bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Ti-27Nb-13Zr Alloy Produced by Powder Metallurgy
Authors: Mendes Marcio W.D. , Bressiani Ana Helena Almeida , Bressiani José Carlos
Published: September 2012

Titanium alloy are widely used in biomedical applications due to their excellent properties such as high strength, good corrosion resistance and excellent biocompatibility. Researches are being developed with elements such as Nb and Zr that reach all criterions for excellent biocompatibility and provide titanium alloys with Young’s modulus close to human bone. The aim of this work was to produce Ti-27Nb-13Zr alloy with different milling times by powder metallurgy process. The mixtures were performed by high energy milling and sintering in high vacuum furnace with temperature of 1300 °C / 3 h. The microstructures of samples were analyzed by SEM and XRD, while the mechanical behavior was evaluated by elastic modulus and Vickers hardness test. The diffraction results of sintering treatment indicate that the alloys are composed of α and β phases. Images obtained by SEM indicate the formation of equiaxial structures. Vickers hardness measurements from sintered samples with 1300 °C / 3 h indicate mean values around 413, 473 and 609 HV for 2, 6 and 10 hours of milling, respectively. The values of elastic modulus enable use the alloy as biomaterial.
Lectinhistochemistry Evaluation of Bone after Implantation with Macroporous Titanium Samples
Authors: Violin Kalan Bastos , Goia Tamiye Simone , Bressiani José Carlos , Bressiani Ana Helena de Almeida
Published: September 2012

Titanium and its alloys are widely used as biomaterials and interact well with bone tissue. In order, to evaluate more than just morphological osseointegration by histological slides the work aimed to approach a molecular evaluation of bone-implant using lectinhistochemistry (LHC), which binds with high specificity carbohydrates (sugar residues) presents in membrane glycoproteins with the use of lectins. The implanted samples were obtained by powder metallurgy, Ti-13Nb-13Zr alloy with and without gelatin. Pores were achieved by adding gellatin 5 wt% to the hydrogenated metallic powder, after near net shape processing, the samples were thermal treated in vacuum (300 °C/90min) and sintered in high-vacuum (1150 °C/14h). The samples were characterized for porosity (~30%), and subsequently were implanted in rat’s femur bone. After 4 weeks of healing process, bone with implant were sampled to perform LHC in paraffin embedded tissue in histological slides using the lectins PNA, UEA-1, WGA, sWGA and RCA-1. All samples osseointegrated well with the bone, no fibrous capsule was present in the bone which was in contact with the implant. With the molecular approach of osseointegration, adjustments in the processing and structure of macroporous titanium based implants can be performed to achieve friendly structure.
Memory Effect of a Different Materials as Charge Storage Elements for Memory Applications
Authors: Salaoru Iulia , Paul Shashi
Published: September 2012

In recent years, the interest in the application of organic materials in electronic devices (light emitting diodes, field effect transistors, solar cells), has shown a rapid increase. Polymer memory devices (PDMs) is a very recent addition to the organic electronics. The polymer memory devices can be fabricated by depositing a blend (an admixture of organic polymer, small organic molecules and metal or semiconductor nanoparticles) between two metal electrodes. We demonstrate the memory effect in the device with simple structure based on blend of polymer with different materials like ionic compound (NaCl), ferroelectrical nano-particles (BaTiO3) and small organic molecules In 2007 Paul has proposed a model to explain memory effect a switching between two distinctive conductivity states when voltage is applied based on electrical dipole formation in the polymer matrix. Here, we investigate if our memory devices based on different types of materials are fitted with the proposed model.
Multi-Component Oxide Thin Films and Heterostructures for Electronics: Growth Principles
Authors: Endo Kazuhiro , Ikenaga Noriaki , Badica P.
Published: September 2012

In the last years oxide materials for electronics show significant progress. However, many details regarding technology control of the properties have to be solved. For electronics, thin films and heterestructures are important taking advantage of integration and synergetic concepts leading to new types of devices and functionalities. It is notable that, while fabrication of new devices and materials showing new phenomena are booming, the growth principles and concepts are somehow developing slowly within this general trend. This is because in many cases, growth of materials is very personalized. Understanding of the bi-directional relationship between the general and particular principles deserves attention. The immediate benefit is that knowledge on growth for one material can be transferred to another one. In our work we have analyzed such relationships for some oxide multicomponent perovskites. Materials used in our examples are Bi-Sr-Ca-Cu-O and YBa2Cu3O7, (Ca, Sr)CuO2, (Ca, Ba)CuO2 and Bi4Ti3O12. Presented thin films or heterostructures are with c-axis and non-c-axis orientations and based on these examples we discuss some of the growth principles.
Design and Optimization of Microwave Triangular Meta-Material Resonators in Coplanar Configuration
Authors: Marcelli Romolo , Proietti Emanuela , Bartolucci Giancarlo , Lucibello Andrea , de Angelis Giorgio , Muzi Gianluca , Solymosi Janos
Published: September 2012

