Department of Physics

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IIT Jodhpur

This paper presents a light-weight and simple structure of monopole antenna using conductive textile. Pure Copper Polyster Tafetta Fabric (PCPTF) is used as a conductive textile, in comparison with conventional microstrip monopole antenna. The prototype is designed with 40mm×60mm total dimension and spaced by a 2mm thick felt fabric for Body-Centric Wireless Communications (BCWC) operating in the 2.45 GHz Industrial, Scientific and Medical (ISM) band. A parametric study has been carried out in order to investigate the antenna basic characteristics, thereby enhancing the antenna performance. The result showed that a slight downward frequency shift of wearable textile monopole was observed against the conventional monopole antenna. The wearable textile antenna is seen to produce about 4 dB higher in reflection coefficient than the conventional monopole antenna. Besides, a satisfactory gain characteristic was obtained by wearable textile monopole comparable to the conventional monopole antenna.

World University root node

Progress in Electromagnetics Research Symposium

Design and simulation of a wearable textile monopole antenna for Body Centric Wireless Communications

This paper focuses on the design of embroidered textile antenna, where a fractal technology is used to integrate. Modern telecommunication systems require an antenna with low cost of fabrication and low profile features. This has initiated antenna research in various directions and one of them is wearable textile antenna. A wearable antenna is meant to be a part of clothing used for communication purposes. Fractal technology allowed us to design miniature antennas and integrate multiple telecommunication services into a single device. This study focuses on the investigation of embroidered Sierpinski carpet textile antenna's design using different fabrics suitable for wearable application. The substrate of this antenna is made of from two different low cost textile materials. Radiating element and ground plane are made of conductive threads. The performance of these two antennas that operated at 2.45 GHz such as return loss, bandwidth, VSWR and impedance are extensively investigated and carried out. All results have been demonstrated using simulation and measurement. From this study, it is found that both antennas from denim and felt fabrics can be used for wireless application. Besides, these antennas also still operate in bending condition. The result shows these antennas suitable for wearable application. However, the antenna that used denim textile shows the best performance compared to the antenna with felt fabrics. © 2012 IEEE.

2012 IEEE Asia-Pacific Conference on Applied Electromagnetics, APACE 2012 - Proceedings

Development of embroidered Sierpinski carpet antenna

We present comprehensive molecular dynamics results for the kinetics of surface-directed spinodal decomposition and surface enrichment in binary mixtures at wetting surfaces. We study the surface morphology and the growth dynamics of the wetting and enrichment layers. The growth law for the thickness of these layers shows a crossover from a diffusive regime to a hydrodynamic regime. We provide phenomenological arguments to understand this crossover. © 2012 Europhysics Letters Association.

Fulltext

Hydrodynamic crossovers in surface-directed spinodal decomposition and surface enrichment

The effects of Nb addition on crystallization kinetics and giant magneto impedance (GMI) properties of Fe39Co39Si8B14 amorphous wires prepared by in-water quenching system have been investigated. Thermal behaviors of the wires have been investigated by thermal electrical resistivity measurement and differential scanning calroimetry. The substitution of 4 at% Nb for Fe and Co increases crystallization temperature and merges two crystallization peaks into one peak, leading to a significant increase in thermal stability against crystallization for Fe37Co37Nb4Si8B14 wire. The formation of Fe2Nb phase due to addition of Nb increases the activation energy for crystallization from 425 to 550 kJ/mol. The GMI properties of the alloys are evaluated at driving current amplitude of 10 mA and a frequency of 400 kHz. The alloys show the single peak behavior in the GMI profile. The change in GMI properties increases from 10% at 0 at% Nb to 25% at 4 at% Nb. © 2011 The Minerals, Metals & Materials Society.

Supplemental Proceedings: Materials Fabrication, Properties, Characterization, and Modeling

Crystallization Kinetics and Giant Magneto Impedance Behavior of FeCo Based Amorphous Wires

The Development of biologically inspired experimental processes for the synthesis of nanoparticles is evolving into an important branch of nanotechnology. The work presented here with the biosynthesis of silver nanoparticles using Moringa oleifera leaf extract as reducing and stabilizing agent and its application in nonlinear optics. The aqueous silver ions when exposed to Moringa oleifera leaf extract are reduced resulting in silver nanoparticles demonstrating the biosynthesis. The silver nanoparticles were characterized by UV-Visible, X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR) and transmission electron microscopy (TEM) techniques. TEM analysis shows a dispersion of the nanoparticles in a range of 5-80 nm with the average around 46 nm and are crystallized in face centred cubic symmetry. To show that these biosynthesized silver nanoparticles possess very good nonlinear properties similar to those nanoparticles synthesized by chemical route, we carried out the Z-scan studies with a 6 ns, 532 nm pulsed laser. We estimated the nonlinear absorption coefficient and compare it with the literature values of the nanoparticles synthesized through chemical route. The silver nanoparticles suspended in solution exhibited reverse saturable absorption with optical limiting threshold of 100 mJ/cm 2. © 2011 American Scientific Publishers.

