Sensitivity Enhancement of Magnetic Sensors Based on Metglas/pvdf Laminates Using the Flux Concentration Effect

In this paper the magnetic flux density concentration of Metglas as a function of its sheet aspect ratio was investigated for Metglas/Polyvinylidene fluoride (PVDF) laminar composites. The magnetic flux density inside a Metglas sheet increases when its aspect ratio (cross-section width/length) is reduced. Both simulations and experimental results verified it. Consequently the magnetostriction of Metglas and the magnetoelectric (ME) voltage coefficients of the laminar composites are enhanced for a small aspect ratio of the Metglas sheet. The ME voltage coefficient for a laminar composite with 1 mm wide and 30 mm long Metglas sheet (25 μm thick) is 21.46 V/cm*Oe, much higher than those reported earlier in similar laminar composites without making use of the flux concentration effect. The results demonstrate an effective means to significantly enhance the sensitivity of the magnetostrictive/piezoelectric composites, thus promoting them as weak magnetic field sensors. For comparison, both a custom-made voltage mode read-out IC and a charge mode read-out circuit were integrated with the laminar composites to form magnetic sensors.