Jan Prášek

Brno University of Technology · Central European Institute of Technology "CEITEC"

We provide fast and sensitive detection of phosphate dissolved in water usingRaman spectroscopy. To this end, phosphate-scavenging planar core/shellsurface-enhanced Raman spectroscopy (SERS) probes consisting of Al2O3-capped Ag nanopatterned sapphire substrate were prepared and optimized.Thanks to scavenging, the probes provide enhancement sufficie...

Novel arrays of Nb2O5-based ceramic nanostructures of various sizes (9–210 nm) and morphologies (dots, goblets, rods) aligned on substrates are fabricated via the anodizing of a thin Nb film through the initially formed porous anodic alumina (PAA) film in 1.5 M selenic acid (H2SeO4) – a new aqueous electrolyte generating extraordinarily thinner PAA...

The need for integrated passive devices (IPDs) emerges from the increasing consumer demand for electronic product miniaturization. Metal-insulator-metal (MIM) capacitors are vital components of IPD systems. Developing new materials and technologies is essential for advancing capacitor characteristics and co-integrating with other electronic passive...

High-κ dielectric materials are commonly used in microelectronic components due to the technological necessity of increasing the capacitance density of dielectric layers. The thickness of the layer is a crucial parameter of this technology because it has a significant influence on dielectric properties, capacitance density, leakage current density–...

Measurement of larger analytes such as many chemical and biological structures or viruses in gigadalton (GDa) range is a reminding fundamental task in analytical chemistry and life sciences, which can be possibly resolved with the resonating nanomechanical systems. Common approaches to mass sensing with these systems model the bound analyte as a po...

An aluminum-on-zirconium bilayer is anodized in oxalic acid solution to transform the Al layer into porous anodic alumina (PAA); this is followed by the PAA-assisted re-anodizing of the Zr underlayer at voltages 40–280 V. The process results in an array of amorphous ZrO2 nanocolumns, 45–330 nm long, partly filling the PAA pores and anchored to a co...

Multi-walled carbon nanotubes (MWCNTs) based heterostructures were prepared by oxygen plasma treatment and atomic layer deposition (ALD) of TiO2 carried on MWCNTs. Different TiO2 structures (island, granular and continuous forms) on the nanotubes were obtained by varying the processing parameters. Chemical inertness of MWCNTs led to the ALD of TiO2...

Here, zirconium‐oxide ceramic coatings comprising arrays of 3D nanostructures are electrochemically synthesized, ranging in shape, size, spacing, and population density, termed as the nanomounds (ø≈65 nm), nanopillars (ø≈130 nm), and nanostumps (ø≈220 nm). The nanostructured coatings, alongside a flat ZrO2 anodic film, are explored as a potential b...

The fabrication of superhydrophobic-oleophobic HfO2 coatings presents a challenge. Here, we synthesize via the self-organized anodizing of aluminum-on-hafnium layers sputter-deposited onto SiO2 and glass substrate arrays of highly aligned HfO2 nanostructures of dissimilar shapes, sizes, spacings, and population densities termed as nanorods, nanopil...

The fabrication of ZrO2 nanostructures, such as nanowires or nanorods, arrayed on substrates and having certain and reproducible microstructures and chemical compositions presents a challenge. Here we synthesize, for the first time, 1- and 3-dimensional zirconium-oxide nanostructures highly aligned on substrates via the self-organized anodizing and...

The continuous emission of nitrous oxides contributes to the overall air pollution and deterioration of air quality. In particular, an effective NO2 sensor capable of low concentration detection for continuous monitoring is demanded for safety, health, and wellbeing. The sensing performance of a metal oxide based sensor is predominantly influenced...

Zirconium oxide (ZrO2) is a widely utilized inorganic material with excellent dielectric, optical, and biocompatible characteristics. The properties and areas of the ZrO2 applications can be further broadened by making the material nanostructured. In this work, anodic ZrO2 nanostructured films were developed and characterized by scanning electron m...

Thin dielectric films are actively investigated as materials for novel resistive random-access memories based on resistive switching effect in metal/insulator/metal structures. Thin HfO2 films are of particular interest due to the high thermal stability, low operating voltages of resulting devices, and complementary metal-oxide-semiconductor techno...

