AMR sensor can well realize the weak magnetic field measurement which in the range of geomagnetic field, and then has been widely applied in many areas, includes the navigation compass, the rotational position sensing, yaw rate sensing and trajectory tracker of virtual reality. AMR sensor needs to equip suitable AMR sensor magnets during measurement of linear and rotation position.
What is Anisotropic Magnetoresisance (AMR) Effect?
Anisotropic Magnetoresistance (AMR) Effect is phenomenon that electrical resistivity of ferromagnetic material (such as NiFe and NiCo alloys) changes with the included angle between the current direction and the external magnetic field applied to the ferromagnetic material. AMR Effect was discovered in the ferromagnetic polycrystal by William Tompson, 1st Baron Kelven in 1857. After that, AMR Effect earned more attention until prepared magnetic disc head based AMR Effect in 1971.
The core material of AMR sensor is anisotropic magnetic sensitive material, and permalloy is the most common option in currently. The thin solid film of permalloy will form resistor strip after deposited on the surface of the silicon chip, therefore, its grain size and morphology have significant impact on the performance of the sensor.
About AMR Sensor Magnets
Both ferrite and rare earth magnets can be utilized as AMR sensor magnets. Thus AMR sensor should equip suitable magnets to exhibit its best performance. It should be noted that relatively high magnetic field is conductive to reduce the influence of stray magnetic field to the sensor accuracy. Alignment degree of geometry center between AMR sensor and magnets also very crucial which will cause error of the whole system. In the meanwhile, the magnetic field strength near the magnet’s surface is not sufficiently homogeneous, thereby, the air gap is determined by many factors. SDM Magnetics has collected many magnetoresistance sensor magnets, and hope to provide a reliable and economical solution for you.
