[Abstract]: This thesis investigates the feasibility of closing wounds in skin tissue by laser welding as a substitute for suturing. Such a process would provide advantages in some surgical procedures. The investigation revised available theory on the action of lasers on skin tissue as a basis for the experimental program. The results of experiments using rat skin are then reported. In addition a thorough investigation of the normal (uninjured) tensile strength of rat skin was undertaken to provide a base line comparison. Laser systems permit very high-energy radiation of a single wavelength to be focused on a tiny spot, and have found application in many areas of engineering. They are also currently used in many branches of medicine including ophthalmology, gynaecology, dermatology, otolaryngology, and gastroenterology. These medical applications employ argon, YAG, and carbon dioxide type lasers. In many cases, lasers have been found to be more effective than conventional treatment methods with advantages including reduced blood loss, more accurate removal of unwanted tissue, shorter operating times and less postoperative pain and care (Gibson and Kernohan, 1993). Tissue welding using laser energy represents a small but growing area of medical research and is largely focused on anastomosis. This thesis investigates, using a specific experimental program, the feasibility of the bipolar contact Nd:YAG laser to weld cutaneous tissue. No similar published research has been identified in this area. The available literature focuses on non-contact lasers of various types and settings and mainly in the area of anastomosis. The experimental methodology and the specific technique for the bipolar contact laser is developed, tested and evaluated as part of this project. The welding techniques developed in this project overcome the previous difficulties of tissue alignment. The use of the bipolar laser probes substantially improves the ability to align the tissue edges to be joined. The probes give tactile feedback to the user and the pressure effect of the probes may assist with the welding process. The developed technique was no faster or easier than suturing. Viable welds and a useable technique for welding skin on rats were developed and tested. The resultant healing was comparable with published literature and both sutured and welded wounds returned to full strength as compared with the baseline data collected. All wounds had returned to full strength within 91 days. At 75 days there was not significant difference between laser welded and sutured wounds and they had achieved approximately 90 percent of full strength. Time to half strength was approximately 42 days and there was a larger standard deviation for both laser welded and sutured wounds. The most significant increase in strength and therefore healing occurred in the first 42 days. Simhon et al, 2001 states that a tensile strength of 0.6 N plus/minus 0.4 N was sufficient to hold tissue together. By day 7 the strength of the wound (laser welded) was more than twice the strength needed to maintain closure. There may have been sufficient healing for this to occur earlier but there were insufficient animals to allow for testing of this theory. In conclusion this experimental program and investigation has reviewed the available literature on the current use of lasers in medicine and their specific laser-tissue interaction which leads to tissue welding. It has provided a large database of tensile strength measurements collected with a reproducible methodology and reported in a standardised format. The developed technique for laser tissue welding using a bipolar contact Nd:YAG laser has been established and verified. It produces viable welds comparable in strength and healing rates to sutures.

As endotoxinas são responsáveis por importantes reações sistêmicas e locais, podendo comprometer o sucesso do tratamento endodôntico. O hidróxido de cálcio, mesmo com limitações, mostra-se como opção única efetiva entre as soluções irrigadoras e as medicações intracanal na redução das endotoxinas nos túbulos dentinários. O experimento realizado avaliou a eficiência do laser de Nd:YAG frente à uma endotoxina inoculada no canal radicular pela utilização de duas cinemáticas de irradiação. Após um período de incubação, confirmada a passagem da endotoxina inoculada no canal radicular através da dentina e do cemento radicular, a irradiação foi realizada ou com cinemática oscilatória ou com cinemática helicoidal, para posterior leitura e comparação com os grupos controle. Os parâmetros utilizados na irradiação com o laser de Nd:YAG de comprimento de onda de 1064 nm foram: 100mJ, 15 Hz, 1,5 W, diâmetro do núcleo da fibra 320 ?m, fluência do pulso 124 J/cm2, largura do pulso 120 ?s e intervalo de relaxação térmica 30 s. Os dados foram