Inhalation of respirable coal mine dust (RCMD) can lead to chronic lung diseases, including coal worker’s pneumoconiosis (CWP) and more severe forms such as progressive massive fibrosis. After the Federal Coal Mine Health and Safety Act was passed in 1969, limits on exposure to respirable dust were set, and the prevalence of CWP abruptly decreased. However, during the last two decades, a resurgence of the disease has been reported. Many authors have argued that the increasing numbers might be related to mining practices, including the extraction of thinner coal seams, characteristics of the mineral deposits, and more powerful cutting machines. Dust particles in coal mines are usually associated with three main sources: Coal particles are produced when the coal seam is being actively extracted. Silica and silicates are generated while cutting the rock strata surrounding the coal or during roof-bolting activities. Finally, rock dust application is the primary source of highly pure carbonates. Timely information about dust composition would allow the identification of potential dust sources and pursue efforts to control dust exposure efficiently. However, this information needs to be provided promptly since dust levels are dynamically changing through the shift. Currently, monitoring technologies such as the continuous personal dust monitor allow real-time measurements, but they are limited to total dust concentration and provide no information about dust composition. More recently, the National Institute for Occupational Safety and Health (NIOSH) has been developing an end-of-shift silica monitor. Still, technologies that offer information on dust composition in a semi-continuous manner are needed. In this work, a new monitoring concept is explored that has the potential to provide near real time data on RCMD constituents. The possible use of a portable optical microscopy (OM) combined with image processing techniques is explored as the basis for a novel RCDM monitoring device. The use of OM in different fields and the rapid development of automated image analysis reveals a clear opportunity that has not been yet exploited for mine dust monitoring applications. This thesis research consisted of two primary studies. The first was an analysis of lab-generated respirable dust samples containing the main mineralogical classes in RCMD (i.e., coal, silica, kaolinite as a proxy for silicate minerals, and a real rock dust product). Samples were imaged using a polarizing microscope and analyzed using an image processing routine to identify and classify particles based on optical characteristics. Specifically, birefringence of particles was exploited to separate coal particles form mineral particles. This is an exciting result since even such a basic fractionation of RCMD would be valuable to track changing conditions at the mine production face and enable rapid decision making. The second study was conducted to explore subclassification of the mineral fraction. A model was built to explore multiple particle features, including particle size, shape, color, texture, and optical properties. However, a simple stepwise method that uses birefringence for separating coal particles first and then classifying silica particles proved most effective. One particular challenge to the silica classification was determined to be the particle loading density. Future work to further enhance the output of the algorithm and next steps were depicted. This thesis research demonstrated that OM and image processing can be used to separate mineral and coal fractions. Subclassification of silica and other minerals using optical properties such as birefringence of particles alone was successful, but showed less accuracy. A robust sampling method that accounts for particle loading density and a more complex model with additional differentiating features might enhance the results. This approach should be considered as a potential candidate for the development of new RCMD monitoring technologies. This tool could enable better tracking of dust conditions and thus better decision-making regarding ventilation, dust controls, and operator position to reduce exposure hazards. / M.S. / Inhalation of fine particles in underground coal environments can lead to chronic lung diseases, such as coal worker’s pneumoconiosis or progressive massive fibrosis (PMF), which is the most severe form of disease. During the last two decades, the rates of reported cases of PMF in underground coal miners have more than doubled. Many authors have suggested different reasons to explain this trend, including the extraction of thinner coal deposits, mining techniques, changes in mineral content, and the use of high-powered cutting equipment. However, detailed information of specific dust constituents and monitoring the variability of dust concentrations during work shifts are needed to determine possible dust sources and comprehend the more recent changing disease patterns. A dust-monitoring system that provides accurate and timely data on specific respirable coal mine dust (RCMD) constituents would enable the deployment of effective control strategies to mitigate exposure to respirable hazards. Optical microscopy (OM) has been used for a long time to analyze and identify dust particles. More recent advances in portable microscopy have allowed the microscope analysis to be implemented in the field. On the other hand, automated image processing techniques are rapidly progressing and powerful imaging hardware has become a reality in handy small devices. OM and image processing technologies offer a path for near real-time applications that have not been explored for RCMD monitoring yet. In this work, a novel monitoring concept is explored using OM and image processing to classify RCMD particles. Images from dust samples captured with a polarizing microscope were used to build a classification model based on optical properties. The method herein described showed outstanding accuracy for separating coal and mineral fractions. Additionally, the Identification of silica particles in the mineral fraction was investigated and has proved more challenging. A particular finding suggests that particle loading density in the images plays an important role in classification accuracy.

