The permeability and barrier properties of various solutes were studied through nanoporous alumin... more The permeability and barrier properties of various solutes were studied through nanoporous alumina membranes by diffusion cell technique. Fabricated membranes were characterized by basic physic-chemical methods. The accurate thickness and roughness was determined by profilometry, the distribution of pores and pore size was detected by mercury intrusion porosimetry, textural properties were studied by scanning electron microscopy and specific surface area by BET analysis. The specific permeability was compared by determination of fundamental diffusion parameters such as diffusion flux and break-through time (lag time). Results show, that the penetration ability and other important parameters such as thickness and the distribution of pores are strongly dependent on experimental setup within preparation of nanoporous alumina membranes. The most important parameters which influenced the final properties of membranes are time of anodization, type of electrolyte, applied voltage and curre...
Nanoporous alumina is useful material for development of electrochemical sensors including filtra... more Nanoporous alumina is useful material for development of electrochemical sensors including filtration, molecule sorting and subsequent detection. Big advantage of alumina is possibility to reliably control size of nanopores and membrane thickness. For sensorial utilization, it is necessary to know diffusion properties of membranes and their permeability of various substances. Therefore, membranes with different pore diameter and thickness were prepared by two step anodization and modified by deposition of gold layers which serve as electrodes. Thereafter, their influence on changes of electrochemical impedance spectra was studied and compared in dependency on membrane morphology.
Graphite oxide has been investigated as a possible room-temperature chemiresistive sensor of ammo... more Graphite oxide has been investigated as a possible room-temperature chemiresistive sensor of ammonia in a gas phase. Graphite oxide was synthesized from high purity graphite using the modified Hummers method. The graphite oxide sample was investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetry and differential scanning calorimetry. Sensing properties were tested in a wide range of ammonia concentrations in air (10-1000 ppm) and under different relative humidity levels (3%-65%). It was concluded that the graphite oxide-based sensor possessed a good response to NH 3 in dry synthetic air (∆R/R 0 ranged from 2.5% to 7.4% for concentrations of 100-500 ppm and 3% relative humidity) with negligible cross-sensitivity towards H 2 and CH 4. It was determined that the sensor recovery rate was improved with ammonia concentration growth. Increasing the ambient relative humidity led to an increase of the sensor response. The highest response of 22.2% for 100 ppm of ammonia was achieved at a 65% relative humidity level.
This work deals with thick-film sensors electrodes properties study during their fabrication proc... more This work deals with thick-film sensors electrodes properties study during their fabrication process, which is crucial question for the next development of this perspective technology. New electrochemical analytical device was developed to ensure a defined mass transport to the electrodes, which is the most limiting process that influences the response quality of the sensor. The device is possible to be used for measurement on final chemical sensors or biosensors too. The sensors current responses were tested on a standard electrochemical couple of potassium ferrocyanide-ferricyanide. Thick film sensor's response dependence on the liquid velocity and geometrical arrangement is presented.
Obor: Mikroelektronika a technologie Zkrácená verze disertace (Ph.D.)--Vysoké učení technické v B... more Obor: Mikroelektronika a technologie Zkrácená verze disertace (Ph.D.)--Vysoké učení technické v Brně, Fakulta elektrotechniky a komunikačních technologií, Ústav mikroelektroniky, 2007
This paper covers an area of construction of planar reference electrodes for thick-film electroch... more This paper covers an area of construction of planar reference electrodes for thick-film electrochemical sensors. Various materials of commercial and own prepared planar reference electrodes were used for electrodes fabrication and compared with classical reference electrode. The focus was on an Ag/AgCl thick-film or electrochemically created layers. Comparison was made in a three-electrode unstirred system using a standard electrochemical solution of potassium ferro-ferricyanide. The results showed a big difference between the electrodes in obtained current responses. The best properties of fabricated electrodes were obtained with commercial thick-film pastes. A big dependence of geometrical arrangement of electrodes in electrochemical cell is showed here too.