comparados pelo método ANOVA, complementado pelo teste de Tukey. As concentrações de endotoxina nos espécimes dos grupos irradiados (helicoidal e oscilatório) foram similares. Além disso, elas também foram similares às dos espécimes controle negativo e significantemente menores (p=0,0271) que as do controle positivo, que não sofreram irradiação. A irradiação com laser de Nd: YAG, nas condições deste experimento é efetiva na inativação da endotoxina da dentina radicular. / The endotoxins are responsible for important systemic and local reactions that could compromise the endodontic success. The calcium hydroxide even with limitations is the only effective option among the irrigant solutions and intracanal medications on the endotoxin reduction in the dentinal tubules. This experiment evaluated the Nd:YAG laser efficacy regarding the inoculated endotoxin in the root canal with two cinematic irradiation procedures. The irradiation was accomplished using an oscillatory and helicoidal technique after an incubation period where the passage of the inoculated endotoxin inside the root canal through dentin and cement was confirmed. Following this the analysis and comparison among the groups was performed. The Nd:YAG laser (?=1064 nm) irradiation, used parameters were: 100mJ, 15 Hz, 1,5 W, core fiber diameter of 320 ?m, pulse fluency of 124 J/cm2, pulse width of 120 ?s and relaxation time interval of 30 s. The data were statistically compared by ANOVA complemented by the Tukey\'s test (p<=0,005). The endotoxin concentration at the irradiated samples, regardless the techniques applied were similar. Moreover these concentrations were also similar to those of negative controls and significantly smaller than those of positive controls that were not irratiated (p=0,0271). The Nd:YAG laser irradiation under this experiment conditions was effective on the root canal endotoxin inactivation.

As endotoxinas são responsáveis por importantes reações sistêmicas e locais, podendo comprometer o sucesso do tratamento endodôntico. O hidróxido de cálcio, mesmo com limitações, mostra-se como opção única efetiva entre as soluções irrigadoras e as medicações intracanal na redução das endotoxinas nos túbulos dentinários. O experimento realizado avaliou a eficiência do laser de Nd:YAG frente à uma endotoxina inoculada no canal radicular pela utilização de duas cinemáticas de irradiação. Após um período de incubação, confirmada a passagem da endotoxina inoculada no canal radicular através da dentina e do cemento radicular, a irradiação foi realizada ou com cinemática oscilatória ou com cinemática helicoidal, para posterior leitura e comparação com os grupos controle. Os parâmetros utilizados na irradiação com o laser de Nd:YAG de comprimento de onda de 1064 nm foram: 100mJ, 15 Hz, 1,5 W, diâmetro do núcleo da fibra 320 ?m, fluência do pulso 124 J/cm2, largura do pulso 120 ?s e intervalo de relaxação térmica 30 s. Os dados foram comparados pelo método ANOVA, complementado pelo teste de Tukey. As concentrações de endotoxina nos espécimes dos grupos irradiados (helicoidal e oscilatório) foram similares. Além disso, elas também foram similares às dos espécimes controle negativo e significantemente menores (p=0,0271) que as do controle positivo, que não sofreram irradiação. A irradiação com laser de Nd: YAG, nas condições deste experimento é efetiva na inativação da endotoxina da dentina radicular. / The endotoxins are responsible for important systemic and local reactions that could compromise the endodontic success. The calcium hydroxide even with limitations is the only effective option among the irrigant solutions and intracanal medications on the endotoxin reduction in the dentinal tubules. This experiment evaluated the Nd:YAG laser efficacy regarding the inoculated endotoxin in the root canal with two cinematic irradiation procedures. The irradiation was accomplished using an oscillatory and helicoidal technique after an incubation period where the passage of the inoculated endotoxin inside the root canal through dentin and cement was confirmed. Following this the analysis and comparison among the groups was performed. The Nd:YAG laser (?=1064 nm) irradiation, used parameters were: 100mJ, 15 Hz, 1,5 W, core fiber diameter of 320 ?m, pulse fluency of 124 J/cm2, pulse width of 120 ?s and relaxation time interval of 30 s. The data were statistically compared by ANOVA complemented by the Tukey\'s test (p<=0,005). The endotoxin concentration at the irradiated samples, regardless the techniques applied were similar. Moreover these concentrations were also similar to those of negative controls and significantly smaller than those of positive controls that were not irratiated (p=0,0271). The Nd:YAG laser irradiation under this experiment conditions was effective on the root canal endotoxin inactivation.