No / Noncontact scanning near-field optical microscope (SNOM) systems can be used to optically resolve samples in atmospheric conditions at theoretical resolutions comparable to those of transmission electron microscope and atomic force microscope systems. SNOM systems are also increasingly used to image biological samples. In this study we custom built a SNOM system with the aim of further demonstrating the potential applications of near-field optical examination of biological material. In this study we were able to image both fixed whole-cell samples in air and liquid environments and live whole-cell samples in liquids. The images acquired were of a relatively low resolution, but this work has shown that SNOM systems can be used to monitor the dynamics of living cells at subnanometric resolutions in the z axis and for fluorescent imaging of whole cells in a liquid medium.

Yes / Plasma technology has been widely used to increase the surface energy of the polymer surfaces for many industrial applications; in particular to increase in wettability. The present work was carried out to investigate how surface modification using plasma treatment modifies the surface energy of micro-injection moulded microneedles and its influence on drug delivery. Microneedles of polyether ether ketone and polycarbonate and have been manufactured using micro-injection moulding and samples from each production batch have been subsequently subjected to a range of plasma treatment. These samples were coated with bovine serum albumin to study the protein adsorption on these treated polymer surfaces. Sample surfaces structures, before and after treatment, were studied using atomic force microscope and surface energies have been obtained using contact angle measurement and calculated using the Owens-Wendt theory. Adsorption performance of bovine serum albumin and release kinetics for each sample set was assessed using a Franz diffusion cell. Results indicate that plasma treatment significantly increases the surface energy and roughness of the microneedles resulting in better adsorption and release of BSA.

A ausência de adaptação passiva em prótese sobre implantes pode sobrecarregar implantes, componentes protéticos e tecido ósseo, levando à perda óssea marginal e até da osseointegração. A soldagem é utilizada com frequência para melhorar o assentamento de estruturas metálicas de próteses em geral e de próteses sobre implantes. Além disso, a precisão no assentamento da peça protética pode estar relacionada com os cuidados na técnica de confecção da mesma. Assim, o objetivo deste trabalho foi avaliar, por meio de microscopia óptica e confocal a laser, a adaptação marginal de barras metálicas tipo protocolo de Branemark, de ligas de niquel-cromo (NiCr) em monobloco e soldadas, confeccionadas a partir de enceramento convencional. Para isso, foi confeccionado um modelo mestre, simulando quatro implantes sobre o qual foram adaptados transferentes e análogos que serviram para transferir a posição dos implantes para o modelo de gesso. Os enceramentos obtidos pelo método convencional foram fundidos em monobloco e em partes separadas (seccionados), sendo os últimos, posteriormente soldados utilizando as técnicas convencional a maçarico e TIG (Tungsten Inert Gas). As leituras da adaptação da barra em cada implante foram feitas nas peças em monobloco (n=5) e nas peças seccionadas (n=10), antes e após as diferentes técnicas de soldagem. Pelo método de medição de microscopia óptica, foram realizadas as medições em duas regiões pré-determinadas ( Vestibular e Lingual ), com três repetições, totalizando 6 leituras por implante. Já no método de microscopia Confocal a laser, foi realizada somente na Vestibular. Para comparar os dados obtidos quanto ao desajuste marginal entre componente protético/implante, considerando-se as peças em monobloco, as peças soldadas, as técnicas de soldagem (maçarico e TIG), os métodos de medição e a posição dos implantes, foram realizados testes estatísticos, onde para cada uma das análises realizadas foi determinada a aplicação do Teste de Normalidade (Shapiro-Wilk ou Kolmogorov-Smirnov (alfa = 5%)) para determinação da distribuição da amostra. Para a amostra com distribuição normal foi determinada a utilização do teste paramétrico, Análise de Variância, enquanto que a amostra com distribuição não normal, determinou-se a utilização do teste não paramétrico de Kruskal Wallis. Os resultados encontrados foram estatisticamente significantes para comparação método e técnica, sugerindo que as peças em monobloco apresentaram maior desadaptação que as peças soldadas, e que as peças soldadas pela técnica convencional não apresentaram diferença estatística, em relação as soldadas pela técnica TIG. Em relação a comparação dos métodos de medição, houve diferença estaticamente significante, onde a microscopia Confocal