Miniature electrochemical sensors can be produced by thick film technology (TFT). The optimal pro... more Miniature electrochemical sensors can be produced by thick film technology (TFT). The optimal properties of thick film electrode materials are main problems of sensors design. The optimisation of graphite pastes properties for TFT chemical sensor is discussed. The commercial TFT graphite pastes, which are used for common application, are cheap and easily producible, but they are not efficient for electrochemical measurement. These pastes have insufficient sensitivity and they have other bad properties. Graphite pastes, which were designed for special chemical analysis, are technically known, but these pastes are not workable by screen-printing. The first step in rheological properties addition to graphite electrochemical pastes is the goal of this work. This will ensure the pastes printability that will enable the reproducible mass production. The graphite powder with paraffin wax mixture is the basic component of common chemical graphite pastes. There were examined different proper...
Miniature electrochemical sensors can be produced using thick film technology. Fabrication techno... more Miniature electrochemical sensors can be produced using thick film technology. Fabrication technology optimization of thick-film sensors, the adjustment of optimal technological properties and especially the optimal properties of thick-film electrode materials and electrode topology are main problems of sensor design. The electrodes topology design represents one of very important parts. It is very complicated, because of many contradictory requests that must be solved. Some aspects about this problem in electrochemical sensor area are discussed in this paper.
The current trends in sensor technology are a sensor miniaturization, integration of sensing elem... more The current trends in sensor technology are a sensor miniaturization, integration of sensing element with measuring circuits and integration of sensors elements to sensor array. The hybrid technology seems to be optimal for design and production of electrochemical sensor array. This work is focused on topology design of thick-film electrochemical sensor array and presents new electrochemical sensor array for voltammetric measurement. This sensor array is placed on 50,8 mm x 50,8 mm alumina substrate. The supposed advantages of this sensor array are the increasing of speed of measurement, accuracy of measurement and enlarging of measuring possibilities against the common optical sensors system.
This paper is devoted to the area of electrochemical sensors. In this work several screen-printed... more This paper is devoted to the area of electrochemical sensors. In this work several screen-printed thick-film electrodes are prepared. These electrodes are commonly used as the working electrodes of electrochemical sensors. The surface of the electrode has been modified with nanopatterned nanostructures. The nanostructures have been formed as vertically aligned carbon nanotubes that were grown directly on the screen-printed working electrode using plasma enhanced chemical vapour deposition method. The aim was to improve electrochemical properties of the electrode by creating homogeneous and high density carbon nanotubes directly on the thick-film layer. The created structures have been investigated by scanning electron microscopy. The electrochemical properties have been investigated by electrochemical detection of cadmium ions in aqueous solutions. The concentration of cadmium ions in units of µmol/L can be determined with the modified electrode.
The aim of this work was to design and to construct new automated system for electrochemical dete... more The aim of this work was to design and to construct new automated system for electrochemical determination of metal ions. For this purpose, we connected three commercially available instruments with sensor field and control box. Suggested field consists from 96 electrode systems, in which working electrode was made from carbon. The detection limit (3 S/N) was estimated as 1 µg/ml. The array was successfully correlated with atomic absorption spectrometry and applied for analysis of rainwater samples.
Carbon nanotubes (CNTs) have been under scientific investigation more than fifteen years since th... more Carbon nanotubes (CNTs) have been under scientific investigation more than fifteen years since their unique properties predestine them for numerous potential applications. The field of nanotechnology and nanoscience push their investigation forward to produce CNTs with suitable parameters for future applications. It is evident that new approaches of their synthesis need to be developed and optimized. In this chapter, brief history, types, structure and especially the different synthesis methods for CNTs preparation are reviewed. The attention is mainly aimed on various types of chemical vapor depositions as CVD methods for uniform vertically aligned CNT synthesis, liquid pyrolysis and solid state pyrolysis.
