Shifting the operating frequency of magnetoelectric sensors

A method is presented for increasing the operating frequency of symmetric and asymmetric magnetoelectric (ME) sensors so that the operating frequency can be equal to the mechanical resonance frequency of the sensor. This increase improves the signal to noise ratio of a symmetric sensor by at least two orders of magnitude because it mitigates the effect of 1/f noise and the sensor has an increased response at its resonant frequency. The method is based on the strong, nonlinear magnetic field dependence of the magnetostriction. Our method has lowered the detection limit to 4 pT/root Hz at 1 Hz in a magnetically unshielded environment. (C) 2012 American Institute of Physics. [doi:10.1063/1.3677840]