Microfluxgate sensor with amorphous cobalt (Co-Nb-Zr) soft magnetic core for electronic compass

A silicon based microfluxgate sensor with a cobalt based amorphous soft magnetic core for electronic compass is presented in this paper. A sputtered Co 85 Nb 12 Zr 3 magnetic core having a rectangular ring shape is combined with microcopper solenoid coils for excitation and pickup, which were wound alternately around the core to increase the number of coil turns. The Co 85 Nb 12 Zr 3 as a core material is adopted for improving properties of the magnetic core and easy integration with micromachining processes to achieve a small size of the sensor. The sputtered Co 85 Nb 12 Zr 3 showed dc effective permeability of ∼ 10 000 and an extremely low coercivity of ∼ 0.03 Oe with the thickness of 1 μ m . The Co 85 Nb 12 Zr 3 as a thin film core with high permeability and low coercivity was easily saturated by a low excitation magnetic field, enhancing the sensitivity and linearity of the microfluxgate sensor. Finally, the sensor showed excellent linearity response over the range of − 300 to 300 μ T with sensitivity of 60 V ∕ T at the excitation condition of 3.0 V p - p and 5.0 MHz square wave form. The sensor size excluding pad region is about 0.55 × 1.4 mm 2 .