The ferromagnetic resonance (FMR) in the frequency range of 0.5 to 12.5 GHz has been investigated as a function of external magnetic field for rapidly quenched Fe3Co67Cr3Si15B12 amorphous ribbons with different features of the effective magnetic anisotropy. Three states of the ribbons were considered: as-quenched without any treatment; after relaxation annealing without stress at the temperature of 350 °C during 1 h; and after annealing under specific stress of 230 MPa at the temperature of 350 °C during 1 h. For FMR measurements, we adapted a technique previously proposed and tested for the case of microwires. Here, amorphous ribbons were studied using the sample holder based on a commercial SMA connector. On the basis of the measurements of the reflection coefficient S11, the total impedance including its real and imaginary components was determined to be in the frequency range of 0.5 to 12.5 GHz. In order to confirm the validity of the proposed technique, FMR was also measured by the certified cavity perturbation technique using a commercial Bruker spectrometer operating at X-band frequency of 9.39 GHz. As part of the characterization of the ribbons used for microwave measurements, comparative analysis was performed of X-ray diffraction, optical microscopy, transmission electron microscopy, inductive magnetic hysteresis loops, vibrating sample magnetometry, magneto-optical Kerr effect (including magnetic domains) and magnetoimpedance data for of all samples.

Magnetic nanoparticles (MNPs) prepared as stable colloidal suspensions dispersed in water have attracted special interest for biological applications. MNPs of iron oxide synthesized by a laser target evaporation (LTE) technique are excellent candidates for biomedical purposes. Magnetic fluid flowing through the blood vessel creates magnetic fields which can be detected by magnetic field sensor. In this work, the finite element method modeling (FEM) was used for calculation of the flow of ferrofluid containing magnetic iron oxide MNPs through a real coronary artery reconstructed from the routine angiography examination of a patient. The main objective of the study is to validate the possibility of the application of magnetic field sensor for the blood vessel geometry evaluation. The contribution of the magnetic susceptibility of MNPs, blood vessel diameter, and particular geometry as well as the orientation of the magnetic field sensor working on the principle of giant magnetoimpedance (GMI) were comparatively analyzed.

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.

The paper presents the calculation results of the coplanar waveguide geometry using the method of conformal mapping and computerized simulation with COMSOL Multiphysics software. Ferromagnetic FeNi/Cu/FeNi magneto-sensitive elements are fabricated in one cycle with the coplanar waveguide which conveys drive signals. Magnetodynamics of the obtained film structures is studied within the frequency range of 1–20 GHz. It is shown that the main parameters of ferromagnetic resonance can be found for the thin film structures on the coplanar waveguide.

The study of the magnetoimpedance effect (MI) in thin film multilayered structures was done by the finite element numerical simulation method (FEM). Longitudinal MI effect (external field and flowing current are parallel to each other) and transverse magnetic anisotropy were considered. The influence of saturation magnetization, anisotropy field, induced magnetic anisotropy peculiarities, electrical conductivity of permalloy layers in a multilayered structure placed in an external magnetic field under the influence of high-frequency alternating current was investigated. The highest sensitivity of the three-layered [FeNi]/Cu/[FeNi] structure was achieved at the maximum saturation magnetization, the smallest magnetic anisotropy field and the lowest dispersion of local effective anisotropy. Assumptions for further improving the model for prediction of the features of the frequency dependence of the MI ratio were discussed. FEM method was shown to be useful for design of MI elements with requested responses.

The possibility of detecting iron oxide nanoparticles in the composition of ferrofluids (FF) and ferrogels (FG) in a hydrodynamic system is demonstrated. The results of measurements using a sensor based on the magnetoimpedance effect of the volumetric flow rate of the FF along a model artery with stenosis are presented. The results of ultrasonic visualization of FG selected as a prototype of a magnetically controlled platform for targeted drug delivery are also given. The advantages and limitations of methods in the context of medical applications are considered.

