Longitudinal and transverse coiled giant magnetoimpedance transducers principle, modeling and performances

New Giant Magneto-Impedance structures are studied both experimentally and theoretically. These transducers are made with one or two anisotropic nanocrystalline ribbons and the magnetic excitation is provided by coils mounted either in transverse or longitudinal direction. Very high sensitivities up to 1000 V/T have been achieved even at low excitation frequencies from 5 kHz to 500 kHz and low consumption driving current (5-10 mA). The eddy current phenomenon and magnetic domain considerations are used to determine a semi-theoretical model of impedance. Intrinsic sensitivity computation approach emphasizes on the role of the differential magnetic permeability in coiled GMI detection performances.