Thickness shear vibration of a ZnO film structure covered with magnetic fluid

This paper aims to reveal the effect of magnetic liquid on the resonant frequency shift and the output impedance. For this purpose, a thin film sensor was designed with a finite-thickness layer of magnetic fluid, and the thickness shear vibration of the film was analysed in details. The main findings are as follows. First, the relative resonance frequency is positively correlated with the intensity of magnetic field, and the viscosity coefficient, density and volume fraction of magnetic fluid. The effect of magnetic field on the shift of the relative resonant frequency depends on various parameters of magnetic liquid. With the increase of the volume fraction, density and viscosity coefficient, the resonant frequency plunges, but the output impedance peak grows in size. Therefore, the relative resonant frequency shift and the output impedance are sensitive to various parameters in the design. The research findings shed new light on the application of thin piezoelectric film in sensors.