a laser obteve os maiores valores de desadaptação. A interação técnica e método não houve diferenças estatísticas. Na comparação de diferentes secções e soldada, para os 2 métodos de medição, em relação ao fator Secção, não houve diferença significante onde 3 secções apresentam os menores resultados e as soldadas tiveram igualdade em relação a 1 secção. Pelo fator Técnica houve diferença estatisticamente significante, onde a técnica convencional obteve as maiores médias. A interação Secção e Técnica, não teve efeito significante. A adaptação marginal da peça em relação a posição do implante na arcada, não houve diferença estatística, para ambos os métodos. Houve diferença apenas no fator Técnica, pela microscopia óptica, onde a Monobloco teve os maiores resultados e a Solda Convencional e TIG, tiveram igualdade nos resultados. A investigação de sistemas de confecção de estruturas da prótese e de técnicas de soldagem é importante na busca pela produção de próteses sobre dente ou sobre implante com precisão no ajuste marginal que possa ser comprovado visual e numericamente utilizando-se recursos tecnológicos que assegurem a utilização clínica das peças protéticas. / The lack of passive adaptation in prosthesis over implant can overload implants, prosthetics components and bone tissue, leading to marginal bone loss and even osseointegration. Weldering is used frequently to improve the settlement of metal structures of prosthetic in general and prosthesis over implants. In addition, the settlement precision of the workpiece may be related to the care in the technique of manufacturing the same. The objective of this study was to evaluate, through optical and confocal Laser microscopy, the marginal adaptation of metal bars Branemark protocol type alloy nickel-chromium (NiCr) monoblock and welded, made from conventional waxing .For this, a master model was made to simulate four implants were adapted over which transferents and analogs that served to transfer the position of the implants for the cast model. Waxing obtained by the conventional method were cast in one-piece and separate parts (sectioned), the latter being subsequently welded using the conventional techniques blowtorch and TIG (Tungsten Inert Gas).The bar adjustment of readings in each implant were made in monoblock pieces (n = 5) and the severed pieces (n = 10) before and after different weldering techniques. By optical microscopy measurement method, measurements were performed in two predetermined regions (Vestibular and lingual), with three replications, totaling 6 readings per implant. However in the methodology of Confocal laser microscope, was done only on Vestibular. To compare the data obtained on the misfit between prosthetic/implant component, considering the pieces monoblock, the welded parts, the weldering techniques (torch and TIG), measurement methods and the position of the implants, tests were performed statistical where for each of the analyzes determined the application of Normality Test (Shapiro-Wilk test and Kolmogorov-Smirnov test (alpha = 5%)) to determine the distribution of the sample. For the sample of normal distribution was determined using the parametric test, analysis of variance, while the sample with non-normal distribution was determined using the nonparametric Kruskal-Wallis test. The results found were statistically significant for method and technique comparison, suggesting that the monoblock parts showed higher misfit than welded parts, and the parts welded by conventional technique showed no statistical difference in relation welded by TIG technique. Regarding the comparison of measurement methods, there was no statistically significant difference, where the Laser Confocal microscopy obtained the greatest misfit. The technical interaction and method there were no statistical differences. When comparing different sections and welded to the two measurement methods, in relation to Section factor, there was no significant difference where 3 sections have the lowest results and welded had equality with 1 section. The technical factor was no statistically significant difference, the conventional technique had the highest averages. The interaction and Technical Section had no significant effect. The marginal adaptation of the play in relation to the implant in the arch position, there was no statistical difference for both methods. There was a difference only in the technical factor, by optical microscopy, where Monoblock had the greatest results and Conventional Welding and TIG, had equality in results. The research of making the prosthesis structures systems and weldering techniques is important in the search for production of prosthetic tooth or on precisely implant the marginal adjustment that can be verified visually and numerically using technological resources to ensure clinical use of prosthetic pieces.

