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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...

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 subsequent re-anodizing of pure Zr (99.99%) layers, following the initial formation of a porous anodic alumina (PAA) overlayer, at voltages ranging 50 to 500 V. The films formed after the dissolution of PAA consist of upright-standing zirconium-oxide nano-protrusions shaped like ‘polyps’ (anodized samples) or pillars and rods (re-anodized samples) anchored by tiny widespread nanoroots to the bottom oxide layer. The arrays synthesized in 0.2 M H3PO4, which was chosen as a model electrolyte, consist of stoichiometric ZrO2, the suboxides Zr2O3 and ZrO, a minor amount of Al2O3, and traces of PO43− species. Unexpectedly, all the anodic zirconium oxide in the re-anodized sample forms in an amorphous and perfectly flawless manner. The oxide grows due to the cross-migration of oxygen and zirconium ions with nearly equal transport numbers, which is a unique situation for anodic films on pure Zr metal. Annealing the films at 600 °C in air increases the oxidation state of the zirconium ions and induces an amorphous-to-crystalline transition, with the formation of highly textured monoclinic ZrO2 (P21/c) nanocrystallites, without generating destructive stresses or physical defects. Annealing under vacuum (10−4 Pa) partly reduces the oxide to Zr metal, with the concurrent growth of a ZrO2 phase of the same structure and texture but in substantially larger amounts. The impact of these new findings, with detailed understanding of the abnormal ionic transport, paradoxical oxide growth, and phase-transition effects, is considered, focusing on specific applications relating to surface finishing, electronics, optics, and biomedicine.

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 fo...

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 similarly long but bigger Nb2O5 nanorods, 100 nm wide, 220 nm spaced, and of 8·108 cm−2 density, aligned directly on a niobium metal without any buffering oxide layer, which was achieved for the first time. Each film was then incorporated in an advanced 3-D architecture and multilayer layout on a silicon chip comprising 33 microsensors, with variable sizes and tuned electrical characteristics, by combining the high-temperature vacuum or air annealing, sputter-deposition and lift-off photolithography to form Pt/NiCr top electrodes and a multifunctional SiO2 interlayer, chemical etching, laser dicing, and ultrasonic wire-bonding. The proposed on-chip sensor solution allowed for a sensitive, fast, and highly selective (toward NH3 and CH4) detection of hydrogen gas. Comprehensive gas sensing tests performed for Type II nanofilm ultimately confirmed the presence of a Schottky-type sensing mechanism, the contribution, however, being substantially weaker than that due to reactions over the surface of the oxide nanorods, especially when the rods show a transition from fully to partially depleted states when interacting with H2 gas. The film formation and chip fabrication technologies may be transferable to other PAA-assisted 1-dimensional metal-oxide nanomaterials suitable for on-chip gas sensing.

This contribution deals with the main parts of the textile-integrated transmitting unit, a transmitter and an antenna, operating in the ISM 5.8 GHz band. The transmitter is based on commercially available WLAN UART Serial Port OWS451 and it is controlled via the UART interface by microprocessor ATmega328. The antenna is based on the circular ring-slot concept and it is able to provide monopolar radiation pattern to ensure maximum coverage of the unit. The unit will be integrated in a seat cover and it will transmit the telemetry of sensors integrated in the seat (temperature, pressure…).

The paper summarizes experience with the development of high-frequency electronic components which are manufactured on a three-dimensional knitted material instead of a conventional microwave substrate. Attention is turned to specific aspects of the design, manufacturing and integration of components to applications. Technological problems, which have not been solved yet, are discussed.

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 microscopy. The films were prepared by anodizing magnetron-sputtered Al/Zr bilayers in two regimes: galvanostatic/potentiostatic anodizing in (COOH)2 and H2SO4 solutions (anodized films) and that followed by the high-speed reanodizing to a significantly higher anodic voltage (reanodized films). The growth of a porous anodic alumina (PAA) layer followed by PAA-assisted oxidation of the Zr underlayer was achieved. The anodized films consist of arrays of self-organized spatially ordered ZrO2 nanohillocks while the reanodized films comprise arrays of vertically aligned ZrO2 nanorods. The growth of amorphous ZrO2 nanohillocks and nanorods within the alumina pores via migration of Zr4+ cations is a unique situation for anodic films on zirconium, which normally grow crystalline and by O2- anion transport at the oxide/metal interface only. The achievement is a milestone towards understanding the ion transport during the PAA-assisted anodization of valve metals with low cation transport numbers