Unter den bösartigen Tumoren hat das Bronchialkarzinom wohl die dramatischste Entwicklung genommen. Die Inzidenz und Mortalität ist in den letzten 15-20 Jahren bei Männern zwar leicht rückläufig, für Frauen ist jedoch ein entgegen gesetzter Trend zu erkennen. Dies wird in erster Linie auf die veränderten Lebensgewohnheiten, wie steigender Zigarettengenuss unter den Frauen, zurückgeführt. Derzeit gibt es in Deutschland circa 20 Millionen Raucher, von denen etwa 140˙000 jährlich an den Folgen ihres Inhalationsrauchens versterben...

Desde o desenvolvimento do laser pelo norte-americano Theodore Harold Maiman em 1960, inúmeras pesquisas têm sido realizadas com o objetivo de avaliar os efeitos sobre os tecidos dentais, principalmente os relacionados com o aumento de temperatura no interior da câmara pulpar. Esta pesquisa foi desenvolvida com o objetivo de avaliar a variação de temperatura em amostras de esmalte/dentina e dentina, após irradiação com os lasers de Nd:YAG, Er:YAG (Kavo KEY Laser®) e Er:YAG (Kavo KEY Laser® 3), através de análise com termômetro de radiação infravermelha. Foram selecionados 110 terceiros molares isentos de cárie, obtidos através do Banco de Dentes Permanentes Humanos que pertence à Faculdade de Odontologia da Universidade de São Paulo e o projeto de pesquisa foi aprovado pelo Comitê de Ética em Pesquisa (CEP) com o parecer nº44/03. As coroas foram separadas das raízes por meio de um disco de carborundum e todas as coroas foram totalmente incluídas no interior de um tubo de PVC com resina transparente. Os cortes foram realizados no aparelho de corte Labcut, paralelamente ao longo eixo das coroas, no sentido mésio-distal, para obter 750 amostras, com 5 diferentes espessuras (1mm, 2mm, 3mm, 4mm e 5mm), sendo 350 amostras de esmalte/dentina e 400 amostras de dentina. Foi utilizado um termômetro de radiação infravermelha (MINIRAY 100 XL) para medição da variação de temperatura nos dois lados das amostras (frente e atrás), irradiadas em diferentes condições e parâmetros com os lasers de Nd:YAG, Er:YAG (Kavo KEY Laser®) e Er:YAG (Kavo KEY Laser® 3). Os resultados obtidos com todos os lasers e parâmetros demonstraram que a associação refrigeração + espessura das amostras foi estatisticamente significante, quanto à redução da variação de temperatura em comparação à associação ausência de refrigeração + espessura das amostras. Houve uma diminuição da variação da temperatura estatisticamente significante de acordo com as espessuras das amostras irradiadas sem refrigeração, porém não o suficiente para evitar grandes elevações de temperatura. No geral, as variações das temperaturas foram sempre maiores no lado da frente das amostras, independente do uso ou não de refrigeração. Para o laser de Nd:YAG, houve menores variações de temperatura, estatisticamente significante, nos grupos irradiados sem contato e sem a presença da tinta nanquim, independente da presença ou não de refrigeração. / The laser was developed in 1960 by Theodore Harold Maiman and many researches have been carried out with the aim to evaluate the effects on the dental tissues, mainly the effects related to the increase of temperature inside the pulp chamber. This research was developed with the purpose of evaluating the variance in temperature of the enamel/dentin and dentin samples after irradiation with Nd:YAG, Er:YAG (Kavo KEY Laser®) and Er:YAG (Kavo KEY Laser® 3) and an analysis with the infrared radiation thermometer was done. A hundred and ten teeth without dental caries were selected and obtained from the Human Permanent Teeth Bank that belongs to the Odontology College of the University of São Paulo and this research has been approved by the Ethic Research Committee (CEP), as the document n° 44/03 attests. The roots were separated from the crowns with the carburundum disc; all crowns were totally inserted inside a PVC tube with transparent resin and they were cut axially in the Labcut machine, in the mesio-distal way, to obtain 750 samples with five different thickness (1mm, 2mm, 3mm, 4mm e 5mm), 350 enamel/dentin samples and 400 dentin samples. An infrared radiation thermometer (MINIRAY 100XL) was used to measure the variance in temperature in both sides of the samples (front and behind), irradiated in different conditions and parameters with the Nd:YAG, Er:YAG (Kavo KEY Laser®) and Er:YAG (Kavo KEY Laser® 3). The results showed that the association of the refrigeration + samples’ thickness was statistically significant in the reduction of the variance in temperature when compared to the association of the refrigeration absence + samples’ thickness. There was a statistically significant reduction of the variance in temperature according to the the samples’ thickness irradiated without refrigeration, although it wasn’t enough to avoid high temperature increase. In general, the variance in temperature was always higher in the front of samples, whether there was refrigeration or not. For the Nd:YAG laser, there was a lower variance in temperature, statistically significant, in the groups that were irradiated without contact and black ink, whether there was refrigeration or not.

