The development of SAW current sensor based on the magnetostrictive effect

In order to achieve a kind of high-performance current sensor with high sensitivity and low temperature drift, this paper put forward a kind of new current sensor combined the surface acoustic wave (SAW) technology with magnetostrictive effect, analyzed its response mechanism and improve its temperature characteristic. This SAW current sensor used dual-delay-line oscillators based on 128°YX-LiNbO₃ piezoelectric substrate as sensing element. LiNbO₃ piezoelectric substrate surface was covered with SiO₂ thin layer whose temperature coefficient polarity is opposite to improve the temperature stability, and one of the SAW delay lines was sputtered with magnetostrictive FeCo film in response to current. The magnetic field of the desired current induces the FeCo film´s magnetostrictive strain and ΔE effect, changes the SAW propagation characteristics. Using the Helmholtz coil, the developed SAW current sensor was characterized, high sensitivity, and good linearity were observed in the current experiment.