  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.
