Improved sensitivity and bandwidth of hybrid magnetic sensor based on electrically modulated amorphous magnetic alloy/piezoelectric composite

Abstract

This study reports an electrically modulated dc and low frequency magnetic sensor with high sensitivity and wide bandwidth. It is based on multiferroic composites consisting of amorphous magnetic alloy Metglas/piezoelectric transformer (i.e., Pb(Zr,Ti)O3/Pb(Zr,Ti)O3)/Metglas layers winded with capacitor connected excitation coils and pickup coils. By electrically exciting the piezoelectric transformer winded with coils, the periodically induced stress and magnetic field modulate the magnetization of Metglas simultaneously and cause the change of magnetic flux within the pickup coils. The output voltage is further enhanced with the resonant converse magnetoelectric (CME) and mutual inductance effects at the mechanical and LC resonance frequency, respectively. Furthermore, the asymmetric wide bandwidth property of hybrid magnetic sensor provides the enhanced low frequency magnetic field sensitivity with negligible extra power consumption compared to the CME effect. When the magnetic sensors are excited with 5 V voltage at the resonance frequency and applied with 10 Hz magnetic field, the hybrid magnetic sensor achieves the maximum magnetic field sensitivity of 2.20 V/Oe and this is about 4.89 times as high as that of CME effect (0.45 V/Oe). The limit of detection for 10 Hz magnetic field is also noticeably improved from 2.97 nT for CME effect to 590pT for the hybrid magnetic sensor.