Xi'an Jiaotong University makes important progress in magnetic field sensor research

[ Instrument Network Instrument R & D ] Magnetic field sensor is a device that detects the strength of a magnetic field or its changes and converts it into an electrical signal output. Based on the magnetic field sensor, a variety of sensing functions can be developed, including current, power, position, distance, speed, angle, etc. , Has been widely used in industrial manufacturing, precision measurement, defense and aviation, medical, geography and other fields. Among them, the magnetic field angle sensor has huge application requirements in the fields of aerospace, satellite attitude adjustment, marine navigation, GPS positioning, and aircraft navigation.

Existing magnetic field angle sensors, such as AMR, magnetic diodes, Hall sensors, and fluxgate magnetometers, can detect the direction or intensity of the magnetic field, but there are limitations. For example, AMR magnetic field angle sensors have low measurement accuracy. A matching calibration algorithm is required; the fluxgate magnetometer is relatively large and expensive; the sensitivity of the magnetic diode is low, and the signal output is only about 0.05 mV / Oe, which requires matching modules such as signal amplification. Therefore, the development of magnetic field angle sensors with high accuracy, low cost, large signal strength, and simple driving methods has become an important research direction in the field of sensors.

Recently, the research group of Professor Liu Ming from the School of Electronic Science and Engineering has designed a new magnetic field sensor based on the "magneto-torsional" effect. The sensor uses a new force-electric coupling structure that can convert magnetic torque into stress. And applied to the piezoelectric material, the output of electrical signals under the action of a magnetic field is achieved. The structure of this device is optimized by finite element simulation software, which can effectively remove the interference signal and significantly improve the purity of the output signal. At the same time, the force-electric coupling structure can significantly improve the sensitivity of the output signal to the detection direction. In theory, the direction of magnetic sensitivity The ratio of the output signal strength to the non-sensitive direction can be "infinite" times. Based on the "magneto-twisting" effect, the research team developed a magneto-electric compass that can be used to detect the magnitude and direction of a two-dimensional planar magnetic field. The sensor can simultaneously measure the intensity and direction of the in-plane AC magnetic field with an accuracy of 0.01 Oe (about Magnetic field size is 1/50 ~ 1/60), and the angular accuracy of the direction is ± 0.2º, which solves the difficult problem of how to measure the strength and direction of the magnetic field with high accuracy at the same time. It has the advantages of measuring, calibrating and monitoring the magnetic field of industrial equipment. Great application prospects. In addition, this device is an ideal passive device, no power supply, no bias magnetic field, no correction algorithm, no signal amplification module, simple driving, almost no energy consumption, high accuracy, high sensitivity (the output can reach dozens to several (100 mV / Oe), high structural strength, wide operating frequency range (several Hz to several hundred Hz), obvious cost advantages, and is expected to be used in large-scale applications in industrial production, national economy, people's livelihood, power systems, and the Internet of Things.

The achievement was published in the international top journal IEEE Transactions on Industrial Electronics (IF = 7.5) under the title "A magnetoelectric compass for in-plane AC magnetic field detection", and applied for a national invention patent. Wu Jingen, a young teacher of the School of Electronic Science and Engineering, is the first author of the paper, and Professor Hu Zhongqiang and Liu Ming are the corresponding authors of the paper. This work is supported by projects such as the National Key R & D Program. Article link: https://doi.org/10.1109/TIE.2020.2978711

Professor Liu Ming's "Magnetoelectric Coupling Functional Materials Team" has long been engaged in the research of magnetoelectric composite materials and devices, including tunable microwave filters, flexible magnetic field sensors, magnetoresistive sensors (AMR, TMR, GMR), spin electronic devices, etc. A series of progress has been made in application. The magnetoelectric sensor developed by the team has great application potential in the fields of power grid energy harvesting (energy recovery), low-frequency magnetoelectric antennas, magnetic field detection, and current sensing of electricity meters.