High-Performance Self-Biased Magnetoelectric Composite Sensor with Low-Frequency and Ultraweak Magnetic Field Detection Capability

The laminated self-biased magnetoelectric (ME) composite magnetic field sensor has detected low-frequency and ultraweak magnetic fields through the external effect method. Composed of an iron-based amorphous alloy (1K101) and a single-crystal macro-fiber composite (MFC), the ME composite (MEA) is designed as a cantilever beam structure, with small-sized magnets (NdFeB) bonded to the free end. The magnets provide the external DC bias magnetic field for the magnetostrictive layer while changing the stress state and adjusting the system’s resonance frequency to enhance the passive self-biased ME effect. Due to the presence of a moderate magnetic field and a smaller stress distribution, the self-biased ME performance of the optimal sample in the vertical placement system (MEA-v9) is superior to that in horizontal placement (MEA-h6). The MEA-v9 sample achieves AC magnetic field detection at a frequency as low as 4.32 Hz, with an ME voltage coefficient αME of 27.17 V/(Oe·cm) and a detection limit of ∼3.0 × 10–4 Oe. Additionally, a piecewise function model is proposed to improve the calculation accuracy of the response voltage to the external AC magnetic field. The self-biased laminated ME composite sensor (MEA-v9) exhibits great potential for low-frequency and ultraweak magnetic field detection and is expected to become the next generation of miniaturized sensors.