Simulating the piezoelectric substrate influence on the characteristics of surface acoustic wave-magnetostriction sensor based on the FeNi magnetic sensitive material

Abstract

This paper simulates the influence of two piezoelectric substrate types on the sensitivity and measuring range of surface acoustic wave-magnetostriction (SAW-MO) sensor by the finite elements method (FEM) based on using the FeNi magnetic sensitive layer with E-H chacrateristics (Young’s Modulus – Magnetic field intensity). The sensor structure selected for the study is the delay-line: the distance between the two sets of electrodes is 5mm, the number of finger pairs of each electrode set is 25, and the distance-width between the fingers is 10m regularly, the electrode material is aluminum. The piezoelectric substrates chosen for simulation are LiNbO3 and AlN in which the LiNBO3 piezoelectric substrate is the block form with the surface velocity of 3318.1m/s and the AlN piezoelectric substrate is the thin film with the surface wave velocity of 5598.9m/s. So the generality is ensured when evaluating their influence on the response of SAW-MO sensor. For magnetic sensitive materials, the group selected the FeNi which E-H characteristics was experimentally built. During simulation by finite elements method, the sensor structure is tested with many datasets whose number of divided elements is different. However, the simulation results have converged with the number of divided elements is 113556. The simulation result shows that the sensivity of the FeNi/IDT/AlN structure magnetic sensor is larger than the FeNi/IDT/LiNbO3 structure magnetic sensor with sensitivities of 8.698kHz/Oe and 2.345kHz/Oe, respectively. The result also indicates that the response range of the FeNi/IDT/AlN magnetic sensor is [0 ÷ 109]Oe, which is smaller than the FeNi/IDT/LiNbO3 magnetic sensor is [0 ÷ 190]Oe.