An orthogonal fluxgate-type magnetic microsensor with electroplated Permalloy core

In this paper, we present a new microfabricated orthogonal fluxgate sensor structure. The sensor consists of an electroplated copper excitation rod surrounded by an electroplated Permalloy layer and has planar pick-up coils for signal detection. The use of electroplating leads to a low-cost fabrication process and the use of planar pick-up coils provides easy integration with CMOS processes. The fabricated sensor has an excitation independent linear range of ±200 μT, a sensitivity of 510 μV/mT, and an average power dissipation of 8.1 mW for 100 mA-peak sinusoidal excitation current at 100 kHz frequency. The equivalent magnetic noise is 95 nT/√Hz at 1 Hz, and the RMS noise is 215 nT for 10 Hz bandwidth.