Magnetic Modeling of a MEMS Flux Concentrator

Magnetic flux concentrators are soft magnetic materials typically used to focus magnetic field lines in an effort to increase the sensitivity of a magnetic sensor. The use of magnetoresistive sensors, especially given the recent development of magnetic tunnel junctions (MTJ) with MgO barriers exhibiting magnetoresistance (MR) values as large as 400%, has created interest in flux concentrators as an avenue to not only increase sensitivity but to also mitigate the 1/f noise that is prevalent in these devices at low frequencies. Here we describe the magnetic modeling that has facilitated the development of the micromechanical system (MEMS) flux concentrator, a device that uses magnetic flux concentrators deposited on MEMS structures that modulate low frequency signals at the position of the sensor, essentially shifting the signal of interest to a frequency range in which 1/f noise is much lower. We present magnetic modeling results of various designs, including our current design, focusing on key design elements.