A ausência de adaptação passiva em prótese sobre implantes pode sobrecarregar implantes, componentes protéticos e tecido ósseo, levando à perda óssea marginal e até da osseointegração. A soldagem é utilizada com frequência para melhorar o assentamento de estruturas metálicas de próteses em geral e de próteses sobre implantes. Além disso, a precisão no assentamento da peça protética pode estar relacionada com os cuidados na técnica de confecção da mesma. Assim, o objetivo deste trabalho foi avaliar, por meio de microscopia óptica e confocal a laser, a adaptação marginal de barras metálicas tipo protocolo de Branemark, de ligas de niquel-cromo (NiCr) em monobloco e soldadas, confeccionadas a partir de enceramento convencional. Para isso, foi confeccionado um modelo mestre, simulando quatro implantes sobre o qual foram adaptados transferentes e análogos que serviram para transferir a posição dos implantes para o modelo de gesso. Os enceramentos obtidos pelo método convencional foram fundidos em monobloco e em partes separadas (seccionados), sendo os últimos, posteriormente soldados utilizando as técnicas convencional a maçarico e TIG (Tungsten Inert Gas). As leituras da adaptação da barra em cada implante foram feitas nas peças em monobloco (n=5) e nas peças seccionadas (n=10), antes e após as diferentes técnicas de soldagem. Pelo método de medição de microscopia óptica, foram realizadas as medições em duas regiões pré-determinadas ( Vestibular e Lingual ), com três repetições, totalizando 6 leituras por implante. Já no método de microscopia Confocal a laser, foi realizada somente na Vestibular. Para comparar os dados obtidos quanto ao desajuste marginal entre componente protético/implante, considerando-se as peças em monobloco, as peças soldadas, as técnicas de soldagem (maçarico e TIG), os métodos de medição e a posição dos implantes, foram realizados testes estatísticos, onde para cada uma das análises realizadas foi determinada a aplicação do Teste de Normalidade (Shapiro-Wilk ou Kolmogorov-Smirnov (alfa = 5%)) para determinação da distribuição da amostra. Para a amostra com distribuição normal foi determinada a utilização do teste paramétrico, Análise de Variância, enquanto que a amostra com distribuição não normal, determinou-se a utilização do teste não paramétrico de Kruskal Wallis. Os resultados encontrados foram estatisticamente significantes para comparação método e técnica, sugerindo que as peças em monobloco apresentaram maior desadaptação que as peças soldadas, e que as peças soldadas pela técnica convencional não apresentaram diferença estatística, em relação as soldadas pela técnica TIG. Em relação a comparação dos métodos de medição, houve diferença estaticamente significante, onde a microscopia Confocal a laser obteve os maiores valores de desadaptação. A interação técnica e método não houve diferenças estatísticas. Na comparação de diferentes secções e soldada, para os 2 métodos de medição, em relação ao fator Secção, não houve diferença significante onde 3 secções apresentam os menores resultados e as soldadas tiveram igualdade em relação a 1 secção. Pelo fator Técnica houve diferença estatisticamente significante, onde a técnica convencional obteve as maiores médias. A interação Secção e Técnica, não teve efeito significante. A adaptação marginal da peça em relação a posição do implante na arcada, não houve diferença estatística, para ambos os métodos. Houve diferença apenas no fator Técnica, pela microscopia óptica, onde a Monobloco teve os maiores resultados e a Solda Convencional e TIG, tiveram igualdade nos resultados. A investigação de sistemas de confecção de estruturas da prótese e de técnicas de soldagem é importante na busca pela produção de próteses sobre dente ou sobre implante com precisão no ajuste marginal que possa ser