bluuebunny/crossref_metadata_2025_split huggingface dataset:
Controlled Assemble and Microfabrication of Zeolite Nanoparticles on SiO2 Substrates for Potential Biosensor Applications
Authors: Ozturk Seckin , Kamisoglu Kubra , Turan Rasit , Akata Burcu 
Published: February 2009

AbstractZeolite nanoparticles were organized into functional entities on SiO2 substrates and microfabrication technique was tested to form patterns of zeolite nanoparticles on SiO2 using the electron beam lithography (EBL). The effect of different techniques for efficient zeolite assembly on the SiO2 substrates was investigated. For this purpose, three different assembly techniques were tested. The first two methods are spin-coating (SC) and ultrasound aided strong agitation (US) methods, which were tested using bare and silanized zeolite nanoparticles. The third technique is the manual assembly method, which was also investigated using bare zeolites. All methods were facile in terms of experimental approach. Full coverage of the substrate was obtained after all three methods, however strong agitation (US) leads to better organization of zeolite nanoparticles. Among all techniques, manual assembly method lead to the most organized zeolite nanoparticles with full coverage. Although strong agitation (US) also results in organized zeolite entities, it was not found to be a suitable technique for EBL studies. Using the manual assembly method, it was possible to form monolayers of zeolite nanoparticles on SiO2 and to make patterns of zeolite nanoparticles by EBL, which offers a simple technique to engineer the surfaces for immobilization of biomolecules.
Multiple Phage-Based Magnetoelastic Biosensors System for the Detection of Salmonella typhimurium and Bacillus anthracis Spores
Authors: Huang S. , Li S. , Yang H. , Johnson M. L. , Lakshmanan Ramji S , Chen I.-H. , Petrenko V. A. , Barbaree J. M. , Chin B. A. 
Published: February 2009

AbstractThis paper presents a multiple magnetoelastic (ME) biosensor system for in-situ detection of S. typhimurium and B. anthracis spores in a flowing bacterial/spore suspension (5 x 101 - 5 x 108 cfu/ml). The ME biosensor was formed by immobilizing filamentous phage (specific to each detection target) on the ME platforms. An alternating magnetic field was used to resonate the ME biosensor to determine its resonance frequency. When cells/spores are bound to a ME biosensor surface, the additional mass of the cells/spores causes a decrease in the resonance frequency of the biosensor. The detection system was composed of a control sensor, an E2 phage-based biosensor (specific to S. typhimurium) and a JRB7 phage-based biosensor (specific to B. anthracis spores). The frequency response curves of the ME biosensors as a function of exposure time were then measured and the detection limit of the ME biosensor was observed to be 5 x 103 cfu/ml. The results show that phage-based ME biosensors can detect multiple pathogens simultaneously and offer good performance, including good sensitivity and rapid detection.
Metal Hydride Fluidic Artificial Muscle Actuation System
Authors: Vanderhoff Alexandra , Kim Kwang 
Published: February 2009

AbstractThe study determines the feasibility of a new actuation system that couples a fluidic artificial muscle designed by Festo [1] with a metal hydride hydrogen compressor to create a compact, lightweight, noiseless system capable of high forces and smooth actuation. An initial model for the complete system is developed. The analysis is restricted in some aspects concerning the complexity of the hydriding/dehydriding chemical process of the system and the three-dimensional geometry of the reactor, but it provides a useful comparison to other actuation devices and clearly reveals the parameters necessary for optimization of the actuation system in future work. The system shows comparable work output and has the benefits of biological muscle-like properties [2] for use in robotic systems. When compared to other previously developed metal hydride actuation systems the potential for increasing the reaction kinetics and improving the overall power output of the system is revealed. A comparison of the system to common actuation devices, including a biological muscle, shows similar stress and strain relations, but a lower power and frequency range due to the slow actuation time. Improving the reaction kinetics of the system will be the first approach to enhancing the system, along with optimization of the mass and type of metal hydride used in the reactor to produce a full actuation stoke of the fluidic muscle while minimizing system weight.
Finite Element Analysis of Aluminum Nitride Bimorph Actuators – The Influence of Contact Geometry and Position
Authors: Pagán V. R. , Korakakis D 
Published: February 2009