IOP Conference Series: Materials Science and Engineering, 2015
The paper describes modern ways for selection of anti-radical substances. Molding of such compone... more The paper describes modern ways for selection of anti-radical substances. Molding of such components with a carbon-based material decreases the rate of its oxidative destruction. Addition of such a component to a carbon-based material decreases the rate of its oxidative destruction. The purpose of this study is to determine the antioxidant activity of ascorbates metals (Ca, Mg, Li, Co, Fe), used in the practice of medicine, as well as mixtures based on them together with well-known antioxidants. In this article we examine the effect of metals on the process of ascorbate oxygen electroreduction. From these ascorbates lithium and magnesium ascorbate showed the greatest activity toward cathode oxygen reduction process. Also mixtures with well-known examined antioxidants ascorbate (glucose, dihydroquercetin) were investigated at different concentrations of components. It is shown that the multicomponent mixtures exhibit lower activity than the individual drugs. Recommended the creation of drugs on the basis of ascorbate Mg and Li with not more than 3 number of components.
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439), 2003
ABSTRACT The novel testing and calibrating sensor for calibration and testing purposes in voltamm... more ABSTRACT The novel testing and calibrating sensor for calibration and testing purposes in voltammetric and amperometric measurements is presented. The device consists of the only electronic components, and was designed to fit standard I-V characteristics of the electrochemical sensors as best as possible. The testing sensor was carefully simulated by PSPICE and tested in temperature chamber for temperatures from 10 to 40 °C. Wider temperature ranges may be added. This special sensor accelerates testing and calibration of all instruments used for voltammetric and amperometric methods.
The experimentally made channel and capillaries by thick-film technology are the main goal of thi... more The experimentally made channel and capillaries by thick-film technology are the main goal of this work. The capillaries are usually made by special membrane, metal etching, by LTCC. This paper is focused on simple experiments with the capillary fabrication using pastes overlaying on two separate substrates that are then joined together forming up the capillary. Some aspects about problem channels and capillaries made by thick-film technology are discussed in this paper.
Miniature electrochemical sensors can be produced using thick film technology (TFT). Fabrication ... more Miniature electrochemical sensors can be produced using thick film technology (TFT). Fabrication technology optimization of thick-film sensors, the adjustment of optimal technological properties and especially the optimal properties of thick-film electrode materials and electrode topology are main problems of sensor design. The electrode topology design is one of very important parts. One method of working electrode area increasing on small sensor substrate with maintenance of sufficient rate between working electrode area size: reference electrode area size is possible by TFT paste elevations on basic electrode surface and optimization of topology. Some aspects about this problem are discussed in this paper.
ABSTRACT The micro-electro-mechanical array for application as fully implantable cochlea is prese... more ABSTRACT The micro-electro-mechanical array for application as fully implantable cochlea is presented in this paper. The complete system including a short overview of energy harvesting and the system configuration is proposed. This study mainly covers mechanical properties of cochlea microfabricated silicon structure. Electro-mechanical simulations are proceeded to optimize the material used for resonators, the size of array membranes and to estimate the resistive change due to the input sound signal. The sound is detected by thin SiXNY diaphragm due to resonant frequency and the displacement of the membrane caused by acoustic pressure. The displacement is detected employing piezoresistive electrodes (NiCr). Design and fabrication process based on MEMS technology are described and discussed. The response measurement of the cochlea structure is performed. The sizes of the membranes vary from (0.5×0.5) mm to (2.0×2.0) mm and the average current change is 6.55·10-3c% corresponding to the acoustic pressure of 0.01 Pa.
