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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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Optimization of electrochemical sensor for detection in microvolume
Gajdoš, Libor ; Pekárek, Jan (referee) ; Prášek, Jan (advisor)
This thesis describes optimization and modification of standard thick-film electrochemical sensor to be able to be used for detection in microvolumes. In the theoretical part, the thick film technology is described. The work is then focused on the wettability of surfaces followed by introduction to electrochemistry and electro-analytical methods. In the experimental part, screen-printing of various types of thick film pastes on ceramic substrates for determination of their wettability and the following modification of the sensors with thick-film paste and with Parylene vaporization can be found, as well as the basic electrochemical measurements in microvolume using the modified sensor. Finally the results are summarized in conclusion.
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Oxygen detection using gas sensor
Jelínek, Tomáš ; Pytlíček, Zdeněk (referee) ; Prášek, Jan (advisor)
In this master´s thesis various types of gas sensors, their characteristics, principle, active layer and structure are described. This work is focused on semiconductor gas sensors. In the experimental part gas test station is used to measure the main characteristic of commercial sensor Figaro TGS 822 and own SnO2 gas sensors and reaction to oxygen. Both sensors and measurement results are compared with each other.
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Thick-film sensors for heavy metals detection
Polický, Jiří ; Adámek, Martin (referee) ; Prášek, Jan (advisor)
This work covers an area of heavy metals detection using thick-film sensors. Fabrication of screen-printed thick-film sensor and electrochemical analytical methods for detection of chemical elements in aqueous solutions are described in this work. Several commercial and own prepared thick-film pastes were used for carbon based working electrodes. The electrochemical properties of the pastes were examined by cadmium ions detection in potassium chloride solution using differential pulse voltammetry. The best results were achieved on the electrode made of direct grown carbon nanotubes on the electrode layer NM22. A detection limit 20×10-6 mol l-1.was reached with this working electrode material during oxidation process.
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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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The system for measurement of little flow
Karásek, Eduard ; Prášek, Jan (referee) ; Adámek, Martin (advisor)
Diploma thesis solves how to create system for measurement of little liquid flows. The basic types of liquid flowmeter, which are possible used for measurement of little liquid flows, are described in the introduction part of thesis. The limit for little flow is often determined as flow 100 mg.min-1 and low. Second part of this thesis describes the ways of capillary production and practical experiments with them. Thesis is focused to thick film technology and LTCC technology. Next part of this work is solution of simple measuring unit for measurement of little flows less than 100 mg.min 1, which is controlled by microprocessor ATmega16. The measuring unit can be worked separately or can be connected to PC. The next possibility of flowmeter optimisation is summarized in end of thesis.
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Carbon nanotubes utilization for fabrication of thick-film sensors electrodes
Polický, Jiří ; Adámek, Martin (referee) ; Prášek, Jan (advisor)
This work covers an area of heavy metals detection by miniaturized thick film sensors. Working electrode of these sensors was fabricated using thick film paste that was prepared as a nanocomposition of carbon nanotubes powder, suitable vehicle and a thinner. The response of fabricated electrodes to cadmium and lead ions was measured using differential pulse voltammetry in an acetate buffer solution using a three electrode sytem. The results were compared with the carbon electrode made from special commercial thick film polymer paste. Finally the possibility of working electrode surface activation with nitric acid and heavy metals on real biological sample detection is described here.
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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 sensor array
Šulc, Jakub ; Prášek, Jan (referee) ; Adámek, Martin (advisor)
In recent years (Of late year)microelectronic technology significantly affected in the field of sensor technology, especially in the field of electrochemical sensors. This thesis deals with design and construction of thick-film voltammetric sensors array. The reason for proposal of voltammetric sensors array is to increase of speed, increase the accuracy and extension possibilities measurement compared with common systems.By reason of increase of sensitivity of these sensors it is efficient use the potentiostat chip for measurement output signal. Created sensors must fulfill the specified parameters and also requirements of thick-film technology. Next step is design the basic blocks of electronic circuit used to evaluate the measured values.
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Impedance methods in toxic substances detection
Feber, Václav ; Prášek, Jan (referee) ; Hubálek, Jaromír (advisor)
The aim of this work was focused on the determination of pesticides concentration in water solution. Pesticides are indissoluble in aqueous solutions and impedance or voltametric/amperometric response of the pure water and water with pesticides is identical. Therefore was necessary find a way how rapidly, effectively and economically measure the pesticides concentration. One way is measurement of conductivity with electrochemical microsensors after enzymatic reaction.
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