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 in an island form. Oxygen plasma treatment ensured deposition of a continuous TiO2 film, 5 nm in thickness. A granular form of TiO2 was obtained on oxygen plasma treated MWCNTs using shorter duration of Ti-precursor pulse. Different imaging modes in high resolution transmission electron microscopy visualized TiO2 nanostructures and defects in MWCNT walls. The latter were also confirmed by Raman spectroscopy. The morphology of TiO2 and oxygen plasma treatment of the MWCNTs highly affected the NO2 sensing behavior of chemiresistive heterostructure sensors at room and elevated temperatures. All investigated sensors exhibited a decrease in the resistance upon exposure to NO2 gas which implies a p-type sensor response. The granular TiO2/MWCNTs heterostructure showed the highest response towards NO2 gas as compared to the island and continuous forms.

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 technology compatibility of this material. In this study, we investigate the resistive switching behavior of nanostructured HfO2 film embedded in a porous anodic alumina matrix. The film was synthesized via self-organized electrochemical anodizing of a sputter-deposited Al/Hf bilayer on a Si substrate in an oxalic acid solution. The film was investigated by scanning electron microscopy. Simple metal/insulator/metal devices were prepared by sputter-deposition of Pt top electrodes through a shadow mask onto the nanostructured film. Assembled devices were characterized by I-V measurements. A bipolar eight-wise resistive switching was obtained, demonstrating a highly repeatable and stable low-voltage behavior in a set potential range. The achieved results indicate the high potential of the anodizing technique as an alternative to commonly used methods for producing insulating thin films for resistive random-access memory application.

We presented the development and characterization of high-k stack HfO 2 /Al 2 O 3 capacitor, fabricated directly on chip. The capacitor is based on nanolaminate material directly grown by plasma-assisted Atomic Layer Deposition (ALD)in a single reactor chamber. The deposition process was performed at a single temperature (250°C). We tested the various numbers of layers in the stack, compared the electrical and material characterizations. Using the optimal deposition conditions, we obtained a structure with nanolaminates of single thickens 5 A, capacitance density of 1.10−12 F.μm−2 and leakage current density of $1.10^{-9}$ A.cm−2.

In this paper we optimize cryogenic deep reactive ion etching processes to achieve the best aspect ratios of holes in a silicon substrate that is supposed to be used for fabrication of on-chip energy storage. By optimizing capacitively coupled plasma source power and oxygen flow, aspect ratio of 28:1 for holes of 2 μm in diameter was achieved. Bottling effect was suppressed by tuning capacitively coupled plasma, inductively coupled plasma sources and process pressure at the same time. The smoothness and purity of the hole walls are other parameters we investigate using atomic force microscopy and X-ray photoelectron spectroscopy.

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 microscopy. Membranes with pore diameters of 90 nm and 30 nm and thicknesses of 115 µm and 163 µm respectively were obtained. Fabrication of membranes with different post-treatment was also done. In this post-treatment process, etching of non-anodized aluminium and opening of barrier layer were replaced with application of reversible potential with equal magnitude as anodization voltage.

Plasma treated and atomic layer deposition (ALD) modified multi-walled carbon nanotubes (MWCNTs) were investigated for their gas sensing properties towards ammonia gas. Titanium dioxide was deposited by ALD on plasma treated nanotubes and these modified and pristine nanotubes were compared for their gas sensing behavior. Functionalized MWCNTs showed higher response as compared to untreated ones. This favored response was the result of the increase in the defect density after plasma treatment and TiO 2 coating by ALD. Defects act as active sites for adsorption of ammonia gas molecules enhancing the sensitivity. Increase in the defect density was also proved with Raman analysis. Morphology and microstructure of the modified MWCNTs were studied using SEM.

