Electronic compass using two-axis micro fluxgate sensing element

Abstract

This paper presents a micro fluxgate sensor fabricated by Si-based Micro Electro Mechanical 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 /spl mu/m thick Ni/sub 0.8/Fe/sub 0.2/ (permalloy) magnetic core layer was electroplated with photoresist frame using sputtered Ni/sub 0.8/Fe/sub 0.2/ seed layer. The fabricated fluxgate chip size was 4.5/spl times/2.7 mm/sup 2/. Excellent linear response over the range of -100 /spl mu/T to +100 /spl mu/T was obtained with 210 V/T sensitivity at excitation square wave of 2.8 V/sub p-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.