A eficiência dos lasers associado ou não a fluoretos no aumento da resistência ácida e na redução da solubilidade do esmalte dentário tem sido confirmada em diversos estudos. Diversos comprimentos de onda têm sido utilizados com esta finalidade, apresentando bons resultados e representando uma abordagem preventiva simples e não invasiva. Apesar do emprego do laser Nd:YAG ter sua ação preventiva bem conhecida, são escassos os estudos em dentes decíduos, principalmente estudos que estabeleçam parâmetros seguros e eficientes, seja associado ao flúor ou isoladamente. Desta forma, o objetivo do presente estudo foi avaliar a resistência ácida e a permeabilidade do esmalte decíduo. Para tanto, foram selecionados 69 molares decíduos humanos, resultando em 132 corpos-de-prova. As variáveis de resposta quantitativa foram a microdureza longitudinal, profundidade da desmineralização e permeabilidade do esmalte, e as variáveis de resposta qualitativa foram morfologia da superfície, presença de íons flúor e análise dos componentes químicos do esmalte. Foram utilizados 60 fragmentos vestibular/lingual para a análise de resistência ácida e midrodureza (n=10), e após preparados e tratados, estes espécimes foram submetidos ao ciclo de desremineralização para formação de lesão de cárie artificial. Para análise da permeabilidade (48 fragmentos n=8), para a análise de MEV e EDX (18 fragmentos n=3) e para DRX (6 dentes n=1) foi realizado apenas o tratamento da superfície em 6 níveis: C- Controle: sem tratamento; FA: aplicação de gel flúor fosfato acidulado 1,23%; FAL: aplicação de gel flúor fosfato acidulado + Laser Nd:YAG 0,5W/10Hz no modo contato; VF: aplicação de verniz fluoretado 5%; VFL: aplicação de verniz fluoretado 5% + Laser Nd:YAG; L: aplicação do Laser Nd:YAG. Os dados de microdureza (%VM) foram avaliados pelo teste de Kruskal-Wallis e os dados de profundidade da desmineralização (PD) e Permeabilidade (P) foram avaliados pelos testes ANOVA e Fisher&prime;s LSD (&alpha;=5% para todos os testes). Observou-se que os grupos FAL e FA apresentaram a menor variação de dureza em relação aos outros grupos; menor extensão de desmineralização foi observada nos grupos FA, FAL, VF, VFL e L e menor permeabilidade foi verificada nos grupos FA, FAL, VF, VFL e L em relação ao grupo controle (C). Na MEV observouse ausência de fissuras, crateras ou qualquer alteração indesejável na superfície. Na EDX observou-se incorporação de flúor em todos os grupos experimentais (FA, FAL, VF, VFL), exceto no grupo laser (L). Nenhum composto novo foi encontrado na análise de DRX após a associação do flúor com o laser. O laser utilizado isoladamente ou associado ao flúor levou a alterações ultra-estruturais na superfície do esmalte, o que pode ter sido responsável pelo aumento da resistência ácida e redução da permeabilidade, indicando que o laser isoladamente ou associado ao flúor, nas condições desta pesquisa, foi capaz de inibir a desmineralização do esmalte dental decíduo. / The efficiency of lasers associated or not with fluorides, in increasing the acid resistance and decrease of enamel solubility of dental enamel has been confirmed by several studies. Several wavelengths have been used for such purpose, providing good results and representing a simple and non-invasive preventive approach. Although the preventive action of Nd:YAG laser is well known, studies on primary teeth are scarce, especially those that establish safe and efficient parameters, when the laser is either associated with fluoride or used alone. Therefore, the aim of this study was to evaluate the acid resistance and permeability of primary tooth enamel. Sixty-nine human primary molars were used, providing 132 specimens. The quantitative response variables were enamel longitudinal microhardness, demineralization depth and permeability, while the qualitative response variables