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/SiO2 substrates by chemical vapour deposition in Ar/C2H2 gas mixture using iron catalytic nanoparticles. The analysis of the grown layer by the scanning and transmission electron microscopy showed the transition from long multiwalled nanotubes (MWCNTs) to bamboo-like hollow carbon nanofiber structure with the decrease of the deposition temperature from 700 to 600°C. Further, the material was analyzed by energy-dispersive X-ray spectroscopy and Raman spectroscopy confirmed the transition from graphitic sp2 structure to highly defective structure at lower deposition temperature. The resistance of the prepared layer strongly depends on deposition temperature (Td) and deposition time (td). High resistance layer, 38.6 kΩ, was formed at Td 600°C and td 10 min, while at Td 700°C and td 60 min, the resistance decreased to 860 ohms. Such behaviour is consistent with MWCNTs being responsible for the formation of the conductive network. Such system was studied using chemiresistor ammonia gas sensor configuration. The sensor resistance increased when exposed to ammonia in all the cases, but their response varied considerably. A decrease in deposition time, from 60 to 10 min, and the deposition temperature, from 700 to 600°C, led to the 10-fold increase in the sensor response. The measurements carried out at room temperature showed the higher sensor response than the measurements carried out at 200°C. This behaviour can be explained by the change in adsorption-desorption equilibrium at different temperatures. Analysis of dependence of the sensor response on the ammonia concentration proved that the underlying resistance change mechanism is chemisorption of ammonia molecules on the carbon network corresponding to the Langmuir isotherm.

Atomic layer deposition (ALD) is a strong method of fabrication of high-k dielectrics with excellent properties. We present the ALD grown high-k CMOS compatible dielectrics used for capacitors on a chip application. Several dielectric films based on Al 2 O 3 and HfO 2 were grown on high-conductive silicon wafers and used as on-chip circular capacitors with diameter from 100 to 1500 µm. The effect of the interface between dielectric layers was examined in oxide stuck-based films deposited by plasma-enhanced atomic layer deposition. Performed material, structural and electrical analyses of deposited dielectrics confirmed their highly promising properties for application in new generation of 3D capacitors, semiconductor devices and energy storage element.

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 elements were designed, and the power consumption was calculated. Fabricated structures are studied and compared with the theoretical data obtained from simulations.

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 performance and the lowest power consumption. Power consumption of the device is decreased to a value which allows designing the device as a zero-powered system using energy harvesting. A combination of micro-mechanized diaphragm filter bank, energy harvesting power source and especially ultra-low power processing electronics is presented in this article. A new technique of output signal generation for nerve stimulation is described. This new technique named charge push-through uses the major part of energy generated by energy harvesting subcircuit for output useful signal generation with minimal undesirable current. Thermal and mechanical parts were investigated using complex electro-mechanical simulations. The real energy harvesting power source (human motion, temperature) was experimentally measured. Signal processing circuits powered by energy harvesting power source were designed and simulated. The new signal processing circuits were simulated in relation to the results of complex electro mechanical diaphragm and SPICE energy harvesting power source simulation.

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 (10-1000 ppm) and under different humidity levels (3-65 %). It was concluded that the graphite oxide based sensor possessed high response to NH3 in synthetic air (R/R0 ranged from 2.5 to 7.4 % for concentrations of 100-500 ppm and 3 % relative humidity) with negligible cross-sensitivity towards H2 and CH4. It was determined that the sensor recovery rate was improved with ammonia concentration growth. Increasing of ambient relative humidity led to increase of sensor response. The highest response of 22.2 % for 100 ppm of ammonia was achieved at 65 % relative humidity level. V článku je oxid grafitu jako možná citlivá vrstva chemorezistivního senzoru na amoniak pracujícího při pokojové teplotě. Snímací vlastnosti byly testovány v širokém rozmezí koncentrací amoniaku ve vzduchu (10-1000 ppm) a při různé vlhkosti (3-65 %). Byl učiněn závěr, že senzor s oxidem grafitu vykazoval vysoké odezvu na NH3 v syntetickém vzduchu R/R0 v rozmezí 2,5 až 7,4 % pro koncentrace 100-500 ppm a 3 % relativní vlhkosti) se zanedbatelnou krossenzitivitou vůči H2 a CH4. Bylo zjištěno, že rychlost zotavení senzoru se zlepšovala s rostoucí koncentrace amoniaku. Zvýšení relativní vlhkosti prostředí vedlo ke zvýšení odezvy senzoru. Na úrovni relativní vlhkosti 65 % bylo dosaženo nejvyšší odezvy 22,2 % pro 100 ppm amoniaku.

