Coupling nonlinear sensors for enhanced sensitivity: a prototype using the 3 coupled-core fluxgate magnetometer

Recently, we have shown the emergence of oscillations in overdamped undriven nonlinear dynamic systems subject to carefully crafted coupling schemes and operating conditions [In, 2003], [Bulsara, 2004]. Here, we present results obtained from a system of N /spl equiv/ 3 coupled-core fluxgate magnetometer system; the oscillatory behavior is triggered when the coupling constant exceeds a threshold value (bifurcation point), and the oscillation frequency exhibits a characteristic scaling behavior with the "separation" of the coupling constant from its threshold value, as well as with an external target dc magnetic flux signal. The oscillations, which can be induced at frequencies ranging from a few Hz to high-kHz, afford a novel new detection scheme for target signals; in addition, the coupled-core system offers the possibility of significantly enhanced responsivity over its single fluxgate counterpart.