Dissertations / Theses on the topic 'PEDOT Surface'

All conducting polymers are potentially electrochromic, owing to the injection of charge carriers that changes their electronic structure and results in a shift of their optical absorption towards higher wavelengths. PEDOT-PSS and PEDOT-S are very promising materials in terms of electrochromic properties, due to the good contrast existing between their doped and undoped forms. However this contrast has to be enhanced in order to design more efficient electrochromic devices, and new solutions should thus be found in order to solve this issue.

Surface plasmons are described as electromagnetic waves propagating along the surface between a dielectric and a metal. Coupled to an incident radiation, they create an energy loss in the light transmitted and reflected by the interface. When the metallic surface is periodically corrugated, this absorption phenomenon due to plasmonic resonance occurs at a specific wavelength that depends on several parameters, such as the incidence angle, the dielectric constants of the two media and the grating period. By coating metallic gratings with electrochromic polymers, we may thus be able to trigger a plasmonic absorption at a given wavelength and shift it upon reduction or oxidation of the material.

Electrochromic devices consisting of PEDOT-PSS or PEDOT-S spin-deposited on gold and silver gratings were investigated by UV-visible reflectance measurements. The periodically corrugated structures were reproduced from commercial gratings by soft nanolithography and were analyzed by AFM. Some electrochromic cells exhibited new colors or a high shift of the plasmonic resonance upon redox switching of the polymer film. Depending on the step and the nature of the grating employed, this shift could reach 20 nm in the case of PEDOT-PSS and more than 100 nm for PEDOT-S. A theoretical model was found to predict the wavelength of plasmonic excitation and the orientation of the shift.

Detection of chemicals is a vital part of chemistry. For this reason, many detection systems are developed by scientists and every detection system has its own advantages. Raman spectroscopy is one of these detection systems having many advantages. However, this technique suffers from low signal intensity disadvantage. By developing a well prepared substrate, this problem can be easily solved
moreover, even single molecule detection can be possible. In this study, a novel surface enhanced Raman scattering (SERS) substrate was prepared in two steps: In the first step, ethylenedioxythiophene (EDOT) monomer was polymerized electrochemically onto indium tin oxide (ITO) coated glass. In the next step, silver ions were reduced electrochemically onto surface prepared in the previous step.In the substrate preparation part, the reduction potential of silver ion, the concentration of silver ions in solution, the polymer film thickness and reduced silver amount on substrates were optimized to get the best SERS performances from substrates. The prepared substrates were characterized by cyclic voltammetry (CV), ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) attached to SEM. In the SERS performance investigation part, homogeneity and the shelf life of the prepared silver-PEDOT substrates were tested. Homogeneity is very important in terms for the applications of Raman technique in quantitative analysis since most of the reported substrates are lack homogeneity consideration, our study will be an important contribution to the literature. The stability of the substrate was investigated for a period of one month. The very small change in the signal at the end of one month indicated that the substrate can be used even longer time with high efficiency. In all the studies, brilliant cresyl blue (BCB) is used as a model compound. Some important Raman active chemicals, namely, rhodamine 6G (R6G) and 4-mercapto benzoic acid (4-MBA) were detected by using the prepared substrates.

On constate une forte demande mondiale d' énergie propre et renouvelable en raison de la consommation rapide des combustibles fossiles non renouvelables et l'effet de serre qui en résulte. Une solution prometteuse pour produire une énergie propre et renouvelable est d'utiliser des cellules solaires pour convertir l' énergie solaire directement en électricité. Comparativement à leurs homologues inorganiques, les cellules solaires organiques (OSCs) sont maintenant intensivement étudiées en raison des avantages tels que le poids léger, la flexibilité, la compatibilité avec les procédés de fabrication à faibles coûts. Malgré ces avantages, l'efficacité de conversion (PCE) des OSCs doit encore être améliorée pour la commercialisation à grande échelle. Les cellules solaires organiques sont réalisées en pile de couches minces comprenant des électrodes, la couche de transport d' électrons, la couche de polymère actif et la couche de transport de trous. Dans cette étude, nous sommes concernés par la couche de PEDOT:PSS qui est couramment utilisée comme une couche tampon entre l'électrode anodique et la couche de polymère actif de cellules solaires organiques. Cette étude vise à intégrer différentes concentrations de nanoprismes (NPSMs) d'argent de taille sub-longueur d'onde dans du PEDOT: PSS afin de profiter de leurs propriétés optiques uniques nées de résonances de plasmons de surface localisées (LSPR) pour améliorer la collecte lumineuse et l'efficacité de génération de charge en optimisant l' absorption et la diffusion de la lumière. Nous avons constaté que les facteurs clés qui contrôlent les performances des cellules solaires plasmoniques comprennent non seulement les propriétés optiques, mais également les propriétés structurelles et électriques des couches hybrides de PEDOT:PSS comprenant des NPSMs d' Ag. D'une part, l'ajout de NPSMs d' Ag conduit ¨¤ (1) une augmentation de l'absorption optique; (2) de la diffusion de la lumière ¨¤ de grands angles ce qui pourrait conduire ¨¤ un meilleur piégeage de la lumière dans les OSCs. D'autre part, (1) la rugosité de surface est augment¨¦e en raison de la formation d'agglomérats de NPSMs d' Ag, ce qui conduit ¨¤ une meilleure efficacité de collecte de charge; (2) la résistance globale des films hybrides est également augment¨¦e en raison de l'excès de PSS introduit par les NPSMs d' Ag incomplètement purifiées, inférieur courant de court-circuit (Jsc) qui en résulte; (3) les Ag NPSMs et leurs agglomérats ¨¤ l'interface PEDOT:PSS/couche photo-active pourraient agir comme des centres de recombinaison, conduisant ¨¤ une réduction de la résistance de shunt, du Jsc et de la tension en circuit ouvert (Voc). Afin de résoudre partiellement l'inconvénient (2) et (3), en intégrant des NPSMs d¡¯Ag davantage purifiés et une petite quantité de glycérol dans le PEDOT:PSS, la résistance des couches hybrides de PEDOT:PSS-Ag-NPSMs peut ¨être réduite à une valeur comparable ou inférieure ¨¤ celles couches vierges. Les futurs progrès en chimie de surface colloïdale et l'optimisation sur le processus d'incorporation des nanoparticules seront nécessaires pour produire des cellules solaires organiques plasmoniques de meilleures performances
Nowadays there has been a strong global demand for renewable and clean energy due to the rapid consumption of non-renewable fossil fuels and the resulting greenhouse effect. One promising solution to harvest clean and renewable energy is to utilize solar cells to convert the energy of sunlight directly into electricity. Compared to their inorganic counterparts, organic solar cells (OSCs) are now of intensive research interest due to advantages such as light weight, flexibility, the compatibility to low-cost manufacturing processes. Despite these advantages, the power conversion efficiency (PCE) of OSCs still has to be improved for large-scale commercialization. OSCs are made of thin film stacks comprising electrodes, electron transporting layer, active polymer layer and hole transporting layer. In this study, we are concerned with PEDOT:PSS layer which is commonly used as a buffer layer between the anodic electrode and the organic photoactive layer of the OSC thin film stack. We incorporated different concentrations of silver nanoprisms (NPSMs) of sub-wavelength dimension into PEDOT:PSS. The purpose is to take advantage of the unique optical properties of Ag MPSMs arisen from localized surface plasmon resonance (LSPR) to enhance the light harvest and the charge generation efficiency by optimizing absorption and scattering of light in OSCs. We found that the key factors controlling the device performance of plasmonic solar cells include not only the optical properties but also the structural and electrical properties of the resulting hybrid PEDOT:PSS-Ag-NPSM-films. On one hand, the addition of Ag NPSMs led to (1) an increased optical absorption; (2) light scattering at high angles which could possibly lead to more efficient light harvest in OSCs. On the other hand, the following results have been found in the hybrid films: (1) the surface roughness was found to be increased due to the formation of Ag agglomerates, leading to increased charge collection efficiency; (2) the global sheet resistance of the hybrid films also increases due to the excess poly(sodium styrenesulphonate) introduced by incompletely purified Ag NPSMs, resulting in lower short circuit current (Jsc); (3) the Ag nanoprisms and their agglomerates at the PEDOT:PSS/photoactive layer interface could act as recombination centers, leading to reductions in shunt resistance, Jsc and open circuit voltage (Voc). In order to partially counteract the disadvantage (2) and (3), by incorporating further purified Ag NPSMs and/or a small amount of glycerol into PEDOT:PSS, the sheet resistance of hybrid PEDOT:PSS-Ag-NPSM-films was reduced to a resistance value comparable to or lower than that of pristine film

