La maîtrise de l’augmentation des doses de rayonnements ionisants en imagerie médicale constitue un objectif prioritaire des exigences réglementaires européennes et nationales. Cette radioprotection passe notamment par le besoin constant de développement de dispositifs de dosimétrie appropriés, permettant l’évaluation de la dose délivrée. Aujourd’hui, les dispositifs de dosimétrie utilisés en radiologie, en radiothérapie ou en imagerie nucléaire ne sont pas adaptés aux contraintes de la radiologie interventionnelle. Dans le cadre de cette thèse, nous proposons d’étudier si l’usage de nouveaux matériaux et des nanotechnologies, non conventionnels au domaine médical, peut contribuer au développement de solutions de mesure de dose radiotransparentes, avec pour cas d’étude la radiologie interventionnelle. Notre approche a consisté en le développement d’un nouveau modèle permettant de prédire le comportement électromagnétique et le caractère radiotransparent d’un matériau. La radiotransparence et la visibilité sur les images radiographiques qui sont d’habitude traitées au cas par cas, sont abordées d’un point de vue plus général en reproduisant toute la chaîne de production de l’image. Ce modèle a mis en perspective l’intérêt du PEDOT:PSS dans la dosimétrie des rayons X. Parallèlement, nous avons considéré les MOSFET comme indicateurs de mesure de dose en radiologie interventionnelle, utilisés généralement en radiothérapie où les énergies mises en jeu sont bien plus élevées. L’originalité de cet axe est d’étudier des MOSFET issus de l’électronique, non dédiés à la dosimétrie. / Controlling the radiation dose in medical imaging is seen by the authorities as a national and European priority. This is more specifically achieved through the development of appropriate dosimetry devices, ensuring accurate patient dose monitoring. Today dosimetry devices used in radiology, radiotherapy or nuclear imaging are not adapted to the constraints of interventional radiology. In this thesis, we propose to study if new materials and nanotechnology can contribute to the development of radiotransparent dose measurement solution, especially in interventional radiology. Our approach included developing a model that can help predict the electromagnetic behavior and radiolucent features of materials. Radiolucency and visibility on radiographic images which are usually addressed on a case-by-case basis, are approached from a more general perspective by reproducing the all image production. The model emphasizes the interest of PEDOT:PSS in the x-ray dosimetry. At the same time, we considered MOSFET as indicators of dose measurement in interventional radiology. These transistors are usually employed in radiotherapy, in which involved energies are much higher. The originality of this part is to study MOSFET used in electronics and not dedicated to dosimetry.

We investigated the different percentage of glycerol or ethylene glycol doped into PEDOT:PSS as anode buffer layer in OSC. The electrical, optical and physical properties of PEDOT:PSS were measured before and after adding glycerol or ethylene glycol. Their optical transparency was almost the same by UV-Vis spectrophotometer. Their HOMO value, measured by PESA, was around 5.1eV. Modified PEDOT:PSS with proper concentration addition increased its conductivity. Finally, surface roughness of PEDOT:PSS layer increased with higher concentration of addition resulted in bad film-forming from spin coating process. We fabricated polymer solar cells with modified PEDOT:PSS as anode buffer layer. The devise was consisted of ITO/PEDOT:PSS (different doping concentration of glycerol or ethylene glycol ) /P3HT:PCBM /Al and measured device parameter of solar cell with sunlight simulation of AM1.5G 100mW/cm2 . We found that improvement of power conversion efficiency of polymer solar cell from 2% to 3% and short-circuit current was improved for 32%, with modified PEDOT:PSS as anode buffer layer. We suggested that the improved short-circuit current was originated from increased conductivity of PEDOT:PSS that was modified by glycerol or ethylene glycol. Finally power conversion efficiency of polymer solar cell was increased with modified.

