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1
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Analysis of Non-Steady Stage in SAW Gas Sensors with Semiconducting Sensor Layers

100%
Urbańczyk M., Hejczyk T.
Acta Physica Polonica A
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2011
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vol. 120
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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.
2
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Numerical Optimization of Structures SAW Gas Sensors

100%
Hejczyk T., Urbańczyk M.
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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.
3
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WO_3-Pd Structure in SAW Sensor for Hydrogen Detection

100%
Hejczyk T., Urbańczyk M.
Acta Physica Polonica A
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2011
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vol. 120
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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.
4
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Surface acoustic wave hydrogen gas sensor based on layered structure of palladium/metal-free phthalocyanine

81%
Jakubik W. P., Urbańczyk M., Maciak E., Pustelny T.
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2008
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vol. 56
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issue 2
5
Content available remote

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

81%
Jakubik W., Urbańczyk M., Maciak E., Pustelny T.
Acta Physica Polonica A
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2009
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vol. 116
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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.
6
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Semiconductor Sensor Layer in SAW Gas Sensors Configuration

81%
Hejczyk T., Urbańczyk M., Jakubik W.
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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.
7
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Numerical Results of Modeling Semiconductor Sensor Layers in SAW Gas Sensors

81%
Hejczyk T., Urbańczyk M., Jakubik W.
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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.
8
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Analytical Model of Semiconductor Sensor Layers in SAW Gas Sensors

81%
Hejczyk T., Urbańczyk M., Jakubik W.
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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.
9
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SAW sensor for detection of hydrocarbons. Numerical analysis and experimental results

81%
Hejczyk T., Urbańczyk M., Wituła R., Maciak E.
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2012
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issue 3
10
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Layered thin film nanostructures of Pd/WO3-x as resistance gas sensors

71%
Pustelny T., Urbańczyk M., Maciak E., Gut K., Jakubik W.
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2011
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issue 4
11
Content available remote

Investigations of SAW Structures with Oxide Graphene Layer to Detection of Selected Gases

52%
Drewniak S., Pustelny T., Setkiewicz M., Maciak E., Urbańczyk M., Procek M., Opilski Z., Jagiello J., Lipinska L.
Acta Physica Polonica A
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2013
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vol. 124
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issue 3
402-405
EN
In this paper we present the results of investigations of graphene oxide layers using the SAW structure (structure with surface acoustic wave propagated) exposed to the affect of low concentrations of hydrogen and nitrogen dioxide in synthetic air. During the measurements, the differential signal (from two measuring channels) was recorded. The sensing graphene oxide layer was deposited only on first channel, whereas the second channel was not covered by any additional layer. The tests were made with various concentrations of the analyzed gases and at various temperatures of the sensing structure during the measurements. Analyses were performed with special emphasis on the time response of the sensor structure to changes in the gas atmosphere.
12
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The sensitivity of sensor structures with oxide graphene exposed to selected gaseous atmospheres

52%
Urbańczyk M., Opilski Z., Pustelny T., Drewniak S., Setkiewicz M., Maciak E., Procek M., Gut K., Jagiello J., Lipińska L.
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2013
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issue 3
13
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Gas sensors based on nanostructures of semiconductors ZnO and TiO2

52%
Pustelny T., Urbańczyk M., Opilski Z., Stolarczyk A., Procek M., Maciak E., Drewniak S., Setkiewicz M., Gut K.
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2012
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issue 4
14
Content available remote

The Influence of Humidity on the Resistance Structures with Graphene Sensor Layer

42%
Pustelny T., Setkiewicz M., Drewniak S., Maciak E., Stolarczyk A., Procek M., Urbańczyk M., Gut K., Opilski Z., Pasternak I., Strupinski W.
Acta Physica Polonica A
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2012
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vol. 122
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issue 5
870-873
EN
In the paper the results of investigations are presented concerning the influence of humidity of air on the resistance of a gas sensor structure with a graphene layer. The affects of nitrogen dioxide and humidity action on graphene were studied. We indicated that humidity might play an important role in determining the gas sensing properties of the graphene layer. In the paper it has been shown that in the case of a nitrogen oxide sensor, the reaction of NO_2 with water vapour can generate permanent defects in graphene.
15
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The sensibility of resistance sensor structures with graphene to the action of selected gaseous media

42%
Opilski Z., Stolarczyk A., Pustelny T., Urbańczyk M., Setkiewicz M., Drewniak S., Maciak E., Procek M., Gut K., Pasternak I., Strupinski W.
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2013
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issue 2
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