Ji Su NASA Langley Research Center
Li-Peng (Leo) Wang TricornTech Corporation
Yasubumi Furuya Hirosaki University
Susan Trolier-McKinstry The Pennsylvania State University
Jinsong Leng Harbin Institute of Technology
Monday PM, December 01, 2008
9:30 AM - **V1.1
Magnetomechanical Behavior of Iron-Gallium Alloys.
Jayasimha Atulasimha 1 , Alison Flatau 2 Show Abstract
1 Mechanical Engineering, Virginia Commonwealth Univ., Richmond, Virginia, United States, 2 Aerospace Engineering, University of Maryland, , College Park, Maryland, United States
10:00 AM - V1.2
Magnetostrictive Fe-Ga Wires with <100> Fiber Texture.
Shannon Farrell 1 , Patti Quigley 1 , Kyle Avery 1 , David Bligh 1 , Allison Nolting 1 , Timothy Hatchard 2 3 , Stephanie Flynn 2 , Richard Dunlap 2 3 Show Abstract
1 Dockyard Laboratory (Atlantic), Defence R&D Canada, Dartmouth, Nova Scotia, Canada, 2 Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada, 3 Institute for Research in Materials, Dalhousie University, Halifax, Nova Scotia, Canada
Fe-based alloys that combine toughness, formability, and mechanical strength with large magnetostriction are becoming increasingly more popular for use as magnetostrictives. In particular, Fe-Ga alloys, that exhibit approximately 20 % of the strain of traditional rare earth element-based giant magnetostrictive alloys (ex., Terfenol-D), are more robust, less expensive and more versatile (may be employed in tension). Fe-Ga magnetostrictives hold promise for energy harvesting applications that supplement battery power to alleviate strain put on current power storage media.Recently, low-cost processing approaches that produce textured thin bodies have engendered interest as a cost-effective approach for fabrication of Fe-Ga alloys. In particular, wire-forming methods that strictly control the solidification direction could lead to some measure of crystallographic texture control that is required for the development of large magnetostriction. The Taylor wire method for processing Fe-Ga alloys is similar to other non-equilibrium techniques (melt spinning, mechanical alloying, etc.) and is both interesting and promising for preparation of magnetostrictive wire. In this paper, the Taylor wire method will be discussed relative to other non-equilibrium techniques for production of textured Fe-Ga magnetostrictive alloys. The influence of parent material (form and composition), experimental drawing techniques and annealing/quench approaches to wire development will be discussed in terms of the resultant microstructure, crystallographic texture and magnetostriction. Results show that the Taylor wire method is an effective and versatile means to draw 1-3 mm diameter textured Fe-Ga wire. Modification of the parent material, temperature and drawing speed led to a variety of wire morphologies while quench conditions had a profound effect on texture development. In the absence of quenching, the 2-3 mm diameter wires showed no indication of a preferred fiber texture. Experimentation with quench conditions on texture development resulted with the production of a strong <100> fiber texture. Preliminary magnetostriction measurements, in the absence of prestress, indicated a maximum magnetostriction of ~160 ppm in a saturation field less than 0.2 Tesla. Magnetostriction values were similar to that expected for oriented Fe-Ga bulk materials with similar composition (up to 170 ppm strain along <100>) and are considered a significant strain for bulk polycrystalline alloys without a pre-stress or a stress-annealing treatment.
10:15 AM - V1.3
Rapid-solidified Magnetostrictive Polycrystalline Strong-Textured Galfenol (Fe-Ga) Alloy and its Applications for Micro Gas-valve.
Chihiro Saito 1 , Teiko Okazaki 2 , Yasubumi Furuya 3 Show Abstract
1 NJC Research Center , Namiki Precision Jewel Co.,Lt, Tokyo Japan, 2 Physical Science , Hirosaki University , Hirosaki Japan, 3 Intelligent Machines and System Engineering, Hirosaki University, Hirosaki Japan
Polycrystalline strong-textured Galfenol (Fe-Ga) alloy ribbon was fabricated by rapid-solidification melt-spinning method. Based on the characterization and discussion of the enhanced magnetostrion mechanism in the ribbon samples, the proto–type micro gas-valve was developed by using bimorph type Galfenol actuator. In recent, A.Clark found that the FeGa (Ga=17-19at%) single crystal showed considerably large magnetostriction of 400 ppm in low magnetic field. however, their fabrication process is not so easy and very expensive. As we know, the advantage of melt-spinning method is extension of solid solubility, grain refinement, reduction or elimination of micro-segregation, and formation of non-equilibrium metastable phase during one process. If the disordered A2 phase at high-temperature region can be frozen to room temperature without precipitating the ordered phases such as fcc ordered L12 as well as bcc ordered D03 phases, more large magnetostriction can be expected even in polycrystalline structure.The former part of this paper, the experimental results of the changes of magnetostriction in the rapid-solidified Fe-Ga system ribbons after heat treatment etc. are overviewed including their special unique microstructures. In fact, the melt-spun, rapid solidified Galfenol (Fe-Ga, (Ga=17-19at%) ribbon sample showed clear angular dependency on magnetostriction and large magnetostriction (=180-200ppm). This large magnetostriction is caused by non-precipitating of the ordered phases, the release of considerable large internal stresses in as-spun ribbon as well as the remained  oriented strong textures. These bring the materials improvement in strength toughness, hardness, wear resistance, heat resistance, and corrosion resistance and these seem worthy for engineering application for a actuator/sensor devices. Therefore, in the latter part of this paper, we will introduce the magnetically controllable micro gas-valve which is composed by the bimorph-type FeGa/Ni or FePd /Ni thin plates with the opposite value (FeGa(+), FePd(+), Ni(-)) of magnetostriction coefficient. Large displacement of opposite type could be obtained and their hysteresis curve changed depending on the volume fraction of the composite structure, The dynamic properties of the developed prototype magnetic micro-gas valve will be shown in more detail.
10:30 AM - V1.4
Development of Actuators and Motors Based on Giant Magnetostrictive Materials by a Modular Innovative Approach.
Nanjia Zhou 1 Show Abstract
1 , Pittsburg State University, Pittsburg, Kansas, United States
10:45 AM - V1.5
Development of Fe-Ga-Al(Galfenol) System Alloys with Large Magnetostriction and High Strength by Precipitation Hardening of the Dispersed Carbides.
Toshiya Takahashi 1 , Teiko Okazaki 1 , Yasubumi Furuya 1 Show Abstract
1 Science and Technology, Hirosaki university, Hirosaki Japan
While magnetostriction materials is observed in all ferromagnetic materials, new materials that exhibit large Joule magnetostriction, at low magnetic fields, are of interest for actual engineering use as acoustic sensors and generators, motors, actuator, damping devices, torque sensors, poisoning devices, transducer etc.. The earliest crystalline magnetostriction alloys used in transducer were Nickel based alloy (Ni-Co system alloys etc λmax=30ppm), and then, large magnetostriction values was obtained in RFe2 intermetallic compounds C15 structure(R=rare-earth elements) such as Terfenol-D alloy with a composition (Dy0.7Tb0.3) Fe2. These alloys show magnetostriction as large as 1000ppm. However, Dy and Tb are high costs, and C15 structure is brittleness, and high fields required for magnetic saturation. In recent work, Fe-Ga and Fe-Ga-Al alloy (Galfenol) produced by Clark et al. Fe-Ga system alloy have A2 structure with (1) high mechanical strength compared to Terfenol, (2) good ductility, (3) large magnetostriction value, (4) low saturation fields, (5) low material prices. However, a strength property is required for industrial application since various applications for actuator/sensor devices are required recently under severe environment, and component mass saving in the machinery etc. This study’s purpose is development of Fe-Ga-Al (Galfenol) system alloy with large magnetostriction and high strength by precipitation hardening effect of the dispersed carbides for application under severe environment and down-sizing. Three kinds of composition bulk samples with additional elements of Carbon, Zirconium, Niobium and Molybdenum to Fe-Ga-Al alloy, (Fe-Ga0.15-Al0.05) 99.0-X0.5-C0.5 (X=Zr, Nb, Mo) [at.%], were prepared. Those bulk samples were given heat treatment after the arc melting. Then, metallurgical characterizations, the magnetic characteristic, magnetostriction characteristic under a free-compressive stress condition and strength property were studied. As a result, (Fe-Ga0.15-Al0.05)99.0-Zr0.5-C0.5 [at.%] arc melted and annealed sample showed a maximum magnetostriction of λmax=90ppm and tensile stress σB=800MPa level, (Fe-Ga0.15-Al0.05)99.0-Nb0.5-C0.5 sample showed λmax=60ppm, σB=730MPa level, and (Fe-Ga0.15-Al0.05)99.0-Mo0.5-C0.5 sample showed λmax=90ppm and tensile stress σB=780MPa level. The compressive stress effect to magnetostriction in some alloy will also investigated. As magnetostrictive alloy with high tensile strength like an 800MPa was not yet reported up to the present, those materials developed here will have a potential of industrial applications such as actuator and sensor, for example, transducer, and force sensor under severe environment.
V2: Multfunctionals and Multiferroics
Monday PM, December 01, 2008
11:30 AM - V2.1
Investigation of Surface und Bulk Properties of Ni2MnGa via X-ray Absorption Spectroscopy (XAS) and X-ray Magnetic Circular Dichroism (XMCD).
M. Kallmayer 1 , P. Poersch 1 , T. Eichhorn 1 , G. Jakob 1 , H. Elmers 1 , C. Jenkins 2 , C. Felser 2 , R. Ramesh 3 , M. Huth 4 Show Abstract
1 Institut für Physik, Johannes Gutenberg-Universität Mainz, D-55128 Mainz Germany, 2 Institut für Anorganische und Analytische Chemie, Johannes Gutenberg-Universität Mainz, D-55128 Mainz Germany, 3 Department of Materials Science & Engineering, University of California, 94720 Berkeley, California, United States, 4 Physikalisches Institut, Goethe-Universität Frankfurt/Main, D-60438 Frankfurt/Main Germany
11:45 AM - V2.2
Growth and Structure of Epitaxial Ni-Mn-Ga Magnetic Shape Memory Films.
Gerhard Jakob 1 , Tobias Eichhorn 1 , Catherine Jenkins 1 2 3 , Peter Poersch 1 , Hans-Joachim Elmers 1 , Claudia Felser 2 , Ramamoorthy Ramesh 3 , Michael Huth 4 Show Abstract
1 Institute of Physics, University of Mainz, Mainz Germany, 2 Institute for Anorganic and Analytical Chemistry, University of Mainz, Mainz Germany, 3 Department of Materials Science & Engineering, University of California, Berkeley, California, United States, 4 Physics Institute, University of Frankfurt, Frankfurt Germany
New perspectives for magnetically induced actuation have been opened by the discovery of huge magnetic field induced strain in Ni2MnGa and related compounds. An alignment of the crystallographic axes with respect to the magnetic field direction is required in order to achieve maximum strain. As thin films are clamped to the substrate, epitaxial free standing films are finally required. We prepared Ni2MnGa films by sputtering from compound targets onto heated single crystalline substrates. As target materials we used the stoichiometric compound Ni2MnGa, delivering films with the martensite transition below room temperature, and a manganese rich target (Ni1.96Mn1.22Ga0.82). Sputtering from the latter resulted in martensite temperatures above 100°C. Epitaxial growth was achieved on a variety of substrates among them MgO(100), Al2O3(11-20), and BaF2(111) yielding films with different out of plane orientations switching from (100) to (110) to (111), respectively. In all cases four circle diffractometry proved the epitaxial in plane orientation. Temperature dependent x-ray diffraction was used to correlate the structural transition with anomalies in the temperature dependent magnetization and electrical transport. High substrate temperatures were beneficial in order to achieve high saturation magnetization. Four circle diffraction showed the films being in the martensite state at room temperature to possess a 7-fold superstructure. This is evident by superlattice lines in x-ray diffraction. The splitting in different variants can also be reconstructed from the intensity distribution in reciprocal space.With respect to free standing films we prepared highly textured films on water soluble single crystalline NaCl substrates. The in-plane orientation shows two epitaxial variants to coexist. Another way to free standing cantilevers was using a focussed ion beam system to cut free standing cantilevers. With optical microscopy and atomic force microscopy we observed the martensite twinning structure and its evolution during the transition. A partial magnetic field induced movement of the twin boundaries in the free standing cantilevers was observed using atomic force microscopy. Annealing experiments to release the blocking stress are in progress.