One of the areas rapidly gaining popularity in all parts of scientific research is Nanotechnology... more One of the areas rapidly gaining popularity in all parts of scientific research is Nanotechnology. The pioneering mechanical and electrical engineering has been overtaken by life sciences including chemistry and biology as well as biophysics and biomedicine. The attractiveness of
The permeability and barrier properties of various solutes were studied through nanoporous alumin... more The permeability and barrier properties of various solutes were studied through nanoporous alumina membranes by diffusion cell technique. Fabricated membranes were characterized by basic physic-chemical methods. The accurate thickness and roughness was determined by profilometry, the distribution of pores and pore size was detected by mercury intrusion porosimetry, textural properties were studied by scanning electron microscopy and specific surface area by BET analysis. The specific permeability was compared by determination of fundamental diffusion parameters such as diffusion flux and break-through time (lag time). Results show, that the penetration ability and other important parameters such as thickness and the distribution of pores are strongly dependent on experimental setup within preparation of nanoporous alumina membranes. The most important parameters which influenced the final properties of membranes are time of anodization, type of electrolyte, applied voltage and curre...
Nanoporous alumina is useful material for development of electrochemical sensors including filtra... more Nanoporous alumina is useful material for development of electrochemical sensors including filtration, molecule sorting and subsequent detection. Big advantage of alumina is possibility to reliably control size of nanopores and membrane thickness. For sensorial utilization, it is necessary to know diffusion properties of membranes and their permeability of various substances. Therefore, membranes with different pore diameter and thickness were prepared by two step anodization and modified by deposition of gold layers which serve as electrodes. Thereafter, their influence on changes of electrochemical impedance spectra was studied and compared in dependency on membrane morphology.
Graphite oxide has been investigated as a possible room-temperature chemiresistive sensor of ammo... more Graphite oxide has been investigated as a possible room-temperature chemiresistive sensor of ammonia in a gas phase. Graphite oxide was synthesized from high purity graphite using the modified Hummers method. The graphite oxide sample was investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetry and differential scanning calorimetry. Sensing properties were tested in a wide range of ammonia concentrations in air (10-1000 ppm) and under different relative humidity levels (3%-65%). It was concluded that the graphite oxide-based sensor possessed a good response to NH 3 in dry synthetic air (∆R/R 0 ranged from 2.5% to 7.4% for concentrations of 100-500 ppm and 3% relative humidity) with negligible cross-sensitivity towards H 2 and CH 4. It was determined that the sensor recovery rate was improved with ammonia concentration growth. Increasing the ambient relative humidity led to an increase of the sensor response. The highest response of 22.2% for 100 ppm of ammonia was achieved at a 65% relative humidity level.
This work deals with thick-film sensors electrodes properties study during their fabrication proc... more This work deals with thick-film sensors electrodes properties study during their fabrication process, which is crucial question for the next development of this perspective technology. New electrochemical analytical device was developed to ensure a defined mass transport to the electrodes, which is the most limiting process that influences the response quality of the sensor. The device is possible to be used for measurement on final chemical sensors or biosensors too. The sensors current responses were tested on a standard electrochemical couple of potassium ferrocyanide-ferricyanide. Thick film sensor's response dependence on the liquid velocity and geometrical arrangement is presented.
Obor: Mikroelektronika a technologie Zkrácená verze disertace (Ph.D.)--Vysoké učení technické v B... more Obor: Mikroelektronika a technologie Zkrácená verze disertace (Ph.D.)--Vysoké učení technické v Brně, Fakulta elektrotechniky a komunikačních technologií, Ústav mikroelektroniky, 2007
This paper covers an area of construction of planar reference electrodes for thick-film electroch... more This paper covers an area of construction of planar reference electrodes for thick-film electrochemical sensors. Various materials of commercial and own prepared planar reference electrodes were used for electrodes fabrication and compared with classical reference electrode. The focus was on an Ag/AgCl thick-film or electrochemically created layers. Comparison was made in a three-electrode unstirred system using a standard electrochemical solution of potassium ferro-ferricyanide. The results showed a big difference between the electrodes in obtained current responses. The best properties of fabricated electrodes were obtained with commercial thick-film pastes. A big dependence of geometrical arrangement of electrodes in electrochemical cell is showed here too.
