Design and Implementation of a High-Sensitivity Magnetic Sensing System Based on GMI Effect

A high-sensitivity magnetic sensing system based on giant magneto-impedance (GMI) effect is designed and fabricated. The system comprises a GMI sensor equipped with a gradient probe and an signal acquisition and processing module. A segmented superposition algorithm is used to increase target signal and reduce the random noise. The results show that under unshielded, room temperature conditions, the system achieves successful detection of weak magnetic fields down to 2 pT with a notable sensitivity of 1.84×10⁸ V/T (G = 1 000). By applying 17 overlays, the segmented superposition algorithm increases the power proportion of the target signal at 31 Hz from 6.89% to 45.91%, surpassing the power proportion of the 2 Hz low-frequency interference signal. Simultaneously, it reduces the power proportion of the 20 Hz random noise. The segmented superposition process effectively cancels out certain random noise elements, leading to a reduction in their respective power proportions. This high-sensitivity magnetic sensing system features a simple structure, and is easy to operate, making it highly valuable for both practical applications and broader dissemination.