The change in magnetoimpedance (MI) during surface modification of the magnetic sensitive element caused by highly corrosive fluid was studied with the aim of creating a robust method to monitor the surface effects. A Mi-based sensor prototype with an as-quenched FeCoSiB or FeCoCrSiB amorphous ribbon sensitive element was designed and calibrated for a frequency range of 0.5-10 MHz at an intensity of the current of 10-60 mA without bath for fluids. Measurements as a function of the exposure time were also made in a regime where chemical surface modification and sensing were not separated (in a bath for fluids). The MI variation was explained by the change of the surface magnetic anisotropy and the geometry of the sensitive element. A simple model was developed to describe MI change. It was shown that the magnetoimpedance effect can be employed as useful method to probe the electric features of surface-modified magnetic electrodes when the corrosive fluid, the material of the sensitive element, and the detection conditions are properly selected.
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