comprovado visual e numericamente utilizando-se recursos tecnológicos que assegurem a utilização clínica das peças protéticas. / The lack of passive adaptation in prosthesis over implant can overload implants, prosthetics components and bone tissue, leading to marginal bone loss and even osseointegration. Weldering is used frequently to improve the settlement of metal structures of prosthetic in general and prosthesis over implants. In addition, the settlement precision of the workpiece may be related to the care in the technique of manufacturing the same. The objective of this study was to evaluate, through optical and confocal Laser microscopy, the marginal adaptation of metal bars Branemark protocol type alloy nickel-chromium (NiCr) monoblock and welded, made from conventional waxing .For this, a master model was made to simulate four implants were adapted over which transferents and analogs that served to transfer the position of the implants for the cast model. Waxing obtained by the conventional method were cast in one-piece and separate parts (sectioned), the latter being subsequently welded using the conventional techniques blowtorch and TIG (Tungsten Inert Gas).The bar adjustment of readings in each implant were made in monoblock pieces (n = 5) and the severed pieces (n = 10) before and after different weldering techniques. By optical microscopy measurement method, measurements were performed in two predetermined regions (Vestibular and lingual), with three replications, totaling 6 readings per implant. However in the methodology of Confocal laser microscope, was done only on Vestibular. To compare the data obtained on the misfit between prosthetic/implant component, considering the pieces monoblock, the welded parts, the weldering techniques (torch and TIG), measurement methods and the position of the implants, tests were performed statistical where for each of the analyzes determined the application of Normality Test (Shapiro-Wilk test and Kolmogorov-Smirnov test (alpha = 5%)) to determine the distribution of the sample. For the sample of normal distribution was determined using the parametric test, analysis of variance, while the sample with non-normal distribution was determined using the nonparametric Kruskal-Wallis test. The results found were statistically significant for method and technique comparison, suggesting that the monoblock parts showed higher misfit than welded parts, and the parts welded by conventional technique showed no statistical difference in relation welded by TIG technique. Regarding the comparison of measurement methods, there was no statistically significant difference, where the Laser Confocal microscopy obtained the greatest misfit. The technical interaction and method there were no statistical differences. When comparing different sections and welded to the two measurement methods, in relation to Section factor, there was no significant difference where 3 sections have the lowest results and welded had equality with 1 section. The technical factor was no statistically significant difference, the conventional technique had the highest averages. The interaction and Technical Section had no significant effect. The marginal adaptation of the play in relation to the implant in the arch position, there was no statistical difference for both methods. There was a difference only in the technical factor, by optical microscopy, where Monoblock had the greatest results and Conventional Welding and TIG, had equality in results. The research of making the prosthesis structures systems and weldering techniques is important in the search for production of prosthetic tooth or on precisely implant the marginal adjustment that can be verified visually and numerically using technological resources to ensure clinical use of prosthetic pieces.

