Ing. Alexandr Laposa, Ph.D.

The selective detection of ammonia (NH3), nitrogen dioxide (NO2), carbon oxides (CO2 and CO), acetone ((CH3)2CO), and toluene (C6H5CH3) is investigated by means of a gas sensor array based on polyaniline nanocomposites. The array composed by seven different conductive sensors with composite sensing layers are measured and analyzed using machine learning. Statistical tools, such as principal component analysis and linear discriminant analysis, are used as dimensionality reduction methods. Five different classification methods, namely k-nearest neighbors algorithm, support vector machine, random forest, decision tree classifier, and Gaussian process classification (GPC) are compared to evaluate the accuracy of target gas determination. We found the Gaussian process classification model trained on features extracted from the data by principal component analysis to be a highly accurate method reach to 99% of the classification of six different gases.

Non-planar fluxgate sensors measuring the magnetic fields in the uT range are required for electric current, position, and torque transducers. We report the first sensor based on an inkjet-printed 17 mm diameter ring core. The sensor wide open-loop linear range of  1.5 mT allows to operate it without feedback. We describe the preparation of the very stable magnetic ink based on citrate-stabilized 13 nm diameter Mn-Zn ferrite nanoparticles that occur in superparamagnetic regime at room temperature. By printing 100 layers the total thickness of the inkjet-printed core was 2.2 µm. The achieved sensitivity was 10 mV/mT for 25 kHz excitation frequency

Refractory metals (titanium, molybdenum, and zirconium) with a gold overlayer were used to form ohmic contacts on {113}-oriented boron doped diamond epitaxial layers (boron concentration ranging from 1019 to 1021 cm−3). Morphology and thickness of deposited layers were determined by AFM and X-SEM; resistivity, carrier concentration and mobility were determined by Hall measurement. Specific contact resistance RCsp of evaporated Ti/Au, Zr/Au, and Mo/Au contacts was measured using c-TLM structures after different annealing stages at temperatures up to 850 °C. Results show that on layers with {113} orientation it is possible to achieve ohmic contacts of comparable quality as for layers with {100} orientation. For all three metal systems, the lowest values for specific contact resistance reached 1 × 10−6 Ω.cm2. Ti/Au contacts show a stable ohmic behavior over the whole range of annealing temperatures, while Mo/Ti contacts had to be annealed above 500 °C to reduce the Schottky barrier and achieve good ohmic contact on lower B doped layers. Zr/Au contacts exhibit the lowest adhesion and required annealing to at least 700 °C to achieve ideal electrical and mechanical properties. Mo/Au and Zr/Au contacts on highly boron doped layers (~1021 cm−3) show excellent contacts when annealed at 700 °C, and therefore can be considered as improved candidates for ohmic contacts for diamond-based high-temperature power electronics than the conventional Ti/Au (Ti/Pt/Au) contact system. In summary, this study confirms the suitability of {113} oriented boron doped diamond epitaxial layers for the fabrication of diamond power electronic devices with excellent ohmic contacts.

The paper solves the model of the miniature Power supply based on the piezoelectric cantilever. The aim of the future is to further hybrid integration and use of nanotechnology. Contents of the article belongs to the category of renewable energy sources with environment energy conversion into electrical energy. The work is focused on the use in small temperature differences.

The article reports for the first time about the successful fabrication of pseudo-vertical diodes on {113} oriented homoepitaxial boron-doped diamond using molybdenum as a metal for both the Schottky and ohmic contacts. Results confirm that the use of {113} oriented homoepitaxial boron-doped diamond for the fabrication of high-temperature power devices is advantageous, as it enables high-quality Schottky and ohmic contacts.

The low resistance of ohmic contacts on diamond layers is important for the fabrication of diamond power electronic devices with fast switching capabilities for future high voltage applications. The low barrier height between the metal and diamond, high level of boron doping and annealing at elevated temperatures are the most critical parameters to reach the lowest contact resistivity. In this work, we report on titanium/gold ohmic contacts prepared on the heavily boron-doped (113) epitaxial diamond layers. The contact resistance has been characterized by the Circular Transmission Line Model (cTLM) structures. We used the analytical model of field enhanced emission, tunneling and the image force influence including Fermi level position dependence on the boron concentration for theoretical Ti/Au contact analysis and the Silvaco TCAD 2D simulation to estimate the measurement error associated with the nonzero metal resistance. We show that the resulting simulation values are consistent with the experimental results.

