Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 15

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

Search:
in the keywords:  68.35.Iv
help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Determination of Parameters of Surface Acoustic Wave Vibration Sensors with the Help of Gravitational Field

100%
Filipiak J., Steczko G.
Acta Physica Polonica A
|
2013
|
vol. 124
|
issue 3
410-412
EN
This work presents results of experimental tests of surface acoustic wave vibration sensor. Measurements of the static sensitivity, resonance frequency, frequency amplitude characteristics and linearity were carried out. Measurements were carried out with the help of the acceleration of gravity and a digital oscilloscope.
2
Content available remote

Electronic Warning System Based on Surface Acoustic Wave Vibration Sensors

100%
Filipiak J., Solarz L., Steczko G.
Acta Physica Polonica A
|
2011
|
vol. 120
|
issue 4
593-597
EN
In the paper feasibility analysis of the surface acoustic wave based electronic warning system was presented. As a transducer in the system the surface acoustic wave delay line was proposed. It is fabricated in standard single mask process as a pair of interdigital transducers placed on the top of piezoelectric crystal substrate. Transducer is a plate with rectangular cross-section and it converts all environmental vibration to electric signal. From electronic point of view it was considered as a two-port network. Necessary condition for proper sensor operation is that the input signal frequency from external generator should be close to central frequency of delay line. Principle of operation of the sensor is that the measured phase shift of high frequency signal has frequency equal resonant frequency of vibrating plate and its amplitude is proportional to vibration amplitude of transducer. The environmental vibrations are defined by amplitude of the output signal and the threat location is pointed by resonant frequency of excited transducer. The described above principles of sensor operation allow us designing electronic warning system consisting of many sensors with different resonant frequencies of transducers. Output signals from precisely located sensors contain all necessary information about the whole warning system. This information is easy to transmit and detect by simple electronic circuits based on phase detector and proper data acquisition system, for which necessary conditions are presented.
3
Content available remote

Analysis of Experimental Stand for Surface Acoustic Wave Vibrations Sensors

100%
Filipiak J., Solarz L., Steczko G.
|
|
issue 6
1118-1123
EN
The analysis of vibrations excitation in surface acoustic wave vibrations sensors is the aim of our work. The sensors are parts of electronic warning system which is intended to be mounted at fences of guarded object. The vibration excitation with expected acceleration is needed during experiments. Elements of fences are replaced by tense strings for experimental purposes and the surface acoustic wave vibration sensors are fastened to these strings. Analysis of the assembly string-sensor takes into account not only the mass of sensor but its moment of inertia, too. Free vibrations of string-sensor assembly are considered. The standard excitation by pulling off string in chosen point causes vibrations. The normal vibrations of assembly (frequencies, orthogonal set of normal functions) are calculated and used for calculations of free vibrations. The spectrum of the standard free vibrations is calculated. The results will be used in the experimental stand. The calculations enable excitation of vibrations with expected spectrum. The stand enables tests of the whole warning system. The thresholds of detection and reaction at concurrent intruder alarm will be investigated at this laboratory stand.
4
Content available remote

Optopneumatic Detector with Platinum Flow Sensor

100%
Jasek K., Budzyński T., Stryszak E.
Acta Physica Polonica A
|
2009
|
vol. 116
|
issue 3
321-324
EN
In optopneumatic detectors, operating on principle of the gaseous infrared detectors, the radiation absorbed in the gas is changed into pressure fluctuation, followed by periodic flow of the gas between detector chambers. This flow is usually measured by means of hot-wire or hot-film anemometers. Their parameters in a great measure determine the quality of the whole detector. The flow sensor used in optopneumatic detectors should have short time constant, high sensitivity, possibility to distinguish the flow direction, and high chemical resistance to the gas which the detector is filled with. To meet these requirements, micro-electro-mechanical system flowmeter consisting of two platinum hot films placed in series in the flow direction was made. Platinum film of 0.3 μm thickness was deposited by magnetron spattering on thin membrane, which was composed of polysilicon substrate (0.5 μm) and two Si_{3}N_{4} layers with thickness of 0.1 μm. The obtained platinum elements have resistance of 32 Ω and temperature coefficient of resistance of 2.31× 10^{-3}/°C. Hot film does not change its parameters up to 350°C, whereas typical working temperature of such films ranged from 150 to 200°C. Anemometer characteristics and voltage-current dependences were determined in this work. The linear range of operation from 0 to 10 ml/min and sensitivity suitable for optopneumatic detectors were found. The time constant of the flowmeter is equal to 11 ms (95% of final signal), that enables the detector to operate with frequency up to 100 Hz. The flowmeters were applied in detectors filled with sulphur dioxide and were tested for six months at temperature of hot-film about 150°C. During that time no changes of their parameters were observed.
5
Content available remote

