bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of Ge2Sb2Te5 thin film for Phase Change Random Access Memory by RF Magnetron Sputtering and DC Magnetron Sputtering
Authors: Kikuchi Shin , Oh Dong Yong , Kimura Isao , Nishioka Yutaka , Suu Koukou 
Published: April 2011

AbstractPhase Change Random Access Memory [PRAM] is one of the candidate for next generation memory due to its non-volitality, high speed, high density and compatibility with Si-based semiconductor process. Ge2Sb2Te5 [GST] thin film , an active layer in this device, is utilized because it has the well-known property of rapid crystallization without phase separation in erasable compact discs industry.We investigated the difference of the character of the GST thin film with various sputtering methods. 100nm thick GST films were prepared with DC magnetron sputtering and RF magnetron sputtering for this experiment. XRF, XRD,SEM and four point probe measurement are used to analyze the electrical properties of these films.As for the composition of the DC sputtered GST films, Te was insufficient from target composition, while the composition of RF sputtered GST films were almost same as target composition. The RF sputtered GST films were composed of hcp by 400°C annealing. On the other hand, the DC sputtered films were mixed-phase of fcc and hcp. The resistivity of DC Sputtered GST films was higher than RF sputtered film cause of poor crystallinity. The uniformity of RF sputtered film was better than DC sputtered film.
Fabrication of Multilayer Metal-Dielectric Nanofilms for Coupled Plasmon Resonant Devices
Authors: Roberts M. Joseph , Guenthner Andrew , Lindsay Geoff , Feng Simin 
Published: April 2011

AbstractWe have developed a process for production of laterally continuous silver layers alternated with glassy polymer films in which the thickness is on the order of 15 nm and 100 nm respectively. Such films can be used to study physical phenomena associated with the coupled plasmon resonance and the resonant transmission in the forbidden bands. Such films may also find applications in photonic bandgap and other nanoplasmonic devices. Since the surface plasmon and evanescent coupling is a means to propagate light inside nanocircuits, the investigation of the coupled surface plasmon in the multilayer structures provides us with fundamental knowledge for the 3D integration. The fabrication technique also allows design flexibility, for example, systems with regions of single M-D-M plane together with multilayer structures facilitating tunable multiple plasmon resonance wavelength response from a single system. Multiple plasmon wavelength resonance absorptions may be obtained from such systems. Utilizing polymer films as the dielectric enables design flexibility and increases the number of applications of the fabricated devices.
Experimental demonstration of negative refraction and subwavelength imaging by left-handed composite metamaterials
Authors: Ozbay Ekmel , Aydin Koray , Ozkan Gonca , Bulu Irfan 
Published: April 2011

AbstractWe report a true left-handed (LH) behavior and focusing in a composite metamaterial consisting of periodically arranged split ring resonator (SRR) and wire structures. The magnetic resonance of the SRR structure is demonstrated by comparing the transmission spectra of SRRs with that of closed SRRs. We confirmed experimentally that the effective plasma frequency of the LH material composed of SRRs and wires is lower than the plasma frequency of the wires. A well-defined left-handed transmission band with a peak value of -1.2 dB (–0.3 dB/cm) is obtained. We also report the transmission characteristics of a 2D composite metamaterial (CMM) structure in free space. At the frequencies where left-handed transmission takes place, we experimentally confirmed that the CMM structure has effective negative refractive index. Phase shift between consecutive numbers of layers of CMM is measured and phase velocity is shown to be negative at the relevant frequency range. Refractive index values obtained from the refraction experiments and the phase measurements are in good agreement and the experimental results agree extremely well with the theoretical calculations. By measuring the refracted electromagnetic (EM) waves from a LHM slab, we found an effective refractive index of -1.86. A 2D scanning transmission measurement technique was used to measure the intensity distribution of the electromagnetic (EM) waves that radiate from the point source. The flat lens behavior of a 2D CMM slab was demonstrated for two different point source distances of ds = 0.5ë and ë. The full width at half maximum of the focused beams is 0.36ë and 0.4ë, respectively, which are both below the diffraction limit.
Ultrasound-induced Functionalization and Solubilization of Carbon Nanotubes for Potential Nanotextiles Applications
Authors: Chen Wei , Tao Xiaoming 
Published: April 2011