Complementary Sierpinski Triangular Resonators (C-STR) in coplanar waveguide (CPW) configuration have been studied for microwave applications. The peculiarity of the coupled triangular structures to exhibit multiple resonances is proposed for dual and three-band purposes, to obtain efficient metamaterial-inspired unit cells for high performance microwave tunable oscillators.
In Situ CCVD Grown Graphene Transistors with Ultra-High On/Off-Current Ratio in Silicon CMOS Compatible Processing
Authors: Wessely Pia Juliane , Wessely Frank , Birinci Emrah , Riedinger Bernadette , Schwalke Udo
Published: September 2012

We invented a novel method to fabricate graphene transistors on oxidized silicon wafers without the need to transfer graphene layers. By means of catalytic chemical vapor deposition (CCVD) the in-situ grown monolayer graphene field-effect transistors (MoLGFETs) and bilayer graphene transistors (BiLGFETs) are realized directly on oxidized silicon substrate, whereby the number of stacked graphene layers is determined by the selected CCVD process parameters. In-situ grown MoLGFETs exhibit the expected Dirac point together with the typical low on/off-current ratios between 16 (hole conduction) and 8 (electron conduction), respectively. In contrast, our BiLGFETs possess unipolar p-type device characteristics with an extremely high on/off-current ratio up to 1E7 exceeding previously reported values by several orders of magnitude. We explain the improved device characteristics by a combination of effects, in particular graphene-substrate interactions, hydrogen doping and Schottky-barrier effects at the source/drain contacts as well. Besides the excellent device characteristics, the complete CCVD fabrication process is silicon CMOS compatible. This will allow the usage of BiLGFETs for digital applications in a hybrid silicon CMOS environment.
Two Dimensional Graphene/h-BCN Based Devices with Large Ion/Ioff Ratio for Digital Applications
Authors: Fiori Gianluca , Bruzzone Samantha , Iannaccone Giuseppe
Published: September 2012

We present a performance assessment of graphene/hexagonal Boron Nitride heterojunctions based transistors able to provide large current modulation. The study is performed by means of a multi-scale approach leveraging ab-initio simulations to capture the physics at the atomic scale, and tight-binding simulations to compute transport. In particular, we focus on two technological solutions, a vertical and a planar structure both able to provide large Ion/Ioff ratios. As we will show, due to reduced capacitative coupling, the planar structure outperforms the vertical device as far as digital applications are concerned.
Thermoelectric Generating Properties of Aurivillius Compounds
Authors: Kohri Hitoshi , Yagasaki Takayoshi
Published: September 2012

Thermoelectric generator is expected as an independent source, an energy converter for co-generation with Refuse Derived Fuel (RDF) and so on. Thermoelectric materials were required high Seebeck coefficient, low electrical resistivity and low thermal conductivity. Thermoelectric oxides are suitable at the high temperature range because of chemical stability. Authors focus attention on Aurivillius compounds. The Aurivillius compounds consist of Perovskite layers and Bi-O layers. It is expected that nano-layered structure shows high Seebeck coefficient due to the quantum confinement of electron in Perovskite layers. It was reported that the Seebeck coefficient of Aurivillius phase Bi2VO5.5 was high value of -28.3 mVK-1 at 1010 K, and the electrical resistivity of the one was also high value of 0.033 Ωm at 1010 K. We investigated about element substitution effects at V site on thermoelectric properties. Bi2V1-xMxO5.5 (M=Cu, Cr, x=0, 0.05, 0.1, 0.2) were prepared by solid-state reaction and hot pressing. From the results of the electrical resistivities and the Seebeck coefficients, Cu and Cr behaved as acceptor to Bi2VO5.5. Cr was effective for reducing the thermal conductivity of Bi2VO5.5. The maximum value of dimensionless figure of merit for Bi2VO5.5 was 0.06 at 910 K.
Phoretic Deposition of Graphene on Manganese-Cobalt Oxide Composites for Supercapacitor Electrodes
Authors: Gutierrez Daniel H. , Lake John , Javier Cristina , Cheng Arthur , Tanaka Zuki , Londoño Nicolas J. , Chen Bin
Published: September 2012

