Planar Components Research Articles

Mechanics Framework for Micron-Scale Planar Structures

Structures are assemblies of planar and three-dimensional objects. Planar components and parts are commonly because the deformation behaviors of plates and beams can be analyzed within the plane problem framework. For micron-scale structures, patterning processes in microfabrications are intrinsically planar and the resulting fabricated structures are also planar. These planar micron-scale structures have been designed and analyzed using conventional mechanics, but increasingly as the sizes of these structures become smaller, higher order effects become significant. In nanometer-scale, surfaces were recognized to play significant roles in affecting the physical behavior. Size dependent elastic and plastic deformation behaviors in micron-scale structures were also observed. Size dependence is an intrinsic part of higher order theory of mechanics and has been used successfully to explain scale dependent behavior in threedimensional structures. In this paper, two-dimensional higher order elastic relations in plane stress and plane strain for compressible solids are developed. The difference between the higher order and conventional elasticity theories is compared

A stress-free packaging solution for planar waveguide-based photonic components

It is a challenge to simultaneously prevent the fiber ribbons from internal stress in the planar waveguide-based components and protect the ribbons from external stress. We have achieved this by simply incorporating two soft elastomer gaskets into each conventional packaging to compensate the mismatched thermal expansion between the fiber ribbon and packaging case, and fastening the fiber ribbon to the case to transfer their external load away. The involved process was easily implemented at a minimum cost, and the packaged variable optical attenuators and arrayed waveguide gratings were free of internal ribbon stress and able to meet the fiber-handling requirement as specified by Telcordia GR 1209 test.

Design Method and Material Technologies for Passives in Printed Circuit Board Embedded Circuits

The integration of passive components into the printed circuit board (PCB) as embedded passives integrated circuits (emPIC) results in a higher power density of power converters. To achieve a highly automated, low cost, integral manufacturing, the devices are constructed layer wise. Materials and processes necessary for the manufacturing of such circuits are described in this publication. Especially for magnetic components like inductors and transformers the design of such thin components is challenge. Because of the high aspect ratio, traditionally used models lead to a high calculation effort or use nonappropriate approximations. This contribution presents an analytic approach for the design. The model considers the magnetic flux distribution in the core and in the winding area and therefore allows a precise calculation of the inductivity as well as the losses in the device and their distribution. It is very well suited for a parametric analysis and thus for the synthesis of thin planar magnetic components. Material technologies for the construction of the capacitive layers and the magnetic cores are investigated. A ferrite polymer compound is adapted to be compatible with the PCB laminating process. Accordingly a 60-W offline converter was designed and fabricated using the new technology. Its transformer is entirely integrated in the PCB as well as 11 capacitors. Standard PCB lamination processes are used for the layerwise integration of the components. The circuit needs an area of the size of a credit card with a PCB thickness of 4 mm. Up to 82% efficiency could be demonstrated.

Reduction of High-Frequency Conduction Losses Using a Planar Litz Structure

A new trend in power converters is to design planar magnetic components that aim for low profile. However, at high frequencies, ac losses induced in the planar inductor and transformer windings become significant due to the skin and proximity effects. A planar litz conductor can be constructed by dividing the wide planar conductor lengthwise into multiple strands and weaving these strands in much the same manner as one would use to construct a conventional round litz wire conductor. Each strand is then equally subjected to the magnetic fields in the winding window, thereby equalizing the flux linkage and improving the current distribution. Three-dimensional finite-element modeling was performed for simple models. The simulation results showed that the planar litz conductor can result in lower ac resistance than a solid conductor over a specific frequency range. The performance of the planar litz winding was also verified with measurements on two experimental prototypes.

Probing the magnetization vectors in layered magnetic structures

Using the X-ray magnetic circular dichroism, we measured the orientations of magnetic moment at exchange-coupled Co/Tb x Fe 1− x bilayers. The moment associated with each element was found tilting an angle with respect to surface normal. Study of the thickness dependence on Co film shows increasing planar component for thicker film. With a fixed 15 Å Co layer deposited on Tb x Fe 1− x , lower Tb percentage leads to larger tilting angle. Element-specific measurements confirm that all three moments have similar orientation at interface, suggesting strong interlayer coupling.

