A Highly Sensitive Magnetometer Based on the Villari Effect

This paper presents a novel magnetometer based on the Villari effect of a permalloy rod. The Villari effect describes that the magnetic properties of a ferromagnetic sample change when under mechanical stress. Theoretical analysis indicates that the output voltage amplitude of the pick-up coil is proportional to the magnetic field density B in the direction along the length of a rod. The sensor element is composed of a permalloy rod, a small lead zirconate titanate (PZT) plate, and one pick-up coil. A prototype is fabricated and the basic performance of the magnetometer is measured. We solve problems, such as the unreliable, nonrepeatable performance and complex manufacturing process of previous Villari effect-based magnetometers, and achieve better overall performance. With a sensitivity of 18.8
${\rm pT}_{\rm rms}/\sqrt{\rm Hz}$
at 1 Hz, the magnetometer has a nonlinearity error of less than 0.7% at a wide range of 2
$\mu{\rm T}$
and a total noise of 40.3
${\rm pT}_{\rm rms}$
from 0.1 to 10 Hz. A working range of 20
$\mu{\rm T}$
is achieved with a nonlinearity error of less than 2.3%. The proposed magnetometer has low inherent noise, low power consumption (only 3.68 mW), a simple structure and signal processing, good linearity, and high resolution .