bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancement of Antibody Binding on SiO2Love Wave Sensor Surface using (3-glycidoxypropyl)trimethoxysilane
Authors: Moll Nicolas , Dinh Duy Haï , Pascal Emilie , Déjous Corinne , Pillot Jean-Paul , Bennetau Bernard , Rebière Dominique , Moynet Daniel , Mas Yan , Pistré Jacques
Published: April 2011

An acoustic Love wave immunosensor dedicated to detect biological species such as bacteria, viruses or toxins is described in this paper. We present and analyze results of antibody grafting on the Love wave device using GPTS as coupling agent between SiO2sensor surface and the sensitive biomembrane layer composed of antibodies. Goat anti-mouse (GAM) antibodies at concentrations from 2μg/ml to 50 μg/ml were introduced on the sensor brass cell. The saturation of the sensor surface by antibodies appears at a concentration of 20 μg/ml. The detection threshold of this primary antibody is around 2 μg/ml, and the lowest concentration allowing antigen detection is around 5 μg/ml.
Localized Surface Plasmon Resonance Biosensor Using Ag Nanostructured Films Fabricated by a Reduction Method
Authors: Arai Tomofumi , Kumar Penmetcha K. R. , Awazu Koichi , Tominaga Junji
Published: April 2011

In this paper, an optical biosensor based on the localized surface plasmon resonance (LSPR) of Ag nanostructured films is proposed and demonstrated. The Ag nanostructured films, which are fabricated by the reduction of AgOx thin films, exhibit a strong LSPR at wavelengths around 370 nm in an air environment. The reflectance spectra of the Ag nanostructured film represent that the shift in the LSPR wavelength follows a linear dependence on the refractive index of the surrounding medium. By varying the concentration of streptavidin solution, we demonstrate that the Ag nanostructured films functionalized with thiol and biotin molecules can sensitively detect a binding event between biotin and streptavidin molecules.
Studies on Biosensing Property and Functionalization of In2O3 and Carbon Nanotube Field Effect Transistor
Authors: Ishikawa Fumiaki , Li Chao , Curreli Marco , Thompson Mark E. , Zhou Chongwu
Published: April 2011

Biosensing property and functionalization of In2O3 nanowire and carbon nanotube field effect transistor were investigated. Low-density lipoproteins adsorbed on their surface were found to give complementary effects on their electrical property, e.g., enhanced conductance in NW and suppressed conductance in CNT. Prostate specific antigen was selectively detected by functionalizing the sensors with PSA antibody via linker molecules. It was found that the exposure to 0.14 nM (5 ng/ml) PSA increases the conductance of In2O3 nanowire by 1.3 %, while 1.4 nM (50 ng/ml) PSA decreases that of carbon nanotube by 2 %. Additionally, selective functionalization of Indium Tin Oxide thin film and In2O3 NWs with probe DNA single strand was achieved by selectively converting hydroquinone into quinone using electrochemistry, as confirmed by the fluorescence study.
Swelling Behavior of Chitosan Hydrogel in Ionic Liquid-Water Binary System
Authors: Lee Chang Kee , Park Sang Jun , Yoon Seong Gil , Shin Kwang Min , Shin Su Ryon , Gu Bon Kang , Kim Min Sup , Shin Min Kyoon , Kim Yu Jin , Kim Seon Jeong
Published: April 2011

The swelling behavior of chitosan hydrogels in ionic liquid–water binary systems was studied using hydrophilic room-temperature ionic liquids (RTILs) to elucidate the swelling properties of chitosan hydrogels. It was confirmed that chitosan hydrogels are much stiffer after immersing in a pure RTIL because the water existing inside the chitosan polymer network is extracted into the RTIL. The pH of the binary system changes when the RTIL is in contact with water. The chitosan hydrogels were fully dissociated at a 90% water content in the BMI-BF4-water binary system. The equilibrium binary system content behavior of the chitosan hydrogels depended upon the amount of free water present. The water behavior in a pure RTIL was examined using differential scanning calorimetry.
Redox Reactions of Bio Molecule for Nano-bio Battery
Authors: Shin Kwang Min , Park Sang Jun , Yoon Seong Gil , Lee Chang Kee , Shin Su Ryon , Shin Min Kyoon , Gu Bon Kang , Kim Min Sup , Kim Seon Jeong
Published: April 2011