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 nonobtrusive cochlear implant. This work presents the solution of Charge Push-Through circuits using the component level design of artificial cochlea. V práci je popsána nová technika protlačení náboje, což je technika zpracování signálu s významným snížením spotřeby zařízení. Metoda protlačení náboje je slibnou technikou u perspektivních systémů se soběstačným napájením využívajících tzv. Energy Harvesting. Článek obsahuje rozbor a simulaci obvodů na součástkové úrovni.

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 to achieve the optimal properties of thin film, we investigated the Ti thin films deposited on an amorphous thermal silicon dioxide using X-ray diffraction, and atomic force microscopy. We have optimized deposition conditions for growing of thin films with the only (001) preferential orientation of film crystallites, and achieved ultra-low surface roughness of 0.55 nm. The deposited films have been found to be stable upon annealing up to 300 °C which is often essential for envisaging subsequent deposition of piezoelectric AlN thin films. Práce se zabývá iontovým naprašováním titanových tenkých vrstev a studiem jejich krystalografie a drsnosti. Tyto parametry obvykle nejsou proveditelné konvenčními metodami magnetronového naprašování nebo vakuového napařování. Naprašování bylo realizováno pomocí Kaufmanova iontové zdroje. Nadeponované tenké vrstvy byly analyzovány pomocí XRD a AFM. Optimalizováním depozičních parametrů bylo dosaženo (001) preferenčně orientovaných krystalitů a velmi nízké drsnosti 0,55 nm. Teplotní stabilita titanových tenkých vrstev byla ověřena do 300 °C pro případné depozice nitridu hliníku, který pro dosažení požadovaných vlastností vyžaduje zahřívání substrátu při depozici.

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 array of microelectromechanical piezoelectric membranes. Oscillations of membranes detect and filter acoustic signals in individual acoustic frequencies. The proposed biomechatronic device of the artificial cochlear implant consists of an active filters array, signal processing electronics, stimulation nerves electrodes and energy harvesting system for autonomous powering of the device. This solution differs from current cochlear implants solutions, which are bulky electronic systems limited by their high power consumption. The multidisciplinary models of the artificial cochlea implant concept are presented. The mechatronic approach based on model seems to be very useful for development of the full implantable cochlear implant which is designed for the sensing and processing of acoustic signals without external energy source.

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 chemical vapor deposition method using microwave plasma torch at atmospheric pressure. This growth method enables us to use a simple electrode structure without need of buffer layer and time-consuming lithography process. Combination of CNTs field emission and MEMS membrane mechanical properties make possible to enhance sensitivity of the sensor. Field emission properties of CNTs are measured by newly developed system enabling us precise measurement of expecting properties, such as dependence on diaphragm (upper electrode) distance, applied voltage, and stability of the sensor. Measured values are compared with a numerical modeling of the membrane system in Coventor Ware software by finite-element method. We also suggest encapsulating the sensor using glass frit bonding because such method is more suitable for high vacuum requirements of the field emission operation.

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 configuration of mechanoelectrical transducers (polycrystalline diffused piezoresistors) displayed in the first experiment is offered. Finally, the eigenfrequencies of resonant membranes calculated employing finite element systems Ansys and CoventorWare are introduced.

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. Mikro-elektro-mechanický pole plně implantabilní hlemýžď je uveden v tomto článku.Kompletní systém včetně krátký přehled o sklizni energie a konfiguraci systému se navrhuje. Tato studie se týká hlavně mechanický vlastnosti hlemýždě mikrofabrikovaném křemíkové struktuře. Elektromechanické simulace pokračoval optimalizaci materiálu používá pro rezonátory, velikost pole membrán a pro odhad odporové změny v důsledku zvukového signálu na vstupu. Zvuk je detekovány tenkou SiXNY membránou v důsledku rezonanční frekvence a posunutí membrány způsobené akustického tlaku. Posunutí je detekován zaměstnává piezorezistivních elektrody (NiCr). Design a zhotovení proces založený na MEMS technologie jsou popsány a diskutovány.Měření odezvy konstrukce hlemýždě se provádí.