Abstract–The effect of heat treatment (HT) on the structural features, magnetic properties, and magnetic impedance of rapidly quenched Fe73.5Si13.5B9Nb3Cu1 ribbons and doped ribbons, in which 10 wt % iron is replaced by either cobalt, nickel, or manganese, is studied in this paper. Cobalt ribbons as a result of HT at a constant temperature showed a significant increase in the value of maximum magnetic induction. The magnetic and magnetic-impedance properties, studied in a wide range of alternating current frequencies from 1 to 400 MHz, showed a significant change in the features of effective magnetic anisotropy and high-frequency responses after HT. A comparative analysis of the results obtained for samples of various compositions can be useful both for understanding the features of the formation of effective magnetic anisotropy in nanocrystalline alloys and from the point of view of practical applications in the search for optimal physicochemical parameters of materials for sensors of low magnetic fields.

Ferromagnetic microwires are widely applied in the ultrahigh frequency engineering. In this work, a system on the basis of a ZVA-67 vector network analyzer which makes it possible to measure the parameters of ferromagnetic resonance of microwires in a frequency range from 0.1 to 14 GHz is proposed. The impedance of FeCoNi/CuBe and CoFeSiB microwires is approximated using the values of the components of the main diagonal of the magnetic susceptibility tensor. The proposed method makes it possible to find interesting characteristic features of the electromagnetic properties of microwires in the regions of frequencies and magnetic fields where ferromagnetic resonance is observed.

The static magnetic field was shown to affect the proliferation, adhesion and differentiation of various types of cells, making it a helpful tool for regenerative medicine, though the mechanism of its impact on cells is not completely understood. In this work, we have designed and tested a magnetic system consisting of an equidistant set of the similar commercial permanent magnets (6 × 4 assay) in order to get insight on the potential of its experimental usage in the biological studies with cells culturing in a magnetic field. Human dermal fibroblasts, which are widely applied in regenerative medicine, were used for the comparative study of their proliferation rate on tissue culture polystyrene (TCPS) and on the polyacrylamide ferrogels with 0.00, 0.63 and 1.19 wt % concentrations of γ-Fe2O3 magnetic nanoparticles obtained by the well-established technique of laser target evaporation. We used either the same batch as in previously performed but different biological experiments or the same fabrication conditions for fabrication of the nanoparticles. This adds special value to the understanding of the mechanisms of nanoparticles contributions to the processes occurring in the living systems in their presence. The magnetic field increased human dermal fibroblast cell proliferation rate on TCPS, but, at the same time, it suppressed the growth of fibroblasts on blank gel and on polyacrylamide ferrogels. However, the proliferation rate of cells on ferrogels positively correlated with the concentration of nanoparticles. Such a dependence was observed both for cell proliferation without the application of the magnetic field and under the exposure to the constant magnetic field.

Microstructures in the form of meanders are widely used as elements of magnetoresistive and magnetoimpedance (MI) sensors. In this paper, for the structures of the “microstrip line” type and the N-shaped meanders prepared from amorphous CoFeNiSiB ribbon, the MI effect is studied in the longitudinal (LMI) and transverse (TMI) configurations. The LMI effect reaches 180%, which is significantly higher than in the case of tapes of the same size (5 mm) without microstructuring.

Biomedical applications of magnetic materials are a hot topic of present day research. Special attention is paid for design and development of appropriate instrumentation. In this work magnetic system consisting of an equidistant set of commercial permanent magnets (6 × 4 assay) was proposed, designed and tested for further employment in the experiments in cell cultivation experiments. Magnetic field distribution was experimentally measured in 3 axes: OX, OY, OZ by gaussmeter. The results were statistically analyzed. Constant magnetic field near the center of XY plane was relatively homogeneous but at edges significant value of magnetic field gradient was observed. With increasing of Z distance, the decreasing of magnetic field strength was observed. Obtained parameters of a designed system are satisfactory and therefore it can be recommended for cell cultivation experiments when application of external magnetic field is desired.