AbstractA simple sonochemical method has been employed for the surface functionalization of carbon nanotubes. Pristine single-walled carbon nanotubes (SWNTs) were irradiated by ultrasound in methyl methacrylate monomer. Polymer grafted carbon nanotubes were easily prepared by in situ sonochemically initiated radical polymerization of methyl methacrylate. FT-IR, TGA, SEM and TEM were used to characterize the polymethyl methacrylate (PMMA) grafted SWNTs. The surface-modified SWNTs afforded are then dispersible in good solvents for PMMA, such as dichloromethane and chloroform. The ‘green’ value involved in this simplifying processing contains low hazard, clean operation, reduced chemical consumption and short time, which undoubtedly generate profound impact on the development of carbon nanotube based nanochemistry and large scale nanotextiles application.
Pressure Sensing Fabric
Authors: Hui Zhang , Ming Tao Xiao , Xi Yu Tong , Sheng Li Xin 
Published: April 2011

AbstractThis paper presents an approach for decoding the pressure information exerted over a piece of fabric by means of resistive sensing. The proposed sensor includes a distributed resistive grids constructed by two systems of orthogonally contacted electrical conductive yarns, with no external sensing element to be attached on the fabric. Since the conductive yarns serve as the sensing and wiring elements simultaneously, this design simplifies the fabrication process, reduces the cost and makes the production of large area flexible pressure sensor possible. The location of the pressure applied on the fabric can be identified by detecting the position where the change of the resistances occurs between two embroidered yarns. Meanwhile, the magnitude of the pressure can be acquired by measuring the variations of the resistance. In order to eliminate the “crosstalk” effect between adjoining fibers, the yarns were separately wired on the fabric surface.
Nanobiomaterials For Controlled Release Of Drugs & Vaccine Delivery
Authors: Vaseashta Ashok , Erdem A. , Stamatin I. 
Published: April 2011

AbstractA number of natural and synthetic, and biodegradable polymers were investigated and remain to be elucidated for both soft and hard tissue repair, and for possible construction of excipient therapeutic templates. Nonwoven matrices from poly (ε-caprolactone) (PCL) homopolymers and poly (L-lactide/ε-caprolactone) (PLLA/CL) copolymers by electrospinning process were investigated for possible applications in burn/wound dressings. Efforts are currently underway to control the release characteristics of these biodegradable fibers by varying aliphatic polyesters. This perspective will have a profound effect on the time-controlled transport of vaccine to a targeted site. These materials will play a key role in developing novel chemotherapeutic agents that could be important in targeting specific genes and may provide selective control of gene expression. Furthermore, these fibers-by-design address many issues relating to the fundamental challenges in the synthesis of novel, biocompatible and safe delivery of vaccine and nanofiber materials to foster antibacterial and/or hygienic functionality, System-on-Fibers (SoF), and will have tremendous application in global security and defense.
Ab Initio Study of Surface Stresses of Charged Au films
Authors: Umeno Yoshitaka , Weissmueller Joerg , Elsaesser Christian , Meyer Bernd , Gumbsch Peter 
Published: April 2011

ABSTRACTIt has been observed in experiments that charging of nanometer-sized porous material can lead to expansion or contraction of this material. This effect can be explained by a change in surface stress as a function of surface electron charge density. Here, we employ ab initio density functional calculations using a mixed-basis pseudopotential approach to study the change in surface stresses, f, as a function of surface charge density, q for Au thin films with (111) and (100) surfaces. The derivative of the surface stress with respect to the charge, ôf/ôq, at equilibrium is related to and can be evaluated from ôμ/ôe of an uncharged slab, where μ is the chemical potential of the slab and e the tangential strain. The responses of the (111) and (100) surfaces to charging are evaluated in this way as −1.86 V and −0.90 V, respectively. The calculated values compare well to experimental observations (−0.9 V).
Development of Electrostatic Actuated Nano Tensile Testing Device for Mechanical and Electrical Characteristics of FIB Deposited Carbon Nanowire
Authors: Kiuchi Mario , Matsui Shinji , Isono Yoshitada 
Published: April 2011

