Macro-magnetic Modeling of the ARL Microelectromechanical System (MEMS) Flux Concentrator

摘要

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 magnesium oxide (MgO) barriers exhibiting magnetoresistance values as large as 400%, has created interest in flux concentrators as an avenue to not only increase sensitivity but also mitigate the 1/function noise that is prevalent in these devices at low frequencies. Here we describe the magnetic modeling performed at the U.S. Army Research Laboratory (ARL) that has facilitated the development of the microelectromechanical 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/function noise is much lower. We present magnetic modeling results of various designs, including our current design, focusing on key design elements.