Cu impedance-based detection of superparamagnetic nanoparticles

A novel method for superparamagnetic nanoparticle detection using copper impedance as the sensing property is presented. The increase of impedance produced by the proximity of the nanoparticles in the copper is comparable to that of classical magnetoimpeditive materials. A physical interpretation of the detection in terms of the induction of eddy currents in the copper element by the oscillating magnetic moments of the particles is proposed. Experimental research has been done to support this hypothesis, namely, analyses of the influence of the driving current frequency and amplitude, and of the geometry and size of the sensing conductor. The ability of copper to quantify the number of nanoparticles was successfully verified, evidencing the great potential of this new method.