A Novel Measurement Approach for the Broadband Characterization of Diluted Water Ferrofluids

The paper presents a novel measurement method for the broadband characterization of the electromagnetic properties of diluted water-based ferrofluids. The approach exploits the possibility of switching ON and OFF the magnetic response of the suspended magnetic nanoparticles, without affecting the electric response of the ferrofluid, by means of an applied polarizing magnetostatic field. In such a way, two different datasets are collected: 1) the OFF data, which only depend on the electric response of the investigated ferrofluid; 2) the ON data, which depend on both the electric and magnetic responses of the ferrofluid. These data, properly processed, allow the physical separation, at the measurement stage, of the electric response from the magnetic one and so a more robust and stable inversion process, especially in the case of diluted water-based ferrofluids. The reported results show the robustness of the approach as compared to standard measurement techniques.