Great focus has been directed towards double-layer capacitance and Faradic, redox reactions because of their long device lifetimes and their high power densities, respectively. Our novel approach to combining these mechanisms in a tri-layered composite electrode promises to increase the energy densities of the device, without sacrificing the supercapacitance and the high power densities attributed with it. Initial analysis of the interfacial interactions of graphene oxide (GO) and manganese oxide (MnO2) were promising. This paper aims to further demonstrate the tri-layered composite by forming a layer of reduced graphene oxide (rGO) on MnO2 nanowires and cobalt oxide nanorods. We have successfully created the first of a kind supercapacitor electrode material as a scalable device. In this paper, in addition to analysis of the composite electrode, we present modifications to the traditional electrophoretic deposition process and optimizations to the thermal reduction of GO in order to create rGO surfaces on substrates that are normally difficult to adhere it to.
pH-Responsive Hyperbranched Copolymers from One-Pot RAFT Copolymerization of Propylacrylic Acid and Poly(ethylene glycol diacrylate)
Authors: Tai Hong Yun , Duvall Craig L. , Stayton Patrick S. , Hoffman Alan S. , Wang Wen Xin
Published: September 2012

pH-Responsive polymers have attracted much attention for biotechnology applications as carriers or matrix to facilitate intracellular or extracellular therapeutic drug delivery and release. In this paper, we report the development of new pH-responsive and hyperbranched copolymers with potential for such applications. These pH-responsive hyperbranched copolymers were synthesized via one pot reversible addition-fragmentation chain transfer (RAFT) copolymerization of propylacrylic acid (PAA) and a branching co-monomer poly(ethylene glycol diacrylate) (PEGDA) (Mn=258 Da) at the monomer feed molar ratios [PAA]0/[PEGDA]0 = 99/1, 90/10 and 80/20. The resultant poly(PAA-PEGDA) copolymers were characterized by Proton Nuclear Magnetic Resonance (1H NMR) and Gel Permeation Chromatography (GPC) to obtain the molecular weight, copolymer composition and degree of acrylate functionality. The hydrodynamic dimensions of these copolymers at pH range between 5.0 and 7.4 were studied using Dynamic Light Scattering technique (DLS). Moreover, these hyperbranched copolymers demonstrated composition- and size-dependent membrane disruptive properties by red blood cell hemolysis assay. Poly(PAA-PEGDA) with the copolymer composition [PAA]/[PEGDA]= 68/32, obtained from the copolymerization at the monomer feed molar ratio [PAA]0/[PEGDA]0 = 99/1, demonstrated significant membrane disruptive activity.
Dielectric Properties of Ba1-xLaxTi1-x/4O3 Ceramics with Different La3+ Content
Authors: Wodecka-Dus Beata , Adamczyk Malgorzata , Osinska Katarzyna , Plonska Malgorzata , Czekaj Dionizy
Published: September 2012

Subscript textIn the present research n-doped BaTiO3 compositions, with lanthanum contents x=0, 0.1, 0.3 and 0.5mol% were prepared by the free sintering method, at temperature T=1350°C for 2 h. The EDS investigations showed that samples exhibited conservation of stoichiometry according to the chemical composition formula. Morphology of the ceramic material was observed by scanning electron microscopy, whereas the crystalline structure was studied by X-ray diffraction method. Influence of La3+ doping on dielectric properties of Ba1-xLaxTi1-x/4O3 ceramics was studied in temperature range T=20-260°C, and frequency f=100Hz-1000Hz by the Precision LCR meter Agilent E4980A. The results show a decrease of Tm with lanthanum addition. The degree of diffuseness of phase transition is more pronounced for high La content, implying the existence of a composition-induced phase transition of the ceramics. Ceramics showed maximally enhanced dielectric permittivity around phase transitions, which are the phase transitions of the pure BaTiO3.
Ethanol Induced Shape Recovery and Swelling in Poly(methyl methacrylate) and Applications in Fabrication of Microlens Array
Authors: Zhao Yong , Wang Chang Chun , Huang Wei Min , Purnawali Hendra
Published: September 2012

