Magnetoimpedance-Based Probe of Various Concentrations of Corrosive Chemicals

We report on the possibility of exploiting the giant magnetoimpedance (GMI) effect of a soft ferromagnetic amorphous ribbon as a magnetic label-free probe of corrosive strengths of chemicals. Scanning electron microscopy, dc magnetization, and GMI measurements reveal that the presence of nitric acid (HNO₃) significantly alters the surface morphology, the magnetic permeability, and consequently the GMI response of a Co₆₅Fe₄Ni₂Si₁₅B₁₄ amorphous ribbon. With an increase in the exposure time, the GMI ratio sharply decreases in the first few minutes and then remains almost unchanged. The relative change in the GMI ratio depends strongly on the corrosive strength of the chemical used (i.e., the concentration of HNO₃). These findings are of practical importance in developing GMI-based detectors of corrosive chemicals.