Metal oxide nanoparticles within the protein ferritin can act as an energy storage source in nano-bio batteries containing ferrous ferritin and a reconstituted ferritin cage containing different inorganic elements, such as Co, Mn, Ni, and Pt. These components were introduced as two ferritin half-cells with different redox potentials existing between the ferrous ferritin and the reconstituted ferritin. The reduction of ferritin was analyzed in a solution containing 3-[N-morpholino] propanesulfonic acid buffer and oxidized methyl viologen using cyclic voltammetry. The reduction and oxidation peaks of the methyl viologen occurred at potentials of −300 and −100 mV, respectively, and the reduction and the oxidation peaks of the released Fe occurred at potentials of −300 and −100 mV, respectively. The reduction of ferritin was influenced by the pH of the ferritin solution.
Mesostructured WO3 as a sensing material for NO2 detection
Authors: Rossinyol E. , Prim A. , Pellicer E. , Arbiol J. , Peiró F. , Cornet A. , Morante J. R. , Solovyov L. A. , Tian B. , Bo T. , Zhao D.
Published: April 2011

Nanostructured tungsten oxide synthesized from SiO2 templates (SBA-15 and KIT-6) has been used for NO2 gas sensing. Chromium has been added as catalytic additive to WO3 in order to enhance sensor response. Several techniques have been used for identifying both additive location in the tungsten oxide matrix and its oxidation state. Raman spectroscopy confirmed the presence of terminal chromium-oxygen bonds at the material surface. Besides, X-ray photoelectron spectroscopy showed chromium peaks attributable to Cr(III) species. Electrical behavior of pure WO3 has found to be highly dependent on the nanostructure type, i. e. 2D SBA-15 and 3D KIT-6 replicas. Chromium addition diminishes response time and improves sensor response at low NO2 concentrations. Electrical differences due to WO3 nanostructure disappears as a result of additive introduction in the material.
Accelerated Chemical Reactions for Lab-on-a-Chip Applications Using Electrowetting-Induced Droplet Self-Oscillations
Authors: Aizenberg Joanna , Krupenkin Tom , Kolodner Paul
Published: April 2011

This paper summarizes the results of experimental investigations of the feasibility of applying electrowetting-induced droplet self-oscillations to induce rapid mixing of small quantities of liquids. The concept was tested using video microscopy to monitor the mixing of passive colored dyes, of spatially-separated reactants that change color upon reaction, and of fluorescent DNA oligomers whose light emission vanishes upon hybridization with appropriately-functionalized complementary DNA strands. Droplet self-oscillation was found to increase the rate of mixing by factors ranging from 15 to 100 as compared with the rate of passive diffusion in undisturbed droplets. This demonstrates that self-oscillation-induced mixing is a viable method for substantially enhancing the speed of chemical reactions in general, and biochemical assays in particular, when performed in small volumes of liquids.
Sub-micron Emission and Charge Transport Modification of ZnO
Authors: Wang Ran Shi , An Jin , Xu Jian Bin , Ong Hock Chun
Published: April 2011