Epitaxial growth of diamond is critically important for the fabrication of diamond-based electronic devices. The emerging study of the epitaxial diamond growth on the (113) vicinal surfaces evidences highly needed high growth rates and low structural defects concentrations with both p- and n-type doping. In this work, we compare the morphology and dopant concentration incorporation of heavily boron-doped (113) epitaxial diamond layers with conventionally studied (100) and (111) epitaxial layers. Epitaxial layers were grown using resonance cavity Microwave Plasma Enhanced Chemical Vapor Deposition (MWPECVD) system. The surface morphology of epitaxial layers was studied by optical microscopy and atomic force microscopy, whereas the boron incorporation homogeneity was determined by Raman spectroscopy mapping. Heavily boron-doped (113) epitaxial diamond layers can be grown at a high growth rate with a smooth surface, without pyramidal hillocks or non-epitaxial crystallite defects, and with homogeneous boron concentration. These results confirm that epitaxial diamond growth on (113) vicinal surfaces is a promising solution for the development and fabrication of diamond-based electronic devices. (9) (PDF) Effect of the substrate crystalline orientation on the surface morphology and boron incorporation into epitaxial diamond layers. Available from: https://www.researchgate.net/publication/349892789_Effect_of_the_substrate_crystalline_orientation_on_the_surface_morphology_and_boron_incorporation_into_epitaxial_diamond_layers [accessed Aug 25 2021].

Although significant efforts have been dedicated to optimize the quality of epitaxial diamond layers, reported properties of diamond based electronic devices do not yet approach expected theoretical values. Recent works indicate that boron-doped and phosphorous-doped diamond can be grown on atomically stepped (113) surfaces (A. Tallaire et al., 2016; M.-A. Pinault-Thaury et al., 2019), however the electrical properties of these layers have not been studied in detail. In this work, we report on structural and electrical properties of boron-doped epitaxial diamond layers grown on (113) substrates. Properties of the diamond layers have been investigated by means of scanning electron microscopy, atomic force microscopy, Hall effect, secondary ion mass spectrometry and Raman spectroscopy. Our results show that boron-doped diamond layers can be grown on (113) substrates at high deposition rates with atomically flat surfaces, excellent electrical properties and high boron incorporation efficiency.

Hydrogen-terminated diamond gas sensors have been prepared by selective deposition of nanodiamond ink using direct inkjet printing on interdigital electrodes, followed by chemical vapor deposition growth of a nanoctrystalline diamond layer. The structure of the deposited layer was characterized and analyzed by scanning electron microscopy and Raman spectroscopy. The effect of ultraviolet light-emitting diode (UV-LED) illumination on the performance of the hydrogen-terminated diamond gas sensor with regard to reducing (NH3) and oxidizing (NO2) gases at various temperatures was studied. UV-LED illumination showed a short response/recovery time to NH3 and NO2 gases, 97 s / 153 s, and 72 s / 186 s, respectively.

The single- and double-layered photodetectorsbased on ZnO and/or detonation nanodiamond (DND) have beendeveloped via a sequential inkjet printing on the interdigital elec-trode platform using a diamond and zinc oxide precursor ink. Themorphological structure of the deposited materials was visualizedand analyzed by scanning electron microscopy and atomic forcemicroscopy. The crystalline configuration and structural qualityof ZnO and nanodiamond were investigated by X-ray diffractionand Raman spectroscopy. The response, response time, andrecovery time were measured for different UV wavelengths(365, 385, and 405 nm), light intensities, temperatures, and biasvoltages. The ZnO/DND structure shows more than ten timeshigher response and faster reactivity in comparison with a single-layered photodetector. Photoresponsivity of the double-layeredphotodetector (ZnO/DND) is 0.35 A/W, whereas bare ZnOis about 0.039 A/W. The interaction between UV light andZnO/DND grains was investigated by two dimensional SilvacoTCAD simulation.