Hafnium-oxide nanostructures of controlled composition and properties are in demand for modern electronic and optical engineering. Here hafnium-oxide nanostructured films are synthesized on substrates via the anodizing/re-anodizing of a thin Hf layer through a porous anodic alumina (PAA) film at 150/400 V in 0.2 m H3PO4 electrolyte and examined by...

Two types of anodic niobium-oxide nanofilms were synthesized via anodization of an Al/Nb bilayer sputter-deposited onto a SiO2-coated Si wafer. Type I nanofilm was composed of a 200 nm thick NbO2 layer holding the upright-standing 650 nm long, 50 nm wide, and 70 nm spaced Nb2O5 nanorods, of 7·10⁹ cm⁻² density, whereas the Type II nanofilm had simil...

The ammonia adsorption on the nanostructured carbon thin film was significantly influenced by the choice of deposition temperature and deposition time of thin film synthesis. The thin films were prepared on Si/SiO 2 substrates by chemical vapour deposition in Ar/C 2 H 2 gas mixture using iron catalytic nanoparticles. The analysis of the grown layer...

In this paper, we design and develop low-power MEMS based microhotplates for chemiresistive gas sensors using computer modelling and microelectronic technologies, respectively. Two geometrical designs of supporting beams of suspended membranes were designed and simulated to evaluate displacement in the structure. Two different patterns of heating e...

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, therm...

In this paper a graphite oxide is investigated as a possible sensing layer of room temperature ammonia chemiresistive gas sensor. The sensing properties were tested in a wide range of ammonia concentrations in air (10-1000ppm) and under different humidity levels (3-65%). It was concluded that the graphite oxide based sensor possessed high response...

This work deals with the new technique called Charge Push-Through technology which is more energy efficient than the currently used approaches. The new energy efficient design regarding utilization of emerging technology such as Energy harvesting (EH) power sources is very promising for future development of energy independent (zero-power) and nono...

Multi-walled carbon nanotubes (MWCNTs) are highly desirable for the integration into functional devices in particular for sensing applications. MWCNTs for testing the gas sensing properties were prepared on Si substrates coated with SiO 2 film. The catalytic Fe films were deposited by vacuum evaporation. Carbon nanotubes (CNTs) were grown in the mi...

The sensing properties of carbon nanomaterials are studied and compared in this paper. Graphene oxide and multi-walled carbon nanotube films were used as active layers of chemoresistive gas sensors and characterized at room temperature towards ammonia detection in concentration levels from 100 ppm to 500 ppm in air. We conclude that graphene oxide...

An implant of artificial cochlea is the only way how to recover lost hearing in some cases. Fully implantable artificial cochlea in comparison with recent approaches including partially implantable devices is proposed and discussed in this work. The proposed implant consists of subcircuits which are designed in close context to reach optimal perfor...

In the paper, planar slot loop antennas are presented. The antennas radiate electromagnetic waves which are polarized perpendicularly to a conductive surface. Therefore, the antennas can be used for on-body or off-body communication. The role of the substrate is played by a three-dimensional textile material. Conductive parts of antennas are fabric...

We propose the ion-beam sputtering deposition providing Ti thin films of desired crystallographic orientation and smooth surface morphology not obtainable with conventional deposition techniques such as magnetron sputtering and vacuum evaporation. The sputtering was provided by argon broad ion beams generated by a Kaufman ion-beam source. In order...

This work describes preparation process of free-standing alumina membranes used in sensor devices for separation or purification (increased selectivity, and sensitivity) purposes. Nanoporous alumina membranes were prepared using anodic oxidation of aluminium foil in two types of acidic electrolytes and characterized using scanning electron microsco...

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 proc...

The aerosol assisted chemical vapor deposition of Fe2O3 nanoparticle-tunctionalized tungsten oxide nanoneedles and their gas sensing properties are presented here. Material analysis demonstrates the incorporation of 4 to 15 nm Fe2O3 nanoparticles at the surface of the tungsten oxide nanoneedles. Gas sensing tests show improved tungsten oxide sensit...

The artificial cochlear implant is the only way how to get lost hearing back in some cases. Existing artificial cochlear devices use two separated parts for this purpose: a signal processing unit with transmitter and an implantable receiver with electrodes. This approach is applicable but not fully implantable. A new complex approach to design of a...

