Flexible Microwire Residence Times Difference Fluxgate Magnetometer

We present a novel realization of the microwire fluxgate magnetometer based on a flexible CoFeSiB core. The readout is underpinned by the residence times difference, wherein the target dc magnetic field information is derived from the temporal positions of the output waveform "spikes" generated by the crossing of two thresholds. This readout is known to be simple, and less noisy, as well as less computationally intensive compared to traditional frequency domain readouts. The design of the magnetometer is discussed with emphasis on the sensor configuration, sensing capabilities, resolution, sensitivity, and hysteresis. We describe a specific device that has been realized using the flexible core technology; in particular, we compare it to a "classical" microwire fluxgate (having a rigid core), previously developed by us. As a part of the evaluation of the sensor performance, its ability to locate the position of a dc quasi-static magnetic source is characterized and related to the radius of curvature of the core. Our results demonstrate the possibility of using the flexible architecture as the sensing element for the detection of weak (dc) magnetic targets with a very good performance in terms of resolution, sensitivity, and magnetic coupling; the performance is far superior to conventional fluxgate magnetometers constructed with nonflexible sensing elements.