A strain sensor element utilizing the inverse magnetostrictive effect and magneto-impedance effect was developed, and the strain-impedance properties of the element were investigated. The Strain-Impedance (SI) element constructed from a CoSiB/Cu/CoSiB layered film was prepared on a Corning No. 0313 glass substrate by magnetron sputtering under a magnetic field. The Co₇₃Si₁₂B₁₅ negative magnetostriction film (l = -6�~10^-6) was selected as magnetostrictive layers, and magnetic anisotropy was induced parallel or perpendicular to applied strain direction. In the SI element, the applied strain e was detected as a change in impedance Z, inductance L or resistance R in the range from 1 MHz to 15 MHz. By applying strain (e = �}2�~10^-3), the impedance dramatically changed due to the change in permeability of the magnetostrictive layers. The maximum gauge factor, Gmax, which was defined as the maximum fractional change in impedance to strain, (DZ/Z)/e, was 1500-2000 at 1-15 MHz. These values are much larger than those of the single-layer CoSiB element. This layered SI element will be very useful for sensing small amounts of strain.

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