Cette thèse a été menée dans le cadre du projet ANR Numtiss. Ce projet vise à mettre au point un outil informatique de modélisation numérique du tissage. Un tel outil permettra d’apporter une plus grande précision dans la conception des préforme composite structurelles et ainsi réduire leurs temps et couts de développements. L’objectif de la thèse est d’apporter des connaissances sur les phénomènes mécaniques agissant sur les fils au cours du tissage. Parmi ces phénomènes, la déformation longitudinale des fils de chaines peut conduire à une perte de performances mécaniques irréversible de ceux-ci et représente le cœur de cette étude. Un capteur d’allongement filaire a été conçu pour réaliser les mesures In-situ sur les fils de chaines pendant le tissage. Celui-ci devant être à la fois représentatif des fils de chaine (en fibre de verre E) utilisés, robuste pour résister à tout le processus de tissage, non intrusif par rapport aux autres fils et sensible aux petites déformations (inférieur à 1%). Le capteur est composé d’un roving de verre E recouvert localement (30mm) d’une enduction piézo-résistive à base de PEDOT:PSS et de PVA. Il a été caractérisé par une série de tests sur banc de traction. Une fois ces paramètres de fabrications optimisés, le capteur a été reproduit en série. Cette série de capteurs a permis de réaliser une campagne de mesure In-situ sur un métier à tisser industriel, configurer pour le tissage de toile 3D interlock orthogonale 4 couches. Les résultats démontrent de l’influence des éléments consécutifs de la machine à tisser à travers des variations significatives et caractéristiques sur l’allure des signaux des capteurs. / This thesis was conducted within the framework of the ANR project Numtiss. This project aims to develop a software tool for numerical modeling of weaving. Such a tool will provide greater accuracy in the design of structural composite preform and thus reduce time and cost of developments. The aim of the thesis is to provide knowledge on mechanical phenomena acting on the yarns during weaving. Among these phenomena, the longitudinal stress of the warp yarns can lead to irreversible loss of mechanical performances of these yarns. The study focuses on this phenomenon. A stress yarn sensor has been designed to perform in- situ measurements of the warp yarns during weaving. It had to be representative of the warp yarns used (fiberglass E), be robust to withstand the whole process of weaving, be non-intrusive compared to the other yarns and be sensitive to small deformations (less than 1 %). The final sensor consists of an E-glass roving locally covered (30mm) by a piezo-resistive coating based on PEDOT:PSS and PVA. It was characterized by a series of tests on a tensile tester bench. Once these manufacturing parameters were optimized, the sensor has been reproduced in series. This series of sensors has run a campaign of in-situ measurements on an industrial weaving loom configured for producing 4 layers 3D orthogonal interlock fabric. The results show the influence of the consecutive elements of the loom through significant and characteristics changes in the appearance of sensor signals.

La bioélectronique utilise des signaux électriques pour interagir avec des systèmes biologiques. Les capteurs qui permettent la lecture électrique de marqueurs de maladies importantes et les implants/stimulateurs utilisés pour la détection et le traitement d'activité cellulaire pathologique ne sont que quelques exemples de ce que cette technologie peut offrir. Du fait de leurs propriétés électro-actives et mécaniques fascinantes, l'électronique organique ou les matériaux conjugués π ont été largement exploités dans le domaine de la bioélectronique. Le mélange intéressant entre conductivité électronique et ionique de ces polymères conducteurs permet le couplage entre les charges électroniques présentent dans le volume des films organiques avec les flux ioniques du milieu biologique. Le matériau prototypique de la bioélectronique organique est le polymère conducteur poly(3,4-éthylènedioxythiophène) (PEDOT) dopé avec du polystyrène sulfonate (PSS). Dans ce rapport, nous étudierons une approche pour moduler les propriétés mécaniques, électriques et électrochimiques du PEDOT: PSS et étudier leur impact sur la performance des transistors électrochimiques organiques. Par ailleurs, nous évaluerons l'effet de la micro-structuration et du nano-patterning sur l'impédance électrochimique des électrodes en or recouvertes de PEDOT: PSS utiles pour de futurs enregistrements et stimulations neurales. Enfin, nous démontrerons l'utilisation du PEDOT:PSS à micro-motifs pour l'adhésion et la migration de cellules. / Bioelectronics uses electrical signals to interact with biological systems. Sensors that allow for electrical read-out of important disease markers, and implants/stimulators used for the detection and treatment of pathological cellular activity are only a few examples of what this technology can offer. Due to their intriguing electroactive and mechanical properties, organic electronics or π-conjugated materials have been extensively explored regarding their use in bioelectronics applications. The attractive mixed electronic/ionic conductivity feature of conducting polymers enables coupling between the electronic charges in the bulk of the organic films with ion fluxes in biological medium. The prototypical material of organic bioelectronics is the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonate (PSS). PEDOT:PSS is commercially available, water-dispersible conjugated polymer complex that can be cast into films of high hole and cation conductivity, good charge storage capacity, biocompatibility, and chemical stability. In the present work we investigate an approach to tailor the mechanical, electrical, and electrochemical properties of PEDOT:PSS and study their impact on the performance of organic electrochemical transistors. In addition, we study the effect of micro-structuring and nano-patterning on the electrochemical impedance of PEDOT:PSS- coated gold electrodes for future neural recordings and stimulation. Moreover we demonstrate the use of micro-patterned PEDOT:PSS in cell adhesion and migration.

