Improved Magnetic Sensor Based on Giant Magneto-Impedance

A low-power, highly stable electronic sensor circuit for measuring a small change in the ambient magnetic field with high sensitivity exploits the giant magneto-impedance (GMI) effect, in which the radio-frequency (RF) impedance of a fiber made of a suitably formulated material varies with the externally generated magnetic field to which it is exposed. The GMI effect has been observed in fibers thinner than a human hair made of amorphous (in the sense of lacking crystalline structure) alloys of cobalt, iron, silicon, and boron.