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/O-2, Ar/cyclopropylamine and Ar/NH3. The surface of the WEs was characterized by scanning electron microscopy and their electrochemical behaviours were studied using potassium ferro/ferricyanide and dopamine as standard electrochemical probes. The most promising results were obtained with the electrodes modified by oxygen plasma because the reversibility and the current response were both improved significantly. The peak-to-peak separation improved from 879 to 116mV after the oxygen plasma treatment of the bare DuPont 7102 electrode. Spray-coated MWCNTs had a positive effect on the performance of the screen-printed DuPont 7102 WE if the sprayed MWCNTs layer was thicker. However, this improvement did not reach the performance of the screen-printed DuPont electrode modified by plasma oxidation. The modification by Ar/NH3 had weak influence on the response depending on the type of the electrode and plasma treatment in Ar/cyclopropylamine plasma led to an inhibition of the electrochemical reactivity due to a preparation of too thick insulating film.

Remote-controlled robotic systems are being used for analysis of various types of analytes in hostile environment including those called extraterrestrial. 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 with a culture chamber with volume 600 μL. The flow rate was optimized to 500 μL/min. The chip was tested primarily for detection of 1-naphthol by differential pulse voltammetry with detection limit (S/N = 3) as 20 nM. Further, the way how to capture bacteria was optimized. To capture bacterial cells (Staphylococcus aureus), maghemite nanoparticles (1 mg/mL) were prepared and modified with collagen, glucose, graphene, gold, hyaluronic acid, and graphene with gold or graphene with glucose (20 mg/mL). The most up to 50% of the bacteria were captured by graphene nanoparticles modified with glucose. The detection limit of the whole assay, which included capturing of bacteria and their detection under remote control operation, was estimated as 30 bacteria per μL.

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 SEM, EIS, and Mott-Schottky analysis. The films are composed of HfOx nanorods, which grow in the pores, anchored to a continuous HfO2 bottom layer by tiny HfOx nanoroots penetrating the alumina barrier layer. The understanding of film nucleation and growth is advanced through disclosing the hidden features and field-assisted modifications of the metal-oxide interfaces, such as O2-filled nanosized voids and individual hafnium-oxide nanoroots dominating within the alumina barrier layer and securing electron transport to each nanorod. The films reveal a unique combination of electrical properties, such that the bottom oxide behaves like an ideal dielectric whereas the roots and rods show semiconducting behavior. A 600 °C annealing at atmospheric pressure surprisingly leaves the rods and roots semiconducting and still amorphous while the annealing at 10−5 Pa transforms the entire film to a nanocrystallite-containing n-type semiconductor, of a high doping density of up to 2 1021 cm−3. Further anodic polarization of the PAA-free vacuum-annealed film generates dielectric anodic oxide over the film, of thickness proportional to applied potential until the thinner roots and finally the dominating root become fully blocked for electron conduction. Potential applications include high-k dielectrics for high-voltage electrolytic capacitors, semiconducting active layers for gas sensing, or photoanodes for photoelectrochemical water splitting.

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 layer to the silicon substrate. All electrodes were characterized by electrochemical impedance spectroscopy and then the electrochemical determination of doxorubicin was studied by differential pulse voltammetry. The impedance spectroscopy measurements proved a bigger electroactive area for nanostructured electrodes. The gold nanocolumns have been found as an important factor in increasing of electrodes active area. This fact is very important for sensors sensitivity. Fabricated electrodes were successfully used for determination of doxorubicin.

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 NH3 in dry synthetic air (R/R0 ranged from 2.5% to 7.4% for concentrations of 100–500 ppm and 3% relative humidity) with negligible cross-sensitivity towards H2 and CH4. 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. Byl zkoumán oxid grafitu jako možný materiál pro chemiresistivní senzor amoniaku za pokojové teploty. Oxid grafitu byl syntetizován z vysoce čistého grafitu modifikovanou Hummers metodou. Vzorek oxidu grafitu byl analyzován pomocí skenovací elektronové mikroskopie, energiově disperzní rentgenové spektroskopie, rentgenové difrakce, thermogravimetrie a diferenční skenovací kalorimetrie. Senzorické vlastnosti byly testovány v širokém rozmezí koncentrací amoniaku ve vzduchu (10 – 1000 ppm) a za různé relativní vlhkosti (3-65 %). Byl učiněn závěr, že senzor na bázi oxidu grafitu má dobrou odezvu na NH3 v suchém syntetickém vzduchu (R/R0 se pohyboval od 2,5 % do 7,4 % pro koncentrace 100-500 ppm při relativní vlhkosti 3 %) se zanedbatelnou krossensitivitou na H2 a CH4. Bylo zjištěno, že se s růstem koncentrace amoniaku zkracovala doba zotavení senzoru. Zvyšení relativní vlhkosti prostředí vedlo k zvýšení odezvy senzoru. Při relativní vlhkost 65 % bylo dosaženo nejvyšší odezvy 22,2 % pro 100 ppm amoniaku.

