Electronic compass using two-axis micro fluxgate sensing element

This paper presents a micro fluxgate sensor fabricated by Si-based Micro Electro Mechnical Systems (MEMS). To measure X- and Y-axis magnetic fields, two fluxgate sensing elements were perpendicularly aligned. The fluxgate sensor was composed of rectangular-ring shaped magnetic core, solenoid excitation and pick-up coils. The 2 mum thick Ni0.8Fe0.2 (permalloy) magnetic core layer was electroplated with photoresist. frame using sputtered Ni0.8Fe0.2 seed layer. The fabricated fluxgate chip size was 4.5 X 2.7 mm(2). Excellent linear response over the range of 100 muT to +100 muT was obtained with 210 V/T sensitivity at excitation square wave of 2.8 Vp-p and 1.2 MHz. When two-axis fluxgate sensing element was rotated in terrestrial field, induced second harmonic voltages from X- and Y-axis were sine and cosine wave without distortion, respectively. It is very useful to commercialize the portable navigation system including north-up and map matching, military research, medical research, and space research.