Journal of Nanoscience and Nanotechnology

Biosynthesis of silver nanoparticles using Moringa oleifera leaf extract and its application to optical limiting

The deliberate control over the spatial arrangement of nanostructures is the desired goal for many applications such as, for example, in data storage, plasmonics or sensor arrays. Here we present a novel method to assist the self-assembly process of magnetic nanoparticles. The method makes use of nanostructured aluminum templates obtained after anodization of aluminum discs and the subsequent growth and removal of the newly formed alumina layer, resulting in a regular honeycomb-type array of hexagonally shaped valleys. The iron oxide nanoparticles, 20nm in diameter, are spin-coated onto the surface of honeycomb nanostructured Al templates. Depending on the size, each hexagon site can host up to 30 nanoparticles. These nanoparticles form clusters of different arrangements within the valleys, such as collars, chains and hexagonally closed islands. Ultimately, it is possible to isolate individual nanoparticles. The strengths of the magnetic interaction between particles in a cluster are probed using the memory effect known from the coupled state in superspin glass systems. © 2011 IOP Publishing Ltd.

Nanotechnology

Template-assisted self-assembly of individual and clusters of magnetic nanoparticles

Cobalt and magnetite nanoparticles were studied with small-angle x-ray and neutron scattering methods under grazing incidence for analyzing their structural and magnetic correlation on silicon substrates. The Co nanoparticles are in the ferromagnetic state while the iron oxide nanoparticles are superparamagnetic at room temperature. After spin-coating the iron oxide particles with a diameter of 20 nm and a very narrow size distribution of only 6 show very nice self-ordering on silicon substrates with nearly perfect six-fold symmetry as can be derived from scanning electron microscopy (SEM) images and from grazing incidence small angle x-ray scattering results. In contrast the dropcasted cobalt nanoparticles show a much higher roughness and less ordering. The corresponding SEM images and grazing incidence small angle neutron scattering maps with polarization of the incident beam reveal less pronounced structural and magnetic correlation. © 2011 American Institute of Physics.

Journal of Applied Physics

Self organization of magnetic nanoparticles: A polarized grazing incidence small angle neutron scattering and grazing incidence small angle x-ray scattering study

We present results from a comprehensive numerical study of morphological phase separation (MPS) in unstable thin liquid films on a 2-dimensional substrate. We study the quantitative properties of the evolution morphology via several experimentally relevant markers, e.g., correlation function, structure factor, domain-size and defect-size probability distributions, and growth laws. Our results suggest that the late-stage morphologies exhibit dynamical scaling, and their evolution is self-similar in time. We emphasize the analogies and differences between MPS in films and segregation kinetics in unstable binary mixtures. © the Owner Societies 2011.

Physical Chemistry Chemical Physics

Morphological phase separation in unstable thin films: Pattern formation and growth

We investigated the electronic properties of FeVO4 films using optical, valence band x-ray photoelectron, and infrared spectroscopies. These studies show that FeVO4 is a direct bandgap system with a 2.7 eV gap with the Fermi level in the middle of the valence band maximum and conduction band minimum. A polaronic excitation is also observed in the middle infrared, indicating the importance of charge-lattice coupling in this multiferroic material. Fits to a model for the optical response of large polarons yield a binding energy of approximately 130 meV. © 2011 American Institute of Physics.

Applied Physics Letters

Electronic structure and polaronic excitation in FeVO4

Our investigations using low-temperature Raman spectroscopy, dielectric, and magnetodielectric studies of as-prepared and vacuum-annealed BiFeO 3 ceramics revealed two dielectric anomalies near 25 and 281 K. Systematic studies were carried out to probe the anomaly near 25 K which exhibits clear frequency dependence and falls close to a previously observed magnetic transition. The low-temperature dielectric relaxation behavior yielded characteristic energy scales of ∼30 and ∼34 meV for the as-prepared and vacuum-annealed BiFeO3 samples, respectively. Raman spectra showed hardening of the E(TO6) and E(TO9) modes near 25 K, and the Raman shift in phonon frequencies is found to be broader in the vacuum-annealed BiFeO 3 than in the as-prepared BiFeO3. We observed a linear magnetodielectric coupling in both samples at 25 K. These experimental results suggest that coupling among spin, lattice, and dielectric properties persist to low temperatures in BiFeO3. © 2011 American Institute of Physics.