The microfluxgate magnetic sensor having closed magnetic path

This paper presents a microfluxgate magnetic sensor in printed circuit board (PCB). In order to observe the effect of the closed magnetic path, the magnetic cores of rectangular ring and two bars were each fabricated. Each fluxgate sensor consists of five PCB stack layers including one layer magnetic core and four layers of excitation and pickup coils. The center layer as a magnetic core is made of a Co-based amorphous magnetic ribbon with extremely high dc permeability of ∼100,000. Four outer layers as excitation and pickup coils have a planar solenoid structure and are made of copper foil. In the case of the fluxgate sensor having the rectangular ring-shaped core, excellent linear response over the range of -100 to +100 μT is obtained with 780-V/T sensitivity at an excitation sine wave of 3 V_P-P and 360 kHz. The chip size of the fabricated sensing element is 7.3×5.7 mm². The very low power consumption of ∼8 mW was measured.