Amorphous and nanocrystalline materials are attractive systems for basic research and technological applications. In a view of the energy economy and global warming concepts there is a request to search for soft magnetic materials for sensor applications, which do not request additional heat treatments and can be produced in most simple technological scheme. In this work the structure, static magnetic properties and magnetoimpedance (MI) were studied for FINEMET-type materials both with classic composition and for compositions with 10 % of iron substitution by Co, Ni, or Mn in initial state, i.e. without any additional heat treatmnet. The best MI responses were obtained for Mn-doped rapidly quenched ribbons.

Amorphous and nanocrystalline soft magnetic materials have attracted much attention in the area of sensor applications. In this work, the magnetoimpedance (MI) effect of patterned soft ferromagnetic meander-shaped sensor elements has been investigated. They were fabricated starting from the cobalt-based amorphous ribbon using the lithography technique and chemical etching. Three-turn (S1: spacing s = 50 m, width w = 300 m, length l = 5 mm; S2: spacing s = 50 m, width w = 400 m, length l = 5 mm) and six-turn (S3: s = 40 m, w = 250 m, length l = 5 mm; S4: s = 40 m, w = 250 m and l = 8 mm) meanders were designed. The n' shaped meander part was denominated as one turn. The S4 meander possesses a maximum MI ratio calculated for the total impedance Z/Z approximate to 250% with a sensitivity of about 36%/Oe (for the frequency of about 45 MHz), and an MI ratio calculated for the real part of the total impedance R/R approximate to 250% with the sensitivity of about 32%/Oe (for the frequency of 50 MHz). Chemical etching and the length of the samples had a strong impact on the surface magnetic properties and the magnetoimpedance. A comparative analysis of the surface magnetic properties obtained by the magneto-optical Kerr technique and MI data shows that the designed ferromagnetic meander-shaped sensor elements can be recommended for high frequency sensor applications focused on the large drop analysis. Here we understand a single large drop as the water-based sample to analyze, placed onto the surface of the MI sensor element either by microsyringe (volue range 0.5-500 L) or automatic dispenser (volume range 0.1-50 mL).

Operation on the principle of the giant magnetoimpedace (GMI) magnetic field sensor was designed and tested for the case of CoFeSiB amorphous wire of 6 mm length. We considered magnetic field displacement of the order of 10 Oe. Piece of amorphous wire was placed as a central conductor of a coaxial cable. The maximum slope of the sensor GMI characteristic was observed at the terminator resistance RT = 50 Ohm, while the maximum of the GMI ratio variation was observed in the not “matched” (RT = 75 Ohm) but closer to the “short” mode. Amorphous wire placed as a central conductor of a coaxial cable serves as a sensitive element with high sensitivity with respect to applied field making possible to use a simple design with a miniature coil for magnetic field biasing.

The paper discusses methodological techniques for increasing the diagnostic value of routine angiographic examinations of patients. It presents algorithms for digital processing of heart video images, which make it possible to quantitatively characterize hemodynamics in the coronary bed by determining the velocity of spread of a contrast agent through the arteries. The proposed approach includes several stages and procedures and takes account of the errors caused by the movement of the arteries due to the mechanical activity of the heart. The paper presents the results of estimating coronary blood-flow velocity in a patient with coronary heart disease, which are compared with computer simulation data. The sources of errors, ways to minimize them, and prospects for using the proposed methodology for effective angiographic diagnosis are discussed.

A comparative analysis of the magnetic properties and specific features of the giant magnetoimpedance has been carried out for amorphous rapidly quenched wires with a composition of (Co0.94Fe0.06)(72.5)Si12.5B15 in the initial state and after the deposition of a carbon coating. The deposition of the defective graphene-like carbon layer was carried out under normal conditions during the exposure in toluene (methylbenzene). The method of the energy-dispersive X-ray spectroscopy made it possible to reliably show that after the modification in toluene, the carbon content on the surface significantly exceeds the natural amount of carbon. The deposition of the carbon coating induced changes in the distribution of the initial quenching stresses in the near-surface layer of amorphous wires. A comparative analysis of the magnetic and magnetoimpedance properties of the samples before and after exposure in the aromatic solvent confirms the occurrence of changes in the effective magnetic anisotropy as a result of this surface treatment.