In this work we demonstrate the realization of a simple and low cost NO 2 gas sensor on a flexible polymer substrate. The sensor was fabricated using inkjet printing and hydrothermal growth and consists of a printed interdigital structure on which a sensitive zinc oxide layer was grown. The chosen growing process does not require an additional seed layer, which allows to directly grow the zinc oxide layer on the substrate. Furthermore, the operating temperature was intrinsically achieved with an inkjet printed heater, which is located at the backside of the sensor.

In this paper we prepared flexible ammonia (NH3) gas sensor based on polyaniline (PAni) as an active sensing thin film layer. The sensors function was based on chemiresistive principle with thin film deposited on top of interdigitated electrodes. We measured the change in resistance of the thin film under gas exposure. The PET based foil has been used as the sensors substrate. The Interdigitated electrodes (IDE) has been printed with Fujifilm Dimatix DMP 2831 inkjet printer by nanocoloid silver ink. The active thin film has been prepared by drop casting method from polyaniline nanoparticle dispersion. The morphology of thin films surface was characterized by atomic force microscopy (AFM). The sensors response was investigated in a gas chamber and the gas flow was controlled by mass flow meters. The sensitivity towards various gases under different concentration in synthetic air has been tested. The tested gases were NH3, NO2, CO2 and CO. The measurement of the sensors response to the different levels of humidity was also conducted. All the measurements were performed at room temperature, which is important feature for the sensor to be able to operate in hazardous environment and it facilitates low-power operation of the sensor as well. We also observed the long-term stability of the sensors response, as well as the effect of bending of the sensing platform on the sensors response and stability.

Microstructured single- and double-layered sensor devices based on p-type hydrogen-terminated nanocrystalline diamond (NCD) films and/or n-type ZnO nanorods (NRs) have been obtained via a facile microwave-plasma-enhanced chemical vapour deposition process or a hydrothermal growth procedure. The morphology and crystal structure of the synthesized materials was analysed with scanning electron microscopy, X-ray diffraction measurements and Raman spectroscopy. The gas sensing properties of the sensors based on i) NCD films, ii) ZnO nanorods, and iii) hybrid ZnO NRs/NCD structures were evaluated with respect to oxidizing and reducing gases at 150 °C. The hybrid ZnO NRs/NCD sensor showed a remarkably enhanced NO2 response compared to the ZnO NRs sensor. Further, inspired by this special hybrid structure, the simulation of interaction between the gas molecules (NO2 and CO2) and hybrid ZnO NRs/NCD sensor was studied using DFT calculations.

The aim of this paper is to present the design of a sensor array based on a single substrate with various composite polymer films as active layers for gas detection. A low power, four element flexible sensor platform with heater and temperature sensor was designed. The advantages of resistive sensors are easy fabrication, simple operation and low production cost. Composite polymer films exhibit good sensitivity to low gas concentrations at room temperatures. The principle of the designed sensor array is a change of electrical resistance in dependence of gas concentration. PANI, PANI/CNT, PANI/SnO2 and PANI/TiO2 composites were used as active layers. Gas sensing properties of active layers for NH3, CO2, NO2, O2, acetone, toluene and relative humidity were studied. PANI composites, unlike pristine PANI, exhibit good reversibility and lower temperature dependence.

The fabrication procedure and characterization of low-cost electrodes for capacitive level sensors realized on a flexible substrate are presented in this paper. The aim was to prepare conductive electrodes by printing of silver and PEDOT:PSS pastes on coated PET foil. Individual interdigital capacitors and a system with embedded microcontroller readout were designed for a comparative study. Individual capacitors in the form of interdigital electrodes (IDT) were designed with different finger width/spacing dimensions from 300/300 mu m to 800/800 mu m, a finger length 10 mm and 15 mm and an overall length of 100 mm. A demonstrator device featuring an integrated microcontroller, sensing and reference capacitive sensors and a resistive temperature sensor was realized to proof a practical utilization. The microcontroller is used to calculate capacitances of IDT electrodes in terms of charging time proportional to the fluid level. The design with reference capacitor can be directly applied to different fluids with a wide range of conductivities and dielectric constants without recalibration. The printed structures were thermally laminated with covering PET foil. The sensitivity of the fabricated devices was characterized in liquids with different relative permittivity and conductivity (water and oil). The highest measured sensitivity was 0.7 pF/mm and 0.08 pF/mm for water and oil respectively, with resolution down to 0.1 mm.