12:00 PM - V2.3
Magnetostriction in Fe-Co Binary Probed Using the Thin Film Composition Spread Technique.
Dwight Hunter 1 , R. Takahashi 1 , R. Suchoski 1 , J. Hattrick-Simpers 1 , S. Lofland 2 , M. Wuttig 1 , I. Takeuchi 1 Show Abstract
1 Department of Materials Science and Engineering, University of Maryland, College Park, Maryland, United States, 2 Department of Physics and Astronomy, Rowan University, Glassboro, New Jersey, United States
Previous investigation of the Fe-Ga binary system using the combinatorial approach showed that this technique can be used successfully to capture bulk trends of magnetostriction as a continuously changing function of composition . Here, the combinatorial technique was applied in the study of magnetostriction in Fe-Co thin film samples. The films with continuously varying composition were deposited at room temperature using a magnetron co-deposition system onto a micro-fabricated array of cantilevers on a Si wafer. Using an optical high-throughput measurement system, the change in magnetostriction across the Fe-Co phase diagram was obtained by systematically monitoring the deflection of each cantilever. The values of magnetostriction as a function of composition mirrors the bulk trend  in which the striction rises to two maxima, one at Fe50Co50 composition and the other spanning over the range between 19 and 27 atomic % of Fe. Microstructural analysis of synchrotron microdiffraction data indicates that the nanocrystal grains are randomly oriented polycrystalline films. In conjunction with annealing experiments,  the results suggest that the maximum striction observed in the Co-rich region might be due to a structural transition occurring close to the bcc/(hcp+fcc) phase boundary. It may be suspected that the peak of the magnetostriction in the Co-rich region is of similar origin as the one reported in Fe-Ga  where the maximum striction occurs at the bcc/DO3 and DO22/DO19/ L12/bcc boundaries. Results of mapping of magnetostriction for other systems will also be discussed.  Hattrick-Simpers, et al., “Combinatorial Investigation of Magnetostriction in Fe-Ga and Fe-Ga-Al”, to be published. Y. Masiyama, Sci. Rpts. of Tohoku Imperial U., 21, 394 (1932). M. Wuttig and L. Dai, Scripta Mat., to be published. G. Petculescua, et al., J. Appl. Phys. 97, 10M315 (2005).This project was funded by ONR-MURI N000140610530.
12:15 PM - V2.4
Magnetoelastic Material as a Biosensor for the Detection of Salmonella Typhimurium.
Ramji Lakshmanan 1 , Rajesh Guntupalli 4 1 , Shichu Huang 1 , Michael Johnson 1 , Leslie Mathison 1 , I-Hsuan Chen 3 , Valery Petrenko 2 , Zhong-Yang Cheng 1 , Bryan Chin 1 Show Abstract
1 Materials Engineering, Auburn University, Auburn, Alabama, United States, 4 Department of Anatomy, Physiology and Pharmacology, College of VetirinaryMedicine, Auburn University, Auburn, Alabama, United States, 3 Department of Biological Sciences, Auburn Unviersity, Auburn, Alabama, United States, 2 Department of Pathobiology, College of VetirinaryMedicine, Auburn University, Auburn, Alabama, United States
Magnetoelastic materials are amorphous, ferromagnetic alloys that usually include a combination of iron, nickel, molybdenum and boron. Magnetoelastic biosensors are mass sensitive devices comprised of a magnetoelastic material that serves as the transducer and bacteriophage as the bio-recognition element. By applying a time varying magnetic field, the magnetoelastic sensor thin films can be made to oscillate, with the fundamental resonant frequency of oscillations depends on the physical dimensions and properties of the material. The change in the resonance frequency of these mass based sensors can be used to evaluate the amount of analyte attached on the sensor surface. Filamentous bacteriophage specific to S. typhimurium was used as a bio-recognition element in order to ensure specific and selective binding of bacteria onto the sensor surface. The sensitivity of magnetoelastic materials is known to be dependent on the physical dimensions of the material. An increase in sensitivity from 159Hz/decade for a 2mm sensor to 770Hz/decade for a 1mm sensor and 1100Hz/decade for a 500micron sensor was observed. The sensors were characterized by scanning electron microscopy (SEM) analysis assayed biosensors to provide visual verification of frequency responses and an insight into the characteristics of the distribution of phage on the sensor surface. The magnetoelastic sensors immobilized with filamentous phage are suitable for specific and selective detection of target analyte in different media. Certain modifications to the measurement circuit resulted in better signal to noise ratios for sensors with smaller dimensions (L<1mm). This was achieved by tuning the circuit resonance close to that of the sensor. According to models and preliminary tests, this method was anticipated in about a 5 times increase in signals for a 200×40×6microns. This technique and further studies into the design and modification of the measurement circuits could yield better, sensitive responses for sensors with smaller dimensions. The magnetoelastic materials offer further advantages of potential miniaturization, contact-less nature and ease of operation.
V3: Sensors and Novel Processing
Frederic Dumas Bouchiat
Monday PM, December 01, 2008
2:30 PM - V3.1
Fabrication of Gas Nanosensors and Microsensors via Local Anodic Oxidation.
Braulio Archanjo 1 , Guilherme Silveira 1 , Alem-Mar Goncalves 1 , Diego Alves 1 , Andre Ferlauto 1 , Rodrigo Lacerda 1 , Bernardo Neves 1 Show Abstract
1 Physics, UFMG, Belo Horizonte Brazil
A new nanosensor, and microsensor, fabrication method, employing scanning probe microscopy (SPM) and local anodic oxidation (LAO), is demonstrated. Two different metal oxides (MoOx and TiOx) are employed as proof-of-concept materials, producing sensors with suitable response and sensitivities down to low concentrations of both reducing and oxidizing gases. Using conventional optical lithography, a thin metal track (Mo or Ti), with electrical contacts, is patterned. The active region of the sensor is directly fabricated onto the track via SPM-assisted LAO, creating nano- and micro-scale metal oxide (MoOx or TiOx) structures, finalizing the sensor fabrication. Two distinct LAO routes, a slow (conventional) and a fast (unusual) one, are employed to produce nano- and micro-sensors, respectively, which are tested at different temperatures using CO2 and H2 as test gases. Sensitivities down to ppm levels are demonstrated and, in principle, this methodology, including both slow and fast LAO routes, could be applied to any desired metal or metal alloys, further extending sensing possibilities of designed nano- and micro-devices. Finally, this novel sensor design and fabrication concept is proposed on a way that it could be readily implemented in conventional industrial microfabrication processes.
2:45 PM - V3.2
Controlled Assemble and Microfabrication of Zeolite Nanoparticles on SiO2 Substrates for Potential Biosensor Applications.
Seckin Ozturk 1 4 , Kubra Kamisoglu 2 , Rasit Turan 1 3 , Burcu Akata 1 4 Show Abstract
1 Micro and Nanotechnology, Middle East Technical University, Ankara Turkey, 4 Central Laboratory, Middle East Technical University, Ankara Turkey, 2 Chemical Engineering, Middle East Technical University, Ankara Turkey, 3 Physics, Middle East Technical University, Ankara Turkey
The development of new fabrication methods of organized nanoparticles on surfaces is important for electronic, optoelectronic, biological, and sensing applications. Usually chemical modification of SiO2 substrates with silanization techniques are used for potential biosensor and electronic applications where the targeted biological components are assembled onto the modified substrates. By combining silanization methods with microfabrication technology, surfaces can be patterned with functional groups, making it possible to attach cellular structures such as microtubules or cells in specific locations.In such components, there is a great need to increase the sensitivity level of the fabricated device, and one way to achieve this can be done via further assembly of nanoparticles on the modified substrates which show promising characteristics for the immobilization of the targeted chemical/biological compounds. Zeolite nanoparticles were shown to display good interactions with biological molecules. They have remarkably large surface area that is available for the immobilization of different molecules, tunable surface properties for controlled variation of surface charge and hydrophilic/hydrophobic characteristics. The zeolite monolayers are suggested to be used as ideal media for organizing semiconductor quantum dots and nonlinear optical molecules in uniform orientations.In the current study, zeolite nanoparticles were organized into functional entities on silanized SiO2 substrates and microfabricated using the electron beam lithography (EBL). The effect of different silanization compounds and different techniques for zeolite assembly on the silanized surfaces were investigated. For that purpose, different experimental procedures and parameters were investigated to efficiently assemble zeolite crystals on SiO2 substrates. Spin-coating (SC) and ultrasound aided strong agitation (US) methods were tested using silanized zeolite micron- and nanoparticles. Both methods were facile in terms of experimental approach. Full coverage of the substrate was obtained after both methods, however strong agitation (US) leads to better organization of zeolite micro and nanocrystals. Furthermore, the obtained zeolite micropatterns formed on the Si wafer substrate were more fully covered upon using the silanized zeolite nanoparticles.
3:00 PM - V3.3
Growth of One-Dimensional Metal Oxide Nanostructures and Nanowire-based Devices.
Sanjay Mathur 1 2 , Sven Barth 2 , Francisco Hernandez-Ramirez 3 , Joan Daniel Prades 3 , Albert Romano-Rodriguez 3 Show Abstract
1 Institute of Inorganic Chemistry, University of Cologne, Cologne Germany, 2 Department of CVD-Technology, Leibniz-Intitut für Neue Materialien, Saarbrücken Germany, 3 IN2UB and EME-Department of Electronics, University of Barcelona, Barcelona Spain
Monday 12/1New Presenter V3.3 @ 2:00 PMGrowth of One-Dimensional Metal Oxide Nanostructures and Nanowire-based Devices. Sven Barth
3:15 PM - V3.4
Catalyst-based Solid State Sensor Schemes for Wide Temperature Range Hydrogen Leak Detection.
Claudiu Muntele 1 , Sandra Sadate 1 , Malek Abunaemeh 1 , Cydale Smith 1 , Daniel McElhaney 1 , Jonathan Gardner 2 , Abdalla Elsamadicy 2 , Daryush Ila 1 Show Abstract
1 , Alabama A&M University, Normal, Alabama, United States, 2 , University of Alabama in Huntsville, Huntsville, Alabama, United States
Silicon carbide based non-linear electronics devices (MOSFET, metal-semiconductor, or p-n junctions) are promising candidates for hydrogen detection schemes if used in conjunction with a good catalyst from the platinum group of elements. For the past decade, the emphasis was mostly on high temperature applications in the automotive (for hydrogen-fueled engines) and in the aerospace industry (for jet engines), but now the focus is broadening to include auxiliary systems such as storage tanks, fuel lines, fuel production systems, all operating in a wide range of temperatures, from ambiental (RT – room temperature) to cryogenic. Hydrazine is a particular hydrogen-containing chemical of interest, as is widely used as a fuel in rocket propulsion systems, fuel cells, pesticides, dyes etc. It is also a neurotoxin, causing damage to most organs in the human body. Therefore sensors able to detect hydrazine leaks at sub-ppm level at RT (anhydrous hydrazine melts at 2 °C and evaporates at 113.5 °C) and in a wide humidity range (hydrazine is fully miscible in water) are highly desirable. Sensitive analytical methods have been developed for the determination of hydrazine in air, water, food, drugs, and cigarette smoke. However, all these methods involve complicated analytical instrumentation generally available only in a specialized laboratory environment. From the variety of detection schemes available for portable devices, two seem of being the most commonly used: color-changing paper readers (e. g. MDA 7100 and newer) and fuel cell-based detectors (e. g. products of PureAire Monitoring Systems, Inc.).While high temperature operation is completely characterized for catalyst-based sensors, low temperature operation presents catalyst-related challenges (such as catalyst “poisoning” due to surface passivation), some of them little understood, some well characterized but without a functional solution. In this paper we are addressing, on a comparative basis, solutions to challenges associated with using catalysts as active agents in capacitive, non-linear (p-n structures), and linear (resistors) hydrazine and hydrogen detection schemes in a temperature range from 77 K (liquid nitrogen) to 400 K. We used e-beam deposition and low energy ion implantation for preparing our samples, and current vs. voltage electrical measurements to monitor the devices’ response to hydrazine and hydrogen. Raman spectroscopy was used for investigating the surface chemistry of the devices exposed to hydrazine at various temperatures.
3:30 PM - **V3.5
Guided Self-assembly of Nanostructured Titanium Oxide.
