Abstract
We are developing a device, the MEMS flux concentrator, that will greatly decrease the effect of 1/f noise in magnetic sensors. It does this by modulating the incoming signal and thus shifting the operating frequency of the sensor. This is accomplished by placing flux concentrators on MEMS structures that oscillate at kHz frequencies. Depending upon the sensor, shifting the operating frequency reduces the 1/f noise by one to three orders of magnitude at one Hz. We have succeeded in fabricating the necessary MEMS structures and observing the desired kHz normal mode resonant frequency. Only microwatts are required to drive the motion. We have used spin valves for our magnetic sensors. The measured field enhancement provided by the flux concentrators agrees to within 3% with the value estimated from finite element calculations. Noise measurements provide strong evidence that the device is likely to reduce the effect of 1/f noise. Flip chip bonding is likely to allow us to fabricate complete, fully functioning sensors.
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Edelstein, A.S., Fischer, G.A., Pedersen, M. et al. Minimizing 1/f Noise in Magnetic Sensors using an AC MEMS Flux Concentrator. MRS Online Proceedings Library 906, 309 (2005). https://doi.org/10.1557/PROC-0906-HH03-09
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DOI: https://doi.org/10.1557/PROC-0906-HH03-09