Modeling Planar Cell Polarity

Epithelial cells of many organisms show planar cell polarity. In the Drosophila wing, hexagonally packed cells accumulate various planar cell polarity signaling components in localized areas (proximally or distally), and an actin-rich hair develops from the distal vertex and points distally. Although several molecular components for this patterning have been elucidated, the complexity in number of factors and their various interactions, including the effects of neighboring cells on each other, has hindered a full understanding of planar cell polarity. Amonlirdviman et al. now combine biology and mathematical modeling to address the complex phenotypes produced by genetic manipulations. The model incorporates transcellular interactions between membrane proteins and is based on reaction-diffusion and partial differential equations. This mathematical model shows how contact-dependent signaling can account for the effect a mutant cell can have on the phenotype of a neighboring cell. K. Amonlirdviman, N. A. Khare, D. R. P. Tree, W.-S. Chen, J. D. Axelrod, C. J. Tomlin, Mathematical modeling of planar cell polarity to understand domineering nonautonomy. Science 307 , 423-426 (2005). [Abstract] [Full Text]

Efficient energy based modeling and experimental validation of liquid filling in planar micro-fluidic components and networks

This paper presents a model that describes how liquid flow fills micro-fluidic components and networks. As an alternative to computational fluid dynamic (CFD) simulations, we use a constrained energy minimization approach. This approach is based on two assumptions that hold in many micro-fluidic devices: (i) The length scales are small, and we consider slow filling rates, hence fluid momentum and viscous terms are small compared to surface tension forces, consequently the liquid/gas interfaces can be viewed as a succession of quasi-steady equilibrium configurations. (ii) Any equilibrium configuration corresponds to a surface tension energy minima which is constrained by the device shape and the volume of liquid in the device. The model is developed for planar micro-fluidic devices, is based on a fundamental physical principle, and shows accurate agreement with experimental data. It takes us only a few minutes to evaluate the model for a planar component of any shape using the Surface Evolver software, and this is significantly less then the computer run time required for CFD simulations. Moreover, once a library of component models has been created (which takes less than an hour of computer time) it then takes only seconds to simulate different network architectures with thousands of components. This fast "reconfigure the network and simulate in seconds" capability is essential for the design of truly complex networks that will enable the next generation of passive, micro-fluidic, lab-on-a-chip systems.

Broadband topology-optimized photonic crystal components for both TE and TM polarizations

Several planar photonic crystal components topology-optimized for TE-polarized light, including 60 masculine bends, Y-splitters, and 90 masculine bends, have been characterized for the TM polarization. The experimental results are confirmed by finite-difference time-domain calculations. The surprising efficiency for TM-polarized light is found and paves the way for photonic crystal components suitable for both polarizations.

InDEC B.V. on the Road Towards Commercialization

InDEC (Innovative Dutch Electro Ceramics) is an HC Starck and ECN owned company that produces planar electrolyte-supported cells (ESC) and anode-supported cells (ASC). InDEC aims to offer cost-effective flat plate cutting edge SOFC technology. At present the planar SOFC component production takes place at the pilot manufacturing plant located in the Netherlands. Since acquiring the majority InDEC shares, HC Starck has built up a significant production technology activity in order to increase production capacity and to reduce manufacturing costs. A (semi)-automated quality controlled SOFC manufacturing plant is being set up in Selb, Germany. InDEC is also continuously improving the intrinsic product properties by R&D efforts focusing on improved cell performance for ESC and high mechanical strength for ASC. As a result, InDEC has introduced two new planar SOFC products, namely a newly formulated high performance ESC cell comprising a TZ3Y electrolyte having reduced thickness, and a new ASC cell having doubled mechanical strength.

Measurements of Spindle Parameters on a Diamond Turning Machine to Nanometer Resolution(Precision positioning and control technology)

A single point diamond turning (SPDT) facility is utilized for the ultra-precision machining of planar surfaces, and aspheric mirror components for geo-orbital x-ray telescopes and x-ray microscopes. The spindle of the machine tool is encased in an ultra-precision hydraulic bearing, and the motion controller is programmable to nanometer resolution. The radii of diamond cutting tools, utilized in the SPDT process, approach nanometer accuracy. This combination of parameters produces planar and aspheric components with nanometer surface and shape quality. We examine the radial and axial motion of the spindle in the static and dynamic domains with an optical nanometer-resolution sensor. The sensing geometry is based on standard optical triangulation off the target surface, and the sensor can be calibrated in situ utilizing the position controller of the machine. We present results, which examine the parametric performance of the diamond turning operation. At 1000rpm we measured a minimum of approximately 35-nm rms radial and the axial spindle error motion.