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 fabricated by a screen-printing technology using a silver paste. Walls of waveguides integrated into the textile substrate are created by sewing with a conductive thread. Functionality of antennas was verified by computer simulations and measurements.

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 based sensor has higher response (2.4% to 7.4% in range from 100 ppm to 500 ppm) than the multi-walled carbon nanotubes based one (1.0–2.4%). On the other hand, the carbon nanotubes based sensor possessed higher recovery rates in a wide range of used concentrations.

In the paper, we compare selected concepts of planar antennas developed for body-centric wireless communication to be operated in ISM frequency bands. Antennas, which were originally designed for Teflon-based substrates, have been redesigned for textile materials to create their wearable versions. Wearable antennas have been implemented using conductive fabrics, inkjet printing and screen printing. As a substrate, conventional fabrics and 3D textile materials have been used. Newly developed textile versions of antennas are compared with original Teflon-based antennas from the viewpoint of impedance characteristics.

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, which showed the presence of spherical aggregations with diameter of 1000 nm. These nanoparticles were successfully used for fabrication of spray-coated and screen-printed working electrodes on alumina substrate for the electrochemical detection of purine bases. We observed that Cu(I) reacts with adenine to form insoluble complex that accumulates on the electrode surface and causes the decrease of current response. In the case of guanine, we did not observed any significant decrease of current response which is probably caused by adsorption of guanine on the electrode surface. V tomto článku jsou Cu2O nanočástice připraveny a použity pro výrobu nového, elektrochemického, voltametrického biosenzoru pro detekci adeninu a guaninu. Cu2O nanočástice byly syntetizovány pomocí jednoduché syntézy s využitím glukózy jako redukčního činidla. Nanočástice byly charakterizovány SEM a XRD analýzou, která prokázala přítomnost kulovitých shluků o průměru 1000 nm. Tyto nanočástice byly úspěšně použity pro výrobu pracovní elektrody metodou sítotisku nebo spray coatingem. Sledovali jsme, že Cu (I) reaguje s adeninem a vytváří nerozpustný komplex, který se hromadí na povrchu elektrody a způsobuje pokles proudové odezvy. V případě guaninu nebylo pozorováno významné snížení proudové odezvy, je to pravděpodobně způsobeno adsorpcí guaninu na povrchu elektrody.

PurposeThe 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 electrochemical analysis, the microsystem has to be equipped with an integrated potentiostat.Design/methodology/approachThe integrated potentiostat with four current ranges (from 1 μA to 1 mA) was designed in the CADENCE software environment using the AMIS CMOS 0.7 μm technology and fabricated under the Europractice program. Memory cells of 48 bytes are implemented with the potentiostat using VERILOG.FindingsThe characteristics of integrated potentiostat are strictly linear; the measured results confirm the simulated values. The potentiostat measurements error is about 1.5 percent and very low offsets are reached by the offset‐zeroing circuitry.Research limitations/implicationsThe detection limit of the current at the lowest range with respect to S/N ratio is about 10 nA.Practical implicationsThe integrated potentiostat is embedded on a screen‐printed sensor and its characteristics are successfully verified. Lower range of 100 nA can be implemented on a new microchip as well as rail‐to‐rail output circuitry would increase the voltage dynamic range.Originality/valueThe integrated potentiostat with very good parameters is designed for a wide spectrum of electrochemical applications such as lab on a chip, embedded electrochemical systems, etc. The integrated system enables storing of information about the system measured, for instance, calibration and fabrication data of the electrochemical sensor.

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 tested to create homogenous and high density carbon nanotubes layer directly on the thick-film silver layer. Based on the characterization of electrodes, we used Au based for detection of nucleic acids. Moreover, we were able to estimated melting points of DNA.

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 electrode. The process of the nanotubes growing was tested to create a homogeneous (CNTs) and high density CNT layer directly on the thick-film silver (Ag) layer. Thereby, the modified electrode is presented to be very perspective in heavy metal detection using electrochemical methods because of improvement of detection properties. The authors were able to determine the concentration of cadmium ions in units of µmol/L.