This paper describes a method of the respiration monitoring based on the sensing of acoustic signals in trachea. Further, the article describes method for signal processing of the acoustic signals. The respiration belongs among basic vital functions and the knowledge of their parameters and quality is necessary in medicine. The research is leading to the methods, which are inconvenienced patients. Monitoring of respiration is important for monitoring respiration towards observation quality sleeping or The Sudden Infant Death Syndrome (SIDS).

The article describes the principles of analysis of pollutants in water by molecular absorption spectrometry. The spectrometer is used for analysis. Design and implementation of software for the evaluation of water analysis is part of the work. The software is designed with ease of use and retrieval of data. Analysis of water is mainly focused on nitrates. The detection is focused on determining levels of particular components, suitable algorithm recognizes the substance.

The article describes the design and realization of the gas analyzer using 4 types of gas sensors – catalytic, electrochemical, semiconductor and infrared sensor. The analyzer is intended for quick orientation measuring the presence of gas. The analyzer includes basic parts - the sensor part, the evaluation and control part, the display and the output actuator part. The analyzer is designed for easy modification of its connection to different types of chemical sensors. The sensor part includes a chemical sensor, an EEPROM and a temperature sensor. The type of the used sensor sets the operation mode of the both part - evaluation and control part. Actuators on the output are ready to control the security elements (ventilation, alarm, etc.). The display shows the basic information - gas concentration, temperature, and more. Evaluation and control part includes microprocessor, memory for long-term data, signaling LEDs, push buttons.

The paper presents fabrication and characteri-zation of a Quartz Crystal Microbalance based gas sensor with a diamond powder sensitive layer deposited using the ink-jet printing technique. The sensor was exposed to a low concentration of ammonia, acetone vapors and different levels of humidity. Impedance characteristics close to the natural resonant frequency of 10 MHz were examined. The sensor exhibits significant shifts in serial resonant frequency under different gas environments.

The aim of this paper is to present design of sensor array with composite polymer films as active layers for gas detection. Low power, four element flexible sensor platform with heater and temperature sensor was designed. The advantages of resistive sensors are easy fabrication, simple operation and low production cost. Composite polymer films exhibits good sensitivity to low concentrations of ammonia at room temperatures. Sensing of toxic gases is very important in many applications as automotive, defense, aerospace, agriculture, chemical industry, medicine, environmental, food and drink.

Gas sensors based on a quartz crystal microbalance (QCM) coated with nanocrystalline diamond (NCD) were developed and tested on NH3, CO2, and humidity detection at room temperature and compared with the bare (uncoated) QCM. NCD films were directly grown on the QCM by a large-area pulsed linear-antenna microwave plasma CVD process from the CH4/CO2/H2 gas mixture at temperatures below 400 °C. The as-grown NCD films on QCM and reference Si substrates were characterized by scanning electron and atomic force microscopies as well as Raman and optical spectroscopies. The NCD-coated QCM gas sensors showed a reasonable performance with a stable repeatability to the tested gases. The response time of the tested diamond-coated sensor was fast (~5s). Moreover, we also observed higher sensitivity and better stability for NCD-coated QCM than for the bare QCM.

The aim of the paper is to present results of design spectrometer for toxic gases detection with pyroelectric multispectral detector. Sensing of toxic gases is very important in many applications. Automotive, defense, aerospace, agriculture, chemical industry, medicine, environmental, food and drink are many important markets for chemical and biological sensors. Principle of designed spectrometers is the interaction of the infrared radiation with studied gases. In the case of photon absorption, we are talking about infrared absorption spectroscopy. In our case, near-infrared spectrum is used.

