Development of a Magnetostrictive FeNi Coated Surface Acoustic Wave Current Sensor

Abstract

Featured Application: The developed magnetostrictive FeNi coated Surface acoustic wave sensor with high sensitivity; fast response; strong anti-interference; good linearity and repeatability; and lower hysteresis error will be a potential candidate for current monitoring application in smart grid line testing; metallurgical and power supplies; rail transit safety warnings and rescue.Abstract: A magnetostrictive FeNi-coated surface acoustic wave (SAW)-based current sensor was proposed in this work. The weak remanence and hysteresis effect of the FeNi itself contributes to suppress the asymmetry in sensor response at increasing and decreasing current. The sensor response was simulated by solving the coupled electromechanical field equation in layered structure considering the magnetostrictive effect and an approach of effective dielectric constant. The effects from the aspect ratio and thickness of the FeNi film on sensor response were analyzed to determine the optimal design parameters. Differential oscillation structure was used to form the sensor, in which, the FeNi thin film was deposited along the SAW propagation of the sensor chip by using RF magnetron sputtering. The magnetostrictive effect of the FeNi coating induced by the magnetic loading generates the perturbation in SAW velocity, and corresponding oscillation frequency. High sensitivity of 10.7 KHz/A, good linearity and repeatability, lower hysteresis error of 0.97% were obtained from the developed prototype 150 MHz SAW FeNi coated current sensor.

Enhanced Sensitivity of FeGa Thin-Film Coated SAW Current Sensor

“…The simulation was done to predict the sensitivity of the proposed sensor. The parameters of LiNbO 3 and SiO 2 used in the simulation were consistent with the literature [11]. The mechanics and electrical boundary conditions were also the same as the literature [11].…”

“…The parameters of LiNbO 3 and SiO 2 used in the simulation were consistent with the literature [11]. The mechanics and electrical boundary conditions were also the same as the literature [11]. The film thickness was set to 500 nm, and the aspect ratio was set to 1:1.…”

“…Using the FeCo thin film as the sensitive interface, the SAW current sensor prototype was constructed successfully, a larger sensitivity of 16.6 kHz/A was achieved, and the patterned design was considered to improve the hysteresis error [1,8,9]. A similar structure was also proposed by Tong et al; the current sensitivity of 10.7 kHz/A was achieved by using the FeNi as the sensing interface [11]. Kadota et al developed a SAW sensing chip constructed using a magnetostrictive Ni electrode on ST-cut 90 • X quartz substrate [12].…”

Contactless measurement of electric current using magnetic sensors

“…However, the performance of these devices is still much worse than that of magnetooptical fiber sensors. A magnetostrictive element can also be coupled to an SAW sensing device [57], [58].…”

Grating-patterned FeCo coated surface acoustic wave device for sensing magnetic field

“…Some meaningful results were reported from the SAW magnetic field sensor configurations using magnetostrictive materials as Ga, FeGa, Ni, and FeCo. [2][3][4][5][6][7][8][9] Kodota et al subsequently presented a SAW magnetic field sensor prototype using interdigital transducers (IDTs) made by magnetostrictive Ni on a quartz substrate, and wireless and passive measurement was offered. Obtained magnetic sensitivity was 730Hz/mT.…”