ABSTRACTThis research develops Electrostatic Actuated NAno Tensile testing devices (EANATs) to evaluate mechanical and electrical properties of carbon nanowires fabricated by focus ion beam- assisted chemical vapor deposition (FIB-CVD). This research carried out nanoscale uniaxial tensile tests for 90 nm- to 150 nm-diametric carbon nanowires using EANATs. Young's modulus of cabon nanowires averaged 58 GPa, which was close to that of hydrogenated diamond-like carbon films. On average, fracture stress and strain of carbon nanowires reached values of 4.2 GPa and 0.08, respectively. This research also measured I-V characteristics of 100 nm-diametric carbon nanowires under tensile loading to reveal the piezo resistivity of nanowires. The piezoresistive effect of carbon nanowire was observed. The tensile load was about 0.75 GPa at maximum value of the resistance change.
Modeling of Supramolecular Systems, Mechanically Docked to Carbon Nanotubes
Authors: Poler Jordan , DuBois T. D. 
Published: April 2011

ABSTRACTCarbon nanotubes and nanowires are important materials for new nanotechnology devices and sensors. Future optoelectronic devices can be made from assemblies of nanostructured materials. One difficulty in preparing these assemblies from nanotubes is the lack of site-specific points of contact and the subsequent compliance of the linkage between nanoparticles. Using molecular mechanics, semiempirical and dynamics calculations, we have modeled the assembly process of two-dimensional and three-dimensional structures of carbon nanotubes. The linkers between the nanotubes consist of novel metallodendrimers. These dendrimers have multiple binding sites with chemically specified chirality. Most importantly, they are mechanically rigid. This enables the multidimensional constraints and geometry, required for advanced electronic and optoelectronic devices.
Thermomechanical Properties of Thin α-Fe Films Above the Brittle to Ductile Transition Temperature
Authors: Wuebben Thomas , Schneider Andreas , Richter Gunther , Arzt Eduard 
Published: April 2011

ABSTRACTThe mechanical properties of thin metal films as compared to their bulk counterparts have been in the focus of materials science in the recent years. Owing to their technological importance, almost only metals with a face centered cubic structure like copper and aluminum have attracted scientific interest. Thin films made of bcc metals, on the other hand, have been largely neglected.However, from a scientific point of view, the mechanical properties of bcc metals are of special interest. As an example, the yield stress of bcc metals is strongly temperature dependent for low temperatures, while it shows a behavior similar to fcc metals for higher temperatures. This is often referred to as the brittle to ductile transition (BDT). Despite intense research the underlying mechanisms leading to this phenomenon are still not understood in full detail. A major problem is the understanding of dislocation dynamics on the microscopic scale, which is different from that of fcc metals because of the special symmetry of the crystal system.A first step is to verify in thin films that for temperatures above the BDT the thermomechanical behavior of bcc metals resembles that of fcc metals. As a model system we chose iron with a BDT temperature slightly above room temperature. We deposited iron by means of an MBE system on sapphire substrates. The so-produced epitaxial thin iron films with thicknesses above 50 nm were then thermally cycled from room temperature to 540°C in a vacuum substrate curvature apparatus to test their thermomechanical behavior.We will present the results of substrate curvature measurements performed with iron films of different thicknesses and discuss similarities and differences to results obtained for metals with fcc crystal structures.
Stretchable Dielectric Material for Conformable Bioelectronic Devices
Authors: Tsay Candice , Lacour Stephanie P. , Wagner Sigurd , Yu Zhe , Morrison Barclay 
Published: April 2011

ABSTRACTWe use a photo-patternable silicone polymer to fabricate an elastically deformable encapsulation film on stretchable gold lines that electrically conduct while stretched to >50% strain. To detect bioelectrical signals, these stretchable gold lines are patterned as leads and micro-electrodes. They need to be encapsulated with a material that is electrically insulating, as stretchable as the elastomeric substrate, and that can be readily patterned to define recording sites. First, we evaluate the biocompatibility of the elastic encapsulation polymer by assessing the viability of the organotypic hippocampal slices cultured on it. Then, to test the electrical performance of the encapsulation film under large mechanical stress, we measure the dielectric strength of the encapsulation film to 50% tensile strain. Our findings indicate that the photo-patternable silicone material is a suitable interface toin vitroliving tissue, and is a reliable stretchable insulator for soft and conformable electronic devices.
Carbon Nanotube Based Electrodes for Neuroprosthetic Applications
Authors: Phely-Bobin Thomas S. , Tiano Thomas , Farrell Brian , Fooksa Radek , Robblee Lois , Edell David J , Czerw Richard 
Published: April 2011

