A Man-Portable Magnetoelectric DC Magnetic Sensor With Extremely High Sensitivity

This letter presents an advanced 3-axis portable dc magnetic sensor unit consisting of magnetoelectric (ME) composites and a custom lock-in amplifier circuit, which has extremely high sensitivity and detection resolution. The Metglas/Pb(Zr,Ti)O3 ME composites driven by a lock-in amplifier circuit exhibit a high sensitivity of 5 V/Oe. Moreover, the equivalent magnetic noise of the unit is limited to 128 pT/√Hz at 1 Hz. Therefore, a dc magnetic field as small as 1 nT can be sensed directly in the time domain. The entire 3-axis dc magnetic sensor is portable and energy-efficient, making it promising for magnetic navigation applications based on sensing variations in the magnitude and orientation of local geomagnetic fields.