Enhancement in the magneto-impedance (MI) effect of multi-ribbon

This article describes the use of a magnetic ribbon to create a highly sens itive magnetic sensor. The sensor employs the impedance change in a magneti c ribbon when a radio frequency (RF) current is passed through it acid an e xternal magnetic held is applied. To achieve a highly sensitive magnetic se nsor, we had to increase the impedance change. We examined stacked magnetic ribbons, each isolated with thin plastic sheets, and interpreted the resul ts by calculating the impedances and relative current in each ribbon. The i mpedance change was enhanced by stacking the ribbons. However, the effectiv e permeability, which greatly affects the sensitivity, decreased as the num ber of ribbons increased. Consequently, the double-layered structure provid ed the maximum sensitivity, which was about three times higher than that of a single-layered structure.