Alexandr Laposa

Alexandr Laposa
Czech Technical University in Prague | ČVUT · Department of Microelectronics (FEL)

Ph.D.

About

29
Publications
2,227
Reads
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119
Citations
Introduction
Inkjet-Printed Sensors on Flexible Substrates for Health and Environment Monitoring. Essential Elements of Diamond Power Electronics.

Publications

Publications (29)
Article
Pseudo-vertical diodes on {113} oriented homoepitaxial boron-doped diamond were successfully fabricated using molybdenum as a metal for both the Schottky and ohmic contacts. After metal deposition, diodes were stabilized by annealing for 20 min at 300 °C and their I-V and CV characteristics were measured at temperatures from 30 to 180 °C. Results s...
Article
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 lea...
Article
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 wer...
Article
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., 201...
Article
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 characterised and analyzed by scanning electron microscopy and Raman...
Article
The single- and double-layered photodetectors based on ZnO and/or detonation nanodiamond (DND) have been developed via a sequential inkjet printing on the interdigital electrode (IDE) platform using a diamond and zinc oxide precursor ink. The morphological structure of the deposited materials was visualized and analyzed by Scanning Electron Microsc...
Conference Paper
Full-text available
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 u...
Article
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 p...
Article
Full-text available
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 rea...
Article
Full-text available
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 ma...
Data
Additional experimental data.
Conference Paper
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...
Conference Paper
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 out...
Article
Full-text available
the paper presents fabrication and characterization 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...
Article
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/H...
Article
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...
Article
Full-text available
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...
Article
The graphene is suitable for gas sensing applications for its two dimensional char-acter which gives the best possible ratio between sensor surface and volume. The interactionbetween graphene surface and gas molecules can signi�cantly change the graphene layer trans-port properties. Therefore graphene can serve as a sensitive layer in a gas sensor....
Article
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 si...
Article
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 (80...
Conference Paper
In this paper, 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 ac...
Article
Modeling and thermal cycling 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....
Article
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...
Article
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...
Article
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 i...

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