The aim of the paper is to present results of design gas sensor with different form of polyaniline active layer for toxic gases detection. . Sensing of toxic gases is very important in many applications. Automotive, defence, aerospace, agriculture, chemical industry, medicine, environmental, food and drink are many important markets for chemical and biological sensors. The advantages of resistive sensors are easy fabrication, simple operation and low production cost. Using of polymer film causes that this sensor is not required heating of active layer. This leads to reduce power consumption. Active layer is operated at room temperature.

Synthetic diamond has remarkable properties comparable with natural diamond and hence is a very promising material for many various applications (sensors, heat sink, optical mirrors, cold cathode, tissue engineering, etc.). Nowadays, deposition of diamond films is normally employed in chemical vapor deposition (CVD) usually at high temperatures (800-900 °C), what limit its application to high melting substrates. Gravimetric (mass) sensors belong to the major categories of chemical sensors and the most common type of mass sensor is the bulk acoustic quartz crystal microbalance (QCM). This contribution deals with a nanocrystalline diamond (NCD) growth from the H2/CH4/CO2 gas mixture at low temperature (400 °C) by pulsed linear antenna microwave plasma system on 10 MHz circular AT-cut quartz resonators substrate. Gas sensor based on the NCD-coated QCM was developed for detection of ammonia (NH3) at room temperature. Measurements not only confirmed the functionality of this first published NCD-coated QCM sensor.

The objective of this paper is to present simulation results of the Thickness Shear Mode (TSM) resonator based on quartz using finite element simulation method. 3D model of quartz resonator and simulations were completed using finite element method in CoventorWare software suite for design and simulation of MEMS devices. Different techniques for simulation of adsorption effect on selective layer were studied: influence of change in mass of the sensitive layer and influence of change in density of the sensitive layer. Analyses of resonant modes were performed for both cases and displacement profiles in selected modes were determined for the resonator under study. Impedance and phase characteristics were calculated and measured for clean sample and sample with selective layer coated. The adsorption model calculates the frequency shift in basic resonant frequency with adsorbed amount of sensed gas. The simulation results were used in design of gas sensors for dangerous substances detection.

This study describes an integrated NH3 sensor based on a hydrogenated nanocrystalline diamond (NCD)-sensitive layer coated on an interdigitated electrode structure. The gas sensing properties of the sensor structure were examined using a reducing gas (NH3) at room temperature and were found to be dependent on the electrode arrangement. A pronounced response of the sensor, which was comprised of dense electrode arrays (of 50 µm separation distance), was observed. The sensor functionality was explained by the surface transfer doping effect. Moreover, the three-dimensional model of the current density distribution of the hydrogenated NCD describes the transient flow of electrons between interdigitated electrodes and the hydrogenated NCD surface, that is, the formation of a closed current loop.

The aim of the paper is to present results of design spectrometer for toxic gases detection with MEMS sensor. Automotive, defense, aerospace, agriculture, chemical industry, medicine, environmental, food and drink are many important markets for chemical and biological sensors. Sensing of toxic gases is very important in many applications. Principle of designed spectrometers is the interaction of the infrared radiation with studied gases. In the case of photon absorption, we are taking about infrared absorption spectroscopy. In our case, near-infrared spectrum is used.

The graphene is suitable for gas sensing applications for its two dimensional character which gives the best possible ratio between sensor surface and volume. The interaction between graphene surface and gas molecules can significantly change the graphene layer transport properties. Therefore graphene can serve as a sensitive layer in a gas sensor. This work is concentrated on the analysis of the conductivity of graphene layer exposed to different gases (NH3, CO2 etc.). Together with the electrical measurement on the interdigital graphene sensor a simulation based on quantum atomistic approach has been performed. We used ATK toolkit by Quantuwise based on density functional theory (DFT) models. The exchange-correlation potential is approximated within the generalized gradient approximation (GGA). The transport properties of the electrode-device-electrode geometry were calculated by means of non-equilibrium Green’s function formalism as implemented in ATK. Experimental conductivity changes are compared with the simulation results

The aim of the paper is to present results of design ammonia sensor. Automotive, defense, aerospace, agriculture, chemical industry, medicine, environmental, food and drink are many important markets for chemical and biological sensors. The advantages of resistive sensors are easy fabrication, simple operation and low production cost. Ammonia is used in many technical applications, therefore it is widely used hazardous chemical. Sensing of gaseous ammonia is very important in many applications. Using of polymer film causes that this sensor is not required high heating of active layer.

