Employing amplitude-modulation technique, we have optimized the giant magnetoimpedance (GMI) sensor. Our approach was to optimize the sensor structure so as to obtain a high signal-to-noise ratio by using finite element analysis. The optimum size of sensor strip is as follows: a thickness of 4.3 μm, a strip width of 20-30 μm, a length of several mm. The meander sensor element [CoNbZr (thickness, 4.3 μm; length, 5 mm; width, 30 μm; number of turns, 3) was fabricated using the lift-off process. A high impedance change over 200% was obtained at several hundred MHz. When a small AC magnetic field was applied to the sensor element, a very small AM signal was detected by the sensor system in a magnetically shielded room. A resolution of 1.7×10-8 Oe/Hz1/2 was obtained at 501 kHz.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics