Research On Love Wave Propagation Properties And Liquid Dielectric Constant Sensing

The acoustic wave sensor is a kind of new sensors which adapts to the development trend of the micro sensor and MEMS, mainly includes SAW sensor, Lamb wave sensor, Love wave sensor and so on. Love wave sensor receives widespread attention because of suiting for liquid characteristic parameters detection. Compared with SAW device and Lamb wave device, Love wave device structure is more complex. So it is a hot research point, and also a difficult research point in the acoustic wave sensing field.First, this paper illustrates the important significance of detecting characteristic parameters about the liquid dielectric constant and current method used commonly. Three kinds of acoustic device structure, principle and application characteristics are introduced in this paper. Besides, through comparative analysis, we can see the superiority of Love wave device used for liquid characteristic parameters detection. Researching on Love wave propagation properties and liquid characteristic parameters about the liquid dielectric constant sensing are the core of this paper which includes theoretical modeling, numerical simulations and experimental test on the basis of the present research of Love wave both at home and abroad.In the process of researching on Love wave propagation properties, the paper begins with coupled wave equations and acoustic field component of piezoelectric materials. According to acoustic propagation theory of the layer media, the theoretical model of three Love wave modes are established on the basis of the partial wave theory and the surface effective permittivity method, and the three Love wave modes include Conventional Love wave, Sagittal vector Love wave and Generalized Love wave. Then combining with the actual production conditions of Love wave device, and taking‘PZT-5H/TiO2’and‘LiTaO3/SU-8’as example, the paper simulate and analysis the propagation properties of Love wave, includes energy leakage, propagation modes, dispersion characteristics, electromechanical coupling coefficient and so on. Besides, we draw some useful conclusions. In the process of researching on liquid characteristic parameters detection, the paper begins withwave characteristics of liquid. The theoretical model of three layer structure“piezoelectric material—non-piezoelectric film—liquid”are established, and the energy leakage and excitation efficiency of loading liquid love wave are researched. This paper dissects sensing characteristic about the liquid dielectric constant of love wave on the basis of above theoretical model, and deeply analyzes the optimization design of corresponding love wave device according to the sensitivity and electromechanical coupling coefficient, simultaneously discusses the liquid mechanical parameters sensing properties of Love wave.Finally, based on the research conclusion of theory modeling and numerical simulation,combining with the actual production conditions of Love wave device, two groups of Love wave devices are designed, and are experimentally test through the network analyzer. The experimental results prove that Love wave propagation properties and liquid dielectric constant sensing properties are correct in this paper. It also show that it is effectiveness for Love wave device used in liquid dielectric constant detection.