共查询到20条相似文献,搜索用时 15 毫秒
1.
Ouali FF Doy N McHale G Hardacre C Ge R Allen RW MacInnes JM Newton MI 《Analytical chemistry》2011,83(17):6717-6721
In this work, we have shown that a 100 MHz Love wave device can be used to determine whether room temperature ionic liquids (RTILs) are Newtonian fluids and have developed a technique that allows the determination of the density-viscosity product, ρη, of a Newtonian RTIL. In addition, a test for a Newtonian response was established by relating the phase change to insertion loss change. Five concentrations of a water-miscible RTIL and seven pure RTILs were measured. The changes in phase and insertion loss were found to vary linearly with the square root of the density-viscosity product for values up to (ρη)(1/2) ~ 10 kg m(-2) s(-1/2). The square root of the density-viscosity product was deduced from the changes in either phase or insertion loss using glycerol as a calibration liquid. In both cases, the deduced values of ρη agree well with those measured using viscosity and density meters. Miniaturization of the device, beyond that achievable with the lower-frequency quartz crystal microbalance approach, to measure smaller volumes is possible. The ability to fabricate Love wave and other surface acoustic wave sensors using planar metallization technologies gives potential for future integration into lab-on-a-chip analytical systems for characterizing ionic liquids. 相似文献
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Xi Chen Dali Liu 《Materials science & engineering. C, Materials for biological applications》2010,30(8):1175-1182
An investigation of viscosity sensitivity for liquid property detection applications based on the ZnO/SiO2/Si layered structure Love mode surface acoustic wave (SAW) sensors is presented. One of our interests in this paper is to optimize the SAW viscosity sensor under the condition of temperature stability by considering the relations among electromechanical coupling coefficient, viscosity sensitivity and temperature coefficient of delay (TCD). Some important results have been obtained by solving the system of coupled electromechanical field equations and Navier–Stokes equation. It is found that the electromechanical coupling coefficient and viscosity sensitivity can be further improved by adjusting the thickness of SiO2 thin film and a zero TCD device also can be obtained by introducing a SiO2 thin film with proper thickness. We try to obtain a device which possesses the viscosity sensitivity as high as possible and has zero TCD. Another interest of this paper is to improve the traditional viscosity sensitivity expression by considering the coupling effect between the liquid viscosity and density. It is shown that the coupling effect cannot be neglected from the numerical results. This modification could make the obtained viscosity more accurate. This analysis is meaningful for the manufactures and applications of the ZnO/SiO2/Si structure Love wave sensor for liquid property detection. 相似文献
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Jakoby B Vellekoop MJ 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2000,47(3):701-705
Microacoustic Love wave delay lines show high sensitivity to perturbations such as mass depositions on the wave-guide surface. Furthermore, because of their shear polarization, Love waves are ideally suited for liquid sensing applications. Using a Love wave delay line as feedback element in an oscillator allows the realization of viscosity sensors, and, using a chemical interface, chemical sensors, where the output signal is the oscillation frequency. To achieve a high effective sensitivity, the cross-sensitivity to temperature has to be kept low. We outline the proper choice of a material and especially focus on the influence of crystal cut and the major device design parameters (mass sensitivity and coupling coefficient) on the temperature coefficient of the sensor. 相似文献
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非饱和地基中Love波的传播特性 总被引:1,自引:0,他引:1
基于非饱和多孔介质的波动方程,考虑了土中水,气体与土骨架之间的粘性耦合作用,建立了弹性半空间上非饱和土层中Love波的弥散方程。首先分析了饱和度与频率对非饱和孔隙介质中剪切波速的影响。然后运用数值方法得到了不同饱和度下土层中多种Love模态波的弥散特性和位移分布情况,并用图表的形式给出。数值计算结果表明,上覆非饱和土层中Love波的传播速度和衰减系数不仅具有频散性,而且与土层的饱和度有关。在不同饱和度时的高模态(n≥2)的Love波的截止频率值不同。此外,讨论了饱和度对Love波水平位移幅值的影响。 相似文献
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Love waves, a variety of surface acoustic waves (SAWs), can be used to detect very small biological surface interactions and so have a wide range of potential applications. To demonstrate the practicality of a Love wave SAW biosensor, we fabricated a 155-MHz Love wave SAW biosensor and compared it with a commercial surface Plasmon resonance (SPR) using glycerol-water solution with known densities and viscosities to calibrate the response signals of the biosensors. And the mass per unit area of anti-mouse IgG bound with protein G onto the sensitive layer of the biosensor was calculated on the basis of the calibration result. The sensitivity of the Love wave SAW biosensor was the same as or greater than that of the SPR biosensor. Furthermore, the Love wave SAW biosensor was capable of measuring a much wider range of viscosities than the SPR biosensor. Although the operating principle of the Love wave SAW biosensor is completely different from that of the SPR biosensor, the subtle changes in the viscoelastic properties of the biological layer that accompany biological binding reactions on the sensitive layer can be monitored and measured in the same ways as with the SPR biosensor. 相似文献