Conducting polymer coating is the new developing area in the field of advanced textiles. In this project the rheological behaviour of paste containing conducting polymer was studied during formulation to coating application. The literature study is done by keeping all the contents of project in mind and a wide area of conductive polymer, coating methods, binder system and rheology modifier is covered. The rheological behaviour of different fluid containing newtanion and non-newtanion behaviour is discussed for better understanding of the project working. Polyester fabric was coated by knife coating method. In paste formulation, the chemicals used were polyurethane binder with two HEUR based rheology modifiers. A lot of experiments were performed to determine the right amount of rheology modifier alone or in combination for paste formulation and coating application and interesting findings were observed during the experimental work which had been justified in results and analysis. After application, the coated fabric was checked for resistivity.
Program: Magisterutbildning i textilteknologi

Les acides ascorbique (AA) et urique (AU) sont d'un grand intérêt biologique vu les différents rôles qu'ils jouent dans l'organisme (agents antioxydant, cofacteur d'hydroxylation, marqueur du métabolisme des purines). Chez les cliniciens, le dosage de ces deux molécules aide à l'établissement de diagnostics et aux suivis thérapeutiques. Face aux méthodes classiques actuellement utilisées (la chromatographie liquide à haute performance et la spectrométrie), qui nécessitent souvent des étapes de prétraitement de l'échantillon, l'objectif de ce travail est de mettre au point un microcapteur voltammétrique fonctionnalisé par un polymère conducteur électrogénéré le poly (3,4-éthylènedioxythiophène) PEDOT. Le capteur a permis de doser sélectivement et simultanément les deux acides. L'étude des conditions d’élaboration du film (paramètres d'électrolyse, épaisseur du dépôt) et des paramètres de mesure électrochimique a permis d'optimiser les performances analytiques du capteur (sensibilité, seuil limite de détection, domaine de linéarité) dans des solutions modèles. L'étude a mis en évidence un mécanisme EC' de régénération de l'acide urique par l'acide ascorbique au voisinage de l'électrode. Le capteur a ensuite été éprouvé directement dans le sérum sanguin sans aucune préparation de l'échantillon. Les résultats des dosages électrochimiques des deux acides sont en très bonne adéquation avec ceux des méthodes chromatographiques et enzymatiques
Ascorbic (AA) and uric (UA) acids are of a great biological interest considering the various physiological roles they play (antioxidants, cofactor of hydroxylation, marker of the purins metabolism). In medicine, the assay of both molecules contributes to the establishment of diagnosis and therapies. In alternative to the traditional methods currently used (high performance chromatography liquid and spectrometry), which are generally time consuming and often require costly materials, complex experimental protocols and sample pretreatment, the aim of this work is to develop a voltammetric microsensor functionalized by a electrogenerated conducting polymer (3,4-ethylenedioxythiophene) PEDOT. This sensor made possible a selective and sensitive simultaneous detection of both acids. The study of the electropolymerization parameters (PEDOT film thickness, electropolymerization potential range, monomer concentration) and of the electrochemical measurements parameters (potential scan rate) allows the optimization of the analytical performances of the microsensor (sensitivity, limit of detection and linear range). The study highlighted also an EC’ mechanism of regeneration of uric acid by ascorbic acid in the vicinity of the electrode. Electrochemical assay of the two acids was finally performed in the human blood serum without any preparation of the sample. The results are in very good agreement with those of the standardized chromatographic and enzymatic methods

This research represents the first effort to apply vertical cavity surface emitting lasers (VCSELs) to the monitoring of interferometric fiber optic sensors. Modulation of the drive current causes thermal tuning of the laser light frequency. Reflection of this frequency-modulated light from a fiber Fabry-Perot interferometer (FFPI) sensor produces fringe patterns which can be used to measure the optical path difference of the sensor. Spectral characteristics were measured for 850nm VCSELs to determine the combination of dc bias current, modulation current amplitude and modulation frequency for which single mode VCSEL operation and regular fringe patterns are achieved. The response characteristics of FFPI sensors were determined experimentally for square, triangular, saw-tooth waveforms at frequencies from 10kHz to 100kHz. The dependence of VCSEL frequency on the dc bias current was determined from spectral measurements to be ~165GHz/mA. An independent measurement of this quantity based on counting fringes from the FFPI sensor as the laser modulated was in good agreement with this value. The effect of optical feedback into the laser was also studied. By observing the fringe shift as the FFPI sensor was heated, a fractional change in optical length with temperature of 6.95 X 10-6/°C was determined in good agreement with previous measurements on a 1300nm single mode fiber. The performance of 850nm VCSEL/FFPI systems was compared with their counterparts using 1300nm distributed feedback (DFB) lasers. The results of these experiments show that the 850nm VCSEL/FFPI combination gives regular fringe patterns at much lower bias current and modulating current amplitudes than their 1300nm DFB/FFPI counterparts.

Les travaux présentés dans ce manuscrit se sont focalisés dans un premier temps sur l'étude de la réduction du 4-nitrobenzène diazonium (NBD). Des études mécanistique et cinétique ont permis d'élucider la réactivité du NBD et de compléter les données bibliographiques sur le sujet. Un capteur à antioxydants fonctionnalisé par le NBD a ensuite été envisagé, ouvrant les portes à la détection de l'acide ascorbique (AA). Dans un second temps, une fonctionnalisation mixte à partir d'un sel de diazonium et un polymère conducteur, le polyéthylènedioxythiophène (PEDOT), a bénéficié de la stabilité du diazonium et des propriétés électrocatalytiques du PEDOT vis-à-vis de l'AA et de l'acide urique, deux antioxydants hydrophiles majeurs. L'optimisation des paramètres de modification de l'interface et la détermination des performances analytiques ont montré que la structure du polymère a une grande influence sur la réponse du capteur
The work here discussed is a fundamental study of the electrochemical reduction of the 4-nitrobenzene diazonium (NBD). Mechanistic and kinetic studies shed some light on the parts of the NBD reactivity and completed literature data about the subject. An NBD-functionalized antioxidant sensor has been envisaged, allowing the assay of ascorbic acid (AA). In a second time, a combined functionalization using a diazonium salt and a conductive polymer, the polyethylenedioxythiophene (PEDOT) coupled diazonium stability and electrocatalytic properties of PEDOT towards AA and uric acid, two major antioxidants. The modification parameters optimization of the interface and analytical performances determination highlighted the influence of the polymer structure on the sensor response

