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Návrh elektrochemických senzorů s integrovaným potenciostatickým systémem
Uhlár, Martin ; Novotný, Marek (oponent) ; Adámek, Martin (vedoucí práce)
Výzkum využitelnosti elektrochemických senzorů v kombinaci s aplikačně definovanými elektronickými obvody je v současnosti velmi rychle se rozvíjející oblastí senzoriky. Snaha o vytvoření parametrově a vlastnostmi jedinečných zařízení je stále běžnější praxí v oblasti návrhu a realizace přístrojů založených na technologickém vývoji oboru mikroelektroniky. Zvyšování možností detekovatelnosti stále nižších koncentrací volných radikálů v roztoku (v našem případě těžkých kovů), rozšiřování efektivního odstupu výstupního signálu od šumu nebo měřících možnosti daného typu zařízení jsou vždy hlavními cíly při realizaci nového typu zařízení. Hlavním cílem diplomové práce je návrh designu senzoru, jeho realizace a provedení experimentálního měření s prototypem senzoru, založeným na technologii tlustých vrstev, pro zjištění, zda bylo dosaženo předpokládaného funkčního spojení senzoru a obvodu, a především zvýšena reprodukovatelnost výsledků měření. Inovace měřícího zařízení spočívá ve zlepšení výstupních vlastností pomocí integrace potenciostatu v obvodu ASIC (IMAM CHIP) a tím odstranění parazitních vlivů, které ovlivňují přesnost měření.
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Electrochemical propertiesand thermal stability of cup-like shape gold nanostructures
Kynclová, H.
Nanostructured surfaces are useful in enlargement of electroactive area of sensing electrodes. The electrodes are very sensitive with maintaining small electrode geometry. In this study, surfaces modified by cup-like gold nanoparticles were fabricated by electrochemical methods. Subsequently, electrochemical properties and thermal stability of fabricated nanostructured electrodes were studied. Thereafter, the electrochemical results were compared with unmodified flat gold layer and contribution of nanostructuring was evaluated. Stability of nanoparticles after thermal vacuum and air pressure treatment was studied using scanning electron microscope. These results are useful for subsequent research of nanostructured sensors.
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Electrochemical Characterization of Poly(methylene Blue) Modified Graphite Electrodes
Zlámalová, Magda ; Janda, Pavel ; Nesměrák, K.
This work deals with electrochemical study of methylene blue (MB) polymerization as well as characterization of deposited conductive film on basal plane highly oriented pyrolytic graphite (HOPG) and pencil-graphite electrode (PGE). Poly(methylene blue) modified electrodes (HOPG/pMB and PGE/pMB) have been prepared by potential cycling in aqueous electrolyte solution containing methylene blue monomer. It has been found that electrochemical properties and electrocatalytic activity of deposited film are greatly influenced by the type of electrode substrate. Developed electrodes have been further investigated as potential sensors for sulfhydryl-containing compounds.
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Electrochemical Study of Oxazaborine Chromophores
Mikysek, T. ; Josefík, F. ; Vytřas, K. ; Ludvík, Jiří
This contribution describes a basic electrochemical study of a series of newly synthesized chromophores based on the oxazaborine core. The attention was focused on determination of the first oxidation and the first reduction potentials, their difference and the relationship to the calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies. The oxidation is mostly a two-electron irreversible process, the first reduction is also irrevesible, but involving one-electron. For better understanding of the relationship between the structure and redox properties, the approach using sigma (para) constants of Hammett type was applied, the difference between E(ox) and E(red) was correlated with the HOMO-LUMO gap.
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Electrocatalytic Oxidation of Unsaturated Hydrocarbons Mediated by Phthalocyanine Derivate
Klusáčková, Monika ; Janda, Pavel
The oxidation of ethylene and propylene respectively, mediated by thin layer -tetramethyltetra-3,4-pyridinoporphyrazinocobalt, simply called CoTmt-3,4-ppa, deposited on basal plane of highly ordered pyrolytic graphite (HOPG) was studied in aqueous phosphate buffer phosphate solution by cyclic voltammetry, backscattering spectroscopy and atomic force microscopy. Our interest has been focused on optimizing conditions of electrocatalytic oxidation unsaturated hydrocarbon on electrode modified by pyridinoporphyrazine.
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Electrochemistry of Potential Eu MRI Complexes
Gál, Miroslav ; Sokolová, Romana ; Kielar, P.
Properties of the several potential contrast agents for magnetic resonance imaging (MRI) with Eu(III)/Eu(II) redox couple were investigated by means of the electrochemical methods. Cyclic voltammetry, phase sensitive AC voltammetry, and DC polarography were utilized to elucidate the mechanism of the reduction/oxidation of Eu ion in the presence of these compounds. Moreover, the stability constants of the Eu(II)-MRI agent complexes were also determined. Some suggestions on the chemical structure of the potential contrast agents for MRI are also made.
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Electroanalysis with phthalocyanine modified HOPG electrodes
Mansfeldová, Věra ; Janda, Pavel
In this papers we presented modification of highly oriented pyrolitic graphite (HOPG) by two different phthalocyanine (Pc) derivatives and two different deposition techniques. We have investigated electrode modified by fullerene-derived phthalocyanine and cobalt tetraneopentoxyphthalocyanine (CoTNPc) to consider how different modification procedure-electrodeposition and drop evaporation and composition of phthalocyanine influences detection of model compound, L-cysteine.
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Polycrystalline gold electrode modified by thiols
Šustrová, Barbora ; Mareček, Vladimír ; Štulík, K.
The article reports on our continued investigation of modification of the gold electrode surface by thiolated compounds aimed at construction of an ion-selective sensor. Our previous work was focused on utilization of calix[4]arene molecules as a cavity sized ligand molecule. In this paper, calixarene and linear undecanethiol molecules were used as modifiers. We compared two ways of deposition thiol molecules, namely the spontaneous self-assembly process and the electrochemical deposition, in which the potential was applied on the electrode immersed into an adsorption solution. The concentration, time and potential conditions were optimized from the point of view of the SAM homogeneity. The modifying layers of calixarene and undecanthiol molecules were visualized by atomic force microscopy.
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