Properties of sensors based on shear-horizontal surface acoustic waves in LiTaO/sub 3//SiO/sub 2/ and quartz/SiO/sub 2/ structures

Herrmann, Falk; Weihnacht, M.; Büttgenbach, S.

doi:10.1109/58.896139

Cited by 58 publications

(31 citation statements)

References 16 publications

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“…The sensitivity reaches the maximum at t/λ = 0.04. The maximum sensitivity of MZO/LiNbO 3 is 6.21×10 -8 m 2 s/kg, which is higher than the literature [4] reported the SiO 2 /Quartz (4.8×10 -8 m 2 s/kg) and SiO 2 /LiTaO 3 (1.8×10 -8 m 2 s/kg) structures. The TCF value of 64 YX-LiNbO 3 is approximately -81 C/ppm [7] , and that of the ZnO film is negative [8] .…”

contrasting

confidence: 42%

“…In liquid environment, Rayleigh surface waves have a displacement component perpendicular to the substrate where exist a compressional waves leading to a strong radiation loss [3] . For this reason, shear horizontal (SH) polarized waves are preferred because they do not couple elastically with ideal liquids and make no radiation loss [3][4][5] . SH modes can be converted into Love modes by means of a layer acting as a guide.…”

mentioning

confidence: 99%

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An investigation of Love wave devices based on ZnO:Mg/LiNbO3 structure

Chang

Chu

Yeh

et al. 2008

Sensors and Actuators B: Chemical

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contrasting

confidence: 42%

mentioning

confidence: 99%

An investigation of Love wave devices based on ZnO:Mg/LiNbO3 structure

Chang

Chu

Yeh

et al. 2008

Sensors and Actuators B: Chemical

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“…The properties of some substrates are summarized in Table 2.1-3. Quartz and lithium tantalate are very promising (see, eg, [61,86]). …”

Section: Substratesmentioning

confidence: 99%

Microacoustic Sensors for Liquid Monitoring

et al. 2001

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In recent years, much effort has been expended to developing miniaturized, reliable sensors for measuring physical and chemical liquid properties. Microacoustic devices may be employed to determinate physical quantities perturbing the propagation conditions of the acoustic wave, even in liquid environments. For liquid sensors, acoustic modes with shear polarization are often used in order to avoid radiation losses. Examples are shear bulk modes, surface skimming bulk waves, shear-horizontal acoustic plate modes, and Love modes. Furthermore, modes with sagittal polarization may be applied if their phase velocity is sufficiently lower than the sound velocity in the adjacent liquid. General interactions between acoustic waves and liquids are viscous coupling, acoustoelectric effects, and mass loading. The resulting changes in device frequency and attenuation may be utilized for sensing purposes.The general advantages of microacoustic sensors are high sensitivity, simple fabrication, and quasidigital frequency readout. Hence, a wide variety of devices based on different modes for very different applications has been discussed in the relevant literature. The aim of this review is to provide a systematic overview of microacoustic sensors particularlay suited for operation in liquids.First, we provide a brief introductionto surfaceacousticwave devices and the underlying physics, basic microacoustic structures, and general measurement techniques. A description of the mechanisms of interaction between liquids and acoustic waves is then followed by a comprehensive survey covering the different types of microacoustic liquid sensors, with emphasis on the mode-specific device properties. Thereafter, aspects of material selection and device fabrication are summarized. Lastly, an overview is given indicating where microacoustic liquid sensors have already been put into practice and where their application may be expected in the near future.

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“…While some recognition of the difference between group and phase velocity exists in literature on acoustic plate mode sensors, [8][9][10] relatively little discussion of this has occurred in literature on Love wave sensors. 11,12 The main effect that has been accounted for is the inclusion of a factor, which is the ratio of the group to phase velocity, in the formula ⌬ f / f ϭ(v g /v)(⌬v/v͒ relating the fractional frequency shift to the fractional change in phase speed due to mass deposition. However, this does not represent a detailed consideration of the effect of dispersion on acoustic wave sensors and how it influences the mass sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Mass sensitivity of acoustic wave devices from group and phase velocity measurements

McHale

Martin

Newton

2002

Journal of Applied Physics

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The effect of dispersion on acoustic wave sensors is considered. The discussion is focused upon layer guided surface acoustic waves ͑Love waves͒, which obtain their high mass sensitivity for the first Love wave mode by optimizing the guiding layer thickness, d, such that dϳ l /4; the wavelength in the layer is given by l ϭ f /v l where f is the operating frequency and v l is the shear acoustic speed of the guiding layer. We show that this optimization of guiding layer thickness corresponds to strong dispersion so that the phase and group velocities can be quite different. From the definition of the phase velocity mass sensitivity, we show that it can be determined from either the slope of the curve of phase velocity with normalized guiding layer thickness, zϭd/ l , or from the phase and group velocities measured for a given guiding layer thickness. Experimental data for a poly͑methylmethacrylate͒ polymer guiding layer on 36°XY Lithium Tantalate is presented. Measurements of phase velocity and group velocity determined by a network analyzer were obtained for systematically increasing guiding layer thicknesses; a pulse transit experiment was also used to provide independent confirmation of the group velocity data. Two independent estimates of the mass sensitivity are obtained for zϭd/ l Ͻ0.22 from ͑i͒ the slope of the phase velocity curve and ͑ii͒ the measurements of the group and phase velocity. These two estimates are shown to be consistent and we, therefore, conclude that it is possible to determine the mass sensitivity for a Love wave device with a given guiding layer thickness from measurements of the phase and group velocities. Moreover, we argue that the formula using group velocity to determine phase velocity mass sensitivity can be extended to a wide range of other acoustic wave sensors. In addition, we suggest that variations in the group velocity due to deposited mass may be a more sensitive parameter than variations in the phase velocity.

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Properties of sensors based on shear-horizontal surface acoustic waves in LiTaO/sub 3//SiO/sub 2/ and quartz/SiO/sub 2/ structures

Cited by 58 publications

References 16 publications

An investigation of Love wave devices based on ZnO:Mg/LiNbO3 structure

An investigation of Love wave devices based on ZnO:Mg/LiNbO3 structure

Microacoustic Sensors for Liquid Monitoring

Mass sensitivity of acoustic wave devices from group and phase velocity measurements

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