Giant magnetic induction in magneto-elastic resonators and its application for magnetic field sensors

The competitive performance of an optimized magneto-elastic resonator as sensor of a local magnetic field is reported. The resonator core is constituted by an amorphous ferromagnetic ribbon in which stationary waves are established by means of magneto-elastic coupling. The appropriate choice of the ribbon composition and the use of a special heat treatment are determinant on the sensor response. In proper conditions, the sensitive parameter, namely the electromotive force (root mean square value) induced in a miniaturized pick-up coil, has relative changes of 10^4 for a magnetic field increment of 10 A/m. Magnetic induction fields as small as 10^−8 T can be measured with a technology simpler than in other used devices. A good linearity of the sensor response at low field (from 0 A/m up to 50 A/m) is demonstrated too.