Although oxide/semiconductor junctions have long been studied in the areas of microelectronics, new phenomena and interests arise from time to time. In particular, in the realm of nanotechnology where materials are shrunk at a length scale of nanometers, the role of heterojunctions in controlling the overall characteristics of the system will become more and more important. In here, we have developed a technique to modify the light emission and charge transport properties of oxide/ZnO system at different dimensionalities. Providing an oxidic overlayer (AlOx) is present on ZnO, a focused electron beam can be used to locally modify optical and electrical properties of ZnO. Under electron bombardment, we find the emission profile of ZnO gradually changes from green-yellow emitting into ultra-violet emitting while the conductivity decreases by more than two orders of magnitude at the same time. Well-defined sub-micron patterns with tunable optical and electrical properties can be fabricated on 2-D ZnO films and 1-D nanoribbons by carefully controlling the dose and energy density of the electron beam. Since ZnO is a versatile material, we believe our studies will shed light on the further use of ZnO in frontier technologies such as gas sensing, display technology, catalysis, spintronics, etc.
Sub-Second Humidity Sensing based on Nanostructured Narrow-Bandpass Optical Filters
Authors: Steele John Jeremiah , van Popta Andy C. , Hawkeye Matthew M. , Sit Jeremy C. , Brett Michael J.
Published: April 2011

An optical-based humidity sensor with a sub-second response time was fabricated from a nanostructured titanium dioxide thin film. A refractive index profile designed to yield a narrow-bandpass optical interference filter was obtained through nanoscale porosity variations produced by glancing angle deposition (GLAD). Under varying humidity conditions the transmittance spectrum of the filter shifts due to effective index changes of the porous structure resulting from adsorption/desorption of water vapor. In the following we will show that this device is highly sensitive, exhibits minimal hysteresis, and is extremely fast. The adsorption and desorption response times were measured to be 270 ms and 160 ms, respectively.
Nanostructured (Sn,Ti, Nb)O2 Solid Solution for Hydrogen Sensing
Authors: Carotta Maria Cristina , Benetti Michele , Guidi Vincenzo , Gherardi Sandro , Malagu' Cesare , Vendemiati Beatrice , Martinelli Giuliano
Published: April 2011

A novel co-precipitation route for preparing pure nanograined (Ti, Sn, Nb)O2 solid solution has been accomplished. The solid solution containing the three elements has been synthesized with the molar ratios for Sn:Ti:Nb 100:42:5. Electron microscopy and X-ray diffraction have been adopted to observe the morphology, the crystalline structure and the mean grain radius. Calcining at 550, 650, 850 or 1050 °C for 2h, showed rutile-like single-phase.

The prepared powders have been deposited to produce gas sensors in form of thick films through screen-printing technology. SEM micrographs of both powders and films showed regularly-shaped particles with grain dimensions at nanometric level, the nanostructure being maintained up to 1050°C. The sensors have been tested with different reducing gases showing large responses to hydrogen and good selectivity.
Thermoreflectance Measurements of the Temperature Distributions in Laser Diodes with Non Injected Facet
Authors: Ochalski Tomasz , Pierscinska Dorota , Pierscinski Kamil , Malag Andrzej , Jasik Agata , Kozlowska Anna , Bugajski Maciej
Published: April 2011

Non Injected Facet (NIF) lasers were developed to increase catastrophic optical damage level of the devices. In this work we present the analysis of the laser diodes (LD) front facet temperature distribution. Micro-thermoreflectance technique is used to perform a detailed temperature maps of the operating LDs. Such a technique gives us temperature maps with a spatial resolution better than 1mm and area of the maps covers active region and substrate crystal. We demonstrate micro thermoreflectance as a perfect tool to determine real temperature distribution of the operating laser diode front facet. Examined series of LDs under investigation have been made in two different ways. Major point of this work is comparison of the front facet temperature distribution of devices with and without injected facets. We compare temperature value and temperature distribution in the waveguide region in both types of the LDs. In our experiment NIF laser diodes exhibit facet temperatures increased by a factor of 1.4.
Thermal Stability of Ru Gate Electrode on HfSiO Dielectric
Authors: Frohlich Karol , Espinos Juan Pedro , Vincze Andrej , Tapajna Milan , Husekova Kristina
Published: April 2011

