Ing. Jiří Kroutil, Ph.D.

Heaters are an indispensable part of gas sensing platforms. It serves to heat the sensor, which increases the sensitivity of the active layer and helps in the desorption of the detected gas. The sensors are also heated to stabilize the parameters against the ambient temperature. For the fabrication of electronic circuits and devices including sensing platforms and heating structures is becoming increasingly popular to use flexible electronics. In particular, the use of inkjet printing technology allowing localized deposition of ink at low temperatures on a large area. Many kinds of inks such as conductive, semi-conductive, or dielectric can be used. In this research, we present the design preparation, simulation, fabrication, and characterization of the inkjet printed heaters. The structures are based on silver nanoparticle ink printed on a flexible substrate and are sintered with intense pulsed light. The printed heaters consist of connection pads, interconnection pathways, and heater patterns. Two types of heater patterns were designed (meander and dual-spiral type). Both of the prepared patterns were simulated in Ansys simulation software to obtain the heat distribution. The microheaters were printed on a polyethylene terephthalate (PET) substrate and characterized with a thermal imaging camera. Based on the results obtained from these measurements, a calibration plot was created.

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.

This paper deals with an overview of mechanical-electrical systems used in generating electrical energy for the purpose of powering secondary systems controlling access control systems. In practice, we can meet them, for example, in administrative buildings, where they serve as sources of electricity for autonomous systems for the authorization of workers in the house. GaN transistors are also beginning to be used in this area and their use leads to higher energy gains

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

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.

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.

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.

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 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.

Presented work deals with crystal oscillators that can be used as a quartz crystal microbalance (QCM) gas sensor. There are presented two basic oscillators that are very common in literature. The oscillators were put into practice and tested in the gas chamber with different crystals of basic frequency 10 MHz. There were tested clean crystal resonators and resonators coated by a sensitive layer. Frequency response of the oscillators is usually very small and it is comparable with the effects such as temperature change or crosstalk in the evaluation circuit. The evaluation circuit thus must be designed carefully. Main goal of this paper is comparison of two basic designs of the oscillators and presentation of the precise evaluation circuit with minimal crosstalk and reverse transmission in signal ways.

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.

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).

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 minimize patients' inconvenience. These methods are important for monitoring the respiration throughout the quality sleeping observation or the SIDS (Sudden Infant Death Syndrome). This paper contains an overview of the methods for the respiration monitoring used not only in practical medicine but also the methods which are under development.

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).

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.

Acoustic signals originate by the flow of air through the trachea during breathing. These signals are possible to pick-up by microphone. 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.

This paper describes a method of the respiration detection based on the sensing of acoustic signals in trachea. Acoustic signals originate by the flow of air through the trachea during breathing. These signals are possible to pick-up by microphone. 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.

Acoustic signals originate by the flow of air through the trachea during breathing. These signals are possible to pick-up by microphone. 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.

Základem zařízení je senzorová část, která snímá kardio-respirační činnost. Snímaná informace o dýchání se převede do elektrické podoby, dojde k úpravě elektrického signálu a ten se následně digitalizuje. Digitalizovaný signál se vyšle vysílačem k přijímací jednotce umístěné mino pacienta. Zde je provedeno zpracování signálu a následné vyhodnocení stavu dýchání pacienta.

This work describes the design and realization of the security system with using of GSM that it makes possible a security against unauthorized intrusion and against fire.

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.

This work describes the design and realization of the security system with using of GSM that it makes possible a security against unauthorized intrusion and against fire. The whole device is constructed of modern and easy available parts. The whole system is based on the modular conception thereby it is flexible. The advantage of this system is possibility localization of the emergence of the invasion at using standard 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.

The aim of this paper is report the scheme of location working things on the table depending up worker performance.

This article mentions the using of piezoelectric materials for the design of sensors. These materials are applied in intelligent sensors. Sensors on the bases of polymerous materials are promising nowadays.

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.

The Article Describes Informations about Polymer Materials Utilization in Electronic Application Especially for Polymer Displays.

The article describes informations about polymers material used in electronics devices.

The article describes the way how to improve the efficiency of the power stage of the RF amplifier operating in the class A, using the adaptive bias technique. Power stage is designed to operate at the frequency of 100 MHz and the maximal wattage of 2W at supply voltage of 20V. The output of the amplifier is adjusted for load of 50Ω and the voltage gain is 18. Designed circuit exhibits very good linearity and the power dissipation can be reduced down to 30 per cent compared to normal power stage in class A.

The article describes function of the piesoresistive pressure sensors in MEMS structures.

The article describes function, manufacturing and electronics characteristics of the primery polymers electronics devices.