La plasmonique est un domaine de la nano-photonique qui étudie le comportement de la lumière à des échelles sub-longueurs d'ondes en présence de métaux. Les plasmons polaritons de surface (SPPs) sont des modes électromagnétiques qui se propagent à l'interface entre un diélectrique et un métal. Les SPPs trouvent des applications dans plusieurs domaines comme la communication et le traitement tout-optique du signal, la spectroscopie, la détection en biologie et en chimie. De nombreux composants plasmoniques (modulateurs, coupleurs, détecteurs ...) ont été démontrés ces dernières années. Cependant, leur l'intégration reste conditionnée par l'absence d'un générateur compact (pompage électrique, dimensions réduites) et par les grandes pertes ohmiques. Les techniques standards de génération de SPs nécessitent l'alignement d'un laser externe sur un prisme ou un réseau de diffraction afin d'adapter le vecteur d'onde incident avec celui du plasmon. L'approche que nous avons choisie est basée sur l'utilisation de lasers à semiconducteur ayant une polarisation transverse magnétique (TM) comme source d'excitation et de gain. Notre approche, permet d'obtenir des dispositifs compacts et facilement intégrables sur puce. Pendant ma thèse j'ai étudié expérimentalement et numériquement les performances d'un laser en fonction rapprochement du contact métallique à sa région active. La proximité du gain optique au métal est nécessaire pour la réalisation de dispositifs plasmoniques actifs. J'ai démontré la génération et l'amplification des plasmons de surface dans la bande télécom (λ=1.3µm), avec des dispositifs compacts, à base de semiconducteurs, fonctionnant par injection électrique et à température ambiante. Notamment, j'ai réalisé une architecture élégante, avec coupleur intégré, pour la génération de SPPs accessibles sur le sommet du dispositif. Un dispositif avec gaine superficielle ultrafine a permis de démontrer un mode hybride plasmonique avec une fraction consistante de champ électrique à l'interface métal/semiconducteur. Finalement, j'ai montrée que la structuration nanométrique du contact métallique réduit les pertes du mode laser. Les résultats sont renforcés par une nouvelle technique de imagerie de champ proche (SNOM) qui a permis de mesurer les SPPs à l'interface métal/or et à l'interface métal/ semiconducteur. Grâce aux mesures SNOM, il a aussi été possible de démontrer sans aucune ambiguïté l'effet de la structuration du métal sur le mode optique
The field of plasmonics is experiencing a rapid development, due to the interest in studying the behavior of light at the nanometer scale. Key ingredients of plasmonics are the surface plasmons (SPs), electromagnetic modes localized at the interface between a metal and a dielectric. SPs rely on the interaction between electromagnetic radiation and conduction electrons at metallic interfaces or in "small" metallic nanostructures. The recent intense activity on plasmonics has been also enabled by state-of-the-art nano fabrication techniques and by high-sensitivity optical characterization techniques. These tools pave the way to promising applications (integration in electronics, chemical and biological detection...), which exploit the SP peculiarity of confining optical fields over sub-wavelength mode volumes. The number of publications concerning plasmonics has been continuously increasing over the last twenty years giving rise to a dynamic research context. Several plasmonic devices have been demonstrated during the last years (modulators, couplers, detectors ...). However their integration is limited by the absence of a compact generator (electrical pumping, small dimensions) and by the huge ohmic losses. Standard techniques for surface plasmon polariton (SPP) generation need an external alignment with a laser source on a prism or on a grating. Our approach is based on semiconductor lasers sources with a transverse magnetic (TM) polarization. Therefore, it is possible to obtain compact semiconductor devices suitable for the on chip integration. During my thesis I studied experimentally and numerically the performance of a diode laser as a function of the metal distance from its active region. The proximity of the gain to the metal is necessary to realize active plasmonic devices. I demonstrated the generation and the amplification of SPP in the telecom range (λ=1.3µm) with compact semiconductor based devices, operating at room temperature and by electrical injection. I realized an elegant architecture with an integrated coupler grating for the SPP generation. The SPPs are directly accessible at the device surface. An ultra-thin cladding device allowed the demonstration of a hybrid plasmonic laser with a consistent fraction of electric field at the metal/semiconductor interface. Finally I demonstrated that the metal patterning allows a loss reduction, decreasing the laser threshold. The results are strengthened by a new near-field technique (NSOM) which permitted to measure the SPPs at the metal/air interface and at the metal/semiconductor interface. Thanks to the NSOM we showed unambiguously the effect of the metal patterning on the optical mode

Le développement de techniques basées sur une seule molécule au cours des dernières décennies a permis de sélectionner, de suivre et de mesurer directement une molécule individuelle. Dans cette thèse, la dynamique structurelle d'un seul émetteur quantique, servi par l'hypéricine, est caractérisée. En utilisant la microscopie à balayage confocale combinée à des modes laser polarisés radialement / azimutalement, une réorientation tridimensionnelle du moment dipolaire de transition d'une seule molécule est observée. Pour quantifier les propriétés temporelles de la tautomérie, la fonction d'autocorrélation des photons est utilisée pour extraire les fluctuations d'intensité. Les résultats montrent l'influence distincte de l'environnement local, comme la matrice PVA et l'effet de deutération. L'environnement photonique local d'une molécule est modifié par la microcavité / nanocavité. Un changement significatif du taux d'émission radiatif et des spectres de fluorescence est discuté. Il nous permet de mesurer le rendement quantique absolu en utilisant une microcavité accordable. Les résultats montrent la possibilité de contrôler la tautomérisation en modifiant l'environnement photonique. Par la suite, la dissociation moléculaire est discutée par des spectres Raman améliorés en surface à molécule unique bénéficiant de l'amélioration en champ proche de la nanocavité. Une stratégie d'optimisation expérimentale rapide vers une amélioration optimale de la fluorescence est décrite
The development of single molecule-based techniques in the last decades has enabled directly selecting, tracking, and measuring an individual molecule. In this thesis, the structural dynamics of a single quantum emitter, served by hypericin, is characterized. By using confocal scanning microscopy combined with radially/azimuthally polarized laser modes, three-dimensional reorientation of the transition dipole moment of a single molecule is observed. To quantify the temporal properties of the tautomerism, photon autocorrelation function is used to extract the intensity fluctuations. The results show the distinct influence of the local environment, such as PVA matrix and deuteration effect. The local photonic environment of a molecule is modified by the microcavity/nanocavity. A significant change of the radiative emission rate and of the fluorescence spectra is discussed. It allows us to measure the absolute quantum yield by using a tunable microcavity. The results show the possibility of controlling tautomerization by changing the photonic environment. Subsequently, molecular dissociation is discussed by single molecule surface-enhanced Raman spectra profiting from near field enhancement of nanocavity. A fast experimental optimization strategy towards optimal fluorescence enhancement is outlined