This paper presents a way how a simulation model of an industrial Ethernet network is designed and how it is parametrised according to a real network. The parameter set up is done by capturing the Ethernet frames in the network and by performing their detailed analysis. The device types in the simulation have been designed as generic that can be parametrised externally and automatically based on the identification of a real network. Thus the parameters of the real devices such as switch delay are used to adapt the simulation and the simulation results are compared to the real traffic in a series of long-term observations. Such a setting can be used to perform diagnostics of industrial Ethernet networks to identify e.g. bursts of messages and thus discovering potential bottlenecks and problems aiming at interrupting or disturbing the connected application process, eventually.

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 fully implantable artificial cochlea is described in this article. The proposed artificial cochlea consists of many subcircuits which have to be designed in close context to reach optimal performance and the lowest power consumption. Power consumption should be decreased to a value which allows using cochlear implant as a zero-powered system. A combination of micro-mechanized diaphragm filter bank, possible energy harvesting power source and especially ultra-low power processing electronics is presented in this article. A unique technique for nerve stimulatory output signal generation is discussed. This new technique named charge push-through electronics should use the major part of energy generated by energy harvesting subcircuit for output useful signal generation with minimal undesirable current. Mechanical parts of the subcircuits were simulated as complex electro-mechanical simulation models in ANSYS, CoventorWare, Matlab and SPICE environment. First, the real energy harvesting power source (human motion and temperature) behavior was measured. The model of this behavior was created in simulation environment and then the whole electronics simulation model for energy harvesting circuits was estimated. Next, signal processing circuits powered from energy harvesting power source were designed and simulated. The new signal processing circuits were simulated in relation to the results of complex electro mechanical diaphragm and SPICE energy harvesting power source simulation.

Miniaturization and integration of chemical devices into modules that are dimensionally comparable with electronic chips (Lab on Chip) is nowadays developing worldwide. The aim of our work was to suggest and optimize the best conditions for fabrication of TFT sensor due to its sensitivity and low experimental deviations. New electrochemical analytical device was developed to ensure certain known mass transport to electrodes, which is the most limiting process that influencing the response quality of the sensor. The device consists from rotating conic vessel for measured sample and stick-in thick-film sensor.. The sensors responses were tested under trace analysis of cadmium. Measurements were done also with the others electrochemical arrangements to compare with the new one. The sensor output current response dependence on the liquid velocity and geometrical arrangement within using standard electrochemical couple of potassium ferrocyanide-ferricyanide is presented. We found out that the new device with controlled flow of electrolyte to sensor worked properly and gave satisfactory results. Dnešním celosvětovým cílem je miniaturizace a integrace chemických zařízení do malých modulů které jsou rozměrově srovnatelné s elektronickými čipy (Lab on Chip). Cílem naší práce bylo navrhnout a optimalizovat co možná nejlepší podmínky pro výrobu tlustovrstvého senzoru tak, aby byl dostatečně citlivý s minimální odchylkou měření. Pro zajištění přesně definovaného přísunu hmoty k elektrodám, což je nejvíce limitujícím procesem majícím vliv na výstupní odezvu senzoru, bylo vyvinuto nové elektrochemické analytické zařízení. To se skládá z rotující konické nádobky pro uložení měřeného vzorku a do ní vloženého tlustovrstvého senzoru. Odezva senzoru byla testována na stopové analýze kadmia. Pro porovnání nového zařízení byla provedena stejná měření i na jiných elektrochemických uspořádáních. Je zde ukázána i výstupní proudová odezva senzoru v závislosti na rychlosti roztoku a geometrickém uspořádání při měření standardního elektrochemického redoxu fero-ferykyanidu draselného. Zjistili jsme, že nové zařízení s řízeným tokem elektrolytu k senzoru pracuje správně a podává uspokojivé výsledky.

Screen‐printed electrodes are widely used in the construction of sensors. The use of graphite material is preferred due to its simple technological processing and low cost. Different graphite pastes are compared for hydrogen peroxide detection. The slope of the calibration curve, linearity and limit of detection have been compared for different pastes and technologies of graphite electrode preparation. The influence of the structure of the paste on response is discussed. Physical methods of sensitivity enhancement are proposed. All results are compared with platinum electrode as technological reference.