Baoxiang Wang 1 , Min Zhou 1 , Zbigniew Rozynek 1 , Jon Otto Fossum 1 Show Abstract
1 Department of Physics, Norwegian University of Science and Technology, Trondheim Norway
Electrorheological fluid (ERF), as a smart materials, are suspensions of polarized dielectric particles in a nonconducting liquid and exhibit drastic changes in their rheological properties, which include a large increase in apparent viscosity and the formation of reversible suspension microstructures. Application of an electric field can induce polarization of the suspended particles. As a result, a chainlike structure can be formed along the electric field direction in a few milliseconds.1-5 So the shape and surface of particle may play a very important role to for the assembly of chainlike structure. Titanium oxide nanowires and nanorods are synthesized by a simple wet chemical method and characterized by the SAXS, AFM, and thermal analysis. Firstly, Tetrabutyl titanate (TBT) precursor was added to ethylene glycol (EG) and heated to form TiOx nanowires.6 Furthermore, TiOx nanorods with high rough surface can be got by hydrolysis of TBT with the help of Cethyl-Trimethyl-Ammonium Bromide (CTAB) as surfactant in EG solution. AFM results show that the nanowires are easy aggregating each other to form boudles and high rough TiOx nanorods is formed by the self-assembly of TiOx nanospheres. The electrorheological (ER) effect is investigated with the suspension of titanium oxide nanowires or nanorods dispersed in silicone oil. Oil suspensions of titanium oxide nanowires or nanorods exhibit a dramatic assembly when submitted to a strong DC electric field and aggregate to forms chains like structures along the direction of applied electric field. We have used small angle X-ray scattering to get insight into the nature of the titanium oxide nanowires and nanorods in the chains. The two-dimensional SAXS images from chains of anisotropic shape particles exhibit a marked anisotropy SAXS patterns, reflecting the preferential guided selfassembly of the particles in the field.
4:30 PM - **V3.6
Development Of Multifunctional Structural Material Systems By Innovative Design And Processing.
Hiroshi Asanuma 1 Show Abstract
1 Mechanical Engineering Course, Chiba University, Chiba-shi Japan
Innovative designing concept and fabrication process to realize smart and robust structural material systems, (1) without using sophisticated functional materials (Type A) and (2) using them in a metallic matrix as a protective environment (Type B), respectively, are introduced in this paper. The Type A route can be explained as follows: There exist a couple of competitive structural materials which normally compete with each other because of their similar and high mechanical properties, and they tend to have another property which is different from each other or opposite among them. So if they are combined together to make a composite, the similar property, normally high mechanical property, can be maintained, and the other dissimilar property conflicts with each other, which will successfully generate a functional property without using any sophisticated functional materials. As successful examples of this type, Ti fiber/Al multifunctional composites and CFRP/aluminum active laminates have been developed. The second one (Type B) can be realized by embedding fragile functional fibers in an aluminum matrix by the interphase forming bonding method developed by the author, and piezoelectric ceramic fiber/aluminum composites and optical fiber sensor/aluminum composites have been successfully fabricated.
5:00 PM - V3.7
Nanoimprinting using Anodic Porous Alumina as a Mold.
Takashi Yanagishita 1 2 , Takahide Endo 1 , Kazuyuki Nishio 1 2 , Hideki Masuda 1 2 Show Abstract
1 , Tokyo Metropolitan Univ., Tokyo Japan, 2 , KAST, Kanagawa Japan
The preparation of nanometer scale structures has attracted much attention due to the utilization for various types of functional application fields. Nanoimprinting is a promising technique for the high-throughput preparation of ordered fine structures on a substrate. The molds used for nanoimprinting are usually fabricated by a combination of electron beam lithography and the dry etching. However, in these processes, it is difficult to prepare the molds with a pattern of high aspect ratios or large sizes. In our previous reports, we described the fabrication of polymer nanostructures with high aspect ratios by nanoimprinting using anodic porous alumina as a mold [1-4]. Anodic porous alumina, which is formed by anodization of Al in an acidic solution, is a promising for the molds to prepare the nanometer-scale structures with high aspect ratios and large sizes, because of its unique geometrical structures . In the present report, we describe the preparation of ordered structures of inorganic materials with high aspect ratios by nanoimprinting using anodic porous alumina as a mold. In the experiment, ordered silica pillar arrays were prepared by nanoimprinting using a spin-on-glass solution. The diameter and height of silica pillars could be controlled by changing the geometrical structures of anodic porous alumina molds. The obtained silica nanopillar arrays will be applied to various types of functional nanodevices. H. Masuda et al., Appl. Phys. Lett., 78, 826 (2001).  T. Yanagishita et al., Jpn. J. Appl. Phys. 45, L804 (2006).  T. Yanagishita et al., Vac. Sci. Technol. B, 25, L35 (2007).  T. Yanagishita et al., Appl. Phys. Exp., 1, 067004 (2008).  H. Masuda et al., Science, 268, 1466 (1995).
5:15 PM - V3.8
Multiple Duplication of Electroformed Nano-Ni Stamps from Si Mother Mold.
Si-Hyeong Cho 1 , Jung-Ki Lee 1 , Jung-Ho Seo 1 , Hyun-Woo Lim 2 , Jin-Goo Park 1 2 Show Abstract
1 Bio-Nano Technology, Hanyang University, Ansan city, Gyeonggi-do, Korea (the Republic of), 2 Materials Engineering, Hanyang University, Ansan city, Gyeonggi-do, Korea (the Republic of)
Nanoimprint lithography (NIL) is an alternative lithographic method that offers a sub-10 nm feature size, high throughput, and low cost. It requires a mold which has a low fabrication cost and long life time. A stamp is the material with various patterns to transfer on the plastic substrate. Materials such as Si, quartz, plastic and Ni have been widely used for micron or sub micron sized stamp fabrication depending on its pattern size and application. Si and quartz are very easy to be broken, and plastic can be deformed easily during process. However, Ni has high enough hardness and life time as a mold material and can be fabricated from on Si micro to nano sized molds with a seed layer by a simple Ni electro-deposition. After electro-deposition, the sample is usually dipped in KOH solution to remove Si from Ni. The consumption of Si mold is necessary step to produce a Ni stamp.In this study, a method was developed to fabricate a Ni stamp without the consumption of Si stamp. Vapor SAM (self assembled monolayer) method was used to deposit hydrophobic layer on Si mold. A low surface energy release layer on stamp surfaces not only helps to improve imprint qualities, but it also increases the stamp lifetime significantly by preventing surface contamination. Hydrophobic layer, which has a low surface energy, makes possible to separate Ni from Si substrate without causing any damages on Si stamp. The characteristics of deposited hydrophobic layer were analyzed by measurements of the contact angle, its hysteresis, surface energy, thickness and lateral friction force. The stiction of Ni on Si mold was observed when the separation of Ni from Si was tried without the SAM deposition.The multiple duplication of Ni stamps has been successfully developed without disposing costly Si mother stamp. Duplicated patterns on Ni stamp showed the same patterns as on Si mother mold when they were observed with optical microscope, FE-SEM, and AFM (atomic force microscope).
5:30 PM - V3.9
A Novel Technique for the Nano-fabrication of Diamond Stamp Structures.
Warren McKenzie 1 , Graham Cross 1 , John Pethica 1 Show Abstract
1 CRANN, Trinity College Dublin, Dublin Ireland
A novel process for the fabrication of complex nano–scaled patterns on flat single crystal diamond surfaces has been developed*. These patterned surfaces could potentially be used as a stamp for the highly reproducible fabrication of nano-electronic circuits via the established techniques nano-imprint lithography or hot embossing. This process utilizes facilities common to most microelectronic laboratories and, on-average, takes approximately one hour to reproduce a complex nanoscaled pattern over an area ~5000µm2. Given the simplicity and efficiency of the process, this technique could easily be adapted for the fabrication of nano-scaled patterns over larger (mm – cm) scaled diamond surfaces.*Note to examiners or conference organizers - this abstract is purposely vague and withholds most of the critical information relating to the subject. This technique will be the subject of a patent application to be filed the week of 30th June 2008. After this time the abstract (and presentation) can be amended to include all relevant details .
5:45 PM - V3.10
Fabrication of PbTe and PbTe@Pb(OH)2 Core-shell Nanocubes and Their Self-Assembly.
Jun Zhang 1 , Jiye Fang 1 Show Abstract
1 , State University of New York at Binghamton, Binghamton, New York, United States
Self-assembly of nanocrystals has attracted increasing attention. However, the fabrication of nanocubic building-block-containing assembly pattern has remained a challenge and requires a precise control in both the size and shape. For identical spheres, both the hexagonal close-packing and cubic close-packing give the highest packing efficiency, 74.04%, whereas nanocrystals as the building blocks could be present in various shapes such as octahedrons and cubes. The preparation of an assembly containing nanocubes can achieve a packing density of as high as 100% if the interparticle spacing is neglected. In this presentation, we report our recent progress in synthesis of PbTe nanocubes and PbTe@Pb(OH)2 core-shell nanocubes through a wet-chemical processing approach. We also present the structural investigation on these self-assembled patterns as well as various characterizations we have performed, including XRD, TEM, and SAXRD. Optical investigation will also be discussed.
V4: Poster Session I
Tuesday AM, December 02, 2008
Exhibition Hall D (Hynes)
9:00 PM - V4.1
X-Ray-Induced Wettability Modification.
Yong Bum Kwon 1 , Byung Mook Weon 1 , Kyu Hwang Won 1 , Jung Ho Je 1 , Yeukuang Hwu 2 , Giorgio Margaritondo 3 Show Abstract
1 , X-ray Imaging Center, Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang Korea (the Republic of), 2 , Institute of Physics, Academia sinica, Taipei Taiwan, 3 , School of Basic Sciences, Ecole Polytechnique Fádárale de Lausanne, Lausanne Switzerland
Light-induced wettability modification is an important surface phenomenon throughout nature and technology (1). In particular ultra violet (UV)-induced wettability modification of inorganic materials such as ZnO and TiO2 has been widely studied (2, 3) owing to advantages of remote controllability and individual addressability. However UV-induced wettability modification remains a challenge for applications because of long recovery time from slow chemical kinetics, and thus has a limitation to UV-specific materials. For fast response or recovery time, charging-induced wetting using an e-beam source in vacuum was suggested as a possible trigger source for inorganic materials (4). In this study we suggest a fast, reversible strategy that is adoptable in air by using an irradiation of X-rays, universally ionizing inorganic materials. We reveal that X-ray-induced wettability modification occurs in a variety of inorganic materials, for instance, Si, ZnO, ZnS, TiN, SrTiO3, and Al2O3. In particular a rapid response dynamics of ~10 min (e.g., ZnS, ZnO, and SrTiO3) is visible and is attributed to a fast charging by X-ray irradiation. Meanwhile a fast recovery time of ~50 min (e.g., ZnO) is obtained owing to discharging mechanism, whereas that is very slow (several tens of hours) for UV-induced transition. Contact angle and surface potential measurements show detailed dynamics and localization of charging and discharging by X-ray irradiation. We suggest a feasible wettability modification using X-ray-induced charging to extend the applications of inorganic materials.References:(1) R. Wang, et al. Nature 388, 431 (1997).(2) R. Sun, et al. J. Phys. Chem. B 105, 1984 (2001).(3) X. Feng, et al. J. Am. Chem. Soc. 126, 62 (2004).(4) D. Aronov, et al. Appl. Phys. Lett. 90, 104104 (2007).
9:00 PM - V4.10
Indium Tin Zinc Oxides Composites Thin Films for Multifunctional Sensors.
Rajini Konda 1 , Alex Lee 2 , Rajeh Mundle 1 , Olu Bamiduro 1 , Gilbert Kogo 1 , Ozgul Yasar 1 , Messaoud Bahoura 1 , Frances Williams 1 , Aswini Pradhan 1 Show Abstract
1 Center for Materials Research, Norfolk State University, Norfolk, Virginia, United States, 2 Chemical Engineering, Virginia Tech, Blacksburg, Virginia, United States
9:00 PM - V4.11
Technique for High-resolution Imaging of Local Lattice Distortion in LSIs by Forbidden Reflection-based Dark-field Transmission Electron Microscopy.