La plasmonique est un domaine de la nano-photonique qui étudie le comportement de la lumière à des échelles sub-longueurs d'ondes en présence de métaux. Les plasmons polaritons de surface (SPPs) sont des modes électromagnétiques qui se propagent à l'interface entre un diélectrique et un métal. Les SPPs trouvent des applications dans plusieurs domaines comme la communication et le traitement tout-optique du signal, la spectroscopie, la détection en biologie et en chimie. De nombreux composants plasmoniques (modulateurs, coupleurs, détecteurs ...) ont été démontrés ces dernières années. Cependant, leur l'intégration reste conditionnée par l'absence d'un générateur compact (pompage électrique, dimensions réduites) et par les grandes pertes ohmiques. Les techniques standards de génération de SPs nécessitent l'alignement d'un laser externe sur un prisme ou un réseau de diffraction afin d'adapter le vecteur d'onde incident avec celui du plasmon. L'approche que nous avons choisie est basée sur l'utilisation de lasers à semiconducteur ayant une polarisation transverse magnétique (TM) comme source d'excitation et de gain. Notre approche, permet d'obtenir des dispositifs compacts et facilement intégrables sur puce. Pendant ma thèse j'ai étudié expérimentalement et numériquement les performances d'un laser en fonction rapprochement du contact métallique à sa région active. La proximité du gain optique au métal est nécessaire pour la réalisation de dispositifs plasmoniques actifs. J'ai démontré la génération et l'amplification des plasmons de surface dans la bande télécom (λ=1.3µm), avec des dispositifs compacts, à base de semiconducteurs, fonctionnant par injection électrique et à température ambiante. Notamment, j'ai réalisé une architecture élégante, avec coupleur intégré, pour la génération de SPPs accessibles sur le sommet du dispositif. Un dispositif avec gaine superficielle ultrafine a permis de démontrer un mode hybride plasmonique avec une fraction consistante de champ électrique à l'interface métal/semiconducteur. Finalement, j'ai montrée que la structuration nanométrique du contact métallique réduit les pertes du mode laser. Les résultats sont renforcés par une nouvelle technique de imagerie de champ proche (SNOM) qui a permis de mesurer les SPPs à l'interface métal/or et à l'interface métal/ semiconducteur. Grâce aux mesures SNOM, il a aussi été possible de démontrer sans aucune ambiguïté l'effet de la structuration du métal sur le mode optique.

Le but de cette étude était de comprendre le comportement des fractions d'acide fulvique et d'acide humiquedans un système de sols podzolisé, compte tenu des caractéristiques du sol et d'étudier la capacité decomplexation de Cu+ 2 et Al + 3 dans des échantillons de ces sols. Pour cela, les méthodes conventionnellesde pédologie et de Spectroscopie de l'absorbance UV-Visible, Spectroscopie Infrarouge à Transformée deFourier et Fluorescence Quenching avec le traitement CP / PARAFAC ont été utilisés pour atteindre lesobjectifs suivants: (i) déterminer les étapes de transformation du pedo-paysage à l'étude des sols et à larépartition spatiale des sols podzols et du gleysol dans un bassin hydrographique; (ii) caractériser substanceshumiques et comprendre les schémas de distribution des acides fulviens et humiques dans une séquence desol podzols le long des profils et dans les horizons du sols en tenant compte des caractéristiquesmorphologiques, de la texture, du pH, carbone variation totale et souterraine dans les horizons des solsd'une séquence de sols podzols; (iii) étudier la capacité de complexation des substances humiques (acidesfulviques et humiques) des échantillons de sol de podzols dans le bassin du Alto Rio Negro, en identifiantles composants fluorescents des substances humiques, en évaluant les capacités et les constantescomplexantes de ces substances avec les métaux Cu+ 2 et Al+ 3 et la comparaison avec les groupesfonctionnels avec la fluorescence infrarouge à transformée de Fourier (FTIR). Encore les acides fulviquessoient plus aromatiques et condensés, leur caractère est principalement aliphatique et hydrophile etsecondairement aromatique et carboxylique. Les acides humiques sont moins aromatiques et moinscondensés que les acides fulviques et sont caractérisés par des fonctions polysaccharide et éther/alcool,mais secondairement leur caractère est aliphatique et hydrophile. Ces différences sont associées à laprésence des groupes fonctionnels qui répondent aux différences dans la dynamique de complexation desmétaux, dans les complexes acide humique, la complexation des métaux Cu+ 2 et Al+ 3 est associée auxfonctions ether/alcool et CO, polysaccharides pendant la période acide fulvic la corrélation est la plus élevéeavec les groupes fonctionnels -CH, -OH et COOH carboxylique
The purpose of this study is understaning the behavior of fulvic and humic acid fractions in a podzolized soilssystem, taking into account soils characteristics and to investigate the complexing capacity of Cu + 2 and Al + 3.For this purpose, conventional pedology and spectroscopic methods, Uv-Visible absorbance Spectroscopy, FourierTransform Infrared Spectrometry (FTIR) and Quenching Fluorescence using the CP/PARAFAC treatment wereused to achieve the objectives: (i) to determine the stages of transformation of the pedo-landscape through thestudy of soils and the spatial distribution of podzolized soils and gleysol in a drainage basin; (ii) to characterize SHand to understand the distribution patterns of fulvic and humic acids in a podzolized soil sequence along a slopeand in the horizons along the soil profiles taking into account the morphological characteristics, texture, pH, carbontotal and groundwater variation in the horizons of the soils of a sequence of podzols soils; (iii) to study thecomplexing capacity of humic substances (fulvic and humic acids) of podium soils samples in the Alto Rio NegroBasin, by identifying the fluorescent components of humic substances, evaluating capacities and complexingconstants of these substances with the Cu + 2 and Al + 3 metals, and the comparison with the functional groupsobtained with FTIR. Although fulvic acids are more aromatic and condensed their character is predominantlyaliphatic and hydrophilic and secondarily aromatic and carboxylic. Humic acids are less aromatic and lesscondensed than fulvic acids and are characterized by polysaccharide and ether/alcohol functions, but secondarilytheir character is aliphatic and hydrophilic. These differences are related to the presence of the functional groupsthat are responsible for the differences in the complexation dynamics of the metals, in the humic acids complexesCu+ 2 and Al+ 3 are associated with the functional groups ether/alcohol and CO polysaccharides while in the fulvicacids the correlation is greatest with the functional groups -CH, -OH and carboxylic COOH

