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Energy harvester working on epidermis
Fecko, Peter ; Prášek, Jan (referee) ; Hubálek, Jaromír (advisor)
This work focuses on theoretical designing of a device harvesting energy from perspiration on human epidermis. Chemical composition of the human sweat was researched from articles and publications dealing with this problem. Following their results the approximate concentration values of ionic salts (and other substances) were established, also an adequate combination of electrode metals were examined, theoretically making the energy harvester functional. Next proposal described a draft and production procedures towards manufacturing the harvester. Evaluation of voltage stability and dependency was made on changes in ionic concentrations of the electrolyte, representing human sweat. Finally, the harvester cell was produced according to proposed manufacturing methods and the cell performance was measured.
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THIN LUBRICANT FILMS STUDY USING SPECTROSCOPIC REFLECTOMETRY
Čudek, Vladimír ; Dzimko, Marián (referee) ; Navrátil, Karel (referee) ; Dobeš, Petr (referee) ; Křupka, Ivan (advisor)
ectroscopic reflectometry is measurement technique that enables the study of the thickness and refractive index of thin layers. This thesis deals with its use for the study of lubrication films within EHD contact and verifies a new approach suggested in recent publications. It is focused on the development of an optical arrangement and mathematical model for the lubrication film thickness measurement within the entire EHD contact. This technique brings the possibility to study the pressure distribution within the contact area through the evaluation of changes in lubricant refractive index.
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Thin Film Electrodes for Electrochromic Devices
Macalík, Michal ; Kadlec, Jaromír (referee) ; Nováková,, Sabina (referee) ; Sedlaříková, Marie (advisor)
The work deals with the deposition of layers for electrochromic device with different methods. Transparent electrically conductive layer of SnO2 was deposited by pyrolytic decomposition of peroxostannate solution. Hydrogen peroxide in starting solution contributes to the oxidation process of growth layers and to increase the electrical conductivity. Active electrochromic layer of WO3 was electrolytic deposited from the peroxotungstic acid solution. Optimal deposition time and the optimal annealing temperature of deposited layers were found. Passive electrochromic layer of V2O5 was deposited using dip-coating method from peroxovanadate solution. A contribution of solution diluted with distilled water was investigated. Found results were used to construct complete electrochromic device with polymer gel electrolyte.
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Photocatalytic activity of hybrid titanium dioxide layers treated by plasma
Koukolová, Anna ; Králová, Marcela (referee) ; Veselý, Michal (advisor)
The bachelor thesis deals with photocatalytic activity of thin layer of titanium dioxide deposited onto PET flexible foil treated by plasma. Photocatalytic activity is measured by two different methods, degradation of dye Acid Orange 7 and benzoic acid. Possible model compounds for evaluation of photocatalytic activity as well as deposition techniques for preparing thin layers of photocatalyst were discuss in the theoretical part. Changes of photocatalytic activity were found insignificant with plasma treatment. Evaluation used Acid Orange 7 is suitable. Unlike method with benzoic acid was discovered inappropriate for measuring of photocatalytic activity for photocatalyst deposited onto PET foil.
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Optimization of production of thin films of metallic materials
Čejka, Marek ; Kadlec, Michal (referee) ; Šubarda, Jiří (advisor)
The present thesis deals with optimization of the formation of thin layers of metallic materials. In the theoretical part was elaborated overview of the implementation of the formation of thin- film structures, particularly using vacuum techniques. Chemical and physical vapor deposition. They were described methods of pretreatment of thin layers. The findings were discussed methods of controlling the pre-treated surface, quality control and mutual adhesion of coating layers. In the experimental part of the pre-treatment methods were selected and applied to selected substrates. Pretreatments were evaluated using a control surface by wetting angles and by atomic force microscopy. Then, the metal structure formed of copper on the pretreated substrates. Implementation by means of magnetron sputtering. Adhesion layers was checked by testing the surface lattice method. The quality was observed by scanning electron microscopy. The results were used to design the technological process of making metal layers.
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Gas sensor based on carbon nanoparticles
Morávek, Petr ; Pytlíček, Zdeněk (referee) ; Prášek, Jan (advisor)
This thesis deals with characterization of gas sensors based on carbon nanomaterials. In the theoretical chapter, the basic terms connected with the gas detection field, properties of different carbon nanoparticles and methods of their preparation are described. Practical experiments include the evaluation of samples` responses to ammonia, influence of annealing on their response and comparison of pure samples and their modifications.
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Diagnostics of thin film barrier properties
Horák, Jakub ; Mazánková, Věra (referee) ; Přikryl, Radek (advisor)
This thesis is focused on characterization of the SiOx thin layers properties prepared by plasma enhanced chemical vapour deposition (PECVD). The layers were characterized with regard to its future possible use for the protection of the museum archives against the corrosion. Liquid hexamethyldisiloxane was used as a precursor. Polypropylene foils and silica wafers were used as substrates for thin film preparation. Metal sheets were chosen for corrosion tests. Methods such as permeation rate measurement (oxygen transmission rate - OTR), Fourier transformation infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ellipsometry and simple corrosion tests of steel sheets coated and uncoated by SiOx thin layer were used for the layer properties characterization.