The aim of the paper is to present results of design ammonia sensor. Automotive, defense, aerospace, agriculture, chemical industry, medicine, environmental, food and drink are many important markets for chemical and biological sensors. The advantages of resistive sensors are easy fabrication, simple operation and low production cost. Ammonia is used in many technical applications, therefore it is widely used hazardous chemical. Sensing of gaseous ammonia is very important in many applications. Using of polymer film causes that this sensor is not required high heating of active layer.

We present the development and considerations of simple acoustic wave chemical sensors. These sensors can be used for identifying environmental contaminants in large applications scale. Various finite element models of a Acoustic Wave sensors are developed using CoventorWare and 3D analysis is performed on the devices to study the acoustic wave propagation and characterize the device. The effects of the various interdigital transducers (IDT) design; intermediate layer on the propagation characteristics is also investigated.

The respiration belongs among basic vital functions and the knowledge of their parameters and quality is necessary in medicine. The research is leading to the methods, which are inconvenienced patients. These methods are important for monitoring respiration towards observation quality sleeping or The Sudden Infant Death Syndrome (SIDS). This paper contains an overview of the methods for the respiration monitoring used not only in practice of medicine but till now developed.

This work describes basic concept of chemical sensors based on surface acoustic wave (SAW). The aim is to depict basic physical concept and simulation rough draft for mis type of sensors. By integrating a SAW measurement platform with a selective sensing layer, a desired chemical microsensor is constructed, which provides some of the functionality of an analytical instrument, but with extraordinary reduced cost, size, and power consumption. The objective of this paper is presents gas sensors based on one-port and two-port interdigitated metal structures. The impulse response model is used for determination of IDT parameters and first order investigation, the transient analysis is performed on the devices to study the acoustic wave propagation and characterize the device in time and frequency domain. The effects of the various interdigital transducer (IDT) design, intermediate layer thickness and chemical sensitivity structure on the propagation characteristics is also investigated. Also, we present some results obtained from the device using automated measurement system for SAW oscillator frequency measurement.

In this paper, we present the design and modeling considerations of SAW (Surface Acoustic Wave) chemical sensors based on various structures. These sensors can be used for identifying environmental contaminants in large applications scale. Various finite element models of a Surface Acoustic Wave sensors are developed using CoventorWare and 3D analysis is performed on the devices to study the acoustic wave propagation and characterize the device. The effects of the various interdigital transducer (IDT) design, intermediate layer on the propagation characteristics is also investigated. Also, we present some results obtained from the device. Results indicate that with increasing the gas concentration the wave velocity decreases and the attenuation of the wave is reduced.

This paper describes a method of the breathing detection based on the sensing of acoustic signals in trachea. Parameters of the breathing, detection inspiration and expiration and apnoea pause are possible to determine from these signals. This method is simple and easy to use, portable and provides an accurate measurement and seems to be well suited for use as a modern breathing monitor. Monitoring of Respiration is important for monitoring respiration towards observation quality sleeping or The Sudden Infant Death Syndrome (SIDS).

This paper describes a method of the breathing detection based on the sensing of acoustic signals in trachea. Parameters of the breathing, detection inspiration and expiration and apnoea pause are possible to determine from these signals. This method is simple and easy to use, portable and provides an accurate measurement and seems to be well suited for use as a modern breathing monitor. Monitoring of Respiration is important for monitoring respiration towards observation quality sleeping or The Sudden Infant Death Syndrome (SIDS).

