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Characterization of working electrodes of electrochemical sensors modified by carbon nanomaterials
Vančík, Silvester ; Majzlíková, Petra (referee) ; Prášek, Jan (advisor)
This bachelor thesis deals with electrochemical detection of substances using screen-printed electrochemical sensors. The theoretical part describes thick film technology, sensors, selected parts of electrochemistry, voltammetry and carbon nanomaterials. The practical part includes the modification of standard screen-printed electrode by oxygen plasma and spray-coated carbon nanomaterials and its experimental comparison using cyclic voltammetry and scanning electron microscopy. The measured values were processed and evaluated numerically and graphically. In comparison with standard working electrode, the current responses of both electrodes were improved significantly.
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Gas sensors, their construction and testing
Pytlíček, Zdeněk ; Boušek, Jaroslav (referee) ; Prášek, Jan (advisor)
This work deals with branch of gas sensors, their construction and methodology of testing. The general aim is a design and implementation of a station for simple testing of conduction gas sensors. The whole station is conceived as virtual measuring apparatus, operated by PC in LabView environment. The station enables mixing of any two gases at concentration demanded and measuring of the basic conduction characteristics of the thick-film and thin-film gas sensors. The central communication interface and modular conception enable easy expansion of possibilities of the whole apparatus in the future. It is possible to measure up to eight gas sensors split into two TO-12 packages simultaneously.
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Electrochemical biosensor for glucose detection
Matula, Tomáš ; Majzlíková, Petra (referee) ; Prášek, Jan (advisor)
This thesis pays attention to electrochemical sensors for the detection of glucose. The theoretical part deals with the technology of thick film, their application and firing. It is further described electrochemistry, electrodes used in electrochemistry and analytical methods based on electrochemical reaction. End of theoretical part deals with electrochemical biosensors for detection glucose using special electrodes based on enzyme glucose oxidase. In the experimental part is processed amperometric measure for detection glucose using screenprinted sensors S10 and S8 with immobilized enzyme glucose oxidase. Next was studied effect of plasma, dissolved potassium chloride, storage, ascorbic acid and the reproducibility of the sensors.
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Gas Microsensors Based on Self-Organized 3D Metal-Oxide Nanofilms
Pytlíček, Zdeněk ; Husák, Miroslav (referee) ; Kolařík, Vladimír (referee) ; Prášek, Jan (advisor)
This dissertation concerns the development, fabrication and integration in a gas sensing microdevice of a novel 3-dimensional (3D) nanostructured metal-oxide semiconducting film that effectively merges the benefits of inorganic nanomaterials with the simplicity offered by non-lithographic electrochemistry-based preparation techniques. The film is synthesized via the porous-anodic-alumina-assisted anodizing of an Al/Nb metal bilayer sputter-deposited on a SiO2/Si substrate and is basically composed of a 200 nm thick NbO2 layer holding an array of upright-standing spatially separated Nb2O5 nanocolumns, being 50 nm wide, up to 900 nm long and of 8109 cm2 population density. The nanocolumns work as semiconducting nano-channels, whose resistivity is greatly impacted by the surface and interface reactions. Either Pt or Au patterned electrodes are prepared on the top of the nanocolumn array using an innovative sensor design realized by means of microfabrication technology or via a direct original point electrodeposition technique, followed by selective dissolution of the alumina overlayer. For gas-sensing tests the film is mounted on a standard TO-8 package using the wire-bonding technique. Electrical characterization of the 3D niobium-oxide nanofilm reveals asymmetric electron transport properties due to a Schottky barrier that forms at the Au/Nb2O5 or Pt/Nb2O5 interface. Effects of the active film morphology, structure and composition on the electrical and gas-sensing performance focusing on sensitivity, selectivity, detection limits and response/recovery rates are explored in experimental detection of hydrogen gas and ammonia. The fast and intensive response to H2 confirms the potential of the 3D niobium-oxide nanofilm as highly appropriate active layer for sensing application. A computer-aided microfluidics simulation of gas diffusion in the 3D nanofilm predicts a possibility to substantially improve the gas-sensing performance through the formation of a perforated top electrode, optimizing the film morphology, altering the crystal structure and by introducing certain innovations in the electrode design. Preliminary experiments show that a 3D nanofilm synthesized from an alternative Al/W metal bilayer is another promising candidate for advanced sensor applications. The techniques and materials employed in this work are advantageous for developing technically simple, cost-effective and environmentally friendly solutions for practical micro- and nanodevices, where the well-defined nano-channels for charge carriers and surface reactions may bring unprecedented benefits.