Surface Acoustic Wave Vibration Sensor Electronic System

80%
Filipiak J., Solarz L., Steczko G.
Acta Physica Polonica A
|
2011
|
vol. 120
|
issue 4
598-603
EN
The paper presents surface acoustic wave vibration sensor electronic system. The system cooperates with surface acoustic wave delay line. The sensor has been designed for electronic warning systems. The sensor is a four-terminal network. In the system, there is a cascade connection of sensors by means of coaxial cable. Test signal and constant supply voltage are jointly sent between sensors. Separating the signals, their summation and amplification of test signal as well as matching the line to impedance 50 Ω are performed by surface acoustic wave vibration sensor electronic system. The electronic system devices and the making of them are discussed. System development of such a sensor is presented and its design is analysed. Experimental examination results of surface acoustic wave vibration sensor are presented. Parasitic effects occurring in vibration sensor electronic system operation connected with electromagnetic coupling and ground current coupling are discussed.
6
Content available remote

New Approach to Rayleigh Wave Propagation in the Elastic Halfspace - Viscoelastic Layer Interface

80%
Pasternak M.
Acta Physica Polonica A
|
2008
|
vol. 114
|
issue 6A
A-169-A-174
EN
The Rayleigh wave propagation problem in the elastic halfspace - viscoelastic layer interface was analysed in the paper. The problem was formulated in the Fourier-Laplace space using the Biot viscoelastic solid model. The characteristic equation has taken the Rayleigh equation form with correction term describing viscoelastic layer properties influence on the wave velocity. The approach presented here seems to be useful for surface acoustic waves gas sensors modelling because many chemisensitive coatings applied to the sensors exhibit viscoelastic properties.
7
Content available remote

Analysis of Non-Steady Stage in SAW Gas Sensors with Semiconducting Sensor Layers

80%
Urbańczyk M., Hejczyk T.
Acta Physica Polonica A
|
2011
|
vol. 120
|
issue 4
789-793
EN
The profile of the gas concentration in the sensor layer can be expressed as a polynomial function involving the diffusion coefficient (D_{K}), semiconductor film thickness (h), rate constant (k), gas concentration outside the semiconductor film (C_{S}). Before reaching a steady state of the concentration profile, its behavior depends on a few factors as the distance from the piezoelectric surface, the rate constant, the thickness of the layer and the diffusion constant and time. We are going to simulate temporary processes in the semiconductor sensor film in the surface acoustic wave gas sensor system and to describe the influence on relative changes of the surface acoustic wave velocity. The numerical results basing on the code written in Pyton, are described and analyzed.
8
Content available remote

SAW Delay Line for Vibration Sensors

80%
Filipiak J., Solarz L., Steczko G.
Acta Physica Polonica A
|
2012
|
vol. 122
|
issue 5
808-813
EN
The paper presents an analysis of surface acoustic wave delay line. The line consists of two simple interdigital transducers placed on a ST-cut quartz plate. Mid-band operation frequency of the line is 74 MHz. The line will be applied for surface acoustic wave vibration sensor. At the immovable end of the plate there are electric signal feeds to both transducers. This is the cause of increase in signal value going directly between the transducers and the cause of line losses. By means of equivalent electric model of interdigital transducer a loss analysis of the line has been made at 50 Ω load. The analysis allows to minimize line losses by matching the transducers to 50 Ω impedance. This has been practically achieved by a design of transducer geometry and configuration matching 50 Ω impedance, by means of inductance. An analysis of repeated operation characteristics of two interdigital transducers has been made. A signal going directly through capacitance between transducers and signals reflected from the edge of piezoelectric substrate have been presented. Results of theoretical analysis have been compared with experimental examinations.
9
Content available remote

Surface Acoustic Wave Vibration Sensors for Linear Electronic Warning Systems

80%
Filipiak J., Solarz L., Steczko G.
Acta Physica Polonica A
|
2009
|
vol. 116
|
issue 3
302-306
EN
The topic of the paper is analysis of feasibility of surface acoustic wave vibration sensors for linear electronic warning systems. In linear warning systems localisation of the object is realised by pointing out the sensors which detect vibrations caused by the object. The information sent out by the detector enables identification of the sensor and its state. The sensor contains surface acoustic wave delay line in four-terminal network. The delay line is formed at the surface of piezoelectric plate. The vibrations of the plate are caused by vibrations of the medium surrounding the sensor. The frequency of the input signal is equal to the working frequency of delay line. The phase of the output signal is shifted in comparison with the input signal. The frequency of the phase shift would be equal to the resonance frequency of the sensor plate. The change of the output signal amplitude would be proportional to the amplitude of plate vibrations. The measured amplitude and frequency of the output signal would be registered by simple electronic devices. The measurements give us knowledge which sensor vibrates and the intensity of these vibrations. Such sensors enable construction of the electronic warning system.
10
Content available remote

Semiconductor Sensor Layer in SAW Gas Sensors Configuration

80%
Hejczyk T., Urbańczyk M., Jakubik W.
|
|
issue 6
1153-1157
EN
A Rayleigh acoustic wave travelling on the surface of a semi-infinite piezoelectric medium may be changed by interaction with carriers and diffused gas in an adjacent semiconductor. The configuration, which uses a thin semiconductor film supported by a catalytic layer (Pd), is described in detail and the theoretical results of gas-sensor layer interaction are presented.
11
Content available remote

