Research progress of tunneling magnetoresistance sensor

Abstract

Sensors play an important role in Internet of Things (IoT) industry and account for a rapidly growing market share. Among them, the magnetic sensor based on tunneling magnetoresistance (TMR) effect possesses great potential applications in the fields of biomedical, navigation, positioning, current detection, and non-destructive testing due to its extremely high sensitivity, small device size and low power consumption. In this paper, we focus on the development of TMR sensor technology routes, covering a series of research advances from a sensor transducer to three-dimensional magnetic field detection, and then to the applications. Firstly, we recall the development history of TMR sensors, explain its working principle, and discuss the method to improve the output linearity of single magnetic tunnel junction. Next, we state the Wheatstone-bridge structure, which can inhibit temperature drift in detail and review several methods of fabricating the full bridge of TMR sensors. Furthermore, for the market demand of three-dimensional magnetic field detection, we summarize the methods of designing and fabricating three-dimensional sensing structure of the TMR sensor. At the same time, we list several optimization schemes of TMR sensor performance in terms of sensitivity and noise level. Finally, we discuss two types of emerging applications of TMR sensors in recent years. The TMR sensors can also be used in intelligence healthcare due to their ultra-high sensitivity. In addition, devices from the combination of spin materials and MEMS structure have attracted wide attention, especially, because of the large commercial market of microphones, spin-MEMS microphones utilized TMR techniques will be the next research hotspot in this interdisciplinary field.

Research on frequency response analysis and bandwidth test method of TMR current sensor

“…The tunnel magneto resistive sensor is based on the magnetic tunnel junction design of the TMR element 5 , and the structure is shown in Figure 1. The basic structure of the magnetic tunnel junction is mostly sandwich structure, the magnetic moment direction of the nailed layer is fixed, and the magnetic moment direction of the free layer will change due to different external magnetic field directions, and the angle between the two magnetic moment directions determines the size of the magnetic resistance of the magnetic tunnel junction.…”

Overview of Magnetic Field Sensor

“…Fig. 6 The concept of the MEMS flflux concentrator Figure 6 is a MEMS vertically moving magnetic flux concentrator based on a cantilever beam structure [27] , The flux is changed by changing the distance between the flux modulating membranes and the gap between the two flux concentrators. When the distance between the magnetic flux modulation film and the gap increases, as the magnetic flux in the air gap increases, so does the magnetic field; When the distance between the magnetic flux modulation film and the gap decreases, the magnetic flux decreases, and the magnetic field decreases accordingly.…”

Research on new magnetic sensor technology

“…Hall effect sensor is a passive sensor, which can work only with an external power supply. This feature enables it to detect the running condition with low rotating speed [3][4][5][6][7][8][9] . (2) Magneto-optical effect sensor Magneto-optical effect sensor is a high-performance sensor developed by laser technology.…”