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MEMS microhotplate platform for chemical sensors
Vančík, Silvester ; Svatoš, Vojtěch (referee) ; Prášek, Jan (advisor)
This master’s thesis deals with design and fabrication of MEMS microhotplate platform for chemical gas sensors. The theoretical part describes MEMS, sensors and processes and technologies needed for fabrication of micro hotplate. The practical part includes simulations, masks and step by step microhotplate fabrication. Fabricated heating membrane was characterized and compared to theoretical values from simulations and to similar devices presented in literature.
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Optimization of thick-film electrochemical sensor's electrode system
Cupal, Miroslav ; Adámek, Martin (referee) ; Prášek, Jan (advisor)
Master’s thesis deals with thick/film sensor’s electrodes optimization. The aim of this work is to determine how the geometric size and shape of the electrodes affect the output current response. Technology and electro-analytical method is described in the theoretical part. The practical part is aimed at thick-films electrodes and sensors optimalization. It is here each optimization TLV electrodes in terms of their impact on the size of the output current response three-electrode electrochemical system using standard electrodes. Similarly, there is a study of the effect size performed on one common electrode free-electrodes sensor. Finally, there are studied various forms of electrode area three-electrode thick-film sensor in terms of their effect on the output current response. Summarized results are described in the final part of the work.
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Optimization of deep reactive ion etching process
Houška, David ; Hrdý, Radim (referee) ; Prášek, Jan (advisor)
This bachelor thesis deals with optimization of cryogenic and Bosch deep reactive ion etching (DRIE) processes. The thesis describes characterization of silicon etching methods, the principle of DRIE and the influence of individual parameters on the resulting etch profile. Based on the analysis of fabricated samples using scanning electron microscopy (SEM), both processes were optimized to create narrow microstructures with diameters ranging from 1 to 16 µm with the highest achieved depth-to-width ratio of 28:1 on a silicon substrate. Furthermore, surface roughness was analyzed using atomic force microscopy (AFM) and the presence of fluorine residues by X-ray photoelectron spectroscopy (XPS) in structures etched by both processes.
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Modification of electrochemical sensors working electrodes for biological substances detection
Weiss, Vojtěch ; Prášek, Jan (referee) ; Majzlíková, Petra (advisor)
The aim of this work is modification of working electrode surface of screen-printed electrochemical sensors using carbon nanotubes. General knowledge about sensors, their categorization, thick-film technology, properties, preparation and utilization of carbon nanotubes and selected electrochemical methods are reported in theoretical part. Three different methods of working electrodes modification with carbon nanotubes are described in the experimental part of the thesis. Furthermore characterization of modified and unmodified electrodes using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy is presented. All results are summarized and discussed in the conclusion of this work.
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Advanced techniques of micromachining
Šalomoun, Vojtěch ; Prášek, Jan (referee) ; Pekárek, Jan (advisor)
Fabrication of micro-electro-mechanical systems (MEMS) requires advanced level of miniaturization, which is not achievable by technology used in microeletronics. Socalled micromachining covers many unique techniques of material processing to get microstructures with possible dimensions below 1 m. This bachelor’s thesis gives a general introduce to micromachining of MEMS. Its focus is on bulk and surface micromachining by wet and dry etching. The practical part contains design of microstructures, their manufacturing process and creation of computer models in CoventorWare suite.
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Difference pulse voltametry for detection of metallothionein
Postránecká, Tereza ; Prášek, Jan (referee) ; Provazník, Ivo (advisor)
Metallothionein (MT) is a protein with a characteristic amino acid composition which thanks to its thiol groups can bind metal ions and be involved in the homeostasis of these ions in organism. The protein has its significance in carcinogenesis, could be a suitable marker for certain types of tumors. MT has many specific functions in organisms. It can be studied using several techniques. In common use electroanalysis is used as method for determining the concentration of MT. More specifically, this work is focused on differential pulse voltammetry using Brdička reaction.
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Tin dioxide based semiconducting gas sensors
Gablech, Imrich ; Pytlíček, Zdeněk (referee) ; Prášek, Jan (advisor)
This project is aimed at semiconductive gas sensors based on tin dioxide. In the first part, gas sensors are divided depending on their principal of functionality. Next part is about functionality of tin dioxide gas sensors and the possibilities of active layer modification. Experimental describes gas sensor from its drawing until construction, testing and characterization. Several microelectronic technologies such as thin-film, thick-film, LTCC, spray-coating or wire-bonding were used for constructing the sensor. In the last part properties of gas sensors and differences in functionality between modified and unmodified gas sensor are summarized.
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Electrode system of thick-film electrochemical sensors optimization
Gablech, Imrich ; Adámek, Martin (referee) ; Prášek, Jan (advisor)
This thesis is about optimization of three-electrode electrochemical sensor for detection of substances in solutions fabricated using standard thick film technology. The theoretical part of this thesis describes the thick film technology, introduction to electrochemistry and electro analytical methods for the detection of substances in solutions. The surface optimization of reference and auxiliary electrode of a three-electrode system is solved in the practical part. In conclusions results of the evaluation and description of the ideal three-electrode system are discussed.
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Electrochemical analytical devices for thick-film sensors measurement
Pytlíček, Zdeněk ; Adámek, Martin (referee) ; Prášek, Jan (advisor)
This work covers an area of electrochemical analytical systems for trace determination of dissolved species in water solutions with use of thick-film sensors. Several types of common electrochemical devices including special ones used for sensors are described and compared in this work. The main goal of this work is to find the suitable electrochemical arrangement with the best, reliable and reproducible current response of the thick film sensors. A new electrochemical arrangement, which should eliminate disadvantages of common devices and unite their advantages with optimization for thick film sensors, is designed here. For better current response of the sensor, suitable improvements and optimization of the new electrochemical arrangement prototype were done in this work. All measurements were done on standard electrochemical couple of potassium ferro-ferricyanide using the cyclic voltammetry. In the end of this work, all the devices are compared in term of their features and presumptions for the best detection limit of the thick film sensors.
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Thick-film sensors for electrochemical detection of species in aqueous solutions
Martynek, Daniel ; Adámek, Martin (referee) ; Prášek, Jan (advisor)
This work deals with the theory, principles and characteristics of electrochemical sensors, thick-film technology and electrodes used in electrochemistry. Methods for the detection of substances matters in solutions are discussed here. Main emphasis is given to differential pulse voltammetry and the influence of the method setup parameters to the measurement results. Experimentally, the work deals with the modification of thick-film working electrode with carbon nanotubes and subsequent activation of the electrode by nitric acid to increase the detection limit and the current response to selected heavy metals ions. Finally, the obtained results are compared with special commercial paste and discussed with the data state in literature.
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