We have investigated advanced MOS structures containing Ru gate electrode, HfxSi1-xOy dielectric film and Si substrate. The Ru gate electrode was grown by MOCVD at 300 °C. The MOS structures were annealed for 30 min in forming gas and nitrogen at temperatures up to 550 °C. Capacitance-voltage measurements showed important shift of the flat band voltage of the Ru/ HfxSi1-xOy/Si gate stack after treatment at 550 °C. X-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), reflection electron energy loss spectroscopy (REELS) and secondary ion mass spectroscopy (SIMS) were used to analyze interface between ruthenium and high-k dielectric film. Based on the analysis we were able to build up energy-band alignement for the Ru/ HfxSi1-xOy interface. We observed that the energy-band structure of the Ru/HfxSi1-xOy interface remains stable upon annealing in forming gas up to 550 °C. Presence of hydrogen revealed by SIMS can account for compensation of negative charges in HfxSi1-xOy during thermal treatment.
Preparation and Characterization of Rare Rarth Scandate Thin Films as an Alternative gate dielectric
Authors: Wagner Martin , Heeg T. , Schubert J. , Lenk St. , Zhao C. , Caymax M. , Mantl S.
Published: April 2011

Rare earth scandate thin films (GdScO3 and DyScO3) were investigated with respect to future high-k applications. They were deposited on (100) silicon substrates using either pulsed laser deposition (PLD) or electron beam evaporation. The investigation of the films was done by means of Rutherford backscattering spectrometry, high-temperature X-ray-diffractometry, X-ray reflectometry, spectroscopic ellipsometry, transmission electron microscopy (TEM) and atomic force microscopy. For the electrical characterization capacitor stacks were prepared. Both materials show very promising characteristics independent from the deposition technique used. The films are stoichiometric and amorphous and exhibit a smooth surface (roughness RMS < 1 Å). The amorphous phase is stable up to 1000°C. The electrical characterization revealed featureless C-V-curves with a small hysteresis. From CET plots (CET = capacitance equivalent thickness) k-values between 20 and 23 could be extracted. The electron beam evaporation produces films with a better homogeneity and a thinner interfacial silicon dioxide and therefore a smaller CET value as confirmed by TEM. The leakage current density of the film with CET = 1.5 nm was as low as 7.7x10-4A/cm2.
Metal Transport and Loss in Hafnium and Lanthanum Aluminate Films on Si Hampered by Thermal Nitridation
Authors: Miotti Leonardo , Driemeier Carlos , Tatsch Felipe , Radtke Cláudio , Baumvol Israel Jacob Rabin , Vincent Edon , Hugon Marie Christine , Agius Bernard
Published: April 2011

The effects on metal transport and loss in Hf and La aluminate films deposited on Si induced by rapid thermal annealing at 1000°C were investigated. Decomposition of HfAlO films on Si during rapid thermal annealing was reveled by the decrease of the Hf and Al contents. Metal loss from LaAlO/Si structures was also observed following annealing in vacuum, while strong metal transport and interfacial reaction were induced by annealing in a O2 containing atmosphere. These instabilities were hampered by means of post deposition thermal nitridation in NH3 at temperatures lower than 1000°C performed before the rapid thermal annealing step. The role of nitridation is discussed in terms of the N profiles in the nitrided structures.
A Comparison of Electrical and Physical Properties of MOCVD Hafnium Silicate Thin Films Deposited using Various Silicon Precursors
Authors: Jamison Paul , Copel M , Chudzik M , Frank M M , Linder B P , Jammy R , Zhu W
Published: April 2011