were surface morphology, presence of fluoride ions and analysis of the chemical components of enamel. Sixty buccal/lingual fragments were used for analysis of acid resistance and microhardness (n=10). After being prepared and treated, thee specimens were subjected to a des-remineralization cycle for artificial caries lesion formation. For analysis of permeability (48 fragments, n=8), SEM and EDX (18 fragments, n=3) and DRX (6 teeth, n=1), only surface treatment was performed in 6 levels: C- Control: no treatment; APF: application of 1.23% acidulated phosphate fluoride gel; APFL: application of 1.23% acidulated phosphate fluoride gel + Nd:YAG laser 0.5W/10Hz in mode contact; FV: application of 5% fluoride varnish; FVL: application of 5%fluoride varnish + Nd:YAG laser; L: application of Nd:YAG laser. Microhardness data (%VM) were analyzed by the Kruskal-Wallis test and demineralization depth (DD) and permeability (P) were analyzed by ANOVA and Fisher&prime;s LSD test (&alpha;=5% for all tests). APFL and APF presented the lowest microhardness variation of all groups; lower extension of demineralization was observed in groups APF, APFL, FV, FVL and L, and lower permeability was observed in groups APF, APFL, FV, FVL and L compared to group C. The SEM analysis revealed absence of fissures, craters or any other undesirable surface alteration. The EDX analysis revealed fluoride incorporation in all experimental groups (APF, APFL, FV, FVL), except for the group L. No new compound was found in the DRX analysis when fluoride was associated with the laser. Laser alone or associated with fluoride produced ultrastructural alterations on enamel surface, which might have caused the increase of acid resistance and decrease of permeability, thus indicating that, under the conditions of this study, the Nd:YAG laser used alone or associated with fluoride was capable of inhibiting the demineralization of primary tooth enamel.

A eficiência dos lasers associado ou não a fluoretos no aumento da resistência ácida e na redução da solubilidade do esmalte dentário tem sido confirmada em diversos estudos. Diversos comprimentos de onda têm sido utilizados com esta finalidade, apresentando bons resultados e representando uma abordagem preventiva simples e não invasiva. Apesar do emprego do laser Nd:YAG ter sua ação preventiva bem conhecida, são escassos os estudos em dentes decíduos, principalmente estudos que estabeleçam parâmetros seguros e eficientes, seja associado ao flúor ou isoladamente. Desta forma, o objetivo do presente estudo foi avaliar a resistência ácida e a permeabilidade do esmalte decíduo. Para tanto, foram selecionados 69 molares decíduos humanos, resultando em 132 corpos-de-prova. As variáveis de resposta quantitativa foram a microdureza longitudinal, profundidade da desmineralização e permeabilidade do esmalte, e as variáveis de resposta qualitativa foram morfologia da superfície, presença de íons flúor e análise dos componentes químicos do esmalte. Foram utilizados 60 fragmentos vestibular/lingual para a análise de resistência ácida e midrodureza (n=10), e após preparados e tratados, estes espécimes foram submetidos ao ciclo de desremineralização para formação de lesão de cárie artificial. Para análise da permeabilidade (48 fragmentos n=8), para a análise de MEV e EDX (18 fragmentos n=3) e para DRX (6 dentes n=1) foi realizado apenas o tratamento da superfície em 6 níveis: C- Controle: sem tratamento; FA: aplicação de gel flúor fosfato acidulado 1,23%; FAL: aplicação de gel flúor fosfato acidulado + Laser Nd:YAG 0,5W/10Hz no modo contato; VF: aplicação de verniz fluoretado 5%; VFL: aplicação de verniz fluoretado 5% + Laser Nd:YAG; L: aplicação do Laser Nd:YAG. Os dados de microdureza (%VM) foram avaliados pelo teste de Kruskal-Wallis e os dados de profundidade da desmineralização (PD) e Permeabilidade (P) foram