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Use of finite element method for stress evaluation in layers for optical applications
Tesařová, Anežka ; Ohlídal, Miloslav (referee) ; Burša, Jiří (advisor)
This thesis is concerned with the mechanical stress generated in thin layers applied on a substrate. The application takes place at high temperatures and due to different coefficients of thermal expansion of materials, the sample is deformed, and thereby the stress is generated. The first part of the thesis includes the derivation of the Stoney formula for uniaxial and biaxial stress in a layer. Besides, analytical calculations of the normal stress in the layer for the simplified link model, and shear stress on the layer interface were evaluated. The main part of the work consists of solving the problem using FEM modeling. Because the actual temperature behavior during the application was not known, a fictitious temperature load was used as an input. For the samples, the coefficients of thermal expansion of the layer were then searched so that the thermal load resulting deflection corresponds to the experimental data. Three types of models were created, namely the link body model, the axisymmetric model, and the solid model. The axisymmetric model was used for the calculation of samples forming circular isolines during deformation and a volume model for samples forming elliptical isolines. The result of the FEM calculations was the normal stress in the applied layers, for which corresponding relationships were created using regression analysis.
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Barier Coatings based on Polyparaxylylene for the Space Research Applications
Horák, Jakub ; Zahoranová, Anna (referee) ; Mráček, Aleš (referee) ; Krčma, František (advisor)
Titan, a moon of the planet Saturn, is interesting to many researchers for its thick atmosphere, which, like its surface, is composed mainly of nitrogen (95%) and methane (5%) with various hydrocarbons, and thanks to the conditions that prevail on Titan, it is considered to be a model of Earth in the time before the origin of life. In order to be able to monitor the processes that take place on various space bodies, it is necessary to successfully transfer a space probe to them and thoroughly protect the electronics, which is affected by many adverse effects during takeoff, flight and landing, like thermal fluctuations, various radiation or the atmosphere of the space body to which the electronics may be exposed if the integrity of the probe shell is compromised (for example, in the case of landing modules). Parylene layers are already used in space research, and the aim of this work is a deeper understanding of the changes of their mechanical, chemical and physical properties after their exposure to the simulated atmosphere of Titan and UV radiation. Two thickness sets of parylene layers (2 and 6 µm) were prepared, which were subsequently exposed to the influence of a simulated atmosphere with a methane content of 1, 3 and 5% – at laboratory and reduced temperatures (cooling with liquid nitrogen). In each set, the samples were always duplicated, thanks to which we obtained two sets of samples – the first was affected only by the conditions used in the simulation of atmospheric events on Titan (reaction products and the used discharge) and the second set, which was additionally degraded using UV radiation (possible influence of photons). The effect of such treatments was characterized using FTIR and other analytical methods. It turns out that even when exposed to the conditions of the simulated atmosphere, photooxidation occurs for most of the samples exposed to the mixture with the highest methane content. For some samples, this led to a reduction of a subsequent effect of applied UV radiation, which is probably the result of the parylene layer cross-linking. AFM confirmed that the reactions taking place on the layers during the simulation of the atmosphere increase their roughness, and that after exposure to UV radiation, the layers exposed to Titan's atmosphere at laboratory and reduced temperatures exhibit strong surface degradation. This was also confirmed during nanoindentation, where the layers without the influence of secondary UV radiation did not show an increase in hardness or elastic modulus, while after UV irradiation the values were almost doubled, and their uncertainties also increased significantly. The strong degradation effect of the applied UV radiation was observed by SEM as well – these samples were almost impossible to measure due to the strong charging and visible in-situ deformation by the used electron beam. The work also included the synthesis of silver and copper nanoparticles for their later targeted incorporation into parylene layers. Nanoparticles were prepared by using electrical discharge in liquids. While the silver nanoparticles were metallic and spherical in shape, a nanowhiskers structure and significant agglomeration were observed for the copper-based particles; their surface was not metallic but formed of oxides/hydroxides. The direct application of nanoparticles into the parylene layers could not be implemented, yet.
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Vliv teploty na plazmonické vlastnosti nanočástic
VOBRUBA, Jan
Nanoparticle-based thin films find the utilization in a wide range of applications, based on the unique properties of these nano-objects. If the metal nanoparticle is illuminated by the light with the correct wavelength, collective oscillations of electrons can be excited in the nanoparticle, which leads either to an enormous increase of electrical intensity near the nanoparticle and to significant optical absorption at a given wavelength. This phenomenon of localized surface plasmon resonance (LSPR) strongly depends on the material, shape, and amount of nanoparticles, but also on the optical properties of the surrounding environment. Nanoparticle surfaces can thus be used for the preparation of LSPR sensors or substrates for surface-enhanced Raman spectroscopy. In this work, silver nanoparticle films were prepared by magnetron sputtering, where a very small amount of material was deposited on the glass substrate, which resulted in the formation of nano-islands. The influence of deposition conditions on the optical properties of the resulting layers was studied. It is shown that both the depth of the LSPR peak and its position can be changed by variation of the deposition time and the heating temperature.
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