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2018-03-23T16:50:55Z No. of bitstreams: 1 PGCS15DA035.pdf: 8233837 bytes, checksum: 2bf2d66cbb50bb2bfe83751d86a81f26 (MD5)
Made available in DSpace on 2018-03-23T16:50:55Z (GMT). No. of bitstreams: 1 PGCS15DA035.pdf: 8233837 bytes, checksum: 2bf2d66cbb50bb2bfe83751d86a81f26 (MD5) Previous issue date: 2015-09-25
Capes
The sustainable use of natural resources, with emphasis on soil exploration in conservation base, demand for detailed information on their characteristics and properties, as an indication of its quality, to recommend the correct land use and the best management system. The study aimed to characterization of the nature and properties of the main soils in the southwestern region of the State of Rio Grande do Sul – Brazil, establishing relationships between the physical and chemical attributes with your mineralogical constitution, and researching the causes of the variability of soil classes resultant from the dynamics of the processes considering the lithological variation and modeled of topographic surface. The area studied is situated in the Basin of Santa Maria River in Rosario do Sul County located at latitude 30°15'28" south and longitude 54°54'50" west, with an average altitude of 132 m, humid mesothermal climate, average annual temperature near to 20°C, and a rainfall in the range of 1300 mm. The cartographic base consisted of topographic charts, geological map, satellite imagery, digital elevation models, and support from global positioning system receivers and geographic information system. Geomorphometric variables maps were used for the correlation of the geomorphic surfaces with pedogenesis applying classic models to the compartmentalization of slopes. Topolithosequence were defined as from soil developed with lithology of the Pirambóia, Sanga-of-Cabral and Guará geological formations, choosing to the soil profiles based on types of source material, variations in relief and altitude. It was proceeded a general and morphological description of soil profiles and a horizons sampling collection for chemical, physical, mineralogical and sedimentological analysis, aiming to study the influence of relief forms and the different source materials in the genesis and mineralogical composition of the soil, as well as to understand and describe the main pedogenic processes actants in their evolution. It was observed that soils developed in the same geological formation, in function to lithological variations of the sedimentary package, can have different chemical and mineralogical composition. Furthermore, the differences between the soils also are due to the strong interaction of the source material to the type and intensity of pedogenic processes, influenced by the position they hold in the landscape, conditioned by the flow of water in the soil, as presumably have evolved under the same preterit climatic conditions
O uso sustentável dos recursos naturais, com ênfase na exploração do solo em base conservacionista, demanda por informações pormenorizadas das suas características e propriedades, como um indicativo da sua qualidade, para recomendar o uso correto do solo e o melhor sistema de manejo. O estudo teve como objetivo geral a caracterização da natureza e das propriedades dos principais solos da região sudoeste do RS, estabelecendo relações entre os atributos físicos e químicos com sua constituição mineralógica, e investigando as causas da variabilidade das classes de solos decorrentes da dinâmica dos processos, considerando a variação litológica e o modelado da superfície topográfica. A área de estudo está situada na bacia hidrográfica do Rio Santa Maria na cidade de Rosário do Sul-RS localizada a 30° 15′ 28″S e 54° 54′ 50″W, altitude média de 132 m, clima tipo Cfa, temperatura média anual próxima a 20 °C e índice pluviométrico médio de 1300 mm. A base cartográfica básica consistiu de cartas topográficas, mapa geológico, imagens de satélite, modelos digitais de elevação e apoio de receptores GPS e de SIG’s. Mapas de variáveis geomorfométricas foram utilizados para a correlação das superfícies geomórficas com a pedogênese aplicando-se modelos clássicos de compartimentação de vertentes. Foram definidas topolitossequências a partir de solos desenvolvidos de litologias das formações geológicas Pirambóia, Sangado- Cabral e Guará, escolhendo-se os perfis de solos com base em tipos de materiais de origem, variações no relevo e na altitude. Procedeu-se à descrição geral e morfológica dos perfis e a coleta de amostras de solo deformadas em cada um dos horizontes para análises químicas, físicas, mineralógicas e sedimentológicas, visando estudar a influência das formas de relevo e dos diferentes materiais de origem na gênese e na composição mineralógica dos solos, assim como compreender e descrever os principais processos pedogenéticos atuantes na sua evolução. Observou-se que solos desenvolvidos da mesma formação geológica, em função de variações litológicas do pacote sedimentar, apresentam composição química e mineralógica diferente. Além disso, as diferenças entre os solos também se devem à forte interação do material de origem com o tipo e intensidade dos processos pedogênicos, influenciados pela posição que ocupam na paisagem, condicionados pelos fluxos de água no solo, já que supostamente evoluíram sob as mesmas condições climáticas pretéritas

Cette thèse contribue à la compréhension fondamentale du phénomène de couplage fort de la lumière avec des molécules organiques en mettant en œuvre de nouveaux systèmes et de nouvelles techniques, afin d'étudier les modifications de propriétés de molécules couplées à des résonances photoniques. Nous présentons des techniques de nanofabrication avancées pour la création de grands réseaux de trous sur des métaux et de cavités de Fabry-Pérot (FP) nanofluidiques. Ces systèmes sont ensuite utilisés pour étudier, sous régime de couplage fort, les modifications des propriétés de surface et de volume de molécules organiques en phase solide et liquide. En particulier les transitions électroniques de molécules du colorant cyanine en solution liquide ont été couplées à des modes photoniques résonants de cavités FP nanofluidiques spécialement conçues. Leur couplage fort a conduit à une amélioration du rendement quantique d'émission, mettant en évidence la nature radiative des états polaritoniques
This thesis contributes to the fundamental understanding of the phenomenon of strong coupling of light with organic molecules by implementing new systems and techniques in order to investigate property modifications of molecules coupled with photonic resonances. State-of-the-art nanofabrication techniques for the formation of large hole-array gratings in metals and nanofluidic Fabry-Perot (FP) cavities are presented. These systems were then invested to study, under strong coupling, surface and bulk properties modifications of organic molecules in the solid and liquid phase. In particular, electronic transitions of cyanine dye molecules in liquid solutions were coupled to resonant photonic modes of specially designed nanofluidic FP cavities. Their strong coupling has led to an enhancement of the emission quantum yield, highlighting the radiative nature of the associated polaritonic states

碩士
明志科技大學
材料工程系碩士班
105
Nanohybrids of poly(3,4-ethylenedioxythio phene) (PEDOT) derivitives were prepared by electro-chemical polymerization, including PEDOT-graphene oxide (GO), PEDOT- polystyrene sulfonates, (PSS). Graphene oxide nanosheets were fabricated through modified-Hummer methods by graphite sheets. EDOT monomers with GO nanosheets, or polystyrene sulfonates, (PSS) were mixed homogenously and then electro-chemical polymerized on SUS316L stainless steel substrate. After PEDOT-GO were prepared by electro-chemical polymerization, using polymer poly-diallyldimethylammonium chloride, PDDA grafted on PEDOT-GO thin film surface to fabricate PEDOT-GO-PDDA. The morphology and self-assembly behavior of PEDOT-GO, PEDOT-PSS and PEDOT-GO-PDDA conductive polymer nanohybrids would be evaluated by scanning electron microscopy (SEM), Energy dispersive x-ray spectroscopy (EDX), Raman spectroscopy, Water contact angle, Atomic force microscope (AFM), Zeta potential, X-ray diffractometer (XRD), and X-ray photoelectron spectroscopy (XPS). It shows different chemical structure and binding energy of PEDOT nanohybrides with different addition of GO, PSS or, GO-PDDA by EDS, Raman and XPS analysis. The results prove self-assembly with PEDOT, GO, PSS and GO-PDDA. The results show that the excellent antibacterial capability in the PEDOT-GO-PDDA nanohybrids due to the strong charge interaction between the positive charges of PDDA and the negative charges of bacterial cell walls, measured by zeta potential. In contrast, PEDOT-PSS nanohybrids display the wonderful anti-fouling capability owing to the excluded smooth roughness. The surface characterizations of PEDOT could be modulated by adding graphene oxide-based nanosheets, PSS or grafting PDDA, which might have a potential for bio-interface coating and biomedical device applications, such as antibacterial coating, eluting stents or biosensors.