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Moreira F. El Hakiki M. Elmazria O. Sarry F. Le Brizoual L. Alnot P. 《IEEE sensors journal》2008,8(8):1399-1403
In this paper, the layered structure ZnO/Quartz (90deg rotated ST-cut) is investigated theoretically and experimentally. Both waves, Rayleigh and Love, are analyzed. Dispersion curves of phase velocities, electromechanical coupling coefficient (K 2) and temperature coefficient of frequency (TCF) were calculated as a function of normalized thickness ZnO film (kh ZnO = 2pih ZnO /lambda) and the optimum value of h ZnO was determined for experimental study. Experimental results combined with simulation lead to clearly identify the generated waves and their higher modes in this structure except the mode 0 that shows comparable velocity for both Rayleigh and Love waves. The identification of the wave type was performed by studying the frequency response of the device with or without a droplet of water in the wave path. We also demonstrate that the highest elastic velocity is obtained for the mode 1 of the Love wave. This Love wave mode exhibits very interesting electrical characteristics, good K 2, high-frequency rejection, low TCF, and very low attenuation in liquid making it very attractive for gas and liquid sensor applications. 相似文献
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The existence and propagation behavior of Love waves in a functionally graded material (FGM) layered structure are theoretically investigated in this paper based on the three-dimensional equations of linear electricity. The Wentzel–Kramers–Brillouin (WKB) method is applied to obtain the analytical solutions in the FGM layer. The dispersion equation for a Love surface wave in this kind of structure is obtained in a simple mathematical form, where the material property variation of the FGM layer is arbitrary. First, the solution is used to study the effect of the gradient coefficients on the dispersion curves and the phase velocities of Love waves. Then, the influence of gradient coefficients on the stress and displacement fields is discussed in detail. The reported results are important in the design of surface acoustic wave (SAW) devices with high performance. 相似文献
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The propagation of Love waves on an elastic homogeneous half-space with a piezoelectric gradient covering layer is studied by the geometric integration method in this article. First, the state transfer equation of a Love wave is derived from the governing equations and constitutive relations. Then, the transfer matrix of the state vector is obtained by solving the state transfer equation of a Love wave and then the stiffness matrix is obtained. By combining transfer matrices and the stiffness matrices of the gradient covering layer and the homogeneous half-space, the total surface stiffness matrix of a Love wave is obtained. Lastly, the application of the electrically open circuit and short circuit conditions and mechanically traction-free conditions gives the frequency dispersive relation of a Love wave. For the gradient covering layer, the material constants at the bottom of the covering layer may be greater or smaller than that at the top of the covering layer. The two situations and three kinds of gradient profiles for each of these two situations are investigated. The numerical results show that the Love wave speed is sensitive to not only the material constants at the bottom and the top of the covering layer, but also the gradient profiles of the covering layer. 相似文献
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Measurements of the width of a shock wave in glycerol dependent on the pressure of shock compression were taken to improve the method of determination of liquids viscosity. It was found that the time of growth of parameters in a shock wave decreases to the limit of time resolution of modern measurements, which is approximately 1 ns at the shock compression pressure of around 2.5 GPa. The values of viscosity, obtained at these parameters, are in agreement with experimental data. The transition to stepwise shock compression expands the pressure range, available for measurement by this method, and also makes possible the opportunity to vary the temperature. 相似文献
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饱和土中Love波弥散特性 总被引:4,自引:0,他引:4
本文利用有限元法推导了饱和土中Love面波的弥散特性方程,讨论了饱和土中Love面波波速度的弥散特性及位移分布规律,并与相应弹性地基Love面波的波速度弥散曲线进行了比较。 相似文献
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《International Journal of Engineering Science》2007,45(2-8):455-466