Shiro Takeno 1 , Mitsuo Koike 1 , Hiroki Tanaka 1 , Teruyuki Kinno 1 , Mitsuhiro Tomita 1 , Fumihiko Uesugi 2 Show Abstract
1 , Toshiba Corporation, Yokohama Japan, 2 , Toshiba Nanoanalysis Corporation, Yokohama Japan
Techniques for precise measurement of local stress (or lattice distortion) in LSIs or nanoscale systems are indispensable for investigating failure mechanisms and significant for the development of reliable devices. In silicon crystal, critical resolved shear stress is fairly low, i.e., around a few MPa for a certain glide system , and imaging of stress field at a microscopic level in LSIs, especially in interfacial regions, has been an important research target. In previous transmission electron microscopy (TEM)-based imaging techniques, diffraction contrast analysis of bright- and/or dark-field images has been tried for stress analysis [2-4]. These studies were based on two-beam conditions that are assumed to be a cause of insufficient effective spatial resolution since the conditions require a high-angle tilting operation to the interfaces of interest in LSIs. (Effective spatial resolution represents the practical resolution for the tilted conditions.) Recently, we proposed a straightforward and sensitive imaging technique for local lattice distortion in an area of hundreds of nanometers in conjunction with the stress relaxation during the TEM specimen foil preparation for Si and related crystals [5,6]. The proposed technique is based on the observation of dark-field image (DFI) formed by a forbidden reflection (FR) under a specific beam incidence condition. (We abbreviate our proposed method to FR-DFI.) The relaxation causes the local change of deviation parameter for a certain Bragg reflection sensitively , and FR-DFI is based on this characteristic phenomenon. We showed that the current best effective spatial resolution of FR-DFI was about 5.2 nm. In order to improve the effective spatial resolution in FR-DFI, we investigated the intensity distribution of 002-DFIs for SiGe/Si system under several experimental conditions such as TEM specimen thickness, incidence beam direction, and acceleration voltage of electron beam. In this presentation, we will show that the intensity distribution of 002-DFI is sensitively influenced owing to a subtle change of the thickness of TEM specimen foil, and the effective spatial resolution of less than 5 nm can be achieved for Si crystal by precise thickness control of the specimen foil. Appropriate experimental parameters for high-resolution FR-DFI observation and artifacts induced under the critical experimental condition as well as the basic concept of FR-DFI will be discussed in detail. (References) S. M. Hu, J. Appl. Phys. 70 (1991) R53 D. D. Perovic et al., Philos. Mag. A64 (1991) 1 S. McKernan et al., Inst. Phys. Conf. Ser. 87 (1987) 201 J. Demarest et al., Appl. Phys. Lett. 77 (2000) 412 S. Takeno et al., Proc. 16th International Microscopy Congress (2006) 1480 S. Takeno et al., Surface and Interface Analysis (to be published) U. Bangert et al., Philos. Mag. A59 (1989) 629
9:00 PM - V4.12
Hydrogen Sensing Properties in PdO Sputtered Thin Films.
Young Taek Lee 1 2 , Eunsong–yi Lee 2 , Da Hye Kim 2 , Kye Jin Jeon 2 , Wooyoung Lee 1 2 Show Abstract
1 Nanomedical National Core Research Center, Yonsei University , Seoul Korea (the Republic of), 2 Department of Materials Science and Engineering, Yonsei University, Seoul Korea (the Republic of)
9:00 PM - V4.14
Hysteretic Resistance in Hydrogenated Pd Thin Films.
Eunsong-yi Lee 1 , Jun Min Lee 1 , Won Jin Choi 1 , Kye Jin Jeon 1 , Wooyoung Lee 1 Show Abstract
1 Department of Materials Science and Engineering, Yonsei University , Seoul Korea (the Republic of)
9:00 PM - V4.15
In-Situ Characterization of Polymer films and Their Interactions with Environmental and Biological Substances by Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D).
Archana Jaiswal 1 Show Abstract
1 , Q-Sense, Inc., Gleb Burnie, Maryland, United States
Recently, there has been an increasing demand of analytical tools for the characterization of interaction between biological molecules and polymeric materials due to its broad scientific interest and great commercial importance. Applications and products developed from this field of study include medical implants, drug delivery formulations, biosensors and biofilms. Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), a nanomechanical acoustic-based analytical technique, is a novel tool to analyze binding events and reactions occurring at a wide variety of biointerfaces. With QCM-D, simultaneous measurement of resonance frequency change (ΔF) and energy dissipation change(ΔD) is performed by periodically switching off the driving power of oscillation of the sensor crystal and recording the decay of damped oscillation as the adsorption and/or structural changes takes place at sensor crystal surface. While change in frequency provides information about mass changes, dissipation (D) provides structural information about the viscoelastic properties of adsorbed films in real time.In the present poster we show the real-time monitoring of hydration/solvation of polymer films in both liquid and gaseous environments, study of crosslinking of polymeric films, characterization of the incorporation and binding of proteins (and other molecules) to polymers, and characterization of polyelectrolyte multilayers at any time during their build-up process.
9:00 PM - V4.16
Multiple Phage-Based Magnetoelastic Biosensors System for the Detection of Salmonella typhimurium and Bacillus anthracis Spores.
Shichu Huang 1 , Hong Yang 1 , Ramji Lakshmanan 1 , Michael Johnson 1 , I-suan Chen 2 , Howard Wikle 1 , Valery Petrenko 3 , James Barbaree 2 , Bryan Chin 1 Show Abstract
1 Materials Engineering, Auburn University, Auburn, Alabama, United States, 2 Dept. of Biological Sciences, Auburn University, Auburn, Alabama, United States, 3 Dept. of Pathobiology, Auburn University, Auburn, Alabama, United States
The paper presented a multiple magnetoelastic (ME) biosensors system for in-situ detection of S. typhimurium and B. anthracis spores in a flowing bacterial/spore suspension (5×101 - 5×108 cfu/ml). ME biosensor was formed by immobilizing filamentous phage (specific to each detection target) on the ME platforms (2x0.4x0.015mm). 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 spores causes a decrease in the resonance frequency of the sensor. The detection system was composed of a control sensor, an E2 phage sensor (specific to S. typhimurium) and a JRB7 phage sensor (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 limits of the ME biosensor was observed to be 5x103 cfu/ml. The results show that the phage-based ME biosensors can detect multiple pathogens simultaneously and offer good performance, including good sensitivity and rapid detection. Additionally, the specificity of this detection system was evaluated by exposure to a flowing mixture of S. typhimurium in the presence of extraneous foodborne pathogens. The E2 phage biosensor was observed to respond to S. typhimurium only, verifying the high specificity of the phage immobilized biosensor.
9:00 PM - V4.17
Wireless Remote 2-D Strain Sensor using SAW Delay Line.
Toru Nomura 1 , Atushi Saitoh 2 Show Abstract
1 Faculty of Engineering, Shibaura Institute of Technology, Tokyo Japan, 2 , Shibaura Institute of Technology, Tokyo Japan
Surface acoustic wave (SAW) devices offer many attractive features for applications as chemical and physical sensors. In this paper, we present a novel SAW strain sensor for radio frequency identification (RF-ID) and structural health monitoring. The strain SAW sensor is passive sensor that can be attached to a structure and then remotely interrogated though a wireless interfaces. SAW delay lines have been designed for measurement of strain. The changes in the structure results in a phase change of the SAW delay lines. Two delay lines were used to measure the two-dimensional strain. The two delay lines crossed each other at right angles on a single substrate. The phase change of the delay lines were measured as the sensor response.Moreover, the SAW sensor requires no internal power supply to operate. A wireless sensing system is also proposed for effective operation of the strain sensor. In addition, an electronic system for accurately measuring the phase characteristics of the signal wave from the passive strain sensor is proposed.The two SAW delay lines that cross each other at right angles with the central frequency of 50 MHz were fabricated on a 128 YX LiNbO3 substrate. Experimental results showed that the phase varied in proportion to the strain applied to the surface. The results also showed that the passive sensor was very effective to measure the strain in a wireless mode and it was found that the system is very suitable to health and safety monitoring of structure.
9:00 PM - V4.18
The Transient Response Modification of a MIS Hydrogen Sensor with Excimer Laser Processing.
Linfeng Zhang 1 , Sachin Thanawala 2 , Ratna Naik 3 , Gregory Auner 2 Show Abstract
1 Electrical Engineering, University of Bridgeport, Bridgeport, Connecticut, United States, 2 Electrical and Computer Engineering, Wayne State University, Detroit, Michigan, United States, 3 Physics and Astronomy, Wayne State University, Detroit, Michigan, United States
Metal-insulator-semiconductor (MIS) type sensors have been developed for several decades and they are sensitive to hydrogen even low as 10 ppm. This type sensor works as a capacitor, the Capacitance-Voltage (CV) curve would shift in the presence of hydrogen. At a constant capacitance, the voltage shift is a function of hydrogen concentration. Usually, this type sensor is operated above room temperature for a quick response. However, a reverse transient response is observed at high temperature (more than 100 oC). To minimize this reverse transient is a challenge. In this study, a sensor with Pd-Ni/AlN/n-Si(111) structure was prepared through magnetron sputtering chamber and the Plasma Source Molecular Beam Epitaxy (PSMBE). Surface segregation of Ni was found and Al was oxidized on the surface of AlN through X-ray Photoelectron Spectroscopy (XPS). In the hydrogen response testing, no reverse transient and baseline shift was observed at 80 oC. However, reverse transient was obvious and always there at 120 oC. This phenomenon is most probably related to some slow mobility charges in AlN. An excimer laser was used to modify the metal alloy and metal/insulator interface. Arraies of micro-bumps (radius: 5 μm) were created on the device surface. Through the testing, the reverse transient disappeared except in the first hydrogen response from a refreshed sensor. Thus, the surface modification with excimer laser can improve the sensor response time. The mechanism of the effect of this laser processing on the sensor performance was discussed further.
9:00 PM - V4.19
Conformable Passive Sensors for Wireless Structural Health Monitoring.
Sharavanan Balasubramaniam 1 , Tarisha Mistry 2 , Niwat Angkawisittpan 2 , Jung-Rae Park 1 , Alkim Akyurtlu 2 , Tenneti Rao 2 , Ramaswamy Nagarajan 1 Show Abstract
1 Plastics Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, United States, 2 Electrical & Computer Engineering, University of Massachusetts Lowell, Rehovot Israel
Currently, sensors for damage detection and non-destructive evaluation are fabricated using techniques like photolithography, inkjet printing or thermal spray and laser micromachining. The commercial success of these sensors, however, depends on their performance and ease of manufacture. The application of conductive inks and pastes for wireless sensing with simple fabrication methods is an attractive proposition. Silver inks based on flaky powder and nanoparticles are very popular in the area of printed electronics due to their high electrical conductivity and environmental stability. Fabrication of sensors using binder-free inks, which can form pure metallic patterns (without leaving any non-metallic residue), will lead to devices with high quality factors and improved detection capabilities. Here, we present a novel binder-free, electrically conductive formulation that can be screen-printed to fabricate conformal sensors for wireless interrogation. On curing, these particulate metal pastes transform into continuous, conductive patterns at temperatures as low as 135C. Resonant inductor-interdigital capacitor circuits are screen-printed on polyester films to yield flexible LC sensors. The RF response of the LC sensors is measured using a vector network analyzer. Physical deformation or fracture of the conductive elements results in a detectable change in the RF response. The development and characterization of the conductive patterns and sensors as well as their wireless interrogation will be presented.
9:00 PM - V4.20
Study the Conduction Mechanism and the Electrical Response of Strained Nano-thin 3C-SiC Films on Si used as Surface Sensors.