This paper deals with a model-based design of an autonomous biomechatronic device for sensing and analog signal processing of acoustic signals. The aim is to develop a biomechatronic artificial cochlear implant for people with hearing loss due to damage or disease of their cochlea. The unique artificial electronic cochlear implant is based on an ar...

The pressure sensor application gained recently substantial interest in many fields of basic and applied research and applications. In this paper, microelectromechanical system (MEMS)-based pressure sensor contains nanostructured electrode consisting of carbon nanotube (CNT) array. CNTs are directly grown on such electrode by plasma-enhanced chemic...

Vertically aligned multi-walled carbon nanotubes (VA-MWCNTs) with an average diameter below 80 nm and a thickness of the uniform VA-MWCNT layer of about 16 µm were grown in microwave plasma torch and tested for selected functional properties. IR absorption important for a construction of bolometers was studied by Fourier transform infrared spectros...

The paper presents the first results of research on an artificial cochlea based on a mechanical filter bank that could be produced by MEMS (Micro Electro Mechanical Systems) technologies and power supplied by energy harvesting systems. First, the basic configuration of the artificial cochlea proposed by our team is described. Then, the configuratio...

The screen-printed working electrode (WE) of an electrochemical sensor was modified with multi-walled carbon nanotubes (MWCNTs) and a plasma treatment. The plasma treatment was performed using radio frequency capacitively coupled discharge in Ar/O2, Ar/cyclopropylamine and Ar/NH3. The surface of the WEs was characterized by scanning electron micros...

Remote-controlled robotic systems are being used for analysis of various types of analytes in hostile environment including those called extra-terrestrial. The aim of our study was to develop a remote-controlled robotic platform (ORPHEUS-HOPE) for bacterial detection. For the platform ORPHEUS-HOPE a 3D printed flow chip was designed and created wit...

Characterization method for active layers for microelectrodes of electrochemical and gas sensors using scanning electron microscopy (SEM) is presented. In order to achieve maximum sensitivity and selectivity of the sensor, it is necessary to obtain precise knowledge of electrode's surface. Characterization was made using FEI Magellan SEM equipped w...

In this study, we compared two types of nanostructured electrodes with gold nanocolumns and flat gold electrodes by measurements with doxorubicin. Nanostructured electrodes were fabricated by electrochemical anodic oxidation followed by deposition of gold to the porous alumina. Flat gold electrodes were fabricated by physical evaporation of gold la...

In this study, we focused on microfluidic electrochemical analysis of zinc complexes (Zn(phen)(his)Cl2, Zn(his)Cl2) and ZnS quantum dots (QDs) using printed electrodes. This method was chosen due to the simple (easy to use) instrumentation and variable setting of flows. Reduction signals of zinc under the strictly defined and controlled conditions...

Two types of working electrodes of electrochemical sensors were fabricated using screen-printing and spray-coating deposition methods and previously synthetized Cu2O micro/nanoparticles and used for direct electrochemical glucose detection. Glucose was successfully electrochemically detected against conventional Ag/AgCl reference electrode and plat...

The aim of this work is the optimization and following characterization of gold nanostructured electrochemical sensors suitable for biomolecules and heavy metal ion detection. Gold nanoparticles need to be examined for biocompatibility and environmental impacts. The EIS (electrochemical impedance spectroscopy) measurements of surfaces with various...

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...

Carbon materials are good candidates as electron emitters. In this article will be described emission properties of carbon nanotubes prepared by chemical vapour deposition (CVD). The measurement of emission current density flowing through the electrodes was carried out in a vacuum chamber pumped by a turbomolecular pump. The vacuum chamber was equi...

Doxorubicin is a planar aromatic molecule and it is commonly used in cancer chemotherapy. In this study, we compared nanostructured electrodes with gold nanocolumns and flat gold electrodes by measurements with doxorubicin. Nanostructured electrodes were fabricated by electrochemical anodic oxidation when the aluminium layer was transformed to the...

Fabrication and electrochemical characterization of disposable working electrodes/transducers of electrochemical sensors is described in this work. The aim was to find the best electrochemical properties of screen-printed electrode substrates modified with multiwalled carbon nanotubes (MWCNTs) based active layers. Two types of platinum electrode co...

