| AVS 54th International Symposium | |
| MEMS and NEMS | Monday Sessions |
| Session MN-MoA |
| Session: | Materials Processing, Characterization and Fab Aspects |
| Presenter: | A.S. Edelstein, U.S. Army Research Laboratory |
| Authors: | A.S. Edelstein, U.S. Army Research Laboratory J. Burnette, U.S. Army Research Laboratory G.A. Fischer, U.S. Army Research Laboratory S.F. Cheng, U.S. Naval Research Laboratory E.R. Nowak, University of Delaware |
| Correspondent: | Click to Email |
Recent innovations will lead to magnetic sensors that are smaller, more sensitive and/or cost less than current magnetometers. Examples of this are the chip scale atomic magnetometer, magnetic tunnel junctions with MgO barriers, and a device for minimizing the effect of 1/f noise, the MEMS flux concentrator. In the chip scale atomic magnetometer researchers have been able to fabricate the light source, optics, heater, optical cell, and photodiode detector in a stack that passes through a silicon wafer. There are limits on decreasing the size of the cell, because collisions with the cell walls limit the spin lifetime. A search is underway for materials to be used as cell liners that have a smaller effect on the spin lifetime. Theoretical and subsequent experimental work led to the observation of magnetoresistance values of 400% at room temperature in magnetic tunnel junctions with MgO barriers. The large magnetoresistance occurs because electrons in the majority band can tunnel more easily through the MgO barrier than electrons in the minority band. The MEMS flux concentrator has the potential to increase the sensitivity of magnetic sensors at low frequencies by orders of magnitude. The MEMS flux concentrator does this by shifting the operating frequency to higher frequencies where 1/f noise is unimportant. The shift occurs because the motion of flux concentrators on MEMS flaps modulates the field at kHz frequencies at the position of the sensor. The concept and development of the MEMS flux concentrator will be presented.