ABSTRACTFoster-Miller, Inc., in conjunction with InnerSea Technology, NanoTechLabs and Dr. Lois Robblee, has demonstrated a simple, low cost process for the fabrication of high capacitance, low impedance, and high surface area carbon nanotube (CNT) electrodes for use as implantable microelectrodes. Implantable microelectrodes for electrical stimulation of neurons and recording neuronal responses are essential tools for neurophysiologists studying the behavior of neurons in the brain, spinal cord and peripheral nerve. Critical properties of an electrode interface should include: low noise, low impedance, biocompatibility, electrical stability during chronic use, and high charge capacity. Iridium oxide has all of these properties and thus has been utilized for significant developments in the neural prostheses area. However, these electrodes have several shortcomings, including: high material cost, labor-intensive processing, and deterioration of long term stability.The results of electrochemical testing of the CNT electrodes show high capacitance and low impedance. Preliminary testing indicates that the CNT felt electrodes have advantages over state of the art iridium oxide electrodes in that their highest charge capacity is distributed within the cathodic portion of the water window, exactly where iridium oxide charge capacity is lowest. When the integration of the cathodic part of a CV is done in the potential window from 0.3 V (open circuit) to −0.7 V, at which the electrode will be used, we obtain a value of 38 μc-cm−2. Similar integration for an iridium oxide electrode gives a value of 15 mC cm−2. The high charge capacity of the CNT felt electrode over the cathodic potential range below 0.0 V is advantageous for electrical stimulation with cathodal current pulses. This is a feature lacking in Iridium oxide electrodes for which most of the charge capacity is accessed over anodic potentials above 0.0 V. In order for Iridium oxide electrodes to utilize their charge capacity during cathodal pulses, it is necessary to apply an anodic bias to the stimulation electrode between stimulus pulses. This leads to increased complexity of stimulation circuitry and the possibility of the intermittent occurrence of low dc current, both of which will be avoided with the CNT felt electrodes.
Polymer-Based Implantable Electrodes: State of the Art and Future Prospects
Authors: Koch Klaus Peter , Ramachandran Anup , Poppendieck Wigand , Feili Dara , Hoffmann Klaus-Peter 
Published: April 2011

ABSTRACTElectrical interfaces between technical system and the biological system differs with respect to material and shape depending on their intended application. Although there are different approaches using silicon as basic material for sieve or needle like electrodes interfacing the nerve tissue. This abstract will focus on polymer-based flexible implantable electrodes.Mechanical interaction between the electrode and tender nerve tissues can induce adverse body reaction such as fibrous tissue encapsulation. Using flexible materials to design the electro-biological interface might reduce this effect. Different designs of such flexible electrodes were proposed for contacting the nerve or as platform for sensors. For example, Cuff like electrodes can be elastically wrapped around the nerve for recording or stimulation of neural signals. Using microtechnology for the structuring of polymer substrates new fiber like electrodes with multiple electrode sites were developed that can be sewed into the nerve. Thereby the possibility of selective nerve recording and stimulation was improved. One major problem of these tiny and flexible electrodes is the connection to recording and stimulation system. Incorporating electronics such as multiplexer or amplifier directly on the flexible substrate could reduce the number of connection lines or improve the sensor capabilities. Further, the integration of flexible organic electronics on the implant allows the design of more flexible and intelligent electrodes. Additionally the electrodes and sensors can be designed using conductive polymers to create a new generation of “All Polymer” active implants. Not only the chemical and mechanical properties of the materials employed can influence the biocompatibility of an implant but also the surface topography in the nanometer range plays a key role such as the growth of cells on the implants. Selective adhesion of different type of cells to different parts of the implant is a challenge for the interdisciplinary research. Finally the combination of surface nanostructuring, for example the interference laser beam structuring, and organic electronics with microstructured polymer implants offers interesting potentials for new active implants of the next decades
Polymer-Based Microelectrode Arrays
Authors: Corbett Scott , Ketterl Joe , Johnson Tim 
Published: April 2011