Ce travail de thèse est dédié à l'étude de quelques phénomènes de surface impliquant des processus d'interactions à l'échelle nanométrique. Les expériences sont réalisées à l'aide un microscope à force atomique (AFM) à grande sensibilité, utilisant un interféromètre différentiel permettant d'atteindre une résolution de E-28m2/Hz dans la mesure de la déflexion de la sonde de force. Combiné à une approche originale d'analyse du bruit thermique, cet outil permet une caractérisation quantitative de la réponse mécanique de systèmes de taille micrométrique et nanométrique, tel que des micro-leviers ou des nanotubes de carbone, sur une large plage de fréquence.La première partie de mon travail porte sur la viscoélasticité du revêtement de leviers AFM. Mis en évidence par un bruit thermique en 1/f à basse fréquence, ce phénomène est présent lorsque le micro-levier est recouvert d'une couche nanométrique de métal (or, aluminium, platine, etc.) À l'aide du théorème fluctuation-dissipation et des relations de Kramers-Kronig, nous mesurons la dépendance en fréquence de cet amortissement viscoélastique dans une large gamme de fréquence (1Hz à 20 kHz. Nous observons une dépendance en fréquence générique sous la forme d'une loi de puissance pour ce processus de dissipation, avec un petit coefficient négatif qui dépend du matériau considéré. L'amplitude de cet effet est linéaire avec l'épaisseur du revêtement, démontrant ainsi que le mécanisme de dissipation est une propriété du volume de la couche métallique plutôt que de ses interfaces.La deuxième partie de mon travail se concentre sur de nouvelles expériences sur l'interaction de nanotubes de carbone avec des surfaces planes. En utilisant notre AFM, nous réalisons une mesure directe de la réponse mécanique (raideur, dissipation) du contact entre le nanotube et la surface, dans une géométrie de pelage (le nanotube est partiellement adsorbé sur la surface). Les résultats de ce protocole sont en accord avec la mesure de la raideur dynamique déduite de l'analyse du bruit thermique, démontrant une dépendance inattendue en loi de puissance de la raideur du contact en fonction de la fréquence. Nous proposons quelques origines physiques possibles pour expliquer ce comportement, tel qu'une couche de carbone amorphe autour du nanotube. / In this thesis, we test some interactions involving surfaces processes at the nanometer scale. The experiments are conducted with a highly sensitive interferometric Atomic Force Microscope (AFM), achieving a resolution down to E-28m2/Hz for the measurement of deflection. Combined with original thermal noise analysis, this tool allows quantitative characterization of the mechanical response of micrometer and nanometer sized systems, such as microcantilevers or carbon nanotubes, on a large frequency range.The first part of my work deals with the viscoelasticity of the coating of AFM cantilevers. Evidenced by a 1/f thermal noise at low frequency, this phenomenon is present when a cantilever is coated with a metallic layer (gold, aluminium, platinium, etc...). Using the fluctuation dissipation theorem and Kramers Kronig relations, we extract the frequency dependance of this viscoelastic damping on a wide range of frequency (1Hz to 20kHz). We find a generic power law dependence in frequency for this dissipation process, with a small negative coefficient that depends on materials. The amplitude of this phenomenon is shown to be linear in the coating thickness, demonstrating that the damping mechanism takes its roots in the bulk of the metallic layer.The second part of my work tackles new experiments on the interaction of carbon nanotubes with flat surfaces. Using our AFM, we perform a true mechanical response measurement of the rigidity and dissipation of the contact between the nanotube and the surface, in a peeling configuration (the nanotube is partially absorbed to the substrate). The results of this protocol are in line with the dynamic stiffness deduced from the thermal noise analysis, showing an unexpected power law dependence in frequency for the contact stiffness. We suggest some possible physical origins to explain this behavior, such as an amorphous carbon layer around the nanotube.

