Microwire Diameter Research Articles

Impact of thermally induced stress gradient on magneto-impedance sensitivity of As-quenched and Joule annealed microwires

The investigation addresses the dependence of rapidly quenched (Co94 Fe6)72.5 Si12.5 B13 Cr2 microwire diameters on their phase transformation evidenced during devitrification and consequent giant magneto-impedance (GMI) behavior. Phase segregation / nucleation in thicker microwires as compared to thinner ones were detected through thermal studies. In addition to such nucleation, the stress effect was more pronounced in thinner microwires as evidenced from GMI output. Structural relaxation through Joule annealing further enhanced the properties. Appropriate choice of operating frequency, alternating current and Joule heating current density vis-à-vis microwire diameter is essential for sensor design.

Comparative Study of the Magnetic Behavior of FINEMET Thin Magnetic Wires: Glass-Coated, Glass-Removed, and Cold-Drawn

In this paper, a comparative investigation of the magnetic behavior and its stress dependence in the case of FINEMET glass-coated, glass-removed, and cold-drawn microwires at low and high frequencies, respectively, is presented. The experimental results show major differences between their magnetic properties depending on the preparation method and microwire diameter. The evolution of the magnetic permeability, coercivity, and magnetoimpedance responses with the applied tensile force was investigated and analyzed in correlation with the stresses induced during preparation, their relief following annealing, and the annealing-induced structural transformations. The coercivity dependence on applied force was found to show the highest sensitivity in the glass-removed microwires, while the magnetic permeability and magnetoimpedance sensitivity to force were found to be higher in the cold-drawn samples. The results of this comparative study will enable an enhanced material selection process for various applications in miniaturized magnetic and stress sensors with increased sensitivity.

Large‐Area Endohedral Metallofullerene Single‐Crystal Arrays for High‐Performance Field‐Effect Transistors and Photodetectors

AbstractA structure with high crystallinity and orderly molecular packing is a requirement for high‐performance optoelectronic devices. However, growing large‐area, long‐range order, highly crystalline micro or nanostructures remains a challenge. Endohedral metallofullerenes (EMFs) are spherical π‐conjugated molecules with unique electronic structures, hence they can be easily assembled into highly ordered crystals through intermolecular π–π interactions. In this work, large‐area single‐crystal microwire arrays of M3N@Ih‐C80 (M = Sc, Lu) are prepared with the assistance of a pillar‐structured template, and the microwire diameter can be tuned via the fullerene concentration. A field‐effect transistor is fabricated using Sc3N@Ih‐C80 microwire arrays, exhibiting a record‐high charge carrier mobility (6.16 cm2 V−1 s−1) among EMF‐based devices. Further, microwire‐based photodetectors are developed, with a response time as low as 0.1 s. The precise arrangement of the M3N@Ih‐C80 molecules helps improve the electron transportation channels, thereby enhancing the device performance.

Flexible High-Resolution Force and Dimpling Measurement System for Pia and Dura Penetration During In Vivo Microelectrode Insertion Into Rat Brain.

Objective:Understanding the in vivo force and tissue dimpling during micro-electrode implantation into the brain are important for neuro-electrophysiology to minimize damage while enabling accurate placement and stable chronic extracellular electrophysiological recordings. Prior studies were unable to measure the sub-mN forces exerted during in vivo insertion of small electrodes. Here, we have investigated the in vivo force and dimpling depth profiles during brain surface membrane rupture (including dura) in anesthetized rats.Methods:A µN-resolution cantilever beam-based measurement system was designed, built, and calibrated and adapted for in vivo use. A total of 244 in vivo insertion tests were conducted on 8 anesthetized rats with 121 through pia mater and 123 through dura and pia combined.Results:Both microwire tip sharpening and diameter reduction reduced membrane rupture force (insertion force) and eased brain surface penetration. But dimpling depth and rupture force are not always strongly correlated. Multi-shank silicon probes showed smaller dimpling and rupture force per shank than single shank devices.Conclusion:A force measurement system with flexible range and µN-level resolution (up to 0.032 µN) was achieved and proved feasible. For both pia-only and dura-pia penetrations in anesthetized rats, the rupture force and membrane dimpling depth at rupture are linearly related to the microwire diameter.Significance:We have developed a new system with both µN-level resolution and capacity to be used in vivo for measurement of force profiles of various neural interfaces into the brain. This allows quantification of brain tissue cutting and provides design guidelines for optimal neural interfaces.