Ronak Rahimi 1 , Chris Miller 1 , Alan Munger 1 , Srikanth Raghavan 1 , Charter Stinespring 2 , Dimitris Korakakis 1 Show Abstract
1 Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, West Virginia, United States, 2 Chemical Engineering, West Virginia University, Morgantown, West Virginia, United States
Various superior properties of SiC such as high thermal conductivity, chemical and thermal stability and mechanical robustness provide the basis for electronic and MEMS devices of novel design . This work evaluates heterostructures that consist of a few nanometers-thin 3C-SiC films on silicon substrates. Nano-thin SiC films differ significantly in their electrical behavior compared to the bulk material , a finding that gives rise to a potential use of these films as surface sensors. To gain a better understanding of the effect of surface states on the electrical response of thin, strained films, these structures have been examined under variable conditions. Gas source molecular beam epitaxy has been used to grow nano-thin 3C-SiC layers on silicon substrates. Reflection high-energy electron diffraction patterns obtained from several 3C-SiC films indicate that these films are strained nearly 3% relative to the SiC lattice constant. Al, Cr and Pt contacts to a nano-thin film 3C-SiC were deposited and characterized. I-V measurements of the strained nano-thin films demonstrate metal-semiconductor-metal characteristics. Band offsets due to biaxial tensile strain introduced within the 3C-SiC films were calculated and band diagram incorporating strain effects have been simulated. Electron affinity of 3C-SiC has been extracted from experimental I-V curves and is in good agreement with the value which has been calculated for a strained 3C-SiC film . Eventually, on the basis of experimental and simulation results, an empirical model for the current transport has been proposed. Fabricated devices have been characterized in a controlled environment under hydrogen flow and also in a reactive ambient, while heating the sample and oxidizing the surface, to investigate the effects of the environment on the surface states. Observed changes in I-V characteristics suggest that these surface-like, nano-thin films can be used as surface sensors. Azevedo R G, Jones D G, Jog A V, Jamshidi B, Myers D R, Li Chen, Xiao-an Fu, Mehregany M, Wijesundara M B J and Pisano A P 2007 IEEE Sens. Jour. 7 568  Hsieh WT, Fang Y K, Wu K H, Lee W J, Ho J J and Ho C W IEEE Trans. Electron Devices 2001 48 801-803  Choyke W J, Feng Z C and Powell J A Jour. of Appl. Phys 1988 64 3163
9:00 PM - V4.21
Carbon Nanofiber-Network Sensor Films for Strain Measurement in Composites.
Nguyen Nguyen 1 , SangYoon Lee 1 , Nikhil Gupta 1 Show Abstract
1 Mechanical and Aerospace Engineering, Polytechnic University, Brooklyn, New York, United States
Conducting sensor films and coatings, comprising carbon nanofibers in epoxy resin, are developed for structural health monitoring of materials. The carbon nanofibers are present as a random network in these sensors. Applied stress or stain can increase or decrease the connectivity of fibers in the network leading to a change in the resistance of the film. Hence, the resistance of the film can be calibrated with respect to the applied stress and these films can be used as sensors. The fabricated sensors are calibrated for voltage drop across a fixed length on the film surface for the applied voltage in the range of 0-10 v. The input and output voltage show a linear relationship. The ratio of the output to the input voltage, defined as efficiency, is between 10-20% depending on the volume fraction of carbon fibers in the film and is a factor in determining the sensitivity of the sensor film. It was observed that the films show low output efficiency because the nanofibers are coated with a coupling agent resulting in their significant wetting with the matrix resin, which increases the contact resistance. Therefore, a process is developed to decrease the contact resistance between nanofibers by embedding them in the resin as a network. The dispersion as a network shows remarkable improvement in the output efficiency to 30-50%. The sensor films are attached to the surface of glass fabric/epoxy matrix laminates and calibrated under three-point bending conditions. The films are attached on the tensile side of the specimen using an epoxy based adhesive. Due to the applied strain the connectivity of nanofiber network changes and the resistance of the film increases. The change in conductivity is calibrated with respect to the applied force. The films were calibrated for five loading cycles and the results are found to be repeatable, showing that these sensors can be used for multiple loading cycles. Nanofiber reinforced epoxy based coatings are also developed and applied as paints to the surface of laminates. These coatings are also tested for conductivity and calibrated for measurement of strain in the laminates. The results for coating are similar to those observed for films. The results show that the nanofiber based sensors have higher efficiency, lower cost, and better tailorability than similar sensors based on carbon nanotubes. The results show that such sensing schemes can be effectively used for structural health monitoring of composite materials.
9:00 PM - V4.22
Influence of Oxygen Partial Pressure on the Physical Properties of Titanium Oxycarbide Thin Films: The Influence of Composition, Bonding Characteristics and Structural Evolution.
Senentxu Lanceros-Mendez 1 , A. Fernandes 1 , J. Serrado Nunes 1 , F. Vaz 1 , A. Pinto 2 , N. Martin 3 Show Abstract
1 Physics, Universidade do Minho, Braga Portugal, 2 , Universidade do Minho, Guimarães Portugal, 3 , Institut FEMTO-ST, UMR 6174, CNRS UFC ENSMM UTBM France
This work is devoted to the investigation of multifunctional titanium oxycarbide, TiCxOy, films prepared by dc reactive magnetron sputtering. Films can be produced with tailor made electrical and optical properties, opening enormous potential for smart system integration. The electrical properties of the films deposited on glass and silicon substrates have been investigated and discussed in relation with their chemical composition and crystalline structure. The effects of the oxygen content on the composition and crystallographic structure were investigated by EMPA, XRD and resistivity measurements. The color of the films changed from metallic tone, for films produced with low oxygen content (< 40 at. %), changing to a very bright yellow-pale and brown colors, to films with an intermediate oxygen content, and finally for higher oxygen content (> 68 at. %) the films present interference color (rainbow-like appearance). This change in optical behavior from opaque to transparent (characteristic of a transition from metallic to insulating-type materials), promoted by the change in the oxygen flow rate (variation in the coatings composition), revealed that significant changes were occurring in the films structure and electronic properties thus opening new potential applications for the films, beyond those of purely decorative ones. Taking this into account, the electrical behavior of the films was investigated as a function of the oxygen content and correlated with the observed chemical, electronic and structural features. The variations in composition disclosed the existence of three different zones, which were correlated to different compositions and the correspondent changes in crystalline structures. For the so-called metallic zone, X-ray diffraction revealed the development of films with a B1 NaCl face-centered cubic titanium oxycarbide-type phase, with some texture changes. Increasing the gas flow (oxygen amount), the structure of the films changed to oxide-type ones, TiO2 (anatase mostly), passing by an intermediate zone where the films are roughly amorphous. The composition/structure variations were consistent with the chemical bonding analysis carried out by X-ray Photoelectron Spectroscopy (XPS), which showed increasing amounts of O bonded to Ti. The electronic properties of the films exhibited significant changes from zone to zone. Resistivity measurements revealed a very wide range of values, varying from relatively high conductive materials (for metallic zone) to highly insulating films within the oxide zone. ACKNOWLEDGMENTThe authors thank the Portuguese Foundation for Science and Technology (FCT)- Grant PTDC/CTM/69362/2006.
9:00 PM - V4.23
Joining Technique for High Temperature Pb-free Solder by Using Vacuum Evaporation Deposition.
Toshihide Takahashi 1 , Tatsuoki Kono 1 , Shuichi Komatsu 2 Show Abstract
1 Corporate Research & Development Center, Toshiba Corporation, Kawasaki, Kanagawa, Japan, 2 , Toshiba Research Consulting Corporation, Kawasaki, Kanagawa, Japan
High temperature solders are used as joining material for semiconductor chip to lead frame in power semiconductor devices. They are required to have a heat resistance of more than 533 K because they are heated up to 523 K in the reflow process for mounting the electronic components. Conventional solders have good heat resistance to use Pb-based alloys that have a melting point of about 507 K. Although restriction of Pb is globally growing, and the practical use of the Pb-free solder has spread, alternative materials are inadequate to replace high temperature Pb-based solder. So, we tried to develop a new joining technology using vacuum evaporation deposition.This study aims to replace Pb-based solder by intermetallic compound (IMC) with vacuum evaporation deposition. To form the IMC that has a high melting point, we used interactions between Ag/Sn/Cu deposited films. The films consisting of Ag, Sn and Cu were prepared by depositing them on Si. Total thickness of the evaporated film was about 5.0 mm. Samples were produced to join the Si chip with the evaporated films to Cu substrate.We confirmed the complete transformation into the IMCs from the evaporated films at 573 K for 30 s. The cross-section of the joining part between Si chip and Cu substrate had two thick layers and one thin layer. They were identified as the following layers by TEM analyses; The upper layer was Cu6Sn5, the middle layer was (Ag,Cu)3Sn based on Ag3Sn, and the lower layer was Cu3Sn. Since their melting points are more than 688 K, they are much higher than heat resistance temperature, 533 K, which is required for high temperature solder. As a result, the joint part showed high strength at high temperature, and the strength at 543 K showed 21.3 MPa, which was a higher value than in use of Pb-based solder. This result proved that the joint part formed by the evaporated films had good heat resistance at high temperature.Moreover, nanoindentation test and modulated thermoreflectance microscopy respectively evaluated mechanical and thermal properties of (Ag,Cu)3Sn and Cu3Sn, including Ag, Cu and Si as reference. Generally, mechanical property of IMC is considered to be hard and brittle. However, the nanoindentation test revealed a large difference between both IMCs. Hardness and elastic modulus of Cu3Sn was much higher than those of (Ag,Cu)3Sn. The elastic modulus of (Ag,Cu)3Sn was also lower than that of Cu, and its hardness was less than half that of Cu3Sn. When the high elastic modulus material forms the joint part, the joint may fracture and the Si chip may crack owing to the thermal stress. Thus, mechanical property of (Ag,Cu)3Sn is expected to relax the stress. Besides, modulated thermoreflectance microscopy revealed (Ag,Cu)3Sn and Cu3Sn has good thermal properties because the thermal properties are better than Pb, Sn. Therefore, thermal energy generated at Si chip is expected to rapidly conduct to the joint part and Cu substrate.
9:00 PM - V4.24
Characterization of Protein Micro-arrays on a Cell Repulsive Film for Cell-surface Interactions.
Ana Ruiz 1 , Laura Ceriotti 1 , Lucel Sirghi 1 , Hubert Rauscher 1 , Ilaria Mannelli 1 , Leonora Buzanska 1 2 , Sandra Coecke 1 , Pascal Colpo 1 , Francois Rossi 1 Show Abstract
1 , Joint Research Center, Ispra Italy, 2 Medical Research Clinical Institute, Polish Academy of Sciences, Warsaw Poland
Cell based micro-arrays represent a promising alternative to microwell plates for high throughput analysis of cellular functions, such as cell adhesion and differentiation on a large variety of materials. In this work, protein arrays are created on plasma deposited polyethylene oxide (PEO-like) film as non adhesive background by using micro-spotting and microcontact printing . The pattern quality produced by both techniques has been characterized and compared in terms of coverage and bio activity. PEO-like films have been proven to be protein and cell repulsive in solution, but protein adhesive when proteins are deposited either by piezoelectric microspotting or microcontact printing techniques. Microspotting deposition has been implemented due to the possibility of testing many proteins on the same substrate, as well as stacking multiple protein layers. Microcontact printing has been chosen due to the flexibility to produce customized layout configurations and the simplicity of its procedure. By these two methods we have been able to obtain protein patterns with different protein coverage on the PEO-like film, as assessed by Atomic Force Microscopy (AFM) and Ellipsometry. The results show that, after spotting, only a small amount of the fibronectin (model protein used in this study) is retained on the surface and present different layer densities depending on the initial protein solution concentration. On the contrary, microstamped protein patterns exhibit a uniform distribution of densely packed proteins regardless on the initial inking concentration. Both the surface analysis methods confirm a stamped protein layer thickness of 3.5 nm height in dried conditions, which increases to 6 nm after immersing in liquid, as observed by AFM and in agreement with the fibronectin dimensions. Both printed and spotted fibronectin molecules resulted to be strongly immobilized on the surface with the active binding sites available for immunorecognition, as assessed by Surface Plasman Resonance Imaging (SPRi) and cell culture experiments. Such protein patterns have been used to create stem cell arrays providing a platform where different cell developmental processes, such as migration, proliferation and differentiation, can be studied.
9:00 PM - V4.25
Absorption Spectra of Ferroic (NH2(C2H5)2)2CuCl4 Nanocrystals Incorporated into the Photopolymer Matrix.
Kazimierz Plucinski 1 , Volodymyr Kapustianyk 2 , Ivan Kityk 3 Show Abstract
1 Electronics Department, Military Univ. of Technology, Warsaw Poland, 2 Scientific Technical and Educational Centre of Low Temperature Studies, Univ. of Lviv, Lviv Ukraine, 3 Faculty of Chemistry, Silesian University of Technology, Gliwice Poland
9:00 PM - V4.3
Remendable Materials Using Reversible Covalent Bonds.