AbstractIn this work, the results of 3-dimensional finite element analysis (FEA) of Aluminum Nitride (AlN) homogeneous bimorphs (d31 mode) are shown. The coupled-field FEA simulations were performed using the commercially available software tool ANSYS. The effect of altering the contact geometry and position on the displacement, electric field, stress, and strain distributions for the static case is reported.Piezoelectric beams are commonly used in microelectromechanical systems (MEMS) and also have many possible applications in smart sensor and actuator systems. For example, they have been used as the active element in microfluidic and microactuator MEMS devices. In the actuator mode, they employ the converse piezoelectric effect to couple electrical energy into mechanical deformation. Aluminum Nitride (AlN) based devices have attracted much interest because AlN is a piezoelectric material with high thermal stability, high dielectric strength, a reasonable electromechanical coupling coefficient, and a perfect compatibility with standard silicon processing techniques.
Sensing Shape Recovery using Conductivity Noise in Thin Films of NiTi Shape Memory Alloys
Authors: Chandni U. , Manjula M.V. , Ghosh Arindam , Vijaya H.S. , Mohan S. 
Published: February 2009

AbstractLow frequency fluctuations in the electrical resistivity, or noise, have been used as a sensitive tool to probe into the temperature driven martensite transition in dc magnetron sputtered thin films of nickel titanium shape-memory alloys. Even in the equilibrium or static case, the noise magnitude was more than nine orders of magnitude larger than conventional metallic thin films and had a characteristic dependence on temperature. We observe that the noise while the temperature is being ramped is far larger as compared to the equilibrium noise indicating the sensitivity of electrical resistivity to the nucleation and propagation of domains during the shape recovery. Further, the higher order statistics suggests the existence of long range correlations during the transition. This new characterization is based on the kinetics of disorder in the system and separate from existing techniques and can be integrated to many device applications of shape memory alloys for in-situ shape recovery sensing.
Multiscale Modeling of Dislocation Mechanisms in Nanoscale Multilayered Composites
Authors: Akasheh Firas , Zbib Hussein M , Akarapu Sreekanth , Overman Cory , Bahr David 
Published: February 2009

AbstractIt is well known that the mechanical behavior of nanoscale multilayered composites is strongly governed by single dislocation mechanisms and dislocation-interface interactions. Such interactions are complex and multiscale in nature. In this work, two such significant effects are modeled within the dislocation dynamics-continuum plasticity framework: elastic properties mismatch (Koehler image forces) and interface shearing in the case of weak interfaces. The superposition principle is used to introduce the stress fields due to both effects solved for by finite elements. The validation of both methodologies is presented. Furthermore, it was found that the layer-confined threading stress of a dislocation in hair-pin configuration increases if the layer is surrounded by layers made of a stiffer material and that this strengthening effect grows more significant as the layer thickness decreases. The observation made through molecular dynamics, that weak interfaces act as dislocation sinks, was also captured with our approach. A dislocation is attracted to the interface independent of its sign or character. Also the force increases sharply as the dislocation approaches the interface. These findings agree with published molecular dynamics simulations and dislocation-based equilibrium models of this type of interaction.
Optical Interferometric Biosensor with PMMA as Functional Layer
Authors: Wang Wenhui , Ma Xiaodong , Clarizia Lisa-Jo , Wang Xingwei , McDonald Melisenda 
Published: February 2009

Abstract
Silica-on-silicon label-free biosensor with PMMA (Poly(methyl methacrylate), as the functional layer was designed, fabricated, and tested. The sensor is based on Fabry Perot (FP) interferometry. Specific binding was tested with Human IgG and anti-Human IgG. Non-specific binding was tested with Human IgG and Mouse IgG. The testing results show that the sensor has a nearly six-fold greater response upon specific binding than upon non specific binding. Thermal and long term stability experiments show that the sensor is insensitive to the environment fluctuation. The fabrication process is simple without special surface treatment. In addition, this biosensor is inexpensive and easy to use.
Investigation of Steady-State and Time-dependent Luminescence Properties of Colloidal InGaP Quantum Dots
Authors: Chatterjee Subhasish , Valappil Nikesh V. , Menon Vinod M. 
Published: February 2009