Radial Domains in DyPr–FeCo–B Microwires

In DyPr–FeCo–B microwires with easy magnetization axis directed along the microwire axis, domains with radial magnetization are detected using magneto-optical indicator films. The width of radial domains decreases as the field increases to 30 mT and increases with the microwire diameter in the range of 60–105 μm. In wires of smaller diameter, the critical field of radial domain formation is lower. The effect of the periodic relief produced by scribing on the magnetization distribution perpendicular to the microwire is detected.

Laser system for measuring the diameter of microwires

Laser system for measuring the diameter of microwires

Review of Domain Wall Dynamics Engineering in Magnetic Microwires.

The influence of magnetic anisotropy, post-processing conditions, and defects on the domain wall (DW) dynamics of amorphous and nanocrystalline Fe-, Ni-, and Co-rich microwires with spontaneous and annealing-induced magnetic bistability has been thoroughly analyzed, with an emphasis placed on the influence of magnetoelastic, induced and magnetocrystalline anisotropies. Minimizing magnetoelastic anisotropy, either by the selection of a chemical composition with a low magnetostriction coefficient or by heat treatment, is an appropriate route for DW dynamics optimization in magnetic microwires. Stress-annealing allows further improvement of DW velocity and hence is a promising method for optimization of DW dynamics in magnetic microwires. The origin of current-driven DW propagation in annealing-induced magnetic bistability is attributed to magnetostatic interaction of outer domain shell with transverse magnetization orientation and inner axially magnetized core. The beneficial influence of the stress-annealing on DW dynamics has been explained considering that it allows increasing of the volume of outer domain shell with transverse magnetization orientation at the expense of decreasing the radius of inner axially magnetized core. Such transverse magnetic anisotropy can similarly affect the DW dynamics as the applied transverse magnetic field and hence is beneficial for DW dynamics optimization. Stress-annealing allows designing the magnetic anisotropy distribution more favorable for the DW dynamics improvement. Results on DW dynamics in various families of nanocrystalline microwires are provided. The role of saturation magnetization on DW mobility improvement is discussed. The DW shape, its correlation with the magnetic anisotropy constant and the microwire diameter, as well as manipulation of the DW shape by induced magnetic anisotropy are discussed. The engineering of DW propagation through local stress-annealing and DW collision is demonstrated.

Морфология и механические свойства микропроводов PrDyFeCoB

PrDyFeCoB microwires were obtained by pendant drop melt extraction (PDME). The diameter and cylindricality of microwires are controlled by the rotation speed of the cooling cylinder and depend on the solidification time of the drop on it. Variations in the cooling regime of the melt drop lead to a change in the shape of the cross section from a completely cylindrical to a semicircle, a crescent, and an almost flat plate. It was established that the cooling mode affects not only morphology, but also mechanical characteristics that are different for microwires of different shapes, and also changes the microhardness and Young's modulus of different surfaces of the same microwire.

In situ fabrication of far-detuned optical fiber wavelength converters.

We demonstrate an in situ approach for the fabrication of all-fiber wavelength converters with a wavelength offset that is both far-detuned and precisely engineered. Such wavelength converters are fabricated using the parametric gain of A2Se3 microwires and finely tuned from successive adjustments of microwire diameter along with real-time monitoring. Wavelength conversion is achieved from a pump at a wavelength of 1.938μm to any far-detuned idler within the spectral range of 2.347-2.481μm, resulting in a detuning of 27.0-33.9THz with a wavelength offset precision within 3.1THz.

Miniaturized Heat-Flux Sensor Based on a Glass-Insulated Bi–Sn Microwire

Thermoelectric-energy conversion based on a single element made of an anisotropic material is considered. In such materials, the heat flux generates a transverse electric field. We fabricate an experimental heat-flux sensor (HFS) sample consisting of a 10-m-long glass-insulated single-crystal tin-doped bismuth microwire (outer diameter D = 18 μm, microwire diameter d = 4 μm). The microwire is wound into a flat spiral after recrystallization in a strong electric field, during which the main crystallographic axis C3 is oriented at the optimum angle with respect to the microwire axis. The sensor sensitivity reaches 10–2 V/W with the time constant τ ≈ 0.2 s. The sensor fabrication technology is rather simple and reliable for industrial applications.

