Study On Modeling And Properties Of Rayleigh Wave And Love Wave Dual Mode Acoustic Wave Generation Device

The Rayleigh wave is a kind of sound wave propagating along the surface of a piezoelectric substrate.Its energy is mainly concentrated in a wavelength range near the surface of the piezoelectric crystal,and the particle trajectory is an ellipse.The Rayleigh wave have been extensively studied and applied in the fields of microfluidic control devices and gas sensors.The Love wave is a shearing transverse wave propagating in a waveguide layer on the surface of a piezoelectric substrate.Since the energy of the Love wave is mainly concentrated in the waveguide layer,it is very sensitive to surface interference.Therefore,Love wave device have been widely studied and applied in the fields of biosensors,electronic devices and analysis chips.In order to solve the complex problem of changing the propagation direction and intensity of the wave in the Rayleigh wave devices,a structure and 3D modeling scheme of the multi-interdigital transducer Rayleigh wave generation device are designed.The piezoelectric substrate material is 128° YX-LiNbO₃,and the interdigital transducer is Al electrode.The three-dimensional model of the multi-interdigital transducer Rayleigh wave generation device with the number of interdigital transducers of 4,6,and 8 is performed,respectively.Finally,the feasibility of the device is verified.The experimental results show that the multi-interdigital transducer Rayleigh wave generation device can induce Rayleigh waves at different angles.The wave only has the particle displacement components in the X and Y directions,and the maximum displacement of the particles is mainly concentrated on the center of the device surface.In addition,the modal frequency and maximum displacement of the device will increase with the number of interdigital transducers increase.Therefore,the Rayleigh wave intensity and the mixing performance of the device will be also enhanced.In order to solve the deficiency of Rayleigh wave and Love wave cannot be generated in the one acoustic wave device,a Rayleigh wave and Love wave dual mode acoustic wave generation device structure and three-dimensional modeling scheme are designed.By means of a three-dimensional model experiment of the dual mode acoustic wave generation device with 128°YX-LiNbO₃ piezoelectric substrate,ZnO thin film waveguide layer,and Al metal inter-digital transducer,the feasibility of the dual mode acoustic wave generation device is verified.The experimental results show that the dual mode acoustic wave generation device has a Rayleigh wave mode solution and a Love wave mode solution with the frequency of 49.5MHz and 49.7MHz respectively in the frequency range of 49MHz?60MHz.The Rayleigh wave at 49.5MHz only has a periodic change of particle displacement in the Y and Z directions,and the particle displacement in the X direction is 0.Meanwhile,the phase difference between the Z direction displacement and the Y direction displacement is 90°.The Love wave at 49.7MHz propagates along the X direction and only has the particle displacement in the Y direction,and there is no particle displacement in other directions.At this frequency,the X direction is the pure mode direction of the Love wave.