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The Influence of External Pressure on Resonant Frequency of SAW Resonator

100%
Jasek K., Pasternak M.
Acta Physica Polonica A
|
2015
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vol. 127
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issue 6
1601-1605
EN
The results of numerical simulations and experimental measurements of surface acoustic wave resonator centre frequency and amplitude dependence on external pressure changes in the range 0-1 atm are presented in the paper. According to the analytical model as well as numerical calculations the pressure influence on the resonator centre frequency is linear. Unfortunately, in the real measurements the linearity is difficult to observe. Additional effects that modify the linear dependence of the centre frequency on pressure are caused by water particles. It is well visible especially in the low pressure range. The phenomenon can be applied for research of water contents in dry gases as well as construction of acoustoelectronic vacuometers.
2
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Influence of Humidity on SAW Sensor Response

100%
Jasek K., Pasternak M.
|
EN
In the surface acoustic wave sensors response analysis the influence of different factors on acoustic wave propagation velocity and resonant frequency of the surface acoustic wave device plays an important role. Because the resonant frequency is commonly assumed to be a sensor response, knowing the magnitude of this influence and its mechanisms is very important. The factors which interfere the most with the surface acoustic wave sensor response include: temperature, pressure, and humidity. The influence of humidity is almost impossible to eliminate because of phenomena connected with water adsorption at the surface of the substrate as well as the electrodes of the device.
3
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SAW Sensor for Mercury Vapour Detection

81%
Jasek K., Neffe S., Pasternak M.
Acta Physica Polonica A
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2012
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vol. 122
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issue 5
825-828
EN
Mercury is the element commonly applied in industry. Because of poisoning properties the monitoring of the mercury vapour concentration in the environment is very important. Mercury forms amalgams in connection with gold that causes a change in the electrical resistance and mass of the gold specimens. This effect was applied to measure mercury vapour concentration in the environment using surface acoustic wave technology. Two kinds of surface acoustic wave mercury sensors have been described in the paper. First one utilizes a thin film of gold deposited between aluminium interdigital transducers and reflectors of two-port surface acoustic wave resonator, and the second one golden interdigital transducers and reflectors without any sensitive film between them.
4
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Optopneumatic Detector with Platinum Flow Sensor

81%
Jasek K., Budzyński T., Stryszak E.
Acta Physica Polonica A
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2009
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vol. 116
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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
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A New System for Acoustoelectronic Gas Sensors Analysis

81%
Jasek K., Miluski W., Pasternak M.
Acta Physica Polonica A
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2013
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vol. 124
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issue 3
445-447
EN
Typical approach to the surface acoustic waves sensors response analysis is based on the use of self-oscillating circuits with surface acoustic wave device working inside positive feedback loop of an amplifier. Such kind of parametric measurement allows to track the center frequency of the sensor changes in particular. The method is widely used mainly due to their relative simplicity. Unfortunately, it has many disadvantages like frequency (phase) instability, sensitivity to unwanted factors, surface acoustic wave substrate mass-load limit etc. A new system to the analysis of surface acoustic wave gas sensors response as well as an exemplary measurement results are described in the paper. The presented system make the first step to the more complex conception realization.
6
Content available remote

New Approach to SAW Gas Sensors Array Response Measurement

81%
Jasek K., Miluski W., Pasternak M.
Acta Physica Polonica A
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2011
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vol. 120
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issue 4
639-641
EN
Majority papers concerning surface acoustic wave sensors technology is devoted to the analysis of self-oscillating circuits with surface acoustic wave device and its basic frequency changes in particular. Such circuits are widely used mainly due to their relative simplicity. Unfortunately the price of the simplicity is such drawbacks like frequency instability, sensitivity to unwanted factors, surface acoustic wave surface load limit etc. A new approach to the analysis of surface acoustic wave gas sensors response is proposed in the paper. The approach significantly eliminates the disadvantages of commonly used so far methods of analysis.
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