Миниатюрный датчик теплового потока на основе микропровода Bi-Sn в стеклянной изоляции

AbstractThermoelectric-energy conversion based on a single element made of an anisotropic material is considered. In such materials, the heat flux generates a transverse electric field. We fabricate an experimental heat-flux sensor (HFS) sample consisting of a 10-m-long glass-insulated single-crystal tin-doped bismuth microwire (outer diameter D = 18 μm, microwire diameter d = 4 μm). The microwire is wound into a flat spiral after recrystallization in a strong electric field, during which the main crystallographic axis C _3 is oriented at the optimum angle with respect to the microwire axis. The sensor sensitivity reaches 10^–2 V/W with the time constant τ ≈ 0.2 s. The sensor fabrication technology is rather simple and reliable for industrial applications.

Thermal Characterization of Convective Heat Transfer in Microwires Based on Modified Steady State “Hot Wire” Method

The convection plays a very important role in heat transfer when MEMS work under air environment. However, traditional measurements of convection heat transfer coefficient require the knowledge of thermal conductivity, which makes measurements complex. In this work, a modified steady state hot wire (MSSHW) method is proposed, which can measure the heat transfer coefficient of microwires' convection without the knowledge of thermal conductivity. To verify MSSHW method, the convection heat transfer coefficient of platinum microwires was measured in the atmosphere, whose value is in good agreement with values by both traditional measurement methods and empirical equations. Then, the convection heat transfer coefficient of microwires with different materials and diameters were measured by MSSHW. It is found that the convection heat transfer coefficient of microwire is not sensitive on materials, while it increases from 86 W/(m$^2$K) to 427 W/(m$^2$K) with the diameter of microwires decreasing from 120 ${\mu}$m to 20 ${\mu}$m. Without knowing thermal conductivity of microwires, the MSSHW method provides a more convenient way to measure the convective effect.

Magnetic-field-induced synthesis and growth mechanism of ultra-long nickel microwires from nanospheres

Abstract One-dimensional nickel (Ni) microwires were synthesized by the magnetic-field-induced (MFI) microemulsion-hydrothermal method using Ni nanospheres as seeds. The influence of the chemical conditions and magnetic field on the morphology and magnetic properties of Ni microwires were investigated by X-Ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). The strength of magnetic field greatly affected the morphology and magnetic properties of Ni microwires. The growth and morphology of Ni microwires depended on the competition between Brownian motion and magnetic dipole moments from magnetic field. The larger nanoparticles with the higher magnetic moments preferred to form one-dimensional Ni microwires and their length increased up to several millimeters with the increasing magnetic field strength, while the average diameter of Ni microwires decreased. Furthermore, the easy magnetization direction of Ni microwires was parallel to the direction of magnetic field and the Ni microwires axis.

Size-dependent UV and gas sensing response of individual Fe2O3-ZnO:Fe micro- and nanowire based devices

In this work, the UV and gas sensing properties of single Fe-doped and Fe2O3-functionalized ZnO micro- and nanowires are reported. The influence of microwire diameter and concentration of Fe2O3 micro- and nanoparticles on the sensing properties of the fabricated devices was investigated. Results clearly reveal that sensors with a higher response can be obtained by a decrease in the diameter of micro- and nanowires and an increase of the Fe2O3 micro- and nanoparticle concentration on the surface of microwires. The enhanced sensing properties can be explained based on excellent charge separation properties of the formed Fe2O3/ZnO heterojunctions in the case of UV response which prolong the photocarrier lifetime and based on excellent catalytic properties of Fe2O3 in the case of gas sensing. The presented results demonstrate the importance of surface functionalization of single ZnO structures with other semiconducting oxide micro- and nanoparticles for the improvement of their sensing properties, i.e., UV and ethanol sensing, even for a single wire/rod with micro- and nanometric diameter.

The stress components effect on the Fe-based microwires magnetostatic and magnetostrictive properties

For glass-coated amorphous ferromagnetic Fe-based microwires both joint and separate effect of metallic nucleus diameter, d, and the ratio of metallic nucleus diameter to the total diameter of microwire in glass shell, d/D, on magnetic properties is investigated. Thereby the contribution of both shell-induced stresses, associated with the ratio of diameters, and internal nucleus stresses (residual, quenching), associated with the diameter of the nucleus are estimated. A strong and non-monotonic effect of the metallic nucleus diameter and metallic nucleus diameter/total microwire diameter ratio on magnetostatic and magnetostrictive properties was established. For analysis, we considered magnetically bi-stable microwires of “classic” Fe77.5Si7.5B15 alloy with positive magnetostriction coefficient.