Availability of appropriate forms of energy is one of the basic needs of the society. The demand for worldwide energy has been increasing, while the conventional energy sources have been depleting fast. As the present main sources are fossil fuels, environmental pollution and its consequences caused by emission from combustion of them has also been a social concern. Thus, exploration of alternate energy sources has become an important area of research and development. Fuel cells are considered to meet a variety of applications. A direct liquid fuel cell (DLFC), which employs a liquid consisting of small organic compound such as methanol as the fuel, is more interesting than the other kinds of fuel cells. In view of this, studies on electrooxidation of organic compounds are important. A suitable catalyst plays an important role on the kinetics of electrooxidation of these compounds. The catalyst needs to exhibit a high activity, economical and stable over a long duration of its use. The catalysts, essentially noble metal-based materials, are usually dispersed on conducting supports such as carbon powder. Conducting polymers are also important for the application of supporting catalysts in view of their high conductivity, ease of preparation and chemical stability. Poly(3,4-ethylenedioxythiophene) (PEDOT) is known to be superior to other conducting polymer such as polyaniline, in the above properties. In the studies described in this thesis, several catalysts in nanodimensions are electrochemically deposited on PEDOT, which is also prepared electrochemically on carbon paper current collectors. Electrooxidation of a few organic compounds is studied and the positive influence of PEDOT is demonstrated. The contents of the thesis are briefly given below. Chapter 1 provides introduction to electrocatalysis with a focus on factors affecting the electrocatalysis, different types of electrocatalysts and supports for catalyst and applications of PEDOT. This chapter also provides aim for various studies performed and presented in the thesis. Experimental details are reported in Chapter 2. Studies on electrooxidation of formic acid on nanoparticles of Pt electrodeposited on PEDOT/C electrode are reported in Chapter 3. The most promising electrocatalyst for formic acid oxidation is Pt. Because Pt based catalysts are expensive, achieving the highest possible catalytic activity from a minimum loading of Pt is a challenging task. Nanoparticles of Pt are electrochemically deposited on PEDOT, which is also electrochemically deposited on carbon paper substrate. A thin layer of PEDOT on carbon paper substrate facilitates the formation of uniform, well-dispersed nanoparticles of Pt, when compared with Pt deposition on a bare carbon paper substrate. TEM studies suggest that the nanoclusters of about 50 nm consist of nanoparticles of about 5 nm in diameter. Dispersion of fine Pt particles on PEDOT is expected to minimize or optimize the loading level of the catalyst. The voltammetry studies suggest that peak current for formic acid oxidation are several times greater on Pt-PEDOT/C electrode than Pt/C electrode. The catalytic activity and CO tolerance of Pt-PEDOT/C electrodes for electrooxidation of formic acid is significantly greater than that of Pt/C electrodes. Results of these studies are described in Chapter 3. Comparison studies for electrooxidation of C1, C2 and C3 alcohols on nanodendritic Pd-PEDOT/C electrode are presented in Chapter 4 and 5. Polyhydric alcohols such as glycol, glycerol have also been investigated as the fuels for DLFCs due to their high boiling points and less toxicity than methanol. The faradic efficiency of polyhydric alcohols is also higher than that of methanol. Thus, electrooxidation of polyhydric alcohols are more interesting than the monohydric alcohols. In this present study, three dimensional tree-like Pd nanodendrites are formed on PEDOT coated carbon paper electrode by a controllable one-step electrodeposition method without the use of any template or additive. A thin layer of PEDOT on the carbon paper substrate facilitates the formation of Pd nanodendrites ranging from 500 nm to 6 μm (Fig. 1). In the absence of PEDOT under-layer, Pd deposition is smooth and non-dendritic. Both Pd–PEDOT/C and Pd/C electrodes are studied for electrooxidation of C1, C2 and C3 aliphatic alcohols in an alkaline electrolyte. Owing to enhanced surface area and surface defects on dendritic Pd, the Pd–PEDOT/C electrode exhibits greater catalytic activity than the Pd/C electrode for oxidation of the three alcohols. Among them, glycerol exhibits a high rate of oxidation. Cyclic voltammetry studies suggest that peak current density increases with an increase in concentrations of alcohols and NaOH in the electrolyte. Cyclic voltammetry studies indicate that Pd–PEDOT/C electrode possesses a high electrochemical stability with greater catalytic activity than Pd/C electrode toward electrooxidation of alcohols. The amperometry and repeated cyclic voltammetry data suggest high stability of nanodendritic Pd in alkaline medium. Pd-PEDOT is expected to be an appropriate Pt-free electrocatalyst in alkaline fuel cells. Among all these alcohols, glycerol is expected to be an appropriate alcohol for application as a fuel in alkaline fuel cells at nanodendritic Pd on PEDOT surface. Fig. 1: SEM micrographs of (a) Pd-PEDOT/C and (b) Pd/C electrodes. Studies on electrooxidation of glycerol on nanoflowers of PdRu deposited on PEDOT/C electrode are reported in Chapter 6. PEDOT supported PdRu catalysts with various Pd:Ru atomic ratios are prepared by one step electrodeposition method. The catalysts are characterised by a several techniques. X-ray diffraction (XRD) studies suggest that the nanoflowers of PdRu catalyst exists on PEDOT surface in an alloy form. X-ray photoelectron spectroscopy (XPS) results indicate a slight modification in electronic structure of Pd by alloying with Ru. SEM micrograph shows the 3D nanoflowers morphology of PdRu alloy on PEDOT/C surface. Ru alloyed with Pd significantly improves the catalytic activity for glycerol oxidation in comparison to Pd-PEDOT/C electrode. However, the activity for glycerol oxidation on pure Ru-PEDOT/C is not observed. Amongst all catalysts, Pd5Ru nanoflowers on PEDOT surface exhibits highest electrocatalytic activity, real surface activity, exchange current density and stability (Fig. 2). Cyclic voltammetry and differential pulse voltammetry (DPV) are performed for analysis of glycerol. A series of voltammograms are recorded at Pd5Ru-PEDOT/C electrode in the concentration range 1-20 mM glycerol in 1 M NaOH supporting electrolyte. Cyclic voltammetry determination of glycerol provides the detection limit of 10 μM. Under optimised conditions, significantly higher sensitivity and lower detection limit were obtained by differential pulse voltammetry (DPV) method in comparison with cyclic voltammetry method. DPV data indicates that Pd5Ru on PEDOT is highly sensitive towards glycerol detection with sensitivity of 99.8 μA μM-1 cm-2 and low detection limit of 0.1μM. Thus, electrochemically deposited nanoflowers Pd5Ru on PEDOT/C are efficient catalysts for direct glycerol oxidation as well as for analysis purpose in alkaline media. The details of electrooxidation and analysis of glycerol are reported in Chapter 6. Current density / mA cm-2 5 Pf 4 (iii)Pd5Ru-PEDOT/C (ii)Pd7Ru-PEDOT/C 3 (iv)Pd4Ru-PEDOT/C (i)Pd-PEDOT/C (v)PdRu-PEDOT/C 2 Pb 1 0 (vi)Ru-PEDOT/C -1 -0.6 -0.4 -0.2 0.0 0.2 Potential / V vs SCE Fig. 2: Cyclic voltammograms of the Pd-PEDOT/C (i), Pd7Ru-PEDOT/C (ii), Pd5Ru-PEDOT/C (iii), Pd4Ru-PEDOT/C (iv), PdRu-PEDOT/C (v) and Ru-PEDOT/C (vi) electrodes in 0.1 M glycerol + 1.0 M NaOH solution at a sweep rate of 5 mV s-1. Current density is calculated on the basis of geometric area (1.4 cm2). In Chapter 7, the effect of Pd decorated Au@Ag core shell on PEDOT surface for glycerol oxidation is investigated. In this study, nanodendrites of Ag are deposited on PEDOT/C surface by potentiostatic method. The nanodendrite of Ag-PEDOT/C electrode is used as a template for the synthesis of Au@Ag core shell via galvanic displacement reaction. The galvanic displacement of Ag with Auleads to the formation of Au@Ag core shell on PEDOT surface with different morphology by controlling the reaction time. The formation of Au@Ag core shell is confirmed by XRD, SEM, EDAX, TEM, HRTEM and XPS studies. XRD study exhibits that the epitaxial growth of Au on Ag surface. EDAX and XPS studies indicate that the atomic ratio of Au to Ag in Au@Ag-PEDOT/C electrode is tuneable by controlling the reaction time. Further to improve the activity of Au@Ag core shell is decorated with Pd by potentiostatic method. Different quantity of Pd deposition is carried out at different charges to optimize the activity of catalyst and it is found that the optimum charge for deposition is 0.25 C. The Ag-PEDOT/C electrode is electrochemically inactive for glycerol oxidation reaction. However, the addition of Au to Ag facilitates the oxidation reaction of glycerol. Electrocatalytic activities of Pd decorated Au@Ag-PEDOT/C electrodes for glycerol oxidation in alkaline medium are characterized by cyclic voltammetry experiments. A high catalytic activity of Pd- (Au@Ag)-PEDOT/C(7.5 h) electrode with lower onset potential and higher current density is observed. In Chapter 8, non-enzymatic oxidation and analysis of glucose is studied on Au naoflowers surface. Glucose is abundant in nature, non-toxic, non-explosive, and non-volatile. The theoretical energy density of DGFCs is 4430 Wh kg-1, which is estimated on the basis of complete oxidation of glucose to CO2 releasing 24 e- per glucose molecule. Therefore, it is attractive and appears to fulfil most of the requirement of a fuel for low temperature fuel cells. Au is potentiostatically deposited on PEDOT as well as carbon paper electrode. A layer of PEDOT on carbon paper substrate facilitates the formation of Au nanoflowers with an enhanced electrochemical active surface area, when compared with sub-micron size Au particles deposited on bare carbon paper electrode. Cyclic voltammetry of glucose is studied by varying the concentration of glucose, NaOH and sweep rate. Cyclic voltammetric peak current density increases with increase in concentrations of glucose and NaOH in the electrolyte. 1H-NMR spectroscopy provides an evidence for oxidation of glucose to gluconic acid and formic acid. Repetitive cyclic voltammetry and amperometry studies suggest that the electrochemical stability of Au-PEDOT/C electrode is significantly higher than that of Au/C electrode. Au nanoflowers on PEDOT surface exhibit a high sensitivity value with low detection limit than that of Au/C electrode. Au-PEDOT/C electrode also exhibits a linear current response in glucose concentration ranging up to 10 μM with sensitivity of 515 μA cm-2 μM-1 (on the basis of geometric area) and a low detection limit of 0.03 μM with signal to noise ratio of 3. It is observed that uric acid and ascorbic acid do not show any significant interference effect on glucose analysis. Thus, electrochemically deposited nanostructured Au on PEDOT/C is an efficient catalyst for the direct glucose oxidation as well as for analysis purpose in alkaline media. Electroanalysis of As(III) is studied on Pd-PEDOT/C electrode in an acidic medium and the details are reported in Chapter 9. Analysis of As(III) is interesting because it is important to remove As(III) in ground water. The Pd nanodendrites are grown on a porous thin film of PEDOT by electrodeposition process. The oxidation of As(0) at low concentration is characterized by an anodic peak at 0.20 V vs. standard calomel electrode (SCE). Cyclic voltammetry studies suggest that Pd-PEDOT/C electrodes exhibit greater electrocatalytic activity towards As(III)/As(0) redox reaction than the Pd/C electrodes. Differential pulse anodic striping voltammetry (DPASV) is performed for analysis of As(III) ion at pH 1.0 (Fig. 3(a)). The PEDOT modified Pd electrode is highly sensitive toward As(III) detection with sensitivity of 1482 μA cm-2 μM-1 (Fig. 3(b)). A wide detection range up to 10 μM and low detection limit of 7 nM (0.52 ppb) are obtained with a pre-deposition time of 120 s under optimum conditions. Interference effect of Cu(II) ions are investigated and it is observed that Cu(II) ions do not interfere. It is found that PEDOT does not have any influence on analysis of As(III). 700 (a) 600 -2 cmA 500 / μ j 400 300 0.0 increasing concentration of As(III) 340 (b) 320 300 -2 280 A cm 260 μ/ 240 j 220 200 Sensitivity : 1482 μA cm-2 μM-1 180 R2= 0.9998 160 0.1 0.2 0.3 0.4 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 Potential / V vs SCE Concentration / μ M Fig. 3: (a) DPASV curves of Pd-PEDOT/C electrode in different concentration of As (III) + 1 M HCl and (b) DPASV calibration plots of Pd-PEDOT/C electrode peak current density versus arsenic concentration (pre-deposition at -0.30 V for 120 s). Current density (j) is calculated on the basis of geometric area (1.4 cm2). Details of the above studies are presented in the thesis. The work presented in the thesis is carried out by the candidate as a part of PhD training programme and most of the results have been published in the literature. A list of publications of the candidate is enclosed. It is hoped that the studies reported here will constitute contribution.