Hidden glassy behaviors in an ideal Heisenberg Kagomé antiferromagnet

Dynamics of classical Heisenberg spins S i on the Kagomé lattice has been studied. An ideal Heisenberg Kagomé antiferromagnet is known to remain disordered down to T = 0 due to the macroscopic degeneracy of the ground state. However, we find that S i and their planar components s i in the thermally selected coplanar nematic state behave in a qualitatively different way and especially planar spins ( s i ) show the exotic glass-like transition in the very low temperature T ∼ 0.003 J ( J: spin exchange). The glassy behaviors of s i would be found to be driven by the spin-nematic fluctuations, different from ordinary spin glasses by disorders or anisotropies.

Second-order perturbation theory for scattering from heterogeneous rough surfaces.

We propose a model to calculate scattering from inhomogeneous three-dimensional, rough surfaces on top of a stratified medium. The roughness is made up of an ensemble of deposits with various shapes and permittivities whose heights remain small with respect to the wavelength of the incident light. This geometry is encountered in the remote sensing of soil surfaces, or in optics wherever there are contaminated planar components. Starting from a volume-integral equation involving the Green's tensor of the stratified medium, we derive a height-perturbative expansion up to second-order. Our formulation, which depends explicitly on the profiles of each deposit and on the Fresnel coefficients of the layered substrate, accounts for double-scattering events and permits an evaluation of depolarization in the plane of incidence. Comparisons with rigorous calculations in the simplified case of two-dimensional geometries are presented. It is shown that the second-order scattering term can be much more important for heterogeneous surfaces than for their homogeneous counterparts.

Comparison of Bar Strengths and Fractions of Bars in Active and Nonactive Galaxies

Gravitational perturbation strengths and bar fractions in active and nonactive galaxies are compared using the Ohio State University Bright Galaxy Survey, which forms a statistically well defined sample of 180 disk galaxies. Bar fractions are studied using (1) the optical and near-IR classification of bars made by Eskridge and coworkers in 2002 and (2) our own bar classification based on Fourier decomposition of near-IR images (Fourier bars). The gravitational perturbation strengths are calculated using the bar torque method, taking the maximum ratio Qg of the tangential force to the mean background radial force as a measure of the nonaxisymmetric perturbation. In addition, two-dimensional bulge-disk-bar decomposition is used to study the properties of bulges of the sample galaxies. In the near-IR, Seyfert galaxies, LINERs, and H II/starburst galaxies were found to have a similar fraction, 72%, of Fourier bars (or SB-type bars), compared to 55% in the nonactive galaxies. However, if SAB-type bars are also included, practically all (95%) H II/starburst galaxies have bars. In addition, a large fraction (34%) of bars in LINERs are obscured by dust in the optical region. We find that bars in early-type galaxies are at the same time long and massive and have weak perturbation strengths. Weak perturbation strengths can be explained by dilution of the nonaxisymmetric forces by the massive bulges: for a bulge-to-disk mass ratio B/D ranging from 0 to 1, the dilution may reduce Qg from as high as 0.6 to as low as 0.1. On the other hand, bar length (relative to disk scale length) is not correlated with B/D, contrary to expectation. Seyfert- or LINER-type nuclear activity is present in most galaxies that have thin and thick planar bar components, whereas nuclear activity does not appear in those late-type galaxies that have extremely massive bars and strong perturbation strengths.

Topology optimization and fabrication of photonic crystal structures

Topology optimization is used to design a planar photonic crystal waveguide component resulting in significantly enhanced functionality. Exceptional transmission through a photonic crystal waveguide Z-bend is obtained using this inverse design strategy. The design has been realized in a silicon-on-insulator based photonic crystal waveguide. A large low loss bandwidth of more than 200 nm for the bandgap polarization is experimentally confirmed.