Structure and properties of amorphous finemet alloy microwires produced by the Ulitovskii-Taylor method

Amorphous Fe73.5Si13.5B9Nb3Cu1 alloy microwires 19–50 μm in diameter are fabricated by the Ulitovskii-Taylor method. The mechanism of crystallization of the amorphous microwires is shown to be analogous to the mechanism of crystallization of an amorphous ribbon made of the same alloy. Microwires up to 30 μm in diameter are found to exhibit ductility upon bending. The near-surface magnetic properties of the microwires are shown to depend on the microwire diameter. The magnetic properties of the amorphous microwires are highly sensitive to elastic tensile and torsional strains in an ac magnetic field.

Four-Wave Mixing in Microwires to All-Optical Signal Processing in Mode-Division Multiplexing Systems

Mode-division multiplexing requires all-optical signal processing techniques that are able to deal with a new coding dimension, the spatial mode. In this context, optical microwires emerge as a potential highly non-linear and multi-modal waveguide envisioning the development of all-optical signal processing devices to mode-division multiplexing systems based on the four-wave mixing process. The inter- and intramodal phase-matching conditions for the four-wave mixing process are mapped as a function of the microwire diameter and the wavelength of signals. Moreover, the efficiency of four-wave mixing considering a strong guiding regime is investigated in the multi-modal regime.

Structural and Magnetic Properties of Thick Fe31Co34Ni10(SiB)25 Microwires Produced by the Modernized Ulitovsky–Taylor Method

Results on the study of the structural and magnetic properties of the as-cast Fe31Co34Ni10(SiB)25 thick microwires with glass shell, produced by the modernized Ulitovsky–Taylor method, are presented. The diameters of the amorphous metallic cores, ${d}$ , of the microwires were equal to 55, 65, 95, 140, and $200~\mu $ m. The microwires had the stable geometric parameters along their lengths and the smooth (almost without defects) surface. The samples under study exhibited the high plasticity and high strength. The destruction of the microwires did not happen even after their full tightening into a knot. It was discovered that the glass shell of the microwires practically does not affect their magnetic characteristics. The saturation field ${H} _{S}$ and coercive force ${H} _{C}$ of the microwires raised with increasing the microwire diameter. The stable geometric parameters of the microwires along their lengths caused the slight dispersion of magnetic anisotropy in the near-surface layers. As a result, the Fe31Co34Ni10 (SiB)25 microwires exhibited the high homogeneity of the near-surface local magnetic characteristics. In particular, the changes of the local magnitudes of the saturation field were revealed to be <5%.

Investigate the Reliable and Accurate Pattern Transfer of IDE Silver Electrode Coated with Zinc Oxide Microwire for Biosensor Application

This paper illustrate a facile route to fabricate and develop zinc oxide microwire which acts as transducer for biosensor application. Pattern transfer process is conducted on the wafer substrate by using conventional photolithography process to form IDE electrode. The substrate is coated with positive photo-resist (PR) and exposed for UV light for 10 seconds. After development, the unexposed area is etched by using hydrochloric acid, HCI. In this study, zinc oxide material have become a remarkable choice for bio-sensing development due to large band gap and tailor for bio-molecular application. Zinc oxide solution was prepared through chemical route, that is by using sol-gel method. The coated ZnO films were annealed in furnace at 500°C for 2 hours. ZnO seed solution undergoes hydrothermal growth to synthesize ZnO microwires. ithThe substrate used for this study is p-type silicon wafer which is oxidized. SiO2 layer is used because it acts as an insulator which is very essential for an electronic device to avoid electrical leakage and improve electron mobility. Further investigation of morphological and electrical characterization is conducted through SEM and I-V test .Average size diameter of Zno microwire is 0.45μm and exhibit 900μA of current at 5V.

Vortex magnetic structure in circularly magnetized microwires as deduced from magneto-optical Kerr measurements

The magneto-optic Kerr effect has been employed to determine the magnetization process and estimate the domain structure of microwires with circular magnetic anisotropy. The diameter of microwires was 8 μm, and pieces 2 cm long were selected for measurements. The analysis of the local surface longitudinal and transverse hysteresis loops has allowed us to deduce a vortex magnetic structure with axial core and circular external shell. Moreover, a bamboo-like surface domain structure is confirmed with wave length of around 10 to 15 μm and alternating chirality in adjacent circular domains. The width of the domain wall is estimated to be less than 3 μm. Finally, closure domain structures with significant helical magnetization component are observed extending up to around 1000 μm from the end of the microwire.