There is a growing interest in using semiconductor quantum dots (QDs) as optical labels for biosensing events. QDs have been linked with bio-recognition molecules such as proteins, peptides and nucleic acids, and have been successfully used in biological and medical fields such as immunoassay, DNA hybridization, cell imaging and potential photodyna...

In this paper Cu2O nanoparticles were prepared and used for the construction of novel electrochemical voltammetric biosensor for the simultaneous detection of adenine and guanine. Cu2O nanoparticles were synthesized via simple wet chemical route, where glucose was used as a reductant. The nanoparticles were characterized by SEM and XRD analysis, wh...

This work covers an area of planar electrochemical sensors for fast and reliable detection of species in environment under field conditions or in vitro/vivo biodetection. In this work, there were fabricated several planar carbon working electrodes using standard thick film technology which were modified with multiwalled carbon nanotubes (MWCNTs) to...

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 o...

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 o...

In many applications, plasma processing of materials appears to be an advantageous alternative to conventional chemical methods because it offers effective and environmentally friendly method for processing of materials. In this work, the surface bound deposition of carbon nanotubes (CNTs) and volume synthesis of iron oxide nanoparticles (NPs) was...

Electrochemical determination of purine bases using screen-printed and spray-coated working electrodes on alumina substrate based on Cu2O nanoparticles is described in this work. Cu2O nanoparticles were synthetized using simple precipitation method and used for thick-film planar microelectrodes fabrication. The Cu2O nanoparticles were characterized...

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 nanodimensions increases in combination with possible life saving fun...

Numerous analytical, bioanalytical, biochemical and biological instruments have been developed for determination of specific and/or group of compounds, species, cells even organisms, but most of them suffer from the impossibility to miniaturize these instruments in spite of the fact that they have many other advantages. Due to the above-mentioned f...

Luminescent quantum dots (QDs) have gained a great attention as promising candidates in optical detection of various biomolecules such as DNA, proteins, etc. In this paper, we focused on fabrication of QDs in the deposited form, which still belongs to less clarified and used approach in biosensing compared to colloidal one. The deposited QDs from n...

Luminescent quantum dots (QDs) have gained a great attention as promising candidates in optical detection of various biomolecules such as DNA, proteins, etc. In this paper, we focused on fabrication of QDs in the deposited form, which still belongs to less clarified and used approach in biosensing compared to colloidal one. The deposited QDs from n...

This paper describes a new approach to study the emission properties of carbon nanotubes in low distances between two electrodes. Each electrode consists of high doped silicon substrate. The field emission works on the principle that the field emission current is correlated with the electrical field intensity, i.e. the anodeemitter distance when th...

The purpose of this work is to characterize the nanostructured electrochemical sensors composed of ordered gold nanowires array. Noble metals, especially, gold, are very suitable for biological applications in the field of fragment DNA detection. In this case, the EIS (electrochemical impedance spectroscopy) is usually used for surface characteriza...

Luminescent quantum dots (QDs) are increasingly attracting the attention as possible optical detectors of biomolecules, such as proteins, DNA, etc. Large amount of different factors influences the selection of material for QDs synthesis when dealing with substances from living organisms. Non-toxic and biocompatible titanium dioxide (TiO2) and gold...

Lead as one part of heavy metals group pose a detrimental risk to human health and the environment due to its toxicity, even exposure to minuscule quantities can be life threatening. Levels of lead are not stable in the environment and vary according to industrial production, urbanization, climate changes and many other factors. It is not surprisin...

Carbon nanotubes (CNTs) have been under scientific investigation for more than fifteen years because of their unique properties that predestine them for many 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 ap...

Electrochemical detection of DNA damage in vitro has been used to evaluate the antioxidant properties of transgenic tobacco plant extracts containing metallothionein (MT). This method is based on assessment of efficiency with which the studied plant extracts are able to reduce to the amount of damage of standard chicken DNA by free OH radicals prep...

The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nuc...

The results of the research in areas of chemical sensors and tools for medical application are presented and described their promising properties, using in techniques, and potential applications. The techniques of surface manufacturing are used for sensing properties advancing, quantum dots and their potential in in-vivo diagnosis can bring nanotec...

This paper deals with problem of miniaturization of sensors for electrochemical analysis of various substances in aqueous solutions. Multiwalled carbon nanotubes based working electrode of electrochemical sensors has been fabricated as carbon nanotubes based nanocomposite sprayed on previously prepared thick-film substrate. Fabricated electrodes we...