Modeling and results of thermal cycling measurement of a high temperature pressure sensor packaging is presented. The packaging is based on the green-state milling of alumina to the desired geometry and conduits for the electrical conductors, followed by sintering of the ceramics with the electrical conductors inside. The electrical interconnections are based on silver. For short term operation, the package can be exposed to temperatures close to the melting temperature of silver (961 °C). It has shown operational in temperature cycling above 600 °C for more than 1800 hours. Modeling of the package shows that the stresses in the electrical interconnections are close to the yield stress of silver at 20 °C. The stress free temperature for simulation was set to 850 °C. Temperature induced stress and strains in the packaging and a fatigue simulation are performed. The package is generic and can be converted to fit most geometries and high temperature applications.

This paper describes a method of the breathing detection based on the sensing of acoustic signals in trachea. Parameters of the breathing, detection inspiration and expiration and apnoea pause are possible to determine from these signals. This method is simple and easy to use, portable and provides an accurate measurement and therefore this approach is promising to be well suited for use as a modern breathing monitor. The respiration belongs among basic vital functions and the knowledge of their parameters and quality is necessary in medicine. The research is leading to the methods, which are inconvenienced patients. Monitoring of Respiration is important for monitoring respiration towards observation quality sleeping or The Sudden Infant Death Syndrome (SIDS).

Vzhledem k tomu, že dýchání patří k základním životním funkcím, je důležité znát jeho parametry a kvalitu. Výzkum je dnes veden u metod monitorujících dýchání tak, aby minimálně zatěžovaly pacienta. Tyto metody jsou důležité například pro monitorování průběhu dýchání během sledování kvality spánku nebo pro monitorování náhlé zástavy dýchání u kojenců. V článku jsou uvedeny metody, užívané nejen v lékařské praxi, ale i metody doposud vyvíjené.

The respiration belongs among basic vital functions and the knowledge of their parameters and quality is necessary in medicine. The research is leading to the methods, which are inconvenienced patients. These methods are important for monitoring respiration towards observation quality sleeping or The Sudden Infant Death Syndrome (SIDS). This paper contains an overview of the methods for the respiration monitoring used not only in practice of medicine but till now developed.

So far the dependence of the spontaneous polarization coefficient for GaN and AlN on temperature has been measured to be minimal, which corresponds with expectation that the spontaneous polarization is reduced at the elevated temperatures of interest. There are also no reports on the piezoelectric polarization at higher temperature. This paper is initial study on the influence of temperature related behaviour in GaN/AlGaN. Summarize recent findings and consideration.

MEMS Based Humidity Sensors

The article describes basic concept of chemical sensors based on surface acoustic wave (SAW). The aim is to depict basic physical concept and simulation rough draft for this type of sensors.

The aim of this paper is to report the design of the simple polymers structure humidity sensors and its mechanical and piezo-rezistive simulation in CoventorWare. Also this paper report about various type of the structure in the area of mems based humidity sensors.

Článek pojednává o vlivu umístění pracovních pomůcek na pracovním stole v závisloti na výkonost pracovníka.

Tento příspěvek zmiňuje užití piezoelektrických materiálů užívané při návrhu senzorů. Tyto materiály nacházejí uplatnění v inteligentních senzorech. Jako velice perspektivní se dnes jeví senzory na bázi polymerních materiálů.

The article describes overview of piezoelectric materials using in sensors and is aimed at polymeric materials. Further, the article observes applications of piezoelectric materials and comparison of ceramic and polymeric sensors.

In this article are taken into consideration main advantages and disadvantages of sensors with surface acoustic wave. Provides a survey of used piezoelectric materials and chemical sensitive layers and characteristics.

Článek informuje o polymerních materiálech používaných v elektronických součástkách.

Článek se zabývá optimalizací účinnosti výkonového stupně zesilovače v pásmu rádiových vln. Výkonový stupeň, pracující ve třídě A, je pomocí metody řízeného biasu výkonového tranzistoru nastavován pro optimální energetickou účinnost. Důraz je dán především na maximální zachování čistoty spektra výstupního signálu, tedy na nalezení optima mezi energetickou účinností a přijatelným harmonickým zkreslením.

Článek popisuje princip funkce piezorezistivních senzorů tlaku ve strukturách MEMS.