Abstract
A direction-sensitive micro-magnetic field sensor is developed using the giant magneto-impedance (GMI) effect in a 30-μm diameter amorphous FeCoSiBNd wire. Consisting of a micro-sized zero-magnetostrictive amorphous wire of about 70-μm length, the GMI sensor was connected to a self-oscillating Colpitts oscillator circuit by laser welding. It shows a high sensitivity with a resolution of 100 nT for DC fields, quick response, and a high temperature stability. Reproducible measurements of a surface-flux distribution of mechanically 100 μm structured magnetic bar codes were carried out. Surface Acoustic Wave (SAW) devices are shown as passive, radio-requestable sensor devices. A new type employs the electrical load of the SAW device by the impedance of conventional sensors. In order to develop a wirelessly interrogable magnetic field sensor, the combination of the GMI sensors and SAW transponders is discussed and the results are shown.
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