This work presents actual modern technique for preparation of nanomechanized surface for sensors application. One of them is metal electrodes which are covered by metal nanowires the second one is array of separated metal nanoelectrods. Central to this issue is the development sensors for high sensitivity, high selectivity, high stability and rapid...

This work focuses on developing TiO2 planar ordered nanostructures (quantum dots) for sensing of various biomolecules (DNA, proteins) in vitro, which may be of great importance for clinical diagnostics and in vivo imaging. This sensor array also called "fluorescence array detector" can provide various emitting QDs depending on wavelengths, and thus...

This paper deals with the problematic of microsensors for electrochemical detection of species in aqueous solutions, where the main problem is reduction of geometrical size of the electrodes in comparison to standard electrodes resulting in lower current response. In this paper there was fabricated thin film substrate of working microelectrode on s...

This contribution presents the production of polymer-coated iron oxide magnetic nanoparticles carrying functional groups on their surface and their basic characterization. The preparation of polymer-coated nanoparticles was carried out by a two-step process. In the first step, magnetite (Fe 3 O 4) nanoparticles were prepared by a co-precipitation m...

There is a growing interest in using semiconductor quantum dots (QDs) as optical labels for biosensing events. The size-controlled fluorescence properties of QDs, the high fluorescence quantum yields of QDs and their stability against photobleaching makes QDs superior optical labels for multiplex analysis. In this paper, biotin-conjugated glutathio...

Current development of miniature analytical instruments for detecting heavy metals in varying samples is very dynamic. One of the most interesting representatives of these instruments are biosensors, which combine the physico-chemical transducer with biological components. Biosensors can operate on different principles and their preparation can lea...

This work covers an area of miniaturized electrochemical systems for detection of substances matters in aqueous solutions. Multiwalled carbon nanotubes powder has been used for preparation of screen-printable paste nanocomposition using suitable polymer vehicle. Fabricated electrode has been used for electrochemical analysis of cadmium and lead ion...

Recent research showed the availability of atmospheric pollutant monitoring using a gas sensor with nanostructured surface of sensing electrode which can be prepared through an anodization process. The use of anodization technique for obtaining oxide porous material which can be used e. g. as nano-template was firstly reported in the work of Masuda...

Purpose The purpose of this paper is to design and create a potentiostat that can be integrated and encapsulated within a microelectrode as a low‐cost electrochemical sensor. Recently, microsystems on sensors or lab on a chip using electrochemical detection of substances matters are pushing forward into the area of analysis. For providing electroch...

This paper describes a new approach to study the emission properties of carbon nanotubes in low distances between two electrodes. Each electrode consists of high doped silicon substrate. The field emission works on the principle that the field emission current is correlated with the electrical field intensity, i.e. the anodeemitter distance when th...

Screen-printed with three electrode system was used in this study. A working electrode has been printed from carbon nanotubes based paste on silver layer modified with nano-patterned structures for the first case. In the second case, vertically aligned carbonnanotubes were grown on the Au working electrode. The process of the nanotubes growing was...

Paper deals with a problematic of thick-film electrochemical sensors for trace analysis of species or elements in aqueous solutions. A problem of replacement of classical Ag/AgCl reference electrodes by planar thick-film electrodes is discussed here. In this paper there were compared several thick-film reference electrodes with classical ones using...

One of current trends is a sensor miniaturization by integration of sensing element with measuring circuits. The hybrid technology seems to be optimal for the miniaturization employing thick-film technology and mounted ASIC. The output signal from thick-film electrochemical sensor is low and output signal quality is often very reduced by long signa...

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 s...

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...

This paper deals with the problem of the replacement of mercury drop electrodes with solid electrodes in standard polarography. The screen-printed thick-film sensor with a three-electrode system was prepared. A working electrode was modified with nanopatterned nanostructures. Vertically aligned carbon nanotubes (CNTs) were grown on the working elec...

An electrode topology design is one of the important parts of thick-film electrochemical sensors design. The rules for optimization of electrode systems in classical electrochemistry exist, but the thick-film electrodes topology design is limited (substrate dimensions, resolution, paste parameters, etc.). Therefore rules for classical electrode sys...