Magnetoimpedance of CoFeCrSiB Ribbon-Based Sensitive Element with FeNi Covering: Experiment and Modeling

Soft magnetic materials are widely requested in electronic and biomedical applications. Co-based amorphous ribbons are materials which combine high value of the magnetoimpedance effect (MI), high sensitivity with respect to the applied magnetic field, good corrosion stability in aggressive environments, and reasonably low price. Functional properties of ribbon-based sensitive elements can be modified by deposition of additional magnetic and non-ferromagnetic layers with required conductivity. Such layers can play different roles. In the case of magnetic biosensors for magnetic label detection, they can provide the best conditions for self-assembling processes in biological experiments. In this work, magnetic properties and MI effect were studied for the cases of rapidly quenched Co67Fe3Cr3Si15B12 amorphous ribbons and magnetic Fe20Ni80/Co67Fe3Cr3Si15B12/Fe20Ni80 composites obtained by deposition of Fe20Ni80 1 μm thick films onto both sides of the ribbons by magnetron sputtering technique. Their comparative analysis was used for finite element computer simulations of MI responses with different types of magnetic and conductive coatings. The obtained results can be useful for the design of MI sensor development, including MI biosensors for magnetic label detection.

An automated detection of influenza virus based on 3-D magnetophoretic separation and magnetic label

An automated detection device was constructed for H7N9 influenza virus hemagglutinin based on 3-D magnetophoretic separation and magnetic label.

Modeling of magnetic label field sensing by gmr structure

An analytical model is developed to calculate 3D spatial distribution of vector magnetic field H(r) around a reference magnetic label of an arbitrary shape. A reliable method of H(r) modelling is important for location and precise positioning of a labelled object using GMR-based magnetic field sensors.

Modelling of thin film magnetoimpedance sensitive element designed for biodetection

Magnetic soft matter (ferrofluids or ferrogels) is one of the rapidly growing areas of research and applications including magnetic biosensing. Giant magnetoimpedance is the effect with proven capacity to magnetic label detection. In this work, we describe a universal model to simulate conditions of magnetic biodetection and to check its validity with giant magnetoimpedance sensitive element based on magnetic multilayer. Finite element method allows calculations of high-frequency current distribution using the Maxwell's equations taking into account the magnetodynamics of iron oxide water-based ferrofluid in small channels similar to the blood vessels. The modelling was realized with the licensed software Comsol©. The calculations were performed on a specialized engineering server based on four processors Intel Xeon E5 and 124 Gb RAM, adapted for parallel computations and suitable for description of individual layers with nanometer dimensions for the number of elements in the mesh structure above 106 cells. The designed model allows calculations of the current density, the outside magnetic flux, resistivity, etc. for each one of the created cells and total values by integration of sub-domains. One can quantitatively describe concentration of ferrofluid, velocity and pressure in the blood vessel. These changes affecting on the giant magnetoimpedance of the FeNi-based multilayer were both calculated and measured.

Magnetoimpedance Effect in CoFeMoSiB As-Quenched and Surface Modified Amorphous Ribbons in the Presence of Igon Oxide Nanoparticles of Water-Based Ferrofluid

Giant magnetoimpedance (GMI) has been proposed as a powerful technique for biosensing. In GMI biosensors based on the magnetic label detection the change of the impedance of sensitive element under the application of an external magnetic field was analyzed in the presence of magnetic nanoparticles in a test solution. Amorphous ribbon-based GMI biodetectors have an advantage of low operation frequency and low cost. In this work, magnetic and GMI properties of amorphous Co68.6Fe3.9Mo3.0Si12.0B12.5 ribbons were studied in as-quenched and surface modified states both without and in the presence of maghemite ferrofluid. After the surface modification the coercivity was slightly increased and saturation magnetization decreased in good agreement with increase of the surface roughness, a decrease of magnetic elements concentrations in the surface layer, and formation of a surface protective oxide layer. The GMI difference for as-quenched ribbons in absence and in the presence of ferrofluid was measurable for the frequency range of 2 to 10 MHz and the current intensities of 1 to 20 mA. Although the proposed surface modification by the ultrasound treatment did not improve the sensitivity limit for ferrofluid detection, it did not decrease it either.