Galvanotaxis is the movement of cells in an applied electric field. The first steps to design a chip for observations of galvanotaxic behavior of cells were done in this work. The chip is a miniaturised system of previous larger galvanotaxis systems and uses materials which are thought to be biocompatible. The system was constructed on microscope slides with a channel in PDMS with adjacent polymer electrodes. The polymer electrodes were made from poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS), glycerol and Silquest A-187. The PEDOT:PSS electrodes were connected with either an evaporated metal electrode of titanium and gold or a gold net. Systems with PEDOT:PSS are neutralised when put in excessive amount of PBS (pH=7.4) for 24 hours. The final system had a channel with dimension length=14 mm, width=0.5 mm and height=0.25 mm. PEDOT:PSS worked as an electrode material and the achieved electric field through the channel was between 55 V/m and 160 V/m with an applied voltage of 1 V. The decrease of the electric field within the first hour was between 10 % and 30%.  Further development of this system could give an easy way to observe galvanotaxic behaviour of cells or an instrument that can distinguish between different cell types.

L'immobilisation d'enzymes sur des supports conducteurs d’électricité est nécessaire afin d’améliorer leur bioactivité et leur stabilité, pour une utilisation et une réutilisation dans des applications dépendant de la réponse bio-électrochimique, telles que des bioélectrodes, des biocapteurs ou des piles à biocarburant. Cependant, les méthodes d'immobilisation utilisées rencontrent encore de nombreux défis en termes de risques pour la santé et d'impact environnemental. Il est donc important de trouver des approches équilibrées et respectueuses de l’environnement pour parvenir à une immobilisation efficace avec un minimum de conséquences néfastes. Ainsi, dans le cadre de cette thèse, l’utilisation d’écotechnologies telles que le plasma froid, le dépôt de polymère conducteur biocompatible (PEDOT: PSS) et d’un agent de réticulation biologiquement basé sur la génipine, peu toxique, permettant l'immobilisation de glucose oxydase (GOx) sur des textiles nontissés à base de fibres de carbone a été étudiée. Ces textiles à base de carbone, quelle que soit leur hydrophobicité, sont des matériaux robustes à utiliser comme alternative aux métaux rigides onéreux, car ils possèdent une bonne conductivité électrique et une bonne résistance à la corrosion dans différents milieux. Les résultats obtenus ont montré que le traitement plasma froid avec un mélange gazeux d'azote et d'oxygène était efficace pour fonctionnaliser la surface des nontissés de carbone vierge et ceuxrevêtus de PEDOT: PSS. Une augmentation des énergies de surface des fibres de carbone facilite l’immobilisation de GOx par adsorption physique avec une bioactivité maintenue et une meilleure capacité de réutilisation. En outre, l’immobilisation de GOx au moyen de génipine en tant qu’agent de réticulation améliore de façon remarquable la stabilité des performances des feutres de carbone bio-fonctionnalisés. Cet agent de réticulation s'est révélé capable de réticuler directement les enzymes sans matrice ni hydrogel. Enfin, les textiles de carbone bio-fonctionnalisés obtenus ont été principalement évalués pour une utilisation dans des applications durables pour le traitement des eaux usées telles que la Bio-Fenton (BF) et la Bio-Electro-Fenton enzymatique (BEF). Les résultats ont montré que la bioactivité et la bio-activité électrique du GOx immobilisé étaient prometteuses pour l’élimination de la couleur du colorant réactif Remazol Blue RR et sa dégradation partielle à partir de la solution dans les deux traitements, ce qui a prouvé l’efficacité des méthodes d’immobilisation choisies pour la production de textiles bioactifs. Ces textiles peuvent être utilisés comme électrodes pour la production d'énergie et la dépollution. / Enzyme immobilization on electrically conductive supports is necessary to improve their bioactivity and stability, for use and re-use in applications depending on bio-electrochemical response, such as in bioelectrodes, biosensors, or biofuel cells. However, the immobilization methods used are still facing many challenges in terms of health hazards and high environmental impact. Thus, it is important to find balanced and eco-friendly approaches to achieve efficient immobilization with minimum harmful consequences. Hence, within the frame of this thesis, the use of eco-technologies such as cold remote plasma, a bio-compatible conductive (PEDOT:PSS) polymer coating, and a bio-based crosslinker “genipin” which has low toxicity, to immobilize glucose oxidase (GOx) enzyme on conductive carbon fiber-based nonwoven textiles was investigated. These carbon-based textiles, regardless of their hydrophobicity, are robust materials to be used as alternative for expensive rigid metals, since they possess good electrical conductivity and good resistance to corrosion in different media. The results obtained showed that cold remote plasma treatment with nitrogen and oxygen gas mixture was efficient in functionalizing the surface of carbon felts and PEDOT:PSS coated felts. This increased carbon fiber surface energies, and facilitated the immobilization of GOx by physical adsorption with maintained bioactivity and improved reusability. Furthermore, immobilization of GOx using genipin as a crosslinking agent improved remarkably the stability of performance of bio-functionalized carbon felts. This crosslinker showed to be able to directly crosslink the enzymes without a matrix or hydrogel. Finally, the obtained bio-functionalized carbon textiles were primarily evaluated for use in sustainable applications for wastewater treatment such as Bio-Fenton (BF) and enzymatic Bio-Electro-Fenton (BEF). The results showed that bioactivity and bio-electro-activity of immobilized GOx was promising in color removal of Remazol Blue RR reactive dye and its partial degradation from solution in both treatments, which proved the success of the chosen immobilization methods in producing bioactive textiles that can be used as electrodes for power generation and pollution control.