La construction de circuits électroniques de section atomique est l'un des grands défis de la nanoélectronique ultime. Pour construire un circuit électronique atomique, il faut d'abord mettre au point l'instrument de construction puis choisir la surface-support stabilisant ce circuit. Sur la surface d'Au(111) préparée en ultra vide, nous avons mis en œuvre et stabilisé le tout premier LT-UHV-4 STM. Ce microscope à 4 pointes STM balayant en même temps et indépendamment une même surface a été construit pour le CEMES par la société ScientaOmicron. Sur l'Au(111), nous avons reproduit tous les résultats expérimentaux obtenus sur les meilleurs LT-UHV-STM à une pointe comme la précision en rugosité de 2 pm, les caractéristiques I-V sans moyenne sur un seul atome pendant plusieurs dizaines de minutes et la manipulation atomique suivant les modes de tiré, glissé et poussé d'un seul atome d'or sur la surface. Une fois cette optimisation réalisée, nous avons appliqué notre LT-UHV-4 STM à la surface de Si(100):H, support probable des futurs circuits atomiques électroniques. Le choix de ce support est discuté en détail avant l'enregistrement et l'analyse des images STM. Les échantillons utilisés proviennent, soit du procédé semi-industriel pleine-plaque de silicium mis au point au CEA-LETI, soit de leur préparation in situ se déroulant directement dans la chambre de préparation du LT-UHV-4 STM. Nous avons pris soin de bien interpréter les images STM de la surface Si(100):H afin par exemple de déterminer la position de chaque atome d'hydrogène. La lithographie atomique par STM a été exploitée, par pointe, sur le LT-UHV-4 STM, en mode manipulation verticale atome-par-atome et mode balayage plus rapide mais rendant l'écriture atomique moins précise. Nous avons construit nos propres fils atomiques puis des plots de contact atomiques, petits carrés de Si(100)H dépassivés de quelques nm de côté. Les courants de fuite à 2 pointes et à l'échelle atomique ont ainsi pu être mesurés sur la surface de Si(100):H entre deux de ces plots. Pour préparer les contacts atomiques à au moins 2 pointes sur un fil atomique ou sur des plots de contact nanométrique, nous avons étudié en détail les différents types de contact pointe STM-liaison pendante unique montrant la difficulté d'atteindre un quantum de conductance au contact, de par un effet de courbure de bandes. Il est donc difficile sans une mesure de force complémentaire de déterminer en partant du contact tunnel les différentes étapes du contact mécanique, électronique au contact chimique. Nos résultats ouvrent la voie à la caractérisation des circuits électroniques construits atome par atome et à l'échelle atomique à la surface d'un semi-conducteur. / The construction of electronic circuits of atomic section is one of the great challenges of the ultimate nanoelectronics. To build an atomic electronic circuit, it is necessary first to develop the dedicated instrument to build up and then to choose the support surface stabilizing this circuit. On the Au(111) surface prepared in ultra-vacuum, we implemented and stabilized the very first LT-UHV-4 STM. This STM 4-probes microscopes scanning at the same time and independently the same surface was built for the CEMES by the ScientaOmicron company. On Au(111), we reproduced all the experimental results obtained on the best LT-UHV-STM with one probe such as the precision in roughness of 2 pm, the IV characteristics recording without any average on a single atom for several tens of minutes and the atomic manipulation following the pulling, sliding and pushing modes of a single gold atom on the surface. Once this optimization was carried out, we applied our LT-UHV-4 STM to the surface of Si(100):H, probable support of the future electronic atomic circuits. The choice of this medium is discussed in detail before recording and analysis of the STM images. The samples used come either from the semi-industrial full-wafer silicon process developed at CEA-LETI or from their in-situ preparation, which takes place directly in the preparation chamber of the LT-UHV-4 STM. We have taken care to interpret the STM images of the surface Si(100):H in order to locate the position of each hydrogen atom. The atomic lithography by STM has been exploited, by using one tip from our LT-UHV-4 STM, by atom-per-atom vertical mode and faster scanning mode. The last makes atomic writing less accurate. We have constructed our own atomic wires and then atomic contact pads, small squares of Si(100)H defeated by a few nm sides. The leakage currents with 2 probes at the atomic scale have thus been able to be measured on the surface of Si(100):H between two of these pads. To prepare the atomic contacts at least 2 probes on an atomic wire or on nanometric contact pads, we studied in detail the different types of contact points STM-single dangling bond showing the difficulty of reaching a quantum of conductance at contact, due to a possible bands bending. It is therefore difficult without a complementary force measurement to determine, starting from the tunnel contact, the different steps of the mechanical, electronic contact at the chemical contact. Our results open the way to the characterization of electronic circuits constructed atom-by-atom and at atomic scale on the surface of a semiconductor.