ABSTRACTWe have developed flexible, polymer-based electrodes for potential medical applications including neural recording and stimulation. Using various combinations of liquid crystal polymer (LCP) substrates, implantable grade silicone and polyimide, we have developed and tested several prototype multi-layer polymer electrodes. We report here on two specific electrodes. In the first case, a multilayer electrode consisting of high-melt temperature liquid crystal polymer (LCP) material with patterned electrodes of sputter deposited and plated gold, laminated together with a lower-melt temperature LCP was produced. Iridium oxide was deposited on the exposed electrode sites to facilitate effective charge transfer for neural stimulation. The electrode was designed for acute implantation in a cat cochlea and contained 12 contacts, with a pitch of 200 microns. The small contact spacing allowed testing of electric field focusing techniques both in vitro and in vivo. We subjected the electrodes to electrical and mechanical tests to assess potential suitability as a long-term biomedical implant. Chronic electrical leakage testing indicated higher than desired ionic permeability of the low and high temperature LCP interface. In a second case we produced a mock circuit using high-melt LCP and medical grade low durometer silicone in place of the low-melt LCP as the interlayer adhesive. Mechanical and electrical testing of the hybrid design indicated the potential to fabricate cochlear electrodes containing up to 72 contacts with a footprint and mechanical performance similar or better than current commercially available cochlear implant arrays (containing up to 24 elements). Multi-layer polymer electrode technology offers the opportunity to create new electrodes with higher numbers of channels, offering improved performance in neural stimulation applications including cochlear implants, retinal arrays, deep brain stimulators and paraplegic remobilization devices.
Thermal Analysis of High-Pressure Metal Hydride Tank for Automotive Application
Authors: Toh Keiji , Kubo Hidehito , Isogai Yoshihiro , Mori Daigoro , Hirose Katsuhiko , Kobayashi Nobuo 
Published: April 2011

ABSTRACTA new type of hydrogen storage tank has been developed for fuel cell vehicles FCHV. The tank design is based on the 35MPa high-pressure cylinder vessel and the heat exchanger module including hydrogen absorbing alloy with high dissociation pressure is integrated in it. To hydrogen absorbing alloy, for example, Ti-Cr-Mn alloy with AB2 laves phase is applied. Its effective hydrogen weight capacity is 1.9 wt% and reaction enthalpy is −2 kJ/molH2. To optimize the heat exchanger, thermal analyzing method was developed to predict the amount of hydrogen absorption or desorption. The simulation consists of heat and mass balance. Heat balance is made by the hydrogen absorbing alloy, heat exchanger and coolant each other. Also reaction heat of the hydrogen absorbing alloy and compressed heat are considered. The reaction heat is calculated from the equation of reaction rate that is derived experimentally.Furthermore, an additional simulation to predict the charging performance of on-board high-pressure MH tank system by the radiator cooling will be reported. With this simulation, it will become possible to make parameter studies to investigate how the operating conditions influence the performance of tank system.
Mechano-Chemical Synthesis and Characterization of New Complex Hydrides for Hydrogen Storage
Authors: Srinivasan Sesha , Rivera Luis , Stefanakos Elias , Goswami Yogi 
Published: April 2011

AbstractMechano-chemical synthesis has been employed to prepare new light weight complex borohydrides. The precursor complex borohydrides such as NaBH4 and LiBH4 have been used since these materials posses high hydrogen storage capacity of 13.0 and 19.6 wt.%. This advanced materials based technology will meet the US-DOE grand challenge technical targets. The thermal calorimetric and gravimetric analysis of these complex borohydrides exhibits the hydrogen decomposition temperature (Tdec) of 100–150° C with theoretical capacity of ∼8.0-10.0 wt%. The catalysts (e.g. ZnCl2, TiFx3) doping and destabilization of the borohydride by reacting with binary hydride (MgH2) reveals the enhancement of decomposition kinetics and reversible dehydrogenation-rehydrogenation behavior.