This research is to synthesize polyaniline (PANI) thin film on the Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) by using potentiostatic deposition of electrochemical method. The hybrid film composed of PEDOT:PSS and PANI was fabricated to replace the ITO layer for polymer solar cells as an anode. In the future, the hybrid film can develop the flexible polymer solar cells. In this study, we fixed the total thickness of the hybrid film, and we investigated optical transmittance, conductivity, Highest Occupied Molecular Orbital (HOMO), surface roughness, and surface morphology of hybrid films by changing the ratio of PEDOT:PSS and PANI, and to discuss the factors on device efficiency. Then, we compared the device structures with anode made by PEDOT: PSS. We found the hybrid films fabricated with different ratio of PEDOT:PSS and PANI, and the HOMO results were similar. In addition, we found optical transmittance, conductivity, surface roughness, and surface morphology of hybrid films that varies with different ratio of PEDOT:PSS and PANI. The power conversion efficiencies of the device mainly were affected by the surface roughness and morphology of the hybrid film surface. Comparing to other parameters, the hybrid film fabricated by PEDOOT:PSS(280nm) and PANI(30nm) owns the most appropriate surface roughness and surface morphology. The power conversion efficiency(PCE) was up to 0.68%, and then via post-annealing of 90¢J 10 minutes the PCE was increase to 1.06% under AM 1.5G illumination based on PEDOT:PSS (280 nm) / PANI (30 nm) / P3HT: PCBM (100 nm) / Al (200 nm), and the device area of 0.16 cm2.

abstract: The hierarchical silica structure of the Coscinodiscus wailesii diatom was studied due to its intriguing optical properties. To bring the diatom into light harvesting applications, three crucial factors were investigated, including closely-packed diatom monolayer formation, bonding of the diatoms on a substrate, and conversion of silica diatom shells into silicon. The closely-packed monolayer formation of diatom valves on silicon substrates was accomplished using their hydrodynamic properties and the surface tension of water. Valves dispersed on a hydrophobic surface were able to float-up with a preferential orientation (convex side facing the water surface) when water was added. The floating diatom monolayer was subsequently transferred to a silicon substrate. A closely-packed diatom monolayer on the silicon substrate was obtained after the water evaporated at room temperature. The diatom monolayer was then directly bonded onto the substrate via a sintering process at high temperature in air. The percentage of bonded valves increased as the temperature increased. The valves started to sinter into the substrate at 1100°C. The sintering process caused shrinkage of the nanopores at temperatures above 1100°C. The more delicate structure was more sensitive to the elevated temperature. The cribellum, the most intricate nanostructure of the diatom (~50 nm), disappeared at 1125°C. The cribrum, consisting of approximated 100-300 nm diameter pores, disappeared at 1150°C. The areola, the micro-chamber-liked structure, can survive up to 1150°C. At 1200°C, the complete nanostructure was destroyed. In addition, cross-section images revealed that the valves fused into the thermally-grown oxide layer that was generated on the substrate at high temperatures. The silica-sintered diatom close-packed monolayer, processed at 1125°C, was magnesiothermically converted into porous silicon using magnesium silicide. X-ray diffraction, infrared absorption, energy dispersive X-say spectra and secondary electron images confirmed the formation of a Si layer with preserved diatom nano-microstructure. The conversion process and subsequent application of a PEDOT:PSS coating both decreased the light reflection from the sample. The photocurrent and reflectance spectra revealed that the Si-diatom dominantly enhanced light absorption between 414 to 586 nm and 730 to 800 nm. Though some of the structural features disappeared during the sintering process, the diatom is still able to improve light absorption. Therefore, the sintering process can be used for diatom direct bonding in light harvesting applications. / Dissertation/Thesis / Masters Thesis Materials Science and Engineering 2018

