Micro-fluxgate sensor incorporating solenoid coil and BCB dielectric

In this paper, a miniaturized fluxgate sensor with high sensitivity is presented by increasing the permeability of the magnetic material. The fluxgate sensor is composed of a rectangular-ring shaped magnetic core and closely coupled solenoid excitation and pick-up coils. In order to induce magnetic anisotropy, the magnetic core (permalloy) was electroplated under an external magnetic field of 7000 gauss. We designed three types of fluxgate sensors with a change of magnetic core size and solenoid coil turn number. Excellent linear responses of these sensors were obtained with more than 117 V/T sensitivity over the range of -200 μT to +200 μT. And the size of the smallest micro-fluxgate sensor was about 1.3×0.7 mm², excluding pad region.