Abstract
Quantum dots play a promising role in the development of novel optical and biosensing devices. In this study, we investigated steady state and time-dependent luminescence properties of InGaP/ZnS core/shell colloidal quantum dots in a solution phase at room temperature. The steady state experiments exhibited an emission maximum at 650 nm with full width at half maximum of ~ 85 nm, and strong first-excitonic absorption peak at 600 nm. The time-resolved luminescence measurements depicted a bi-exponential decay profile with lifetimes of τ1 ~ 47 ns and τ2 ~ 142 ns at the emission maximum. Additionally, luminescence quenching and lifetime reduction due to resonance energy transfer between the quantum dot and an absorber are demonstrated. Our results support the plausibility of using these InGaP quantum dots as an effective alternative to highly toxic conventional Cd or Pb based colloidal quantum dots for biological applications.
Amplified Fluorescence Turn-on Assay for Mercury(II) Based on Conjugated Polyfluorene Derivatives and Nanospheres
Authors: Wang Yusong , Liu Bin 
Published: February 2009

AbstractDetection of mercury with high sensitivity and selectivity constitutes a significant research concern. Here, we report an amplified fluorescence turn-on assay for mercury(II) with an improved performance. This sensing system takes advantage of optically amplifying fluorescent conjugated polyfluorene derivatives and DNA immobilized silica nanospheres (NSs) in addition to the specific thymine- mercury(II)-thymine(T- Hg2+-T) interaction. The employment of ion-specific T- Hg2+-T coordination increases the melting temperature (Tm) of the double-stranded DNA (dsDNA) on the hybridized NS surface. After thermal washing at 45 °C, the Hg2+ treated sample (dsDNA-NS) was effectively differentiated from that treated with nonspecific ions through monitoring fluorescence emission of fluorescein (Fl) labeled target DNA remained on the NS surface. Finally, a cationic conjugated polyfluorene derivative (CCP) was introduced to electrostatically associate with the DNA molecules on the NS surface, resulting in an amplified Fl signal via fluorescence resonance energy transfer (FRET) from the CCP to the dye molecule. In comparison with the use of Fl alone as a signal reporter, the presence of CCP significantly enhances the detection fluorescence intensity, reduces false-positive signal, and improves the detection selectivity for mercury(II). Further improvement in the probe design could yield more efficient metal ion sensors, which have the potential to be operated at room temperature and for the detection of other metal ions besides mercury(II).
Stochastic System Identification of the Compliance of Conducting Polymers
Authors: Pillai Priam Vasudevan , Hunter Ian W. 
Published: February 2009

AbstractConducting polymers such as polypyrrole, polythiophene and polyaniline are currently studied as novel biologically inspired actuators. The actuation mechanism of these materials depends upon the motion of ions in and out of the polymer film during electrochemical cycling. The diffusion of ions into the bulk of the film causes the dynamic mechanical compliance (or modulus) of the material to change during the actuation process. The mechanism of this change in compliance is not fully understood as it can depend on many different factors such as oxidation state, solvation of the film and the level of counter ion swelling. In-situ measurement of the dynamic compliance of polypyrrole as a function of charge is difficult since the compliance depends upon the excitation frequency as well as the electrochemical stimulus. Pytel et al [1] studied the effect of the changing elastic modulus in-situ at a fixed frequency. In this study we describe a technique to measure the compliance response of polypyrrole as a function of frequency and electrochemistry. A voltage input and a simultaneous stress input was applied to polypyrrole actuated in neat 1-butyl-3-methylimidazolium hexaflourophosphate. The stress input was a stochastic force with a bandwidth of 30 Hz and it allows us to compute the mechanical compliance transfer function of polypyrrole as function of the electrochemistry. Our studies show that the low frequency compliance changes by 50% as charge was injected into the polymer. The compliance changes reversibly as ions diffuse in and out of the film which indicates that the compliance depends upon the level of counter ion swelling.
Dielectric Response of Ceramic-Polymer Composite with High Permittivity
Authors: Shan Xiaobing , Zhang Lin , Wu Pei-xuan , Xu Canran , Cheng Zhong-Yang 
Published: February 2009