Amy Peterson 1 , Giuseppe Palmese 1 Show Abstract
1 Chemical & Biological Engineering, Drexel University, Philadelphia, Pennsylvania, United States
Materials that can recover mechanical properties following failure offer increased safety and service life. Inspiration for remendable materials comes from nature and has led to many biomimetic mechanisms for healing such as the inclusion of vascular networks that “bleed” healing agent upon crack formation. Two approaches for healing polymer networks have captured much attention. In one method, polymer networks are made to self-heal by adding encapsulations filled with uncured resin, which break open upon crack formation, causing resin to flow into and fill the crack surface. The other mechanism relies on the inherent reversibility of bonds (covalent, noncovalent, or physical) in the polymer network to heal. Our approach to self-healing composites combines many advantages of healing via encapsulation and healing via reversible bonds. Incorporation of a healing agent allows for crack healing while maintaining the desirable physical and mechanical properties of the base thermoset. Reversible bonding of the healing agent provides crack healing multiple times.We report on the development of two healing systems for epoxy-amine thermosets based on the thermoreversible Diels-Alder reaction of furan and maleimide. In one, crack healing of a traditional epoxy-amine thermoset is induced by thermally reversible crosslinking of a secondary phase. In the other, furan functionalization of an epoxy-amine thermoset allows for in situ crack healing of this thermoset with a bismaleimide solution. Both phenomena occur at room temperature and minimal pressure and significant load recovery is possible multiple times in a given location.Load recovery is postulated to be the result of both physical and chemical bonding across the crack surface. Physical bonding is caused by solvent-mediated swelling and subsequent interlocking of crack surfaces, while chemical bonding results from the Diels-Alder reaction of furan and maleimide. This form of the Diels-Alder reaction is reversible, forming a ring structure at room temperature and reforming the respective diene and dienophile between 60 and 90°C.
9:00 PM - V4.4
Experimental Method for Characterizing Force Response in Hydrogels
John Springmann 2 , Wendy Crone 1 2 Show Abstract
2 Engineering Mechanics, University of Wisconsin - Madison, Madison, Wisconsin, United States, 1 Engineering Physics, University of Wisconsin - Madison, Madison, Wisconsin, United States
Responsive hydrogels are polymers that undergo volume changes when exposed to stimuli such as temperature, pH, or electric current. Due to their autonomous response, they have been used as components in microfluidic devices. In order to be implemented successfully as a sensor/actuator, the amount of force the hydrogel exerts when it swells must be known. However, a method for accurately characterizing the force response has not yet been demonstrated in the literature. This research seeks to develop a validated method to characterize a range of responsive hydrogel characteristics. In this research, cylindrical posts of UV-polymerizered 2-(dimethylamino)ethyl methacrylate 2-hydroxyethyl methacrylate hydrogels with a diameter of 600 μm and a height of 250 μm are investigated using a displacement-controlled mechanical testing technique. Results show that the force response varies with gel volume and with polymerization intensity of the gel.
9:00 PM - V4.5
Solvomechanical Response of Diazobenzene Polymer Films in Organic Solvents.
Jianxia Zhang 1 2 , John Wiley 1 2 Show Abstract
1 Chemistry, University of New Orleans, New Orleans, Louisiana, United States, 2 AMRI, University of New Orleans, New Orleans, Louisiana, United States
Diazobenzene polymer thin films show rapid mechanical response on exposure to select solvent systems. Either on emersion or evaporation of particular organic solvents, films can bend or curl within seconds. The response not only depends on the nature of the solvent but also on film thickness and the geometry of the polymer piece. In this presentation, the various trends in solvomechanical response will be reported and mechanistic implications for this behavior discussed.
9:00 PM - V4.6
Preparation of Asymmetric Thermosensitive Double-layer Gel.
Takashi Iizawa 1 , Akihiro Terao 1 Show Abstract
1 Department of Chemical Enginering, Hiroshima University, Higashi-Hiroshima Japan
Poly(N-alkylacrylamide) (PNAA) gels containing C2-C3 alkyl groups have attracted much attention as smart materials because they have lower critical solution temperatures (LCST), depending on the alkyl groups. They are usually prepared by the radical polymerization of the corresponding monomers. Recently, we have reported novel synthesis method of PNAA by direct condensation of poly(acrylic acid) gel-DBU salt (DAA) with an alkylamine using triphenylphosphite (TPP) as an activating agent, and its application to preparation of core-shell type gels containing two different thermosensitive PNAA layers such as poly(N-isopropylacrylamide) gel (PNIPA, LCST: 32°C) and a poly(N-n-propylacrylamide) (PNNPA, LCST: 21°C). To develop thermosensitive gels deformed markedly by the swelling-deswelling, this paper investigates a new approach to the preparation of asymmetric thermosensitive PNIPA-PNNP double-layer gels by several procedures using the synthetic method of the core-shell type gels.When a DAA sample (diameter: 5.3 mm, length: about 20 mm) was placed in N-methyl-2-pyrrolidone containing an excess of alkylamine and TPP, selective amidation occurred from the outside to give the corresponding DAA-PNAA core-shell type gel consisting of an unreacted DAA core and a quantitatively amidated shell layer, and finally afforded a PNAA gel. Further amidation of DAA-PNAA core-shell type gel with other alkylamine resulted a novel core-shell type gel consisting of two different PNAA layers, PNAA(2) and PNAA(1). Thermal properties of the resulting gel such as swelling/deswelling behavior and equilibrium swelling ratio were measured in water at various temperatures. The swelling/deswelling of shell layers and cores in the PNAA(2)-PNAA(1) core-shell type gel occurred almost independently in response to the temperature changes, although the swelling/deswelling rate of the core was affected by the hydrophilic/hydrophobic properties of the shell layer. However, the resulting cylindrical PNAA(2)-PNAA(1) core-shell type gel cannot deform markedly by the swelling-deswelling because of its axial symmetry. In contrast to the cylindrical gels, the semicylindrical PNIPA-PNNPA double-layer gel prepared by cutting the cylinders into halves was bent markedly in water at a temperature between LCSTs of both layers. The deformations among the swelled gel (a temperature below the LCSTs), the bent gel (a temperature between the LCSTs), and the deswollen gel (a temperature above the LCSTs) occurred reversibly in response to the stepwise temperature changes. We also proposed the several procedures of asymmetric thermosensitive PNIPA-PNNPA double-layer gels, such as a thin long asymmetric thermosensitive double-layer gels (diameter: 0,8 mm, length: about 80 mm) bent in zigzag with high-speed responsivity, using the synthetic method of the core-shell type gels.
9:00 PM - V4.7
Formation of Wrinkle Patterns on Porous Elastomeric Membrane and Their Fabrication of Hierarchical Architectures.
Yue Cui 1 , Shu Yang 1 Show Abstract
1 Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States
9:00 PM - V4.9
Thin Poly(styrene-block-4-hydroxystyrene) Block Copolymer Films Spin Coated Directly on Topographic Pre-pattern Substrates.
Geuntak Lee 1 , Pil Sung Jo 1 , Bokyung Yoon 1 , Taehee Kim 1 , Himadri Acharya 1 , Ho-Cheol Kim 2 , June Huh 3 , Cheolmin Park 1 Show Abstract
1 Materials science and engineering, Yonsei University , Seoul Korea (the Republic of), 2 , IBM Almaden Research Center, San Jose, California, United States, 3 Materials science and engineering, Seoul National University, Seoul Korea (the Republic of)
We have investigated the formation of as-cast thin films of a poly(styrene-block-4-hydroxystyrene) (PS-b-PHOST) copolymer directly spin coated on topographic pre-pattern substrates. Either wetting or dewetting of a polymer thin film occurs in non-equilibrium state during spin coating process with solvent vapor saturated and strongly depends on the dimensions of the pre-patterns. The ratio of periodic unit area to elevated one of a pre-pattern ( β value) is found as one of the most important factors for wettability of a thin film. The dewetting of a thin film, guided by the edges of both elevated individual periodic lines and mesas, took place with self assembled block copolymer nanostructure when β value was greater than a critical value of approximately 4 which tends to decrease with the trench depth of the pre-patterns in our system.
Ji Su NASA Langley Research Center
Li-Peng (Leo) Wang TricornTech Corporation
Yasubumi Furuya Hirosaki University
Susan Trolier-McKinstry The Pennsylvania State University
Jinsong Leng Harbin Institute of Technology
V5: Novel Active Materials: Polymers
Tuesday AM, December 02, 2008
9:30 AM - **V5.1
An Artificial Muscle Actuated by Metal Hydrides.
Alex Vanderhoff 1 , Kwang Kim 1 Show Abstract
1 Mechanical Engineeering, Univ. of Nevada, Reno, Reno, Nevada, United States
A pneumatic artificial muscle has been converted into a smart actuation system powered with hydrogen gas using a metal hydride reactor unit. The actuator contracts when pressurized, creating a pulling force and the design is based on McKibben muscle concepts. The metal hydride material used in the reactor absorbs and releases hydrogen gas upon cooling and heating, respectively, therefore providing the gas to pressurize the actuator. The system is compact, lightweight, noiseless, provides smooth muscle-like actuation, and has a high force to weight ratio. The experiments conducted in this study show that the system has the potential to be used for biorobotic applications in a wide range of temperature environments and that the embedded braided pneumatic muscle is a feasible design for these applications.
10:00 AM - V5.2
Cellulose Electroactive Paper (EAPap): The Potential for a Novel Electronic Material.
Joo-Hyung Kim 1 , Kwangsun Kang 1 , Sungryul Yun 1 , Sangyeul Yang 1 , Min-Hee Lee 1 , Jung-Whan Kim 1 , Jaehwan Kim 1 Show Abstract
1 Mechanical Engineering, INHA University, Incheon Korea (the Republic of)
10:15 AM - V5.3
Rheology and Electrorheology of Nanorod-Loaded Liquid Crystalline Polymers.
Ana Cameron-Soto 1 , Sonia Aviles-Barreto 1 , Aldo Acevedo-Rullan 1 Show Abstract
1 Department of Chemical Engineering, University of Puerto Rico, Mayaguez, Mayaguez, Puerto Rico, United States
The effect of carbon nanotube concentration and dispersion on the rheology of liquid crystalline solutions of hydroxypropyl cellulose (HPC) has been experimentally studied. The rheology of nanocomposites of HPC and multiwalled carbon nanotubes (MWCNT) in m-cresol were characterized in steady-state, transient dynamic tests. The rheology as particle loading increases shows a very distinct response in the magnitude and scaling of the steady-state viscosity, and the storage and loss modulus. The liquid crystalline phase was characterized by direct observations by reflected polarized light microscopy. Additionally, an electric-field effect was observed on the rheology of the HPC/MWCNT in m-cresol soft composites. The HPC in m-cresol matrix is non-responsive, thus the electrorheological effect is due to the presence of the carbon nanotubes. The mechanism for this effect is still uncertain, since it does not follow the scaling predicted by simple models for heterogeneous and homogeneous ER fluids.
10:30 AM - V5.4
Mechanics of Soft Active Materials.
Xuanhe Zhao 1 , Wei Hong 1 2 , Zhigang Suo 1 Show Abstract
1 School of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts, United States, 2 Department of Aerospace Engineering, Iowa State University, Ames, Iowa, United States
Polymers and polymeric gels are representative of “soft materials” as opposed to “hard materials” (e.g., metals and ceramics). Soft materials can be made active in that they can undergo large deformation in response to diverse stimuli, including mechanical stresses, electric fields, and trace amount of enzymes.Our interest in active soft materials has been stimulated by recent development in the fields of dielectric elastomer actuators and stimuli-responsive gels. In this talk I’ll focus on our new formulation of nonlinear field theory of elastic dielectrics.Two difficulties have long troubled the field theory of finite deformation in dielectric solids. First, when two electric charges are placed inside a dielectric solid, the force between them is not a measurable quantity. Second, when a dielectric solid deforms, the true electric fieldand true electric displacement are not work conjugates. These difficulties are circumvented in our new formulation of the theory. Imagine that each material particle in a dielectric is attached with a weight and a battery, and prescribe a field of virtual displacement and a field of virtual voltage. Associated with the virtual work done by the weights and inertia, define the nominal stress as the conjugate to the gradient of the virtual displacement. Associated with the virtual work done by the batteries, define the nominal electric displacement as the conjugate to the gradient of virtual voltage.Our approach does not start with Newton’s laws of mechanics and Maxwell-Faraday theory of electrostatics, but produces them as consequences. We show that the notion of Maxwellstress, which is widely used in the literature, has no general theoretical basis. However, for a very special class of materials, which we call ideal dielectric elastomers, the theory recovers the Maxwell stress.
10:45 AM - V5.5
Absorption-induced Deformations of Nanofiber Yarns and Nanofibrous Webs.