Miniature electrochemical sensors can be produced by thick film technology (TFT). The optimal pro... more Miniature electrochemical sensors can be produced by thick film technology (TFT). The optimal properties of thick film electrode materials are main problems of sensors design. The optimisation of graphite pastes properties for TFT chemical sensor is discussed. The commercial TFT graphite pastes, which are used for common application, are cheap and easily producible, but they are not efficient for electrochemical measurement. These pastes have insufficient sensitivity and they have other bad properties. Graphite pastes, which were designed for special chemical analysis, are technically known, but these pastes are not workable by screen-printing. The first step in rheological properties addition to graphite electrochemical pastes is the goal of this work. This will ensure the pastes printability that will enable the reproducible mass production. The graphite powder with paraffin wax mixture is the basic component of common chemical graphite pastes. There were examined different proper...
Miniature electrochemical sensors can be produced using thick film technology. Fabrication techno... more Miniature electrochemical sensors can be produced using thick film technology. Fabrication technology optimization of thick-film sensors, the adjustment of optimal technological properties and especially the optimal properties of thick-film electrode materials and electrode topology are main problems of sensor design. The electrodes topology design represents one of very important parts. It is very complicated, because of many contradictory requests that must be solved. Some aspects about this problem in electrochemical sensor area are discussed in this paper.
The current trends in sensor technology are a sensor miniaturization, integration of sensing elem... more The current trends in sensor technology are a sensor miniaturization, integration of sensing element with measuring circuits and integration of sensors elements to sensor array. The hybrid technology seems to be optimal for design and production of electrochemical sensor array. This work is focused on topology design of thick-film electrochemical sensor array and presents new electrochemical sensor array for voltammetric measurement. This sensor array is placed on 50,8 mm x 50,8 mm alumina substrate. The supposed advantages of this sensor array are the increasing of speed of measurement, accuracy of measurement and enlarging of measuring possibilities against the common optical sensors system.
This paper is devoted to the area of electrochemical sensors. In this work several screen-printed... more This paper is devoted to the area of electrochemical sensors. In this work several screen-printed thick-film electrodes are prepared. These electrodes are commonly used as the working electrodes of electrochemical sensors. The surface of the electrode has been modified with nanopatterned nanostructures. The nanostructures have been formed as vertically aligned carbon nanotubes that were grown directly on the screen-printed working electrode using plasma enhanced chemical vapour deposition method. The aim was to improve electrochemical properties of the electrode by creating homogeneous and high density carbon nanotubes directly on the thick-film layer. The created structures have been investigated by scanning electron microscopy. The electrochemical properties have been investigated by electrochemical detection of cadmium ions in aqueous solutions. The concentration of cadmium ions in units of µmol/L can be determined with the modified electrode.
The aim of this work was to design and to construct new automated system for electrochemical dete... more The aim of this work was to design and to construct new automated system for electrochemical determination of metal ions. For this purpose, we connected three commercially available instruments with sensor field and control box. Suggested field consists from 96 electrode systems, in which working electrode was made from carbon. The detection limit (3 S/N) was estimated as 1 µg/ml. The array was successfully correlated with atomic absorption spectrometry and applied for analysis of rainwater samples.
Carbon nanotubes (CNTs) have been under scientific investigation more than fifteen years since th... more Carbon nanotubes (CNTs) have been under scientific investigation more than fifteen years since their unique properties predestine them for numerous potential applications. The field of nanotechnology and nanoscience push their investigation forward to produce CNTs with suitable parameters for future applications. It is evident that new approaches of their synthesis need to be developed and optimized. In this chapter, brief history, types, structure and especially the different synthesis methods for CNTs preparation are reviewed. The attention is mainly aimed on various types of chemical vapor depositions as CVD methods for uniform vertically aligned CNT synthesis, liquid pyrolysis and solid state pyrolysis.