AbstractBased on solution casting method, a ceramic [CaCu3Ti4O12 (CCTO)]-Polymer [P(VDF-TrFE)] composite with flexibility has been synthesized and its dielectric response has been studied. The CCTO ceramic powders were prepared by traditional sintering method and were milled with a relative uniform size. The dielectric properties of these films with micro-size and nano-size CCTO particle, as well as different polymer matrixes were determined. The process was optimized by hot pressing and surface modification to achieve high dielectric constant. A dielectric constant about 175 for one layer composite with high flexibility using silane coupling agent was obtained at 1 kHz at room temperature.
Strain Sensitivity in Ion-implanted Polymers
Authors: Di Girolamo Giovanni , Massaro Marcello , Piscopiello Emanuela , Pesce Emanuela , Esposito Ciro , Tapfer Leander , Vittori Antisari Marco 
Published: February 2009

AbstractIon implantation process was used to fabricate ultra-thin conducting films in inert polymers and to tailor the surface electrical properties for strain gauge applications. To this aim, polycarbonate substrates were irradiated at room temperature with low energy Cu+ ions of 60 keV at 1 μA/cm2 and with doses ranging from 1×1016 to 1×1017 ions/cm2. XRD and TEM measurements on the nanocomposite surfaces demonstrated the spontaneous precipitation of Cu nanocrystals at 1×1016 ions/cm2 fluence. These nanocrystals were located at about 50 nm - 80 nm below the polymer surface in accordance with TRIM calculations. Optical absorption spectra exhibited a surface plasmon resonance (SPR) at 2 eV, in accordance with the formation of Cu nanoparticles. For doses of 5×1016 ions/cm2 the formation of a continuous nanocrystalline Cu subsurface film occurred and a well pronounced SPR peak was observed. Otherwise, for higher doses (1×1017 ions/cm2) a damaged and structurally disordered film was obtained and the SPR peak was smeared out. Electrical conductivity measurements clearly indicated a reduced electrical resistance for the samples implanted with a doses up to 5×1016 ions/cm2, whereas higher doses (1×1017 ions/cm2) resulted detrimental for the electrical properties, probably due to the radiation induced damage. The dependence of electrical resistance from surface load was evaluated during compression tests up to 3 MPa. A significant linear variation of the electrical resistance with the surface load was found and could be related to the changes in the spatial distribution of nanoparticles inside the copper film.
Characterization of the Charging and Long Term Performance of Cytop Electret Layers for MEMS Applications
Authors: Bartsch Ulrich , Gaspar Joao , Paul Oliver 
Published: February 2009

AbstractThis paper reports on the characterization of the charge stability of an amorphous fluoropolymer electret called Cytop. Cytop is a dissolved polymer material, compatible with standard micromachining fabrication technologies. In this study, Cytop layers are deposited and patterned on Pyrex and silicon substrates, followed by the electrical poling of the material by corona discharge using a customized charging station. The long-term performance of Cytop as an electret material is evaluated as a function of several relevant charging parameters. The results reveal highly stable layers, able to keep at least 92% of the initial charge 143 days after the corona charging stored at 23°C.
Liquid Crystal Nanoparticles- LCNANOP: A SONSII Collaborative Research Project
Authors: Goodby John William , Bates Martin , Saez Isabel , Gorecka Ewa , Kitzerow Heinz , Guillon Daniel , Donnio Bertrand , Serrano Jose-Luis , Deschenaux Robert 
Published: February 2009

