Magnetic Field and Displacement Sensor Based on Giant Magneto-Impedance Effect

A two-core transducer assembly using a Fe73.5Nb3Cu1Si13.5B9 ribbon to detect a change of magnetic field is proposed and tested for displacement (linear and angular) and current sensor. Two identical inductors, with the ribbon as core, are part of a two-series resonance network, and are in a high impedance state when excited by a small AC field of 1 MHz in the absence of a DC biasing field (Hdc). When the magnetic state of one inductor is altered by the biasing field, produced by a bar magnet or current carrying coil, an AC signal proportional to H dc is generated by the transducer. The results for the sensitivity and linearity with displacement (linear and angular) of a magnet and with field from the current carrying coil are presented for two particular configurations of the transducer. High sensitivities of voltage response as much as 12 µV/µm and 3 mV/degree have been obtained for the transducer as a linear and angular displacement sensor, respectively, in the transverse configuration of exciting AC and biasing DC fields.