The propagation behavior of transverse surface waves (Love waves) in a piezoelectric half space of polarized ceramics carrying a functionally graded material layer is studied from the three-dimensional equations of linear piezoelectricity. The Wentzel–Kramers–Brillouin (WKB) asymptotic technique is adopted for the theoretical derivations of analytical solutions in the functionally graded layer. The dispersion relations of Love wave in the structure are obtained for both electrically open and shorted cases. Firstly, these solutions are used to study effect of the gradient coefficients on the dispersive relations and phase velocities of Love wave propagation. Then influence of the gradient coefficients on the electromechanical coupling factor is discussed in detail. The results reported are meaningful for the design of surface acoustic wave (SAW) devices with high performance. 相似文献
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Collet B Destrade M 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2006,53(11):2132-2139
Consider a layer consisting of a m3m dielectric crystal, with faces cut parallel to a symmetry plane. Then bond it onto a semi-infinite mm2 piezoelectric substrate. For a X- or Y-cut of the substrate, a Love wave can propagate in the resulting structure and the corresponding dispersion equation is derived analytically. It turns out that when the upper (free) face of the layer is metalized, a fully explicit treatment can also be conducted in the case of a Y-cut rotated about Z. In the case of a germanium layer over a potassium niobate substrate, the wave exists at any wavelength for X-and Y-cuts but this ceases to be the case for rotated cuts, with the appearance of forbidden ranges. By playing on the cut angle, the Love wave can be made to travel faster than, or slower than, or at the same speed as, the shear bulk wave of the layer. A by-product of the analysis is the derivation of the explicit secular equation for the Bleustein-Gulyaev wave in the substrate alone, which corresponds to an asymptotic behavior of the Love wave. The results are valid for other choices for the layer and for the substrate, provided they have the same, or more, symmetries. 相似文献
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The aim of the present paper is to study the effect of gravity on visco-elastic surface waves in solids. The wave velocity
equations are deduced from Biot’s theory of initial stress on the assumption that gravity creates a type of initial stress
— hydrostatic in nature. Resulting equations are used to investigate surface waves of the Rayleigh, Love and Stoneley types.
Results are in good agreement with corresponding classical results when gravity and viscosity are neglected. 相似文献
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Love wave propagation in layered magneto-electro-elastic structures with initial stress 总被引:1,自引:0,他引:1
Summary An analytical approach is taken to investigate Love wave propagation in layered magneto-electro-elastic structures with initial
stress, where a piezomagnetic (piezoelectric) material thin layer is bonded to a semi-infinite piezoelectric (piezomagnetic)
substrate. The magneto-electrically open and short conditions are applied to solve the problem. The phase velocity of the
Love wave is numerically calculated for the magneto-electrically open and short cases, respectively. The effect of the initial
stress on the phase velocity and the magneto-electromechanical coupling factor are studied in detail for piezomagnetic ceramics
CoFe2O4 and piezoelectric ceramics BaTiO3. We find that the initial stress has an important effect on the Love wave propagation in layered piezomagnetic/piezoelectric
structures. 相似文献
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Analysis and optimization of Love wave liquid sensors 总被引:1,自引:0,他引:1
Jakoby B Vellekoop MJ 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1998,45(5):1293-1302
Love wave sensors are highly sensitive microacoustic devices, which are well suited for liquid sensing applications thanks to the shear polarization of the wave. The sensing mechanism thereby relies on the mechanical (or acoustic) interaction of the device with the liquid. The successful utilization of Love wave devices for this purpose requires proper shielding to avoid unwanted electric interaction of the liquid with the wave and the transducers. In this work we describe the effects of this electric interaction and the proper design of a shield to prevent it. We present analysis methods, which illustrate the impact of the interaction and which help to obtain an optimized design of the proposed shield. We also present experimental results for devices that have been fabricated according to these design rules. 相似文献
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覆盖层为功能梯度材料弹性半平面中的Love波 总被引:1,自引:0,他引:1
对均匀各向同性弹性半平面上覆盖一层功能梯度材料中存在的Love波的频散问题进行了研究,给出了Love波频散方程的一般形式。利用WKBJ近似理论,给出了功能梯度材料层的位移、应力近似解析解,导出了Love波WKBJ近似频散方程的一般形式。该文以功能梯度材料层的剪切弹性模量和质量密度沿厚度方向均为指数函数变化为例,进行了实例计算和分析,给出了频散曲线,讨论了Love波在功能梯度材料覆盖层弹性半平面中传播的一般性质。这些结论对无损检测和反问题分析方法的改进提供理论依据。 相似文献