Le microscope à force atomique (AFM) est un outil privilégié pour sonder la matière à l'échelle nanométrique. Dans cette thèse, nous l'utilisons comme instrument de mesure de force. Nous montrons que la mesure des fluctuations thermiques des ressorts permet de déterminer précisément leur raideur à condition d'utiliser un modèle qui prend en compte la forme des modes et la méthode de détection. A l'aide de nouvelle méthodes d'analyse des courbes de rétraction, nous étudions la conformation de polymères et de copolymères adsorbés, ainsi que l'interaction spécifique entre un complexe du nickel (Ni-NTA) et l'acide aminé histidine. Nous mettons en évidence des comportements inattendus en présence de liens multiples et nous en proposons une interprétation basée sur un équilibre entre formations et ruptures des liaisons. Nous présentons des premiers résultats expérimentaux concernant la transition conformationnelle de la polylysine sous étirement.

This master thesis deals with possibilities of using nanoparticles of different metals as markers for immune labeling in the low voltage electron microscope. It presents the low voltage elektron microscope LVEM 5 (Delong Instruments, Brno, Czech Republic) as a new type of a table-size microscope specially designed for observation of specimens composed from elements with low atomic numbers.

L'étude des fluctuations dans les milieux confinés constitue un domaine de recherche très récent, que ce soit du point de vue théorique ou expérimental. Afin d'analyser le rôle du confinement sur les propriétés des fluctuations de densité dans un mélange binaire, nous avons développé un système de mesure d'une grande sensibilité, où l'intensité des fluctuations et leur longueur de corrélation peuvent être amplifiées. L'idée consiste à travailler proche du point critique d'une transition de phase de démixion d'un mélange binaire. En effet, la longueur de corrélation augmente exponentiellement lorsqu'on s'approche de la température Tc du point critique de démixion.Nous avons développé un montage permettant de confiner le mélange entre un échantillon plan et une sphère colloïdale attachée à l'extrémité d'un levier de Microscope à Force Atomique (AFM). D'après les prédictions de Fisher et De Gennes, un effet intéressant émerge lorsque la longueur de corrélation est comparable avec la taille du confinement: les deux surfaces vont soit s'attirer, soit se repousser suivant les préférences d'adsorption des composants du mélange pour chacune des surfaces. On nomme cet effet l'effet Casimir critique, en référence à la force de Casimir électrodynamique qui résulte du confinement des fluctuations quantiques du champ électromagnétique.Durant cette thèse, nous avons mesuré la force de Casimir électrodynamique avec le système de mesure que nous avons développé, d'abord dans une atmosphère d'azote puis dans l'éthanol. Ces mesures prouvent que notre appareil de mesure est assez sensible pour mesurer des forces très faibles de l'ordre de la dizaine de pN. Les forces mesurées sont comparées à la théorie de Lifshitz, où les effets de conductivité finie des surfaces sont considérées. / The study of density fluctuations inside confined liquid systems has received the attention of recent theoretical and experimental papers. In order to analyze the role of confinement on the statistical properties of fluctuations, we developed a highly sensitive system where the intensity of fluctuations, as well as their spatial correlation length can be simply tuned. The idea will be to enhance the role of fluctuations working close to the critical temperature Tc of a second order phase transition in a binary mixture. Indeed, the correlation length dramatically increases when one approaches the critical demixion point.The confinement is obtained by using a sphere-plane geometry with a colloidal particle attached to the cantilever of an Atomic Force Microscope (AFM). When the correlation length is comparable with the distance of confinement, Fisher and De Gennes predicted the existence of an interesting effect: the two surfaces will be submitted to either an attracting or a repelling force, depending on boundary conditions. This effect is called the critical Casimir force in reference to the quantum Casimir force resulting from the confinement of quantum fluctuations of the electromagnetic field.During this thesis, we measured the quantum Casimir force between the sphere and the plate, first in a nitrogen atmosphere and then in ethanol, showing that the developed instrument is sufficiently sensible to measure very weak force, of the same order of magnitude or even weaker than the critical Casimir force. Measurements are compared to Lifshitz theory, taking into account the finite conductivity of surfaces.