Development of a One-Dimensional Fluxgate Array and Its Application to Magnetocardiogram Measurements

We have designed an excitation part of the driving circuit of the fundamental mode orthogonal fluxgate (FG) to avoid an interference problem between fluxgates that may occur when individually operating fluxgates are placed closely. In this new design, three sensor heads are driven by a common excitation current while their outputs are processed separately to yield their own outputs. With magnetometers of this design, we have built a 6-channel FG array of a linear arrangement with the spacing of 3 cm, as a step to a 6 × 6 fluxgate array. The excitation frequency was shared by two excitation circuits, each of which provides a set of three sensor heads with the excitation current. A magnetocardiogram (MCG) was measured with the 6-channel FG array by repeatedly sliding the top plate of a bed carrying a healthy volunteer by 3 cm. The distribution of the QRS complex observed on a 5 × 6 of array measurement points resembles with that observed by a SQUID MCG measurement system.