Triaxial fluxgate sensor with electroplated core

A novel fluxgate sensor with a single ferromagnetic core capable of measurement in three principal axes is presented. The sensor manufacturing process and internal coil structure is explained and its excitation is modelled using FEM. The sensor was implemented utilizing multilayer printed circuit board copper routes and electroplated through holes to create appropriate coils. The sensor magnetic core was electroplated on the printed circuit board surface and through holes using Permalloy (Ni80Fe20). The core material properties were identified using a PCB based transformer device showing relative permeability of 2300 at 50 kHz. Sensor excitation effects are investigated with special emphasis on sensor axis orthogonality revealing a significant sensitivity axis tilt due to excitation means. The sensor is characterised in terms of sensitivity, linearity and noise. Measurements show a significant influence of core material anisotropy on sensitivity (90 V/T in x axis vs. 112 V/T in y axis). The z-axis sensitivity (198 V/T) is significantly higher due to the different core geometry in corresponding direction and different number of pick-up coil turns.