We report on the impact of silicon precursor choice on the electrical and physical properties of hafnium silicate (HfSiO) gate dielectrics deposited by metalorganic chemical vapor deposition (MOCVD). Hafnium tert-butoxide (HTB) was used as the hafnium source and silane and tetraethylorthosilicate (TEOS) were used as silicon sources. Elemental depth profiles were measured with sub-nm resolution using medium energy ion scattering (MEIS). For Hf-rich films employing TEOS as the silicon precursor, relatively little Si is incorporated at the bottom interface compared with the top; while using SiH4, a more uniform Si distribution is achieved. These physical differences are then correlated with the electrical performance of transistors employing polysilicon gate electrodes. Transistors incorporating SiH4 based HfSiOx gate dielectrics with low silicon concentrations have lower C-V hysteresis and higher high field mobility than those using TEOS based dielectrics. We demonstrate polysilicon gated transistors which have an electrical thickness in inversion (Tinv) that can be scaled to ~21 A with good leakage reduction when employing nitrided bottom interface layers in combination with optimized HfSiOx dielectrics. Reduced silicon concentration resulted in a lower inversion thickness for a fixed physical thickness contributing to the higher drive currents in transistors.
Processing Impact on Electrical Properties of Lanthanum Silicate Thin Films
Authors: Jur Jesse Stephen , Lichtenwalner Daniel J. , Inoue Naoya , Kingon Angus I.
Published: April 2011

The consequence of tungsten metal purity on the electrical properties of an annealed MOS gate stack with a lanthanum silicate gate dielectric has been investigated. Optimization of the electrical and physical properties of a device with any given dielectric requires the proper choice of metal gate electrode and capping layer. This study is intended to show the importance of tungsten processing optimization and subsequent effects on the equivalent oxide thickness, fixed charge, and density of interface states of La-Si-O gate dielectric MIS devices. In the experiment, La-Si-O films of physical thickness of 1.6 nm were deposited on a Si substrate, subsequently depositing TaN as the gate electrode and W as a capping layer. A post metallization anneal in flowing nitrogen at 1000°C for short times resulted in widely different measured properties of the MIS devices, dependent on the quality of the tungsten deposited. XRD and SIMS profiles of the gate stacks showed a clear relationship between concentration of oxygen and processing of the tungsten. A 1000°C, 10 sec anneal resulted in an EOT change from 1.1 nm to 2.2 nm on gate stacks with low and high oxygen concentration in the tungsten, respectively. Defect densities decreased with increased anneal temperature and time, and annealing with low oxygen-concentration tungsten resulted in higher effective fixed charge. SIMS data suggests that oxygen in the tungsten diffuses to the Si/La-Si-O interface through the TaN electrode, resulting in the observed differences in the defect densities and EOT.
Why phase-change Materials work: An EXAFS Investigation of Ge-Sb-Te Alloys
Authors: Paesler Michael , Agarwal S.C. , Lucovsky G. , Paesler M.A. , Taylor P.C.
Published: April 2011

Studies of amorphous (a-) semiconductors have been driven by technological advances as well as fundamental theories. Observation of electrical switching, for example, fueled early interest in a-chalcogenides. More recently a-chalcogenide switching has been applied quite successfully to DVD technology where the quest for the discovery of better-suited materials continues. Thus, switching provides researchers today with an active arena of technological as well as fundamental study. On the theoretical front, bond constraint theory and rigidity theory provide a powerful framework for understanding the structure and properties of a-materials. Applications of these theories to switching in a-chalcogenides holds the promise of finding the best composition suited for switching applications. Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy is an ideally suited technique to investigate the switching properties of these materials. Results of previous EXAFS experiments will be presented and viewed through the lens of bond constraint theory and rigidity theory.
OUM Nonvolatile Semiconductor Memory Technology Overview
Authors: Hudgens Stephen J.
Published: April 2011

OUMTM (Ovonic Unified Memory), also called PCRAM (phase-change RAM) or CRAM (chalcogenide RAM) is a nonvolatile semiconductor memory technology being developed by Ovonyx, Inc. in a number of industrial joint development programs. OUM technology is based on an electrically initiated reversible amorphous to crystalline phase change process in multi-component chalcogenide alloy materials similar to those used in rewriteable optical disks. Fundamental processes in OUM devices, manufacturing technology, and progress towards commercialization of the technology will be reviewed.
Impact of Material Crystallization Characteristics on the Switching Behavior of the Phase Change Memory Cell
Authors: Gille Thomas , Goux Ludovic , Lisoni Judit , De Meyer Kristin , Wouters Dirk J.
Published: April 2011

