Embedded Micro-Flux-Gate Magnetic Sensor in Printed Circuit Board

We have developed a micro-flux-gate magnetic sensor using a new printed circuit board (PCB) technology. The flux-gate sensor consists of five PCB stack layers including one layer of magnetic core and four layers of excitation and pickup coils. The center layer as a magnetic core is made of a micropatterned amorphous magnetic ribbon with an extremely high DC permeability of ∼100,000; the core has a rectangular ring shape. The four outer layers as excitation and pickup coils have a planar solenoid structure. The amorphous magnetic core is easily saturated due to the low coercive field and closed magnetic path of the excitation field. The chip size of the fabricated sensing element is 9.8 ×5.7 mm 2 . Excellent linear response over the range of -100 to +100 µT is obtained with 1460 V/T sensitivity at an excitation sine wave of 3 V p–p and 360 kHz. A low power consumption of ∼10 mW was measured.