Application of Tunnel Magnetoresistance Sensor in Two-Dimensional Magnetic Tracking

摘要

In this experiment, a two-dimensional (2D) position detection device using a tunnel-magnetoresistance (TMR) sensor combined with orthogonal gradient coils was designed and fabricated. Typical magnetic trackers rely on three-axis field sensing to detect the AC or pulse DC fields induced by dipole transmitters [1]. In our design, a single axis TMR sensor is the target object which converts the position information into the output voltage with an in-phase and quadrature synchronous detector, as show in Fig. 1(a). The sensing direction of the TMR sensor was set perpendicular to the plane of two gradient coils. The two coils were driven by sine wave currents at 1 kHz with 90° phase difference to generate the fields with uniform gradients along the x-and y-axes of the plane, as shown in Fig. 1(b) and (c). The distances from the sensor to the two coils were analysed numerically to achieve the maximum linear range, which corresponds to the detection area of the device. The observed result shows that the device with gradient coils and a TMR sensor is promising in applications related to 2D magnetic field mapping to allow the sensor position be determined accurately in real-time during scanning.