avaliados pelos testes ANOVA e Fisher&prime;s LSD (&alpha;=5% para todos os testes). Observou-se que os grupos FAL e FA apresentaram a menor variação de dureza em relação aos outros grupos; menor extensão de desmineralização foi observada nos grupos FA, FAL, VF, VFL e L e menor permeabilidade foi verificada nos grupos FA, FAL, VF, VFL e L em relação ao grupo controle (C). Na MEV observouse ausência de fissuras, crateras ou qualquer alteração indesejável na superfície. Na EDX observou-se incorporação de flúor em todos os grupos experimentais (FA, FAL, VF, VFL), exceto no grupo laser (L). Nenhum composto novo foi encontrado na análise de DRX após a associação do flúor com o laser. O laser utilizado isoladamente ou associado ao flúor levou a alterações ultra-estruturais na superfície do esmalte, o que pode ter sido responsável pelo aumento da resistência ácida e redução da permeabilidade, indicando que o laser isoladamente ou associado ao flúor, nas condições desta pesquisa, foi capaz de inibir a desmineralização do esmalte dental decíduo. / The efficiency of lasers associated or not with fluorides, in increasing the acid resistance and decrease of enamel solubility of dental enamel has been confirmed by several studies. Several wavelengths have been used for such purpose, providing good results and representing a simple and non-invasive preventive approach. Although the preventive action of Nd:YAG laser is well known, studies on primary teeth are scarce, especially those that establish safe and efficient parameters, when the laser is either associated with fluoride or used alone. Therefore, the aim of this study was to evaluate the acid resistance and permeability of primary tooth enamel. Sixty-nine human primary molars were used, providing 132 specimens. The quantitative response variables were enamel longitudinal microhardness, demineralization depth and permeability, while the qualitative response variables were surface morphology, presence of fluoride ions and analysis of the chemical components of enamel. Sixty buccal/lingual fragments were used for analysis of acid resistance and microhardness (n=10). After being prepared and treated, thee specimens were subjected to a des-remineralization cycle for artificial caries lesion formation. For analysis of permeability (48 fragments, n=8), SEM and EDX (18 fragments, n=3) and DRX (6 teeth, n=1), only surface treatment was performed in 6 levels: C- Control: no treatment; APF: application of 1.23% acidulated phosphate fluoride gel; APFL: application of 1.23% acidulated phosphate fluoride gel + Nd:YAG laser 0.5W/10Hz in mode contact; FV: application of 5% fluoride varnish; FVL: application of 5%fluoride varnish + Nd:YAG laser; L: application of Nd:YAG laser. Microhardness data (%VM) were analyzed by the Kruskal-Wallis test and demineralization depth (DD) and permeability (P) were analyzed by ANOVA and Fisher&prime;s LSD test (&alpha;=5% for all tests). APFL and APF presented the lowest microhardness variation of all groups; lower extension of demineralization was observed in groups APF, APFL, FV, FVL and L, and lower permeability was observed in groups APF, APFL, FV, FVL and L compared to group C. The SEM analysis revealed absence of fissures, craters or any other undesirable surface alteration. The EDX analysis revealed fluoride incorporation in all experimental groups (APF, APFL, FV, FVL), except for the group L. No new compound was found in the DRX analysis when fluoride was associated with the laser. Laser alone or associated with fluoride produced ultrastructural alterations on enamel surface, which might have caused the increase of acid resistance and decrease of permeability, thus indicating that, under the conditions of this study, the Nd:YAG laser used alone or associated with fluoride was capable of inhibiting the demineralization of primary tooth enamel.