Daria Monaenkova 1 , Konstantin Kornev 1 , Taras Andrukh 1 Show Abstract
1 MSE, Clemson University, Clemson, South Carolina, United States
Current advances in manufacturing of nanotubular and nanofibrous materials with high surface- to - volume ratios call for the development of adequate characterization methods and predictive estimates of their absorption capacity. Extremely high flexibility of these materials poses a challenge: their pore structure easily changes upon contact with the fluid in question. One more complication is that the absorption process is sufficiently fast: one hundred micron droplets disappear in milliseconds. This paper sets a physical basis for analyses of absorption processes in nanotubular and nanofibrous materials. As an example, we study absorption of droplets by yarns made of nanofibers and nanofibrous webs. Through our experiments we show that absorption can induce different types of nanoyarn deformations: visible deformations of the yarn profile and deformations of the yarn diameter/length caused by the capillary pressure. Using our experimental data and theory, we estimate elastic and transport characteristics of the nanofibrous materials. The reported experiments and proposed theory open a new area of research on absorption-induced deformations of nanotubular and nanofibrous materials and show their potential applications as sensors to probe minute amount of absorbable liquids.
V6: Novel Active Materials: Composites
Tuesday PM, December 02, 2008
11:30 AM - **V6.1
Recent Progress and Application of Novel Smart Composite Materials.
Shanyi Du 1 , Jinsong Leng 2 Show Abstract
1 Centre for composite materials, Harbin Institute of Technology, Harbin China, 2 Centre for composite materials, Harbin Institute of Technology, Harbin China
12:00 PM - V6.2
High Modulus Nanolayer / Elastomer Hybrids for Vibration Damping.
Erik Dunkerley 1 , Hilmar Koerner 2 , Richard Vaia 2 , Daniel Schmidt 1 Show Abstract
1 Plastics Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, United States, 2 , Air Force Research Labs, Wright-Patterson AFB, Ohio, United States
Engineered laminates find use in everything from automotive applications to airframes, in large part due to their unique combination of toughness and modulus. Nature also utilizes laminates, nacre being one of the most well-known. Comprised of hexagonal platelets of aragonite 10-20 µm wide and 0.5 µm thick separated by protein-based elastic biopolymers, the mechanical interlocking of the platelets, the immobilized protein within the CaCO3 and “hidden length” of the intervening biopolymer chains give rise to exceptional toughness and damage tolerance. Coupled with the ideas of mechanical contrast and interfacial slip, it may be possible to take lessons from these examples to produce uniquely stiff, robust, highly damping materials from nanoscopic laminates.In this study, hybrids consisting of organically modified montmorillonite (MMT) nanolayers and 0-30 vol% polyisobutylene (PIB) are produced via spray-coating and solvent-casting. Free-standing films result, and in addition to their optical transparency, display a unique combination of stiffness and damping capacity, including simultaneous storage and loss moduli as high as ~7-10 GPa and ~0.7-0.8 GPa respectively, and loss moduli of ~0.3-0.8 GPa over a temperature range of nearly 200 K and four decades of frequency. Small angle x-ray scattering indicates a highly aligned (Sd > 0.75) superstructure parallel to the plane of the film, with the polymer distributed throughout the structure and strongly confined between the nanolayers.Alterations in the preparation technique modify the process of evaporation-induced self-assembly (EISA) by which these materials form, allowing for variations in hierarchical structure and control over the hybrid’s thermomechanical properties. In contrast to bottom-up approaches like layer-by-layer deposition, the methods developed here represent a rapid, readily scalable means of achieving nanoscopic interpenetrating brick-and-motor morphologies, in this case consisting of rigid nanolayers coupled by a soft polymeric phase, and allow for alterations in the mesoscopic organization of these nanostructures that are otherwise difficult to achieve. The combination of large dynamic mechanical losses and structurally relevant moduli provide novel options to suppress vibration in rigid composites.
12:15 PM - V6.3
A Novel Approach for Processing 2 – 2 Single Crystal / Polymer Composites.
Michael Ugorek 1 , Gary Messing 1 , Susan Trolier-McKinstry 1 Show Abstract
1 Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State Universtiy, University Park, Pennsylvania, United States
An understanding of microstructure evolution in ceramic materials, including texture development and abnormal / enhanced grain growth should enable more controlled final microstructures. In this study, a novel approach for fabricating 2-2 single crystal / polymer composites with a kerf of < 5 microns was demonstrated. As a model system, surface templated grain growth was used to propagate a single crystal interface into a polycrystalline BaTiO3 or Ba(Zr0.05Ti0.95)O3 matrix with lamellar metal layers. Grain growth evolution and texture development were studied using both  and  BaTiO3 single crystal templates. It was found that the growth kinetics can be controlled by a small initial grain size, atmosphere conditions, and the introduction of a liquid phase at selective areas / interfaces. By using a PO2 of 1x10-11 atm during high temperature heat treatment, matrix coarsening was limited while enabling single crystal boundary motion up to 0.3mm during growth between 1250oC and 1300oC. By removing the inner electrodes, a 2-2 single crystal composite can thus be prepared. The piezoelectric and dielectric properties of the composites as a function of composition and single crystal orientation will be reported. This method is expected to be generally useful in preparing single crystal composites of a wide range of compositions.
12:30 PM - V6.4
The Influence of Processing Variables on the Morphology and Performance of a Two-Dimensional Conducting Fiber Reinforced Dielectric Elastomer Composite Material.
Brian Stewart 1 , Kathryn Logan 1 Show Abstract
1 Materials Science and Engineering, Virginia Polytechnic Institute, Blacksburg, Virginia, United States
Dielectric elastomer (DE) actuators based on elastomeric films have been intensely studied in recent years. Most of this prior work was based on one-dimensional planar actuators with a compliant electrode on either side to generate the necessary electric field. Typical analyses of planar actuators began with the one-dimensional form of the Maxwell stress tensor and assumed a uniform electric field. While this approach resulted in simple geometry and representation of the electric field, the use of the sheet form of the DE material combined with the 1-D field assumption imposed severe limits on possible composite morphologies. There have also been notable attempts to include “inextensible fibers” as reinforcement in the elastomer matrix. These were likewise fabricated from the sheet form of DE, with various attempts to form actuators by rolling, folding or stacking fiber reinforced sheets. Our research departs from prior work by producing an intrinsic two-dimensional fiber-reinforced composite material with electrically conductive reinforcing fibers. This material is produced by processing the uncured liquid precursor form of the elastomer while in direct contact with the fibers. The use of the liquid form allows for a wider array of potential configurations, and permits the inclusion of electrically conductive reinforcing fibers throughout the bulk of the composite. The use of the two-dimensional configuration requires analyses using the two-dimensional formulation of the divergence of the Maxwell stress tensor to compute field-generated body forces and surface tractions. The analysis is further complicated by the coupling of the two-dimensional electrical domain with that of the three-dimensional structural domain. The result is an analysis that includes not only the effects of fiber fraction normally found in passive composite materials, but also the effects of dielectric elastomer physical features such as electrode spacing on performance variables such as actuation voltage. The results to be presented include static finite element analysis (FEA) predictions, actuator performance data, and observations of the effect of processing parameters on both the morphology and performance of the composite material. The numerical results are compared to the measured force and displacement data from tensile actuators fabricated using the new method. The effects of processing variables such as elastomer precursor viscosity and curing environment on fiber spacing and fiber fraction are presented to show how different processing options affect the form and performance of the finished product. The processing observations will be used to guide more detailed materials characterization studies. The combination of numerical and experimental results provides an estimation of the performance envelope of this novel material system.
12:45 PM - V6.5
Ionic Polymer-Metal Composites Processed by Hot Pressing: Effect on Capacitance and Energy Harvesting.
Rashi Tiwari 1 , Sang_Mun Kim 1 , Kwang Kim 1 Show Abstract
1 Mechanical Engineeering, Univ. of Nevada, Reno, Reno, Nevada, United States
Tuesday PM, December 02, 2008
2:30 PM - V7.1
Nano-optical Negative-index Photonic Crystal Lenses for Subwavelength Imaging and Next-generation Optoelectronics.
Bernard Casse 1 , Wentao Lu 1 , Yongjian Huang 1 , Srinivas Sridhar 1 Show Abstract
1 Electronic Materials Research Institute, Northeastern University, Boston, Massachusetts, United States
We use bandstructure engineering principles to engineer photonic crystal (PhCs) lenses which exhibit an effective negative index of refraction to manipulate light at the nanoscale level for subdiffraction imaging and next-generation optoelectronics applications. The PhC lenses are nanofabricated in an InP/InGaAsP heterostructure semiconductor platform using modern lithography techniques and characterization is performed using near-field scanning optical microscopy. We report the first experimental observation of subwavelength imaging (~0.40λ) in a photonic crystal superlens at optical frequencies (1.5 µm). Then, we experimentally demonstrate that by exploiting the periodicity of the surface corrugation, a binary-staircase optical element can be engineered to exhibit an effective negative index of refraction and focus plane-waves. Finally we demonstrate a superior negative-index 2D PhCs planoconcave microlens having compact footprint, ultra-short focal length (~8λ), diffraction-limited spot size (~0.68λ), larger numerical aperture (close to unity) and reduced spherical aberrations compared to a conventional positive index planoconvex lens.This work was supported by the Air Force Research Laboratories, Hanscom through grant no. FA8718-06-C-0045 and the National Science Foundation through grant no. PHY-0457002.
2:45 PM - V7.2
Characterization of Optical Metamaterials.
Nicholaos Limberopoulos 1 , Alkim Akyurtlu 1 , Aram Karakashian 2 , William Goodhue 2 , Michael Coulombe 2 Show Abstract
1 Electrical and Computer Engineering, University of Massachusetts, Lowell, Massachusetts, United States, 2 Physics and Applied Physics, University of Massachusetts, Lowell, Massachusetts, United States
Validation of the unique properties, i.e. negative index of refraction, of optical metamaterials is an important aspect of metamaterial design and applications. In this work, a testbench structure, based on surface-plasmon coupling, for the characterization of optical metamaterials will be demonstrated. The main idea behind this structure is based on the fact that in conventional (positive index materials), surface plasmon coupling only occurs for p-polarization, where it has been shown (R. Ruppin, Journal of Physics: Condensed Matter 13, 1811-1819, 2001, and N. Limberopoulos, G. S. Banks, A. Akyurtlu, A. S. Karakashian, W. D. Goodhue, and V. Limberopoulos, 2007 USNC/URSI National Radio Science Meeting, July 23 2007, Ottawa, ON, Canada.) that for a negative index metamaterial, surface plasmon coupling occurs for both p- and s-polarizations. We take advantage of this property to validate negative index properties of our optical negative index metamaterials (NIMs) (A. G. Kussow, A. Akyurtlu, A. Semichaevsky, N. Angkawisittpan, Physical Review B, 76, 195123, 1-7, 2007). The test bench structure is composed of a BK7 prism coupler and the NIM slab under test. The structure is exposed to free space. This design configuration has been chosen over typical Otto and Kretschmann configurations for its simplicity. The prism coupler is used to couple the light into the NIM under test that is to be characterized. The design parameters of the metamaterial samples, the thicknesses of the layers in the test bench structure, as well as the details of the coupling mechanisms are determined by the Finite Difference Time Domain (FDTD) method. Results of the theoretical and computational models will be validated through experimental results of the fabricated structures.
3:15 PM - **V7.4
Mapping the Surface Plasmon Resonance Landscape of Gold Nanocrystals.
Paul Mulvaney 1 Show Abstract
1 School of Chemistry & Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
3:45 PM - V7.5
Supercontinuum Generation in Toroidal Chalcogenide Microresonators.