We have studied the effect of adhesion promoters (bismuth and copper oxides) on the gas sensing properties of screen-printed tin and tungsten oxide sensors. The gas-sensitive pastes were prepared by mixing either tin or tungsten oxide powders with an organic vehicle based on therpineol. Two different additives to enhance the adhesion of the active films to the substrate (Bi 2 O 3 or Bi 2 O 3 +Cu 2 O) were included in the paste composition. The films that resulted after printing and firing have high porosity and excellent adherence. Morphology studies have shown that the films have well-defined microstructure and gas sensitivity studies have shown that additives, not only help in promoting film adhesion, but also modify the response of the sensors. Their sensitivity at different operating temperatures was evaluated for ammonia, nitrogen dioxide, ethanol, benzene, carbon monoxide, methane and water vapour. It was found that WO 3 sensors containing Bi 2 O 3 and Cu 2 O were always more sensitive to ammonia and, that WO 3 sensors containing Bi 2 O 3 only were more sensitive to nitrogen dioxide when operated at 250 °C. The reaction paths that explain the sensitivity changes observed by the inclusion of Cu 2 O in tungsten oxide sensors are introduced and discussed.

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 um 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 spectroscopy. Basic electrochemical characterization was performed by cyclic voltammetry. Comparing the obtained results with the standard or MWCNT modified screen-printed electrodes, the prepared VA-MWCNT electrodes indicated their high potential for the construction of electrochemical sensors. Resistive CNT gas sensor revealed a good sensitivity to ammonia taking into account room temperature operation. Field emission detected from CNTs was suitable for the pressure sensing application based on the measurement of emission current in the diode structure with bending diaphragm. The advantages of microwave plasma torch growth of CNTs, i.e., fast processing and versatility of the process, can be therefore fully exploited for the integration of surface-bound grown CNTs into various sensing structures. Vertikálně uspořádané vícestěnné uhlíkové nanotrubice (VA-MWCNTs) se středním průměrem pod 80 nm a tloušťce VA-MWCNT vrstvy asi 16 um byly vyrobeny v mikrovlnném plazmovém výboji a testovány na vybrané funkční vlastnosti. IR absorpce důležitá pro stavbu bolometrů byla studována pomocí Fourierovy infračervené spektroskopie. Základní elektrochemická charakterizace byla provedena pomocí cyklické voltametrie. Srovnáme-li získané výsledky se standardními nebo MWCNT modifikovanými tištěnými elektrodami, připravené VA-MWCNT elektrody ukazují vysoký potenciál pro konstrukci elektrochemických senzorů. Rezistivní CNT senzor plynu ukázal dobrou citlivost na amoniak při pokojové teplotě. Emisni vlastnosti rovněž potvrdili, že CNTs jsou vhodné pro aplikaci ve snímačích tlaku, kdy je měřena změna emisního proudu ve struktuře diody během ohýbání membrány. Výhody růstu CNTs v mikrovlnném plazmovém výboji, jako jsou rychlost a všestrannost procesu, mohou být plně využity pro integraci povrchově vázaných, přímo rostlých, CNTs do různých snímacích struktur.

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 with TLD secondary electron (SE) and CBS back-scattered electron (BSE) detectors, Energy-dispersive X-ray spectroscopy (EDS) and beam deceleration system. SEM at lower energies offers several advantages, among them the most important are: increase of material contrast, high ratio SE, BSE signal and noise, smaller interaction volume and elimination of charging effects.

Remote-controlled robotic systems are being used for analysis of various types of analytes in hostile environment including those called extraterrestrial. 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 with a culture chamber with volume 600 μL. The flow rate was optimized to 500 μL/min. The chip was tested primarily for detection of 1-naphthol by differential pulse voltammetry with detection limit (S/N = 3) as 20 nM. Further, the way how to capture bacteria was optimized. To capture bacterial cells (Staphylococcus aureus), maghemite nanoparticles (1 mg/mL) were prepared and modified with collagen, glucose, graphene, gold, hyaluronic acid, and graphene with gold or graphene with glucose (20 mg/mL). The most up to 50% of the bacteria were captured by graphene nanoparticles modified with glucose. The detection limit of the whole assay, which included capturing of bacteria and their detection under remote control operation, was estimated as 30 bacteria per μL.