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Cutting module implementation into the Aurel ALS 300 trimming laser software
Štrympl, Martin ; Kosina, Petr (referee) ; Prášek, Jan (advisor)
is project deals with the implementation of a cutting module for trimming laser system Aurel ALS 300. The conversion programme designed to convert the Gerber format into the input laser format was written in C language. Integration of the conversion programme to the control programme of PROTOMAT laser was implemented in Visual Basic 6. The first part of the semester work describes the basic thick-film technology and the use of thick-film resistors trimming. An analysis of allowed input formats PostScript, DWG and Gerber follows. The Gerber format, which is analyzed in detail here, was selected as the input format for conversion. Input data of the laser Aurel ALS 300 are also analyzed. Finally the way of creation of the converstion programme and its use described here too.
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Influence of liposomal platinum cytostatics on cancer cells – voltammetric study
Laníková, Petra ; Prášek, Jan (referee) ; Hynek, David (advisor)
Aim of this thesis is voltammetric study influence of liposomal platinum cytostatics on cancer cells. One of the goals is summarize available informations about influence of cisplatine on cancer cells, its encapsulation into liposome and affection of this cytostatic cisplatin encapsulated in liposome on cancer cell lines. In literary recherche is detail description of these issues. Than is there specification of voltammetric methods, which serve to electrochemical detection of cisplatin. Based on literary recherche was chosen the best method for detection and subsequently the method was optimalized and than was applied to measuring itself.
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Spray-coated working electrodes of electrochemical sensors
Lechner, Filip ; Majzlíková, Petra (referee) ; Prášek, Jan (advisor)
This thesis is about the selection of the better type of thick film working electrode for the detection of substances in aqueous solutions, modified by spray coated carbon nanotubes. The theoretical part of this thesis describes the technology of thick film, properties and production of carbon nanotubes, introduction to electrochemistry and electroanalytical methods for the detection of substances in aqueous solutions. The practical part is aimed to realization of the working electrodes by thick film technology and their modification by spray-coated layer consist of carbon nanotubes. Electrodes are characterized using voltammetric methods, electrochemical impedance spectroscopy and electron microscopy. In conclusions is selected the most suitable type of working electrodes for reproducible electrochemical analysis.
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Graphene as the active layer for gas detection
Zach, Pavel ; Prášek, Jan (referee) ; Gablech, Imrich (advisor)
The aim of this bachelor thesis is to sum up theoretical knowledge concerning gas detection by sensor with a graphene active layer. It is focused on principles and construction of selected sensors. Furthermore, this work describes values characterizing the measurement results. Both crystallographic and electrical properties of graphene are discussed as well. This thesis explains the methods of production of graphene and its derivatives and also gives a look into selected characterization methods for the study of graphene. Furthermore, this work describes the phenomena behind the sensor's ability to detect gas. At the end of this study, the results of gas measurements (NO2, NH3, H2 etc.) by a graphene transistor are interpreted.
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Nanopatterned alumina-based materials for electrochemical sensors and biosensors
Kynclová, Hana ; Hynek, David (referee) ; Trnková, Libuše (referee) ; Prášek, Jan (advisor)
The doctoral thesis is focused on basic research and development of nanostructured surfaces prepared using anodic alumina material. Various types of gold nanostructured surfaces and nanoporous aluminum membranes for electrochemical sensors and biosensors were prepared using the anodic oxidation method. Nanostructured surfaces were prepared by electrochemical anodization of aluminum material to form hexagonally arranged nanopores. Gold was then deposited into the nanoporous masks by electrochemical reduction from potassium dicyanoaurate solution using a pulse deposition method. The prepared nanostructured gold surfaces were electrochemically characterized by electrochemical impedance spectroscopy and voltammetry. Temperature stability and the effect of annealing on their electrochemical behavior at atmospheric pressure as well as in the vacuum were investigated. Then, gold nanostructures of various dimensions were prepared and the influence of their shape and dimensions on the electrochemical behavior was studied. Nanostructured surfaces were also modified with 11–mercaptoundecanoic acid, and the effect of this modification on the electrochemical results was studied. In the last part of the work, nanoporous aluminum membranes were prepared, and their permeability was studied.
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Diagnostics of genom conditioned diseases with the use of micro- and nanoparticles
Mondeková, Věra ; Prášek, Jan (referee) ; Provazník, Ivo (advisor)
The bachelor´s thesis discusses possibilities of viral genome´s detection through use of biosensors, more specifically through use of magnetic particles. The introductory part consists of brief characteristic of viruses, mentioned as originator of genom conditioned diseases, followed by chapters related to selected methods of nucleic acid´s extraction and analysis. The main part is dedicated to magnetic particles. The practical part of thesis deals with possibility of use of biosensors in specific viral pathogen´s detection, selection of biocompatible molecules suitable for magnetic particle modification and description of specific DNA sequence isolation procedure through use of magnetic particles.
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