AbstractLC-NANOP is an ESF EUROCORES SONS Collaborative Research Project that is addressing an innovative approach to self-organized nanostructures by combination of a variety of organic, inorganic and metal scaffolds with the unique self-organization properties of liquid crystals to obtain liquid crystal nano-particles. LC-NANOP is concerned with the synthesis, analysis, characterization, modeling and physico-chemical properties of super- and supra-molecular systems which are formed from a nano-particle as a central scaffold, surrounded by a layer of liquid crystal. The self-organization properties of the liquid crystal coating is the driving force leading to the self-assembly of the nano-particles into secondary or tertiary hierarchical structures, with emphasis on the systematic variation of nano-particle size, chirality, shape and functionality. This bottom-up approach to nano-structuring is very powerful as it combines the extraordinary variety of morphologies that liquid crystals present with the combination of functional entities, relevant for chemical, biological, optoelectronic, and photonic tasks, etc, to create ordered nano-structures that can be controlled by external stimuli.
Design and Fabrication of MEMS Piezoelectric Rotational Actuators
Authors: Gee Danny , Churaman Wayne , Currano Luke , Zakar Eugene 
Published: February 2009

AbstractAs Microelectromechanical Systems (MEMS) continue to mature and increase in design complexity, the need to exploit rotation in MEMS devices has become more apparent. An in-plane piezoelectric rotational actuator is proposed that provides free deflections on the order of 1.5° with applied biases of less than 35V and nanoampere currents. Moments up to 6×10−8 N·m, corresponding to forces of 125 μN, were measured using MEMS cantilever springs. The actuator utilizes the low-power, high-force characteristics of lead zirconate titanate and a coupled, dual offset-beam design to provide efficient rotational displacement. The resulting power consumption is three orders of magnitude less than current electrothermal rotational designs.
Fast and Controlled Integration of Carbon Nanotubes into Microstructures
Authors: Xu Wenjun , Ji Chang-Hyeon , Shafer Richard , Allen Mark 
Published: February 2009

AbstractIn this paper, we report the results of a rapid and room temperature integration approach for the selective and structured deposition of carbon nanotubes (CNTs) into three-dimensional microstructures. The approach exploits electrophoretic deposition (EPD) from an aqueous suspension of CNTs, together with suitably patterned and electrically-energized microstructure-bearing substrates. Uniform 2-D and 3-D micropatterns of CNTs on wafer scale have been achieved in less than 4 minutes with controllable thicknesses ranging from 133nm to several micrometers. Orientation of the deposited CNTs was observed in microstructures with certain dimensions. Surface hydrophobicity of the microstructures was found to be critical in achieving well-defined micropatterning of CNTs. A hydrophobic microstructure surface leads to the selective patterning profiles of CNTs, while a hydrophilic surface induces CNTs assembly over the entire microstructure, with resultant loss of selectivity. This approach can be further extended to fabricate 3-D micropatterns with multilayer materials on flexible substrate through the aid of transfer micromolding techniques.
A Novel Technique to Determine Elastic Constants of Thin Films
Authors: Martinschitz Klaus , Daniel Rostislav , Mitterer Christian , Jozef Keckes 
Published: February 2009

AbstractA new X-ray diffraction technique to determine elastic moduli of polycrystalline thin films deposited on monocrystalline substrates is demonstrated. The technique is based on the combination of sin2ψ and X-ray diffraction wafer curvature techniques which are used to characterize X-ray elastic strains and macroscopic stress in thin film. The strain measurements must be performed for various hkl reflections. The stresses are determined from the substrate curvature applying the Stoney's equation. The stress and strain values are used to calculate hkl reflection dependent X-ray elastic moduli. The mechanical elastic moduli can be then extrapolated from X-ray elastic moduli considering film macroscopic elastic anisotropy. The derived approach shows for which reflection and corresponding value of the X-ray anisotropic factor Γ the X-ray elastic moduli are equal to their mechanical counterparts in the case of fibre textured cubic polycrystalline aggregates. The approach is independent of the crystal elastic anisotropy and depends on the fibre texture type, the texture sharpness, the amount of randomly oriented crystallites and on the supposed grain interaction model. The new method is demonstrated on a fiber textured Cu thin film deposited on monocrystalline Si(100) substrate. The advantage of the new technique remains in the fact that moduli are determined non-destructively, using a static diffraction experiment and represent volume averaged quantities.