The main components of the vibration-based microgenerator incorporate vibratile structure, magnetic thin film, and coils. In this thesis work, bulk-micromachining technology and laser-micromachining technology were used to fabricate the vibratile structure of the microgenerator. And this is the beginning of the development of the microgenerator. Bulk-micromachining technology was widely used in micro-electromechanical system (MEMS). The most advantage of the technology is that it can be integrated with IC process in the future. And the roughness of the wafer is the key point of the etching process. In addition, 355nm UV Nd:YAG laser was also used to fabricate the vibratile structure. The period of fabricating prototype can be shortened by laser-micromachining. In laser-micromachining system, the dual-prism was used to change the direction of the laser beam by adjusting the initial phase of one of the prisms. When the laser beam moves relatively to workstation, the cutting process can be proceeded. By this system, the cutting linewidth is controllable. This technology has be used to fabricate the microstructure successfully, and the aspect ratio is up to 10, and the feature size is 50&#x00B5;m. Circular spiral spring structure was fabricated successfully, and it is to be the vibratile structure of the microgenerator. Finite element software ANSYS was used to simulate the dynamic characterization of the vibratile structure and the vibration testing experiment was carried out. The result shows that the experimental resonant frequency is very close to the simulative resonant frequency. So this vibratile structure can be used in microgenerator.

Die vorliegende Arbeit zielte auf die Erarbeitung der verfahrens- und legierungstechnischen Grundlagen zur Randschichtbehandlung von TiAl6V4 durch Dispergieren/Legieren mit Diboriden ab. Für die Untersuchungen zum Dispergieren/Legieren wurden sowohl unterschiedliche Lasersysteme (CO2, CO2-Slab, diodengepumpter Nd:YAG, Diodenlaser) als auch der Elektronenstrahl gewählt. Das Konzept für die Vorbehandlung und die Prozessgestaltung wurde entwickelt und erfolgreich getestet. Anhand von Untersuchungen zum Dispergieren/Legieren wurde das Prozessparameterfeld erarbeitet, wobei sich die nachfolgend aufgeführten Einflussgrößen als wesentlich erwiesen: • Pulverkorngröße (Kornfraktion 5 - 125 µm), • Pulvereintragsmenge (Förderparameter, Förderrate, Pulvervor-/-nachlauf, Pastenschichtdicke), • Prozessparameter (Strahlleistung, Defokussierung, Streckenenergie, Ablenkfigur). Zusammenfassend wurde die gute Eignung des Dispergierens/Legierens mittels Hochleistungsstrahlquellen für die Erzeugung boridverstärkter Randschichten an Bauteilen aus TiAl6V4 nachgewiesen.

Our aim was to establish a methodology for laser assisted oxidation of semiconductor and metal surfaces. One advantage of laser oxidation is the fact that radiation is heavily absorbed in a thin surface layer of the sample and the other is its ability for local oxidation. In addition to this, laser beam can be directed into some areas that other processes cannot reach. For these reasons, Nd:YAG pulsed laser working at 1064 nm wavelength is used for the oxidation purposes of Si and Ta films. First, SiO2 layer was obtained for various O2 pressures and laser powers. The thickness, refractive index, structural, dielectric, electrical and optical characteristics of the SiO2 layers have been determined. We have established that there exists an interval of laser power in which the oxidation occurs without surface melting. The oxidation process is controlled by the laser power rather than by the substrate temperature (673 &ndash / 748 K). It was found that better film quality is obtained at higher substrate temperatures and laser power greater than 3.36 J/cm2. Second, rf-sputtered Ta films were oxidized by laser, because Ta2O5 appears to be a good promising candidate to replace SiO2 because of its high dielectric constant, high breakdown voltage and relevant small leakage current values. It was found that the substrate temperature is an important parameter to obtain denser layers with reduced amount of suboxides and the most suitable substrate temperature range is around 350 C to 400 C. &amp / #946 / -orthorhombic crystal structure was obtained when the substrate temperature is 350 &ndash / 400 C for thinner films (up to 20 &ndash / 25 nm) and 300 &ndash / 350 C for thicker films (40 nm). The refractive index values of laser grown thin tantalum oxide films were between ~1.9 and 2.2 being close to those of bulk Ta2O5 (2.0 &ndash / 2.2). Oxide thicknesses in uniform Gaussian&ndash / like shapes were measured as around the twice of those initial Ta films. Effective dielectric constant values reached ~26 when the substrate temperature was increased from 250 C to around 400 C. It was shown that the leakage current density level decreases with increasing substrate temperature. However, the refractive index values of the films were smaller than those of thermally grown films. Porous structure formed during laser oxidation might be the reason for lower refractive indices and can be improved by post&ndash / oxidation annealing.