Enhanced Sensitivity of Surface Acoustic Wave (SAW) Current Sensor Based on TbDyFe Thin Film

In this paper, a new TbDyFe thin-film coated Surface Acoustic Wave (SAW) sensor is proposed for sensing current. A 150 MHz SAW device with delay line pattern is fabricated photolithographically on 128° YX LiNbO
3
substrate. Then the TbDyFe thin-film is deposited into the propagation path of surface acoustic wave by magnetron sputtering to build the sensing device. The reference sensing device with TbDyFe thin-film and the naked device are collected in a dual-channel differential oscillator so as to build the current sensor. When the magnetic field excited by the current is applied, the magnetostrictive effect produced by the TbDyFe thin-film causes the change of SAW propagation speed. And then the change of the corresponding oscillator frequency is used to characterize the current. Taking advantage of the TbDyFe thin-film such as high magnetostrictive coefficient and low coercive force, high sensitivity of 16.8 kHz/A is achieved in the experiments.