Research on GMI Probe Performance in Biomagnetic Field Range in Unshielded Environments

A gradient probe based on the Giant Magneto-Impedance (GMI) effect using the CoFeSiB glass-covered amorphous microwires. We set up a weak magnetic experiment system to test the sensitivity and linearity of the GMI probe in a magnetic field with a frequency of 1–100 Hz and an amplitude of 0–100 pT. The results show that the GMI gradient probe can detect a magnetic field signal as low as 12 pT in unshielded environments. And the GMI gradient probe has good linearity in both amplitude and frequency domain. A signal segmentation superposition process is proposed which can enhance the signal and reduce the random interference. This study is a foundation for the development of biomagnetic sensors, and provides a possibility for non-contact biomagnetic field measurement, diagnosis and analysis in unshielded environments.