Giant magnetoimpedance: new electrochemical option to monitor surface effects?

Abstract

Magnetoimpedance, MI, change due to surface modification of the sensitive element caused by biofluids was studied with the aim of creating a robust sensor capable of separating the chemical surface modification from the sensing process. A MI sensor prototype with an as-quenched FeCoSiB amorphous ribbon sensitive element was designed and calibrated for a frequency range of 0.5 to 10 MHz at an intensity of the current of 60 mA. Measurements as a function of the exposure time were made, first, in a regime where chemical surface modification and sensing were separated and then, in a regime where they were not separated (in a bath for fluids). The MI variation was explained by the change of the surface magnetic anisotropy. It was shown that the magnetoimpedance effect can be successfully employed as a new electrochemical option to probe the electric features of surface-modified magnetic electrodes when the biofluid, the material of the sensitive element, and the detection conditions are properly selected and synergetically adjusted.