No description available.

In this thesis, the process of fabricating PEDOT:PSS/c-Si hybrid solar cells has been investigated with the goal of performing a proof of concept as well as to determine the influence on solar cell performance of some processing parameters. Properties of PEDOT:PSS film formation and metal contact formation were investigated as a first step. Additionally, the surface passivation properties of PEDOT:PSS on n-Si have been studied and carrier lifetimes of 300 <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cmu" />s were measured by quasi steady-state photoconductance and photoluminescence carrier lifetime imaging of silicon substrates that had PEDOT:PSS spin-coated onto both sides. Finally, working PEDOT:PSS/c-Si hybrid solar cells of both the FrontPEDOT and BackPEDOT concepts were successfully fabricated and their current-voltage characteristics were measured. The champion device showed a JSC of 23.0 mA/cm2, a VOC of 520 mV and a FF of 59% as measured directly after fabrication. Repeating the measurements the following day showed a strong degradation of the cells, particularly of the JSC. It can be concluded from this work that fully working PEDOT:PSS/c-Si hybrid solarcells of both the FrontPEDOT and BackPEDOT types can be fabricated through a simple and low-cost production route. The quality of the metal contacts is of very high importance for the function of the cells. The cells are heavily degraded within less than 24 hours when stored in atmoshperic conditions, but some of the function can be regained by annealing and edge isolation. Achieving better wetting on Si substrates after certain cleaning procedures is an important point for further study. PEDOT:PSS has been seen to have some excellent passivation properties on c-Si, although these results show a strong dependency on the specific type of PEDOT:PSS. / I denna uppsats har tillverkningen av PEDOT:PSS/c-Si hybridsolceller undersökts med målet att tillverka en fungerande solcell samt att bestämma påverkan på cellens prestanda av vissa processparametrar. Polymerfilmbildning och metallkontaktbildning undersöktes som ett första steg. Dessutom studerades polymerfilmens förmåga att passivera n-Si ytor, och livstider hos laddningsbärare på ca 300<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cmu" />s mättes genom QSSPC och PL-I på kiselsubstrat med polymerfilmer på båda sidor. Slutligen tillverkades fungerande polymer/kisel hybridsolceller av både FrontPEDOT och BackPEDOT typ och de elektriska egenskaperna bestämdes. Den bästa cellen hade JSC=23.0 mA/cm2, VOC=520 mV och FF=59%, uppmätt direkt efter tillverkningen. Upprepning av mätningarna följande dag visade en stark degradering av cellerna, i synnerhet av kortslutningsströmmen. Man kan dra slutsatsen från detta arbete att fullt fungerande polymer/kisel hybridsolceller av både FrontPEDOT och BackPEDOT typ kan tillverkas genom en enkel och kostnadseffektiv produktionsväg. Kvaliteten på metallkontakterna är av mycket stor betydelse för cellernas funktion. Cellerna försämras kraftigt inom mindre än 24 timmar vid förvaring i atmosfäriska förhållanden, men en del av funktionen kan återfås genom upphettning och kantisolering. Att uppnå bättre vätning på kiselsubstrat efter vissa rengöringsmetoder är en viktig punkt för vidare studier. Polymerfilmer av PEDOT:PSS har visat sig ha utmärkta passiveringsegenskaper på kiselytor, även om dessa resultat visar ett starkt beroende på den specifika typen av PEDOT:PSS.