The transportation phenomenon of ethanol in pre-deformed poly(methyl methacrylate) (PMMA) is systematically investigated. Two different phenomena simultaneously occur during this process. One is shape recovery, which is resulted from the ethanol induced softening and plasticization of PMMA. The other is swelling, which is produced by the ethanol induced molecular relaxation. Based on this study, a novel surface patterning method is proposed to fabricate PMMA microlens arrays in a simple and cost-effective manner.
Recent Progress in Disposable Ion-Selective Sensors for Environmental Applications
Authors: Matzeu Giusy , Zuliani Claudio , Diamond Dermot
Published: September 2012

Solid-contact Ion Selective Electrodes (SC-ISEs) for the detection of lead are prepared on screen printed substrates in order to have low-cost and disposable sensors which may be useful in long-term environmental monitoring. It is shown that the materials used as solid contact layer, the deposition techniques and their thickness affect greatly the performances of the sensors. Poly(3-octylthiophene-2,5-diyl) (POT) and poly-3,4-ethylenedioxithiophene (PEDOT) are employed in this investigation. A trend showing an optimum is found for sensors prepared with POT as the batch reproducibility depends on the amount drop-cast, i.e., thickness. In case of PEDOT which is grown amperometrically the trend is more complex but an optimum for the batch reproducibility is again found depending on the current density. In the latter case, the film thickness and the overoxidation degree of the polymer probably concur in determining a more complex relationship.
Enhanced Piezoelectric Properties of Electrospun Poly(vinylidene fluoride)/ Multiwalled Carbon Nanotube Composites
Authors: Ahn Yong Jin , Im Joon Young , Seo Yong Sok , Hong Soon Man
Published: September 2012

We prepared poly(vinylidene fluoride)/multiwalled carbon nanotube (MWCNT) nanocomposites using electrospinning process and investigated its effect on the polymorphic behavior and electroactive properties. The remanant polarization and piezoelectric response increased with the the amount of MWCNT and piezoelectric -phase crystal. Interfacial interaction between MWCNT and PVDF caused high degree of -phase derived from external stretching.
A Model Reference Adaptive Control of a Magnetorheological Fluid Brake
Authors: Russo Riccardo , Terzo Mario
Published: September 2012

The paper describes an experimental/theoretical activity that involves a magnetorheological fluid brake (MRFB). The variability affecting the plant parameters suggests the employment of a model reference adaptive control finalized to regulate the braking torque. This feedback control method is able to minimize the tracking error in presence of a plant characterized by a known dynamics and uncertain parameters. Numerical simulations have been carried out and the obtained results confirm the goodness of the proposed approach.
Devices for Rehabilitation Applications
Authors: Pittaccio Simone , Viscuso Stefano , Garavaglia Lorenzo
Published: September 2012

Recent research is showing that Shape Memory Alloys (SMA) can be advantageously employed for a number of applications in Rehabilitation Medicine and the related field of Neuroscience. This innovative use of SMA was investigated with the specific aim of improving the treatment approach to neurological patients with sequelae from stroke, traumatic brain injury, cerebral palsy, etc. Several examples of devices built for this purpose will be presented together with an outline of the reasons why the shape-memory and pseudoelastic effects can be regarded as interesting resources on account of scientific, technical and clinical reasons. In particular the design and functioning of an SMA-based ankle exerciser and pseudoelastic repositioning splints for the upper and lower limbs will be discussed in relation with results of neurophysiologic and clinical tests. The main observations so far suggest that this type of devices is able to support patients’ physical rehabilitation by adapting to changing conditions and needs during functional recovery. Furthermore, due to their improved tolerability relative to traditional treatments SMA devices can be used for longer times and tend to produce interesting effects in the control of spastic syndromes.
Design of a Solid State Shape-Memory-Actuator with Guidance Functionality
Authors: Pagel Kenny , Bucht Andre , Drossel Welf-Guntram , Neugebauer Reimund
Published: September 2012

Machine tools for small work pieces are characterized by an extensive disproportion between workspace and cross section. This is mainly caused by limitations in the miniaturization of drives and guidance elements. Due to their high specific workloads and relatively small spatial requirements, Thermal Shape-Memory-Alloys (SMA) possess an outstanding potential to serve as miniaturized drives in small machines. However, most of the known SMA drive applications necessitate additional guidance elements to realize a certain mechanical stiffness. In this paper we present a novel SMA actuator design, which does rather not require an additional guidance. The stiffness in directions different from the actuators moