A longitudinal series-structured high-sensitivity magnetoelectric sensor for weak magnetic field detection

Magnetoelectric (ME) sensors have emerged as promising candidates for weak magnetic field detection, yet achieving ultra-high sensitivity remains a significant challenge. Current ME sensors face limitations in noise reduction and coupling efficiency, particularly for low-frequency biomedical and geophysical applications. This study presents a longitudinal series-structured ME sensor comprising three Mn-doped PMN-PZT piezoelectric single crystals, employing an innovative electrical series and mechanical parallel architecture. Finite element simulations and equivalent magnetic noise analysis reveal that the design enhances acoustic coupling, volume effects, and mechanical quality factor Qm. The sensor demonstrates a high magnetoelectric coupling coefficient of 6104 V/(cm Oe), along with a low equivalent magnetic noise density of 2.24 fT/Hz1/2 and an ultra-low detection limit of 17.2 fT at 11.99 kHz. These advancements significantly outperform existing ME sensors, bridging the performance gap with superconducting quantum interference devices while operating without cryogenic cooling. The proposed design offers a transformative solution for high-sensitivity magnetic field detection in biomedical imaging, geophysical exploration, and low-frequency antenna systems.