have been developed. The characterization of realized acoustic wave devices is also presented
Glasser, Alizée. "Polymer Electronic Inks : Synthesis, Formulation and Processing". Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0381.
Pełny tekst źródłaIn this work, two organic functional inks for printed electronic were studied. The first is composed of a semi-conducting polymer, poly(3,4-ethylene dioxythiophene) (PEDOT), in complex with an insulating polyanion, poly(4-styrene trifluoromethyl (bissulfonylimide)) (PSTFSI), which stabilizes PEDOT in water. The second ink contains the piezoelectric polymer poly(vinylidenefluoride-co-trifluoroethylene) (P(VDFTrFE)) in organic solvents. To be processable using a wide range of deposition processes, the rheological behaviors, wettability and capillary properties of these inks have to be adjusted. For that purpose, both types of inks were formulated. PEDOT inks were formulated for inkjet printing, screen-printing, doctor blading, and for a deposition of lines using a soft blade. No additive is necessary to modify the rheological properties of these inks: by simply tuning the concentration in polymer, their behavior go from Newtonian to shearthinning with gel properties. Further formulations to improve the wettability, the elasticity of the inks, and the conductivity of dried films were performed. P(VDFTrFE) inks were formulated for screen-printing using a gelifying agent, which modify the organization of the polymer in solution, or a mixture of a good and a poor solvent, which gives rise to a micro-emulsion. The Newtonian inks thereby become shear-thinning. Once the properties of the dried films were studied, both types of polymeric inks were used to create functional pressure sensors
Thevenot, Camille. "Élaboration de membranes polymères piézoélectriques souples en vue d’applications biomédicales". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0197/document.
Pełny tekst źródłaThe work presented here focuses on the preparation of a piezoelectric polymer material aimed to be the sensitive element of a strain sensor of biological tissues. This includes the study of the softening of the copolymer P(VDF-TrFE) necessary to be close of the mechanical properties of an artery, without reducing the piezoelectric coefficient. Plasticized P(VDF-TrFE) films with diethyl phthalate (DEP) were made according to different protocols including doctor blade technique or spin-coating and polarization under high voltage to activate the ferroelectric properties. Depending on the preparation conditions, two distinct structures were obtained with physical properties specific to each of them. For the first type of film, the study of the morphology and the hysteresis loops polarization-electric field showed a new structure of the material, with a demixing of the plasticizer in the matrix. In this case, the coercive field is strongly reduced which allows a decrease of the required high polarization voltage up to 40%, even if the film only contains 50wt% of P(VDF-TrFE). The second type of film, obtained after an annealing at lower temperature, has an almost homogeneous structure and properties close to a mixing law. The coercive field remains comparable to that of the pure P(VDF-TrFE) but the flexibility of the material is greatly increased. The study of the mechanical properties showed that the plasticizer can reduce the Young modulus to 40MPa for 30wt% of DEP in the film. In addition, the remanent polarization and the piezoelectric coefficient are also reinforced. In vitro and in vivo experiments, performed on arteries, of sensors based on these films demonstrated the high potential of the material to detect the strain of soft tissues and to function at biologic human frequencies
Liao, Tzu-Kang, i 廖孜康. "Structural-resolved Study of Photon-sensitive Piezoelectric Properties of P(VDF-TrFE) Films". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/6z87jj.
Pełny tekst źródła國立中央大學
化學工程與材料工程學系
102
Semi-crystalline polymer, Poly(vinylidene fluoride-co-trifluoroethylene) coupled with TiOPc powder, which has excellent sensitivity to visible light, is expected to bridge photo sensor and piezoelectric actuators. This composite material does not only retains good piezoelectric efficiency and possesses high sensitivity to visible light. The beta-phase P(VDF-TrFE) exhibits a good piezoelectric property. Our sample is composed of P(VDF-TrFE) and with and without TiOPc, respectively. When the samples were heated continuously, applied electrical voltage, light illumination, we used in-situ XRD to measure the microstructure evolution. In this study, we investigated the phase transition induced by heating up to 90℃. We observed the changes of lattices distance subjected to temperature, electric field and light illumination. We also measured the bulk (piezoelectric properties) d33. We found a linear correlation between the macroscopic d33 and microscopic lattice strain. Our equation can well describe the d33 variation and lattice evolution subjected to various temperature and voltages.
Chan, Chen-Hao, i 詹宸豪. "Development of Aligned P(VDF-TrFE) Piezoelectric Nanofiber Bundles for Cardiac Drug Screening Application". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/88932792643888731554.
Pełny tekst źródła國立臺灣大學
應用力學研究所
104
In current development for cardiovascular drug discovery, the main parameters are the cardiac systolic and diastolic profiles, beating frequency, and contractile profile. Among these parameters, cardiac systolic and diastolic profiles are the most common, and the monitoring systems are usually based on flexible substrates fabricated by MEMS based microfluidic system is widespread. However, the systems for monitoring cardiac systolic and diastolic profiles are mostly based on an optical systems, and the force profiles is estimated from calculation of the deformation of cells or flexible substrates. Hence, the detection is not direct and could not directly infer relationship between cardiac contraction and drug. To achieve a fully automatic, real-time and direct massive cardiac drug monitoring system, a platform for real-time monitoring cardiac contractile profile was developed in this study. A piezoelectric material, [poly[(vinylidenefluoride-co-trifluoroethylene]; P(VDF-TrFE:75/25)], was chosen to be the core of the transducer. It is composed of multiple nanofibers to create piezoelectric nanofiber bundles. In order to rapidly develop nanofiber bundles, the electrospinning method was applied. The parallelly oriented piezoelectric nanofiber bundles could be massively fabricated. The overall platforms could be fabricated in one day. A biomimetic substrate coating for facilitating cardiomyocyte adhesion and maturation was also developed. Furthermore, an interface system for monitoring contraction of cardiac micro-tissue was developed and could directly and automatically convert the mechanical force of cardiomyocyte to electrical signals. Also, we verified that this platform can detect cardiac contractile profile by administrating Isoproterenol and Verapamil compounds.