Numerical Results of Modeling Semiconductor Sensor Layers in SAW Gas Sensors

80%
Hejczyk T., Urbańczyk M., Jakubik W.
|
|
issue 6
1158-1160
EN
The paper presents the numerical results of investigations of the layered gas surface acoustic waves sensor. The base electric load of the piezoelectric acoustic line is predicted by the effect of surface acoustic waves velocity changes vs. surface conductivity, which depends on the profile concentration by gas diffused molecules into the porous film. Inside the sensor layer Knudsen's model of gas diffusion was used.
12
Content available remote

Analytical Model of Semiconductor Sensor Layers in SAW Gas Sensors

80%
Hejczyk T., Urbańczyk M., Jakubik W.
|
|
issue 6
1148-1152
EN
In the paper a new theoretical model for analyzing a surface acoustic wave gas sensor is presented. Basing on the electric load of the piezoelectric acoustic line the effect of surface acoustic wave velocity changes vs. surface conductivity is predicted which depends on the profile concentration of gas molecules diffused into the porous film. Inside the sensor layer Knudsen's model of gas diffusion was used.
13
Content available remote

Numerical Optimization of Structures SAW Gas Sensors

80%
Hejczyk T., Urbańczyk M.
|
EN
This paper presents the results of the analysis of surface acoustic waves sensor equivalent model. They were the sensor response of the surface acoustic waves sensor in the steady state gas: H_2, CO_2, NO_2, NH_3, C_nH_m, CO. Thin layer of WO_3 has been used as a sensor layer. Impedance replacement of sensor layer, taking into account the profile of the concentration of gas molecules in the layer, has been implemented into the equation of Ingebrigtsen, which enabled us to obtain analytical expressions for the relative changes in surface wave velocity in the steady state. The results of the analysis show that there is an optimum thickness of layer sensor for which an acoustoelectric effect (change in the acoustic wave velocity) is the highest.
14
Content available remote

WO_3-Pd Structure in SAW Sensor for Hydrogen Detection

80%
Hejczyk T., Urbańczyk M.
Acta Physica Polonica A
|
2011
|
vol. 120
|
issue 4
616-620
EN
In the paper a new sensor structure for surface acoustic wave gas system is presented. A bilayer structure WO_3-Pd thin films may be useful for hydrogen detection in low concentration in air. A bilayer sensor structure of tungsten oxide WO_3 with a very thin catalytic film of palladium on the top has been studied for gas-sensing application at room temperature (about 25°C) in surface acoustic wave system. The bilayer structure of WO_3 layers with a thickness of about 50 nm, 100 nm and 150 nm was made onto a LiNbO_3 Y-cut Z-propagating substrate by means of the vacuum sublimation method using a special aluminum mask. The vapor source consisted of commercially available WO_3 powder (Fluka 99.9%) and molybdenum heater. The thin palladium (Pd) layer (about 10 nm) was made separately on each WO_3 layer by means of vapor deposition in high vacuum. There have been investigated three structures: 50 nm WO_3 + 10 nm Pd, 100 nm WO_3 + 10 nm Pd and 150 nm WO_3 + 10 nm Pd in three canal surface acoustic wave system with reference oscillator. Numerical results obtained by analysis of the surface acoustic wave gas sensor model have been compared with experimental results.
15
Content available remote

Bilayer Structures of NiO_{x} and Pd in Surface Acoustic Wave and Electrical Gas Sensor Systems

70%
Jakubik W., Urbańczyk M., Maciak E., Pustelny T.
Acta Physica Polonica A
|
2009
|
vol. 116
|
issue 3
315-320
EN
A bilayer sensor structure of nickel oxide NiO_x ( ≈ 60 nm) with a very thin film of palladium (Pd ≈ 18 nm) on the top, has been studied for gas-sensing application at relatively low temperatures of about 30°C and 60°C. The bilayer structure was obtained by rf sputtering and by vacuum deposition (first the NiO_{x} and then the Pd film) onto a LiNbO_{3} Y-cut Z-propagating substrate, making use of the surface acoustic wave method, and additionally (in the same technological processes) onto a glass substrate with a planar microelectrode array for simultaneous monitoring of the planar resistance of the layered structure. Such a bilayer structure was investigated in a low concentration range (from 50 ppm to 400 ppm in air) of nitrogen dioxide (NO_{2}), carbon monoxide (CO) and ammonia (NH_{3}) in a dry and wet air atmosphere and in a medium hydrogen concentration (1-2.5%) in dry air. The NiO_{x} and Pd bilayer structure interact rather weakly with NO_{2} molecules but with CO and NH_{3} this interaction is much greater, especially at higher temperature ( ≈ 60°C). The hydrogen sensitivity is on the medium level, not exceeding 600 Hz (relative change in the differential frequency of ≈ 2.3%) at interaction temperature of 35°C.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.