Trenches for Building Blocks of Advanced Planar Components

Trenches are fundamental structures used to build advanced optical planar waveguide components. The fabrication of trenches across silica-on-silicon waveguides using inductively coupled plasma etching is presented. These trenches were etched deep into the silicon substrate and their widths were varied between 24 and 100 μm. The insertion loss for waveguides with 24- and 28-μm-wide trenches etched across them were measured for trenches filled with air and oil. The measured results followed those expected from simulations.

Solid Oxide Fuel Cell Materials: A Review

Solid Oxide Fuel Cell (SOFC) is a solid-state electrochemical device that converts the chemical energy of a fuel directly into electrical energy. Due to its multi-fold inherent advantages SOFC is projected as the power source for the future generation. All over the world, extensive research activities are being pursued for the past decade and accordingly an immense wealth of literature is avaitable in this field of research. Though this field of research activity is very wide and multidisciplinary, this review is mainly directed towards the processing, properties and fabrication of the state of the art ceramic materials, viz., yttria stabilized zirconia (YSZ) as the electrolyte material, Sr-doped LaMnO3 as the cathode material, Ni-YSZ cermet as the anode material and Ca-doped LaCrO3 as the interconnect material, that are being considered for the development of present day SOFC power modules. Special attention is given to the development of planar SOFC components fabrication taking into consideration the advantages of the planar design compared to the tubular design. A brief account of the future research and development direction is also discussed with an emphasis to widen the scope of materials research in the area of solid oxide fuel cells.

Fabrication of Photonic Crystals in Microchannels

AbstractWe have developed a fabrication procedure for growing photonic crystals in the lithographic defined microchannels, which enables easy integration with other planar optical components. This technique is based on the directed evaporation induced self-assembly of nanoparticles in the microchannels. Substrates with pre-patterned microchannels (30-100 μm wide) were dipped into solution of nanoparticles for several days. By controlling the evaporation rate, the meniscus contacting the microchannels will undergo evaporation-induced self-assembly. The capillary forces cause nanospheres to crystallize within the microchannels forming colloidal photonic crystals in the microchannels. Two types of colloidal particles, polystyrene and silica, have been employed to fabricate colloidal photonic crystals in the microchannels. Both types of colloidal particles were found to form large-area well-ordered colloidal single crystals in the microchannels. The optical reflection spectra from the (111) surfaces of the colloidal crystals formed by various sizes of nanoparticles have been measured. And the measured reflection peaks agree with the photonic bandgap calculated by the plane wave expansion method.

Magnetic Technique for Nondestructive Evaluation of Residual Stresses

A technique has been designed for measuring planar components of stray fields from ferromagnetic samples placed in a constant magnetizing field. The technique is based on recording the field of magnetization reversal of a thin magnetic film with the small coercive force being the sensor device of a microwave detector. The possibility of measuring the deformation inhomogeneities caused by mechanical treatment when manufacturing products from ferromagnetic materials is demonstrated. The results of the magnetic measurements agree with the data from X-ray diffraction analysis.

5-Hydroxy-3,3′,4′,5′,7-pentamethoxyflavone (combretol)

The structure of the title compound, C20H20O8, which was extracted from Rhodomyrtus tomentosa, confirms the connectivity and is consistent with the results from spectroscopy. The structure, notable for the crowded sequence of (3′,4′,5′) tri­methoxy substituents, is compared with that of its previously recorded analogue lacking the methyl at the 4′-oxy­gen (two polymorphs), and with myricetin which lacks all O-methyl­ation (cocrystallized with tri­phenyl­phosphine oxide). The latter, interestingly, has a dihedral angle of 36.4 (3)° between its planar aromatic components, but the overall cyclic framework of the title mol­ecule is essentially planar. In the crystal structure, the mol­ecules stack obliquely along the short [4.244 (2) Å] c axis of the orthogonal cell.

Encapsulating Planar Waveguide-Based Photonic Components with Polymer Coatings

Polymer encapsulation was applied to protect waveguide-based photonic components from moisture attack at the lowest cost. A thin-coating method was developed by analyzing the water transportation in polymers and by evaluating the impact of encapsulation on the waveguides. The results showed that a 7 μm-thick Parylene coating can provide sufficient protection to the wire bonds and fiber-to-waveguide coupling materials. The coated variable optical attenuator easily passed the damp heat test of Telcordia GR 1221. This coating did not have any stress or heat effect on the components, and it costs 90% less than hermetic packaging.