Duygu Akbulut 1 , Abdullah Tulek 1 , Mehmet Bayindir 1 2 Show Abstract
1 UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara Turkey, 2 Department of Physics, Bilkent University, Ankara Turkey
Whispering gallery mode microresonators confine light to a micron scale volume via total internal reflection mechanism. Among many different types of such structures, microtoroids have attracted much attention since their first demonstration due to the possessed features of ultra-high quality factor, small mode volume and integrability to chip based applications. Until now, such structures have been employed for a variety of purposes including sensor applications, observation of nonlinear optical effects and laser action. Chalcogenide glasses are materials that maintain considerably high nonlinear refractive index compared to other glasses; hence they have drawn much attention in nonlinear optics applications such as supercontinuum generation and parametric processes. In this work, we propose to combine the small mode volume and ultrahigh quality factor of the toroidal microcavity with high nonlinearity of the chalcogenide materials to obtain a strong nonlinear optical effect and to observe generation of new frequency components inside the microresonator which would result in a chip-integrable device that could be used for optical frequency metrology, spectroscopy, tunable parametric amplification and pulse compression purposes. For this purpose, toroidal microresonators are fabricated from SiO2 material via conventional lithography and etching techniques combined with a laser reflow procedure. The obtained SiO2 microtoroid is used merely as a template which is to be modified for intended applications and a chalcogenide material with nonlinear refractive index ~1000 times higher than that of silica is thermally evaporated on top for observing supercontinuum generation in the toroidal microresonator. 2D finite difference time domain (FDTD) simulations have been performed for the chalcogenide coated SiO2 microtoroids. The simulation results revealed that the cavity modes are mostly confined in the nonlinear material layer due to high refractive index contrast at the chalcogenide-air and chalcogenide-silica interfaces and new frequency components in the cavity due to nonlinear processes of self phase modulation are indeed observed.
4:30 PM - V7.6
An Approach to Develop an Integrated Process for the Development of Smart Luminescent Sensor Materials for Structural Health Monitoring Systems: The Case Study of BAS:Eu Triboluminescent Ceramics.
Kaustav Sinha 1 , Brett Pearson 1 , Said Casolco 2 , Javier Garay 2 , Olivia Graeve 3 1 , Brandon Williams 1 Show Abstract
1 Chemical and Metallurgical Engineering, University of Nevada, Reno, Reno, Nevada, United States, 2 Mechanical Engineering, University of California Riverside, Riverside, California, United States, 3 Kazuo Inamori School of Engineering, Alfred University, Alfred, New York, United States
4:45 PM - V7.7
Optical Characterization of GaN Nanorods by Spectroscopic Ellipsometry.
Shih-Hsin Hsu 1 , Ching-Hua Chiu 2 , Hao-Chung Kao 2 , Tien-Chang Lu 2 , Shing-Chung Wang 2 , Yuh-Jen Cheng 1 , Yia-Chung Chang 1 2 Show Abstract
1 Research Center for Applied Sciences, Academia Sinica, Taipei Taiwan, 2 Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu Taiwan
GaN nanorods demonstrating broad angular and spectral antireflection are characterized by spectroscopic ellipsometry (SE). The undoped GaN samples were first epitaxially grown by metal organic chemical vapor deposition on c-plane sapphire (0001) substrates. Thin Ni films with various thicknesses ranging from 5 to 20 nm were subsequently evaporated, and followed by a rapid thermal annealing process under N2 gas to form Ni nano-dots of different sizes, which served as the etching masks. After being etched by an inductively coupled plasma reactive ion etching process till the heights of GaN rods were over 700 nm, the samples were dipped into a heated nitric acid to remove the residual Ni nano-masks. The fabricated samples consist of a layer of irregular GaN nanorods with various in-plane sizes (from below 50 to 400 nm) and shapes and a homogeneous GaN film on a sapphire substrate, and the total thicknesses of the GaN layers are all around 2 μm. Optical reflection measurements show the reflectance for both p- and s-polarizations is held well below 10 percent from ultraviolet to infrared wavelengths and at incident angles up to 60 degree.Variable-angle spectroscopic ellipsometry measurements of the GaN nanorods were carried out in a spectral range from ultraviolet to infrared (300 to 2200 nm in wavelength) using a rotating analyzer ellipsometer system with an adjustable retarder, which is capable of measurements of depolarization degree and generalized ellipsometry. Effective medium approximation (EMA) theory was employed to analyze this kind of porous nanostructure. Within the analysis, the GaN nanorods were modeled as a graded-index layer, in which each sub-layer is modeled as a mixture of GaN, whose uniaxial optical constants were obtained from SE studies on homogeneous planar GaN films, and voids with varying porosity fraction. In addition to material anisotropy, the columnar structure of nanorods also introduces anisotropy, which was modeled by adjusting the depolarization factor to describe the directional dependence of the EMA screening effect. The model fitting based on a 3-node, graded EMA layer model works pretty well in the infrared region, where the feature sizes of the nanorods are relatively small compared with probe wavelengths. For the samples with smaller rod sizes, the model could fit the experimental data down to visible wavelengths. It is worth noting that the refractive index profiles of GaN nanorods extracted from the analysis also verify the broad spectral and angular antireflection is mainly attributed to the gradually varying porous structure.  This study demonstrates that SE measurements coupled with an adequate modeling could be a useful, nondestructive tool for the characterization of structures in micro to nano scale. C.-H. Chiu, P. Yu, H.-C. Kuo, C.-C. Chen, T.-C. Lu, S.-C. Wang, S.-H. Hsu, Y.-J. Cheng, and Y.-C. Chang, Opt. Express 16, 8748 (2008).
5:00 PM - V7.8
Pb(Zr,Ti)O3 Nanofibers Produced by Electrospinning Process.
Ebru Mensur Alkoy 1 , Canan Dagdeviren 1 , Melih Papila 1 Show Abstract
1 Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul Turkey
5:15 PM - V7.9
Light-powered Electrical Switch Based on Cargo Lifting Azobenzene Monolayers: the Role of Cooperativity in Molecular Motors.
Paolo Samori 1 2 , Giuseppina Pace 1 , Jeffrey Mativetsky 1 , Mark Elbing 4 , Michael Zharnikov 5 , Marcel Mayor 6 4 , Maria Anita Rampi 3 Show Abstract
1 Institut de Science et d'Ingénierie Supramoléculaires, Université Louis Pasteur de Strasbourg, Strasbourg France, 2 Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, Bologna Italy, 4 Institute for Nanotechnology, Forschungszentrum Karlsruhe , Karlsruhe Germany, 5 Angewandte Physikalische Chemie, Universität Heidelberg, Heidelberg Germany, 6 Department of Chemistry, University of Basel, Basel Switzerland, 3 Department of Chemistry, University of Ferrara, Ferrara Italy
Nature exploit to a great extent light as a source of energy for operating biological systems. Within photochromes which can convert photonic energy into mechanical energy, azobenzenes have been extensively studied for their unique photoisomerization, potentially enabling switching properties in molecular devices. This is the first study carried on fully conjugated and rigid azobenzene derivatives exhibiting reversible trans-cis photo-isomerization when organized in single-component SAMs (Self-Assembled Monolayer) on Au(111). High-resolution STM images showed that the AZO molecules, both in trans and cis configuration, adopt a rectangular unit cell. Interestingly, we found that the light-induced isomerization is extended over many adjacent molecules arranged into 2D crystalline domains. The long range order found for the cis-domains can be explained in terms of a cooperative nature of the process. The stabilization of the intermolecular interactions among adjacent molecule in the SAM is responsible for the considerably increased yield of isomerization on the surface with respect to solution. Such an azobenzene SAM has been successfully used to modulate the current through metal-organic-metal junctions. By incorporating the azobenzene SAM between a Au(111) support and a metal coated AFM tip, we could detect a 30-fold difference in the current through the junction, providing the first example of conducting AFM measurement on a bi-stable system. Given the occurrence of the isomerization on many thousands adjacent molecules, i.e. on the several hundreds of micrometers scale, we employed a macroscopic mercury drop as counter-electrode and found a reversible change of 1.5 orders of magnitude in the current. Significantly, the cooperative and high yield of switching of many adjacent molecules, chemisorbed on Au was also employed to generate forces acting simultaneously against gravitational effects, atmospheric pressure, and surface tension on a heavy Hg drop. The joint effort of 1011 adjacent molecules, each of them exerting a force of at least 2.6x10 14 N, led to the generation of an overall force per unit area as high as 1x105 N/m2. This unambiguously demonstrates that our azobenzene SAM represents a prototype of a molecular machine able to transport mass, and in particular to act as a cargo lifter.Noteworthy, our cis-trans photoisomerization is fully reversible. In principle it might be used to gate optical signals, and therefore has potential for implementing logic operations on arrays of switching elements, and ultimately for high density data storage based on artificial molecular systems. G. Pace, V. Ferri, C. Grave, M. Elbing, C. von Hänisch, M. Zharnikov, M. Mayor, M. A. Rampi, and P. Samorì, PNAS 2007,104,9937 J. Mativetsky, G. Pace, M. Elbing, M.A. Rampi, M. Mayor, P. Samorì, J. Am. Chem. Soc. 2008 in press V. Ferri, M. Elbing, G. Pace, M. Zharnikov, P. Samorì, M. Mayor, M.A. Rampi, Angew. Chem. Int. Ed. 2008,47,3407
5:30 PM - V7.10
Study on the Effect of Temperature on Optical Properties of ZnO Thin Film Using SPR.
Shibu Saha 1 , K. Sreenivas 1 , Vinay Gupta 1 Show Abstract
1 Department of Physics & Astrophysics, University of Delhi, Delhi, Delhi, India
Zinc Oxide (ZnO) is an important multifunctional material having good electro-optic, photoconducting, piezoelectric, elasto-optic and optical wave guiding properties with wide range of applications. Recently it has attracted a lot of interest towards UV-Lasers due to excellent optical properties and tunable band-gap. The properties of the material are known to depend upon the temperature and may affect the device performance. However, no report is available on temperature dependent optical properties of ZnO thin film. In the present study the optical properties of a RF-sputtered ZnO thin film has been investigated using a simple Surface Plasmon Resonance (SPR) setup based on Kretschmann-Reather configuration. The dip in reflectance for gold-air interface is observed at an angle of 36.8°. The experimentally obtained SPR reflectance curve is fitted with the theoretical curve generated using the Fresnel's equation and dielectric constant of the gold film as the fitting parameter. Hence the dielectric constant of the gold film is obatined. On deposition of ZnO layer on the gold film the SPR dip angle is observed at 46.0°. The dielectric constant of the ZnO film at optical frequency corresponding to 633 nm wavelength is obtained by fitting the experimental SPR reflectance curve with the theoretical curve generated using Fresnel's equation. The SPR reflectance curve of this system (Prism/Au/ZnO) is obtained at different temperatures from 27°C to 250°C. Hence, the dielectric constant and refractive index of the ZnO thin film at different temperatures are obtained. The refractive index of the ZnO thin film is found to increase linearly from 1.95 to 1.98 with increase in ambient temperature, from 27°C (room temperature) to 250°C. Further calculations shows that the bandgap decreases from 3.32eV to 2.91eV with increase in temperature in the same range.The observed linear increase in the refractive index with temperature shows the promising application of ZnO film as an effective temperature sensor.
5:45 PM - V7.11
Optical Fiber Loop Sensors for Structural Health Monitoring of Composites.
Nikhil Gupta 1 , Nguyen Nguyen 1 Show Abstract
1 Mechanical and Aerospace Engineering, Polytechnic University, Brooklyn, New York, United States
A variety of intrinsic and extrinsic fiber-optic sensors are used in structural health monitoring of composite materials, including Bragg grating, Fabry-Perot, and interferometric sensors. Most of these sensors are relatively expensive and require elaborate instrumentation for data acquisition and interpretation of results. In the present work an optical-fiber loop sensor is designed and tested for possible applications in structural health monitoring in composite materials. The sensor design and principle are simpler than other optical fiber-based sensors. It is known that bending an optical fiber beyond a critical curvature leads to loss of intensity through the curved region. The intensity loss depends on the radius of curvature. The transmitted light intensity can be measured by a photodetector and a change in the intensity due a change to the curvature can be measured. In the present research optical fiber based loop sensors are developed that can exploit this concept. Single mode optical fiber sensors having different loop radius, from 5-20 mm, are fabricated and calibrated for applied strain on the loop. The calibration is carried out using a 9.8 N load cell and a computer controlled translation stage having 50 nm step resolution. Results show that the sensors provide highly repeatable results for several loading cycles. Smaller loop radius leads to higher intensity losses, resulting in higher sensitivity for the same applied displacement. A theoretical framework is developed for validation of the calibration results and the theoretical results of intensity loss show close agreement with the experimental data. In the next step the loop sensors are embedded in glass fiber/epoxy resin laminates. Two types of laminates, having fibers in 0-90 and ±45 degrees orientation, are used in the study. Result show that the sensors results are consistent with the calibration data and such sensors can be used in structural health monitoring applications. In this approach the coating and cladding of optical fibers are maintained intact; therefore, the sensors are robust and can withstand the fabrication process of various types of composites. These sensors can also be used for temperature measurements.