Hanna, Amir. "Transport and Fatigue Properties of Ferroelectric Polymer P(VDF-TrFE) For Nonvolatile Memory Applications". Thesis, 2012. http://hdl.handle.net/10754/244572.
Pełny tekst źródłaMetello, Daniela Filipa Figueiredo Marques. "Modeling, Simulation and Experimental Validation of PVDF-based Electroactive Actuators". Master's thesis, 2020. http://hdl.handle.net/10316/93993.
Pełny tekst źródłaNos últimos 20 anos, os polímeros electroactivos (EAPs) têm recebido mais atenção no mundo dos mecanismos de actuação. O termo "electroactivo" significa que o polímero é electricamente activo ou reactivo, ou seja, que terá uma resposta mecânica a um estímulo eléctrico. Como qualquer polímero, este é conhecido por ser leve e fácil de processar. Para além disso, os EAPs são resistentes e capazes de produzir grandes tensões de actuação, quando comparados com actuadores convencionais. Portanto, a sua importância está a aumentar em várias aplicações, nomeadamente biomédicas, tais como instrumentos médicos, implantes biónicos, próteses e "músculos artificiais". Os EAPs dividem-se em iónicos e electrónicos, sendo a principal diferença o transporte físico: os EAPs iónicos utilizam cargas iónicas, enquanto os EAPs electrónicos utilizam cargas eléctricas. O P(VDF-TrFE-CTFE) é um polímero "ferrorelaxor" pertencente aos EAPs electrónicos e é considerado um material promissor pela sua elevada constante dieléctrica (~50), bem como pela elevada resposta electromecânica e densidade de energia elástica.Neste trabalho, três actuadores (cinco camadas) foram caracterizados electromecanicamente para estudar a influência de dois parâmetros geométricos: a espessura da camada do P(VDF-TrFE-CTFE), e a largura total do actuador. A defleção, a força de bloqueio e a rigidez à flexão de cada actuador foram obtidas através de testes mecânicos sob três valores de campo eléctrico. Subsequentemente, foi executada uma análise por MEF em COMSOL Multiphysics®. Realizou-se um estudo estacionário de cada actuador para avaliar o comportamento electromecânico sob três valores de campo eléctrico. A defleção em cada simulação foi comparada com os testes experimentais.A partir dos resultados dos testes, concluiu-se que a largura não influencia o desempenho do actuador. Além disso, um aumento da espessura do P(VDF-TrFE-CTFE) provocou um aumento da defleção, força de bloqueio e rigidez de flexão. Mais ainda, a simulação foi validada, pois o comportamento observado revelou-se semelhante nos testes experimentais, ou seja, a defleção aumentava linearmente com o aumento do campo eléctrico aplicado.Finalmente, comparando os três actuadores com outras tecnologias electroactivas, é possível afirmar que as defleções observadas são mais elevadas, mas a força de bloqueio exercida por estes actuadores é significativamente inferior a outras tecnologias de actuação já estabelecidas.
In the last 20 years, electroactive polymers (EAPs) have gained attention in the world of actuation mechanisms. "Electroactive" means that the polymer is electrically active or responsive, i.e. that it will have a mechanical response to an electric stimulus. As any polymer, they are known for being lightweight and easy to process. Adding to this, EAPs are resilient and able to produce large actuation strains, when compared to conventional actuators. Therefore, their importance is increasing in several applications, namely biomedical applications such as surgery-assisting tools, bionic implants, prosthetics and "artificial muscles". EAPs are divided into ionic and electronic, with the major different being the physic transport: ionic EAPs use ionic charges, while electronic EAPs use electric charges. P(VDF-TrFE-CTFE) is a ferrorelaxor polymer that belongs to electronic EAPs and it is considered one of the most promising materials for its high dielectric constant (~50), as well as its high electromechanical response and elastic energy density.In this work, three cantilever-like multilayered actuators (five layers) were electromechanically characterized to study the influence of two geometry parameters: the thickness of the active layer, P(VDF-TrFE-CTFE), and the total width of the actuator. The tip displacement, blocking force and bending stiffness of each actuator were obtained through mechanical testing under three values of electric field. Subsequently, a FEM analysis was executed on COMSOL Multiphysics®. A stationary study was performed for each actuator, to evaluate the electromechanical behavior under the three values of electric field. The tip displacement in each simulation was also obtained and compared with the experimental tests.From the tests' results, it was concluded that the width of the actuator does not play a major influence in the performance of the actuator. Moreover, an increase in the thickness of the active layer translated in an increase of the tip displacement, blocking force and bending stiffness. On the other hand, the simulation was validated as the tip displacement increased linearly with the electric field, which was a behavior already observed in the experimental tests.Finally, comparing these three actuators with other electroactive technologies, it is possible to state the displacements observed are higher, but the blocking force exerted by these actuators is significantly lower than other existing actuation technologies.
Gheorghica, Dan. "Imprinted Polymer-Based Ultrasound Transducers for Medical Imaging". Master's thesis, 2019. http://hdl.handle.net/10362/90933.
Pełny tekst źródłaMehner, Erik. "Pyroelektrische Materialien: elektrisch induzierte Phasenumwandlungen, thermisch stimulierte Radikalerzeugung". Doctoral thesis, 2017. https://tubaf.qucosa.de/id/qucosa%3A31917.
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