IOP Conference Series: Materials Science and Engineering, 2015
The paper describes modern ways for selection of anti-radical substances. Molding of such compone... more The paper describes modern ways for selection of anti-radical substances. Molding of such components with a carbon-based material decreases the rate of its oxidative destruction. Addition of such a component to a carbon-based material decreases the rate of its oxidative destruction. The purpose of this study is to determine the antioxidant activity of ascorbates metals (Ca, Mg, Li, Co, Fe), used in the practice of medicine, as well as mixtures based on them together with well-known antioxidants. In this article we examine the effect of metals on the process of ascorbate oxygen electroreduction. From these ascorbates lithium and magnesium ascorbate showed the greatest activity toward cathode oxygen reduction process. Also mixtures with well-known examined antioxidants ascorbate (glucose, dihydroquercetin) were investigated at different concentrations of components. It is shown that the multicomponent mixtures exhibit lower activity than the individual drugs. Recommended the creation of drugs on the basis of ascorbate Mg and Li with not more than 3 number of components.
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439), 2003
ABSTRACT The novel testing and calibrating sensor for calibration and testing purposes in voltamm... more ABSTRACT The novel testing and calibrating sensor for calibration and testing purposes in voltammetric and amperometric measurements is presented. The device consists of the only electronic components, and was designed to fit standard I-V characteristics of the electrochemical sensors as best as possible. The testing sensor was carefully simulated by PSPICE and tested in temperature chamber for temperatures from 10 to 40 °C. Wider temperature ranges may be added. This special sensor accelerates testing and calibration of all instruments used for voltammetric and amperometric methods.
The experimentally made channel and capillaries by thick-film technology are the main goal of thi... more The experimentally made channel and capillaries by thick-film technology are the main goal of this work. The capillaries are usually made by special membrane, metal etching, by LTCC. This paper is focused on simple experiments with the capillary fabrication using pastes overlaying on two separate substrates that are then joined together forming up the capillary. Some aspects about problem channels and capillaries made by thick-film technology are discussed in this paper.
Miniature electrochemical sensors can be produced using thick film technology (TFT). Fabrication ... more Miniature electrochemical sensors can be produced using thick film technology (TFT). Fabrication technology optimization of thick-film sensors, the adjustment of optimal technological properties and especially the optimal properties of thick-film electrode materials and electrode topology are main problems of sensor design. The electrode topology design is one of very important parts. One method of working electrode area increasing on small sensor substrate with maintenance of sufficient rate between working electrode area size: reference electrode area size is possible by TFT paste elevations on basic electrode surface and optimization of topology. Some aspects about this problem are discussed in this paper.
ABSTRACT The micro-electro-mechanical array for application as fully implantable cochlea is prese... more ABSTRACT The micro-electro-mechanical array for application as fully implantable cochlea is presented in this paper. The complete system including a short overview of energy harvesting and the system configuration is proposed. This study mainly covers mechanical properties of cochlea microfabricated silicon structure. Electro-mechanical simulations are proceeded to optimize the material used for resonators, the size of array membranes and to estimate the resistive change due to the input sound signal. The sound is detected by thin SiXNY diaphragm due to resonant frequency and the displacement of the membrane caused by acoustic pressure. The displacement is detected employing piezoresistive electrodes (NiCr). Design and fabrication process based on MEMS technology are described and discussed. The response measurement of the cochlea structure is performed. The sizes of the membranes vary from (0.5×0.5) mm to (2.0×2.0) mm and the average current change is 6.55·10-3c% corresponding to the acoustic pressure of 0.01 Pa.
One of the areas rapidly gaining popularity in all parts of scientific research is Nanotechnology... more One of the areas rapidly gaining popularity in all parts of scientific research is Nanotechnology. The pioneering mechanical and electrical engineering has been overtaken by life sciences including chemistry and biology as well as biophysics and biomedicine. The attractiveness of
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