Giant magnetoimpedance biosensor for ferrogel detection: Model system to evaluate properties of natural tissue

Thin-film based magnetoimpedance (MI) sensors were used for quantitative determination of the concentration of magnetic nanoparticles (MNPs) in ferrogels. Ferrogels (model systems for biological tissue) were synthesized by radical polymerization of acrylamide in a stable aqueous suspension of gamma-Fe2O3 MNPs fabricated by laser target evaporation. MI [FeNi/Ti](3)/Cu/[Ti/FeNi](3)/Ti sensitive elements were prepared by sputtering. Thorough structural and magnetic studies of MNPs, ferrogels, and multilayered sensitive element insure the complete characterization of biosensor prototype. The MI response of the sensitive element was carefully evaluated in initial state and in the presence of ferrogels with different concentration of iron oxide MNPs from 0 to 2.44 wt. %, which produced systematic changes of the MI in a frequency span of 300 kHz to 400 MHz. (C) 2015 AIP Publishing LLC.