The research work described in this PhD thesis focuses on methods and strategies of employing a polymer substrate for poly(3,4-ethylenedioxythiophene) (PEDOT) synthesis. For the purpose an ethylene vinyl alcohol copolymer (EVAL) was chosen. It offers many potentialities. Serving as mechanical support and/or functionalizable phase, it was differently combined with PEDOT to give conducting composite polymer flms or it was modified to obtain electro-active materials. Aim of the work is to show how, starting from the same base, it is possible to introduce functionalities into supported conducting systems both through the substrate and through the conducting phase, and all the strategies that were adopted.

碩士
國立臺灣科技大學
電子工程系
104
Biosensors need to own the capability to recognize the biomolecules immobilized to the surface as the sensing element. Through biological interactions and matching molecules the specificity and high sensitivity for analyte could be demonstrated in optical, electrical, and magnetic properties with qualitative or quantitative composition analysis. Surface plasmon resonance (SPR), occurring in the interface between the metal film and the dielectric material, demonstrates the characteristics of label-free, immediate inspection, specificity and high sensitivity. There are three coupling approaches in SPR : grating, optical waveguide, and prism coupling. In this thesis, a prism coupling with the telecommunication wavelength modulation, deeper penetration depth and higher sensitivity than traditional optical source, is utilized to demonstrate SPR biosensing. The analytes will include the large molecules MTB DNA (about hundreds of nucleotides) and small molecule miRNA-21 (about 21 to 25 nucleotides) through the SPR wavelength modulation and Fabry-Perot interferometer (FPI) for sensitivity comparison. The Fourier filtering function of Origin software and matlab are also used for data analysis, respectively, for SPR and FPI. The experimental data show that the immobilized probe gets higher sensitivity. A comparison and analyses between SPR and FPI will be further studied. The longer wavelength owns the good sensitivity on the large molecule. Our data successfully demonstrate the significant signal from small molecule biosensing under telecommunication wavelengths.

碩士
國立成功大學
電機工程研究所
82
External optical modulators are essential for long-haul optical fiber transition systems,in lightwave communication, optical signal processing and sensor applications.Particularly ,modulators having a multiple-quantum-well (MQW) structure are expected to be high-performance external modulators due to the large electroabsorption effect (the quantum confined Stark effect) and low chirping effects. In our search,we will demonstrate the low chirping in the (M)QW electroabsorption( EA) modulators and consider the theoretical design optimization of the surface normal incident electroabsorption modulators using the asymmetric Fabry-Perot structure.The maximun change in the absorption coefficient may be at some wavelength under some electric field for each well size and the corresponding magnitude of the chirping parameter is very smaller than 1 for (M)QW.The MQW EA modulator is design to maximize the ratio of absorption Change and the sqrare of field. The optical analogy modulator require low insertion loss, high contrast ratio(CR),small drive power.We presented a systematic approach to design the total performance of normal incident AFPM based on the quantum-confined Stark effect.

