Improved GMI Sensors Using Strongly-Coupled Thin Pick-Up Coils

version longue issue de : 7th European Magnetic Sensor and Actuator Conference, EMSA'08, Caen, France, Jun30-Jul02, 2008International audienceThe performance of Giant Magneto-Impedance (GMI)-based magnetometers is currently limited by electronics, particularly as regards the equivalent magnetic noise. Thus, it is crucial to increase the sensitivity before demodulation. With that objective, we analyze one solution, using a wire-wound device, consisting of a very thin pick-up coil wrapped around a GMI wire, as a sensing element. We present an electrical sensor model using classical two-port network impedance parameters. It allows us to predict the expected improvement in sensitivity, simulating the device implementation in an appropriate electronic design. Preliminary results suggest an improvement in sensitivity by a factor 2 for a 0 dBm sinusoidal excitation voltage source at 10 MHz. Noise measurements support this analysis and show an intrinsic output magnetic noise improvement in the same ratio