A normal mode theory for the Rayleigh wave amplifier

Kino, G. S.; Reeder, T.M.

doi:10.1109/t-ed.1971.17304

Cited by 88 publications

(23 citation statements)

References 17 publications

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“…In this paper a new analytical model of a SAW gas sensor and numerical results have been shown for the gases H 2 , CO 2 , NO 2 , NH 3 and sensing layers WO 3 .The profile of the concentration of gas in the sensor layer has been applied in order to model the acoustoelectric effect in the SAW gas sensor. A porous semiconductor layer has been divided into sub-layers.…”

Section: Discussionmentioning

confidence: 99%

“…The best agreement between the perturbation theory and exact numerical calculations is obtained by using the so-called weak-coupling approximation, in which the stress field T is assumed to be unchanged by the perturbation [3,5]. It is most convenient to express the electrical boundary conditions in terms of the electrical surface impedance per unit area: Figure 1: Electrical boundary conditions.…”

Section: Electrical Surface Perturbationsmentioning

confidence: 99%

“…Ingebrigtsen's formula [3], the impedance transformation law, gas concentration profiles, and predicts the influence of a thin semiconductor sensor layer on the SAW velocity. In the paper a new theory of analyzing a SAW gas sensor is proposed.…”

Section: Introductionmentioning

confidence: 99%

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Analytical model of a SAW gas sensor

Urbańczyk

2011

Computational Methods and Experimental Measurements XV

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SAW gas sensors are attractive because of their remarkable sensitivity due to changes of the boundary conditions (mechanical and electrical in the acoustoelectric effect) propagating of the Rayleigh wave, introduced by the interaction of a thin chemically active sensor film with gas molecules. This unusual sensitivity results from the fact that most of the acoustic wave energy is concentrated near the waveguide surface within approximately one or two wavelengths. In the paper a new theoretical model of analysing a SAW gas sensor is presented. The effect of SAW velocity changes depends on the profile concentration of diffused gas molecules in the porous sensor film. Basing on these analytical results, the sensor structure can be optimized. Some numerical results are shown.

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Section: Discussionmentioning

confidence: 99%

Section: Electrical Surface Perturbationsmentioning

confidence: 99%

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Analytical model of a SAW gas sensor

Urbańczyk

2011

Computational Methods and Experimental Measurements XV

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“…Using the transformation law for the n-th sublayer, it is possible to calculate the electrical admittance on the surface of the waveguide, which is "seen" by the surface wave. Then, the resultant of the admittance is used in Ingebrigtsen's formula [9][10][11] to determine the changes in the velocity of the surface wave resulting from the acoustoelectric interaction between the SAW and the sensor layer with a variable concentration of gas molecules in the y direction (in the depth of the layer). .…”

Section: Analytical Model Of a Gas Sensormentioning

confidence: 99%

SAW sensor for detection of hydrocarbons. Numerical analysis and experimental results

Hejczyk¹,

Urbańczyk²,

Wituła³

et al. 2012

Bulletin of the Polish Academy of Sciences: Technical Sciences

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Abstract. The paper presents the results of numerical analyses of the SAW gas sensor in the steady and non-steady state. The effect of SAW velocity changes vs. the surface electrical conductivity of the sensing layer is predicted. The conductivity of the porous sensing layer above the piezoelectric waveguide depends on the profile of the diffused gas molecule concentration inside the layer. Knudsen's model of gas diffusion was used. Numerical results for the gases CH4, C2H4, C3H8, C6H6 in the steady state and CH4 in the non-steady state in the WO3 sensing layer have been shown. The results of numerical analyzes allow to select the sensor design conditions, including the morphology of the sensor layer, its thickness and operating temperature. Some numerical results were verified in experimental studies concerning methane.

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“…This unusual sensitivity results from the simple fact that most of the acoustic wave energy is concentrated near the crystal surface within approximately one or two wavelengths. The surface wave is in its first approximation highly sensitive to any changes of the physical or chemical properties of the thin active layer previously placed on the crystal surface [1][2][3].…”

Section: Introductionmentioning

confidence: 99%