Research Of Inductive Magnetic Sensor Based On Planar Coil And Ribbons

The giant magneto-impedance(GMI)effect has been attracting widespread attention from academic circles both at home and abroad since its discovery.The GMI sensor is a type of high performance sensor developed based on the GMI effect.GMI sensors are widely used in current sensing,bio-sensing,pressure sensing,and magnetic field detection due to their high sensitivity,fast effect speed,low power consumption,small size,and other advantages that are difficult to match with other sensors.The GMI effect from early amorphous to amorphous ribbons and amorphous films,the potential of the GMI effect is stimulated step by step.As a magnetic field sensor,a Hall sensor,a giant magnetoresistive(GMR)sensor,and a fluxgate sensor cannot be comparable to a GMI magnetic sensor.Due to the limitation of the mechanism of the GMI effect itself,the current working frequency of the GMI magnetic sensor is higher than 10 MHz or even GHz level.When the operating frequency is lower than 1 MHz,the GMI magnetic sensor is difficult to work normally.In order to compensate for the high operating frequency of GMI magnetic sensors,this paper aims to study inductive magnetic field sensors based on planar coils and amorphous multilayer structures at low frequency(<MHz)operating frequencies.This paper proposes a thin-film laminated structure formed by the combination of a planar coil and an amorphous ribbon,and theoretically derives the output inductance expression under the circumstance that the planar coil and the amorphous ribbon lamination structure are simplified;actually,several kinds of different sensor sensitivity have been designed through theoretical guidance.The structure was tested and compared with several different structures.The crystal in the classical Pierce oscillator circuit was replaced with the sensor's sensitive structure as the frequency-selective component.A suitable inductive oscillation circuit was designed and the sensing circuit was completed.Theoretical analysis;finally included the magnetic sensor performance testing and summary.By testing and comparing the output inductances of several different sensitive structures,the correctness of the theoretical derivation is confirmed.The inductive magnetic field sensor based on multi-layer thin-film laminated structure designed in this paper has a lower operating frequency than 1 MHz.It can achieve a very high inductance change rate,making up for the inability of the GMI magnetic sensor to work at frequencies below 1 MHz.Experimental results show that when the operating frequency is 100 kHz,the inductance change rate of the magnetic sensor's sensitive structure reaches 157.7%.The sensitivity of the magnetic sensor at this time is 1.235 kHz/Oe.