Electronic microchips have now firmly plateaued in switching speed. A promising solution for increasing performance on unparallelizable tasks is to switch digital data purely in the optical domain on a photonic chip, as all-optical switching can reach up to terahertz speeds and beyond. Because ultrafast optical effects are weak phenomena, materials with extremely high nonlinear sensitivity must be developed, and very high optical intensities and coupling efficiencies are required to adequately switch data streams of light. In this thesis, unique all-optical platforms, waveguides, fiber-waveguide grating couplers, and an ultrafast optical switch were experimentally demonstrated as proofs-of-concept for the validity of densely integrated all-optical switches. Two horizontal slot waveguiding structures were designed and fabricated from scratch: a multiple horizontal slot waveguide with polycrystalline silicon sandwiching third-order nonlinear slots and a nonlinear cover-cladding with slot-like behavior over a thin crystalline silicon waveguide. Perfectly vertical grating couplers were then designed from a novel genetic algorithm, fabricated, and experimentally tested for both platforms with two promising nonlinear materials: silicon nanocrystals or a supra-molecular assembly, DDMEBT. Vertical grating couplers in the multiple horizontal slot waveguide achieved a theoretical coupling efficiency of 63% and an experimental coupling efficiency of 60%, which is the highest coupling efficiency into nonlinear slot waveguides to date. Vertical grating couplers for the cover-slot waveguide experimentally demonstrated a coupling efficiency of 38% and an extrapolated 1 dB bandwidth of 66 nm, the largest grating-coupled 1 dB bandwidth obtained for slot waveguides to date. A grating coupler was then designed to be included as one of two grating reflectors in a nonlinear resonator switch. Coupled mode theory and vectorial eigenmode propagation simulations were used to optimally design the grating coupler/resonator device, resulting in a record low footprint of 710 μm² per combined switch and fiber coupler device. The third-order nonlinear molecular material, DDMEBT, was, for the first time, successfully spun onto pre-patterned silicon-on-insulator chips with repeatable, defect-free results. Extremely sensitive experimental autocorrelation of the resonator's impulse response yielded output pulse durations as low as 600 femtoseconds. At high power and low pulse repetition rates, the switch's resonances redshifted by 4 nm with 4 dB of switching contrast, revealing an ultrafast Kerr effect which matched previous works. The resonator switch is therefore capable of modulating a single optical carrier frequency at 1 THz and switching an optical data stream at 500 GHz. These are the fastest switching speeds demonstrated by an integrated all-optical switch and validate the proof-of-concept needed for a future of densely integrated all-optical processing.
text

abstract: Obtaining local electrochemical (EC) information is extremely important for understanding basic surface reactions, and for many applications. Scanning electrochemical microscopy (SECM) can obtain local EC information by scanning a microelectrode across the surface. Although powerful, SECM is slow, the scanning microelectrode may perturb reaction and the measured signal decreases with the size of microelectrode. This thesis demonstrates a new imaging technique based on a principle that is completely different from the conventional EC detection technologies. The technique, referred to as plasmonic-based electrochemical imaging (PECI), images local EC current (both faradaic and non-faradaic) without using a scanning microelectrode. Because PECI response is an optical signal originated from surface plasmon resonance (SPR), PECI is fast and non-invasive and its signal is proportional to incident light intensity, thus does not decrease with the area of interest. A complete theory is developed in this thesis work to describe the relationship between EC current and PECI signal. EC current imaging at various fixed potentials and local cyclic voltammetry methods are developed and demonstrated with real samples. Fast imaging rate (up to 100,000 frames per second) with 0.2×3µm spatial resolution and 0.3 pA detection limit have been achieved. Several PECI applications have been developed to demonstrate the unique strengths of the new imaging technology. For example, trace particles in fingerprint is detected by PECI, a capability that cannot be achieved with the conventional EC technologies. Another example is PECI imaging of EC reaction and interfacial impedance of graphene of different thicknesses. In addition, local square wave voltammetry capability is demonstrated and applied to study local catalytic current of platinum nanoparticle microarray. This thesis also describes a related but different research project that develops a new method to measure surface charge densities of SPR sensor chips, and micro- and nano-particles. A third project of this thesis is to develop a method to expand the conventional SPR detection and imaging technology by including a waveguide mode. This innovation creates a sensitive detection of bulk index of refraction, which overcomes the limitation that the conventional SPR can probe only changes near the sensor surface within ~200 nm.
Dissertation/Thesis
Video for Figure 3.2 C to H
Video for Figure 3.5
Video for Figure 5.5
Video for Figure 6.7
Video for Figure 6.11
Ph.D. Electrical Engineering 2011

In recent years, microwave, millimeter-wave, and THz applications such as medical and security imaging, wireless power transfer, and near-field focusing, just to mention but a few, have gained much attention in the area of ICT due to their potentially high social impact. On one hand, the need of highly-directive THz sensors with tunable radiating features in the far-field region has recently boosted the research activity in the design of flexible, low-cost and low-profile devices. On the other hand, it is of paramount importance to focus energy in the near-field region, and thus the generation of limited-diffraction waves in the microwave and millimeter-wave regime is a topic of recent increasing interest. In this context, leaky-wave theory is an elegant and extremely useful formalism which allows for describing in a common fashion guiding and radiating phenomena in both the near field and the far field, spanning frequencies from microwaves to optics passing through THz. In this PhD thesis we aim to exploit the intrinsic versatility of the leakywave approach to design advanced radiating systems for controlling the far-field radiating features at THz frequencies and for focusing electromagnetic radiation in the near field at millimeter waves. Specifically, the use of relatively new materials such as graphene and liquid crystals has been considered for the design of leaky-wave based radiators, achieving very promising results in terms of reconfigurability, efficiency, and radiating capabilities. In this context, an original theoretical analysis has provided new general formulas for the evaluation of the radiating features (e.g., half-power beamwidth, sidelobe level, etc.) of leaky-wave antennas. Indeed, the current formulations are based on several simplifying hypotheses which do not allow for an accurate evaluation of the beamwidth in different situations. In addition to the intriguing reconfigurable capabilities offered by leaky waves in far-field applications, interesting focusing capabilities can be obtained in the near field. In particular, it is shown that leaky waves can profitably be used to generate limited-diffraction Bessel beams by means of narrow-band radiators in the microwave range. Also, the use of higher-order leaky-wave modes allows for achieving almost the same performance in the millimeter-wave range, where previous designs were subjected to severe fabrication issues. Even more interestingly, the limited-diffractive character of Bessel beams can also be used to generate limited-diffraction pulses as superpositions of monochromatic Bessel beams over a considerable fractional bandwidth. In this context, a novel theoretical framework has been developed to understand the practical limitations to efficiently generate limited-diffraction, limited-dispersion pulses, such as X-waves, in the microwave/millimeter-wave range. As a result of this investigation, a class of wideband radiators has been thoroughly analyzed, showing promising capabilities for the generation of both zeroth-order and higher-order Xwaves. The latter may pave the way for the first localized transmission of orbital angular momentum in the microwave range.