The impact of material crystallization characteristics on the switching behavior of phase change memory cells has been investigated using finite element simulation. Both a conventional vertical cell and a horizontal line cell have been analyzed, using the widely used Ge2Sb2Te5 (GST) which is a nucleation dominated material for the vertical cell, and Ag5.5In6.5Sb59Te29 (AIST) which is a growth dominated material for the horizontal cell. Nucleation and growth models were implemented for both materials. Both RESET and SET program cycles were simulated. From these simulations, it was shown that the crystallization models gave realistic results for switching voltages, currents and switching times for the two different cell types. It is found that for GST, both nucleation (at lower voltages) and growth (at higher voltages) can play an important role in the crystallization. However, for AIST, crystal growth from non-amorphized crystal regions dominated over nucleation for all program conditions. The high growth rate of AIST moreover is shown to allow much shorter SET times in the line cell compared to that of GST in the vertical cell.
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

Phase 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

We 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

We 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

A 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

This 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

A 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

It 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

This 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

Carbon 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

The 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

We 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

Foster-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

Electrical 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

We 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

A 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

Mechano-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.
Room-temperature Ferromagnetic Zn0.95Co0.05O Diluted Magnetic Semiconducting Thin Films by Pulsed Laser Deposition
Authors: Zhang Yuebin , Liu Qing , Sritharan Thirumany , Gan Chee-Lip , Li Sean
Published: April 2011

Co-doped ZnO thin films with room-temperature ferromagnetism have been successfully synthesized on (001) Si substrates at 450 °C by pulsed-laser deposition using a Zn0.95Co0.05O ceramic target. Their microstructural properties are carefully studied using atomic force microscopy, x-ray diffraction and high-resolution transmission electron microscopy. The oxidation state of Co and the ratio of Co/Zn are examined by x-ray photoelectron spectroscopy, and magnetic measurements are performed using SQUID. The results show that a single-phase crystalline Co-doped ZnO film was grown with (002) preferential orientation and some edge dislocations formed during the film growth. The origin of room-temperature ferromagnetism is explored. The presence of nanoclusters of any magnetic phase can be ruled out. The dislocations, coupled with oxygen vacancy, may contribute to the ferromagnetic properties in the much diluted magnetic semiconductor.
Some studies on Molybdenum doped Indium oxide thin films rf sputtered at room temperature
Authors: Elangovan E. , Barquinha P , Pimental A , Viana A. S. , Martins R , Fortunato E
Published: April 2011

Thin films of molybdenum doped indium oxide (IMO) were rf sputtered onto glass substrates at room temperature. The films were studied as a function of oxygen volume percentage (OVP) ranging 1.4 - 10.0 % in the sputtering chamber. The thickness of the films found varying between 180 and 260 nm. The X-ray diffraction pattern showed the films are polycrystalline with the peaks corresponding to (222) and (400) planes and one among them showing as a preferential orientation. It is observed that the preferred orientation changes from (222) plane to (400) as the OVP increases from 1.4 to 10.0 %. The transmittance spectra were found to be in the range of 77 to 89 %. The optical band gap calculated from the absorption coefficient of transmittance spectra was around 3.9 eV. The negative sign of Hall coefficient confirmed the films were n-type conducting. The bulk resistivity increased from 2.26 × 10−3 to 4.08 × 10−1 Ω−cm for the increase in OVP from 1.4 to 4.1 %, and thereafter increased dramatically so as the Hall coefficients were not detectable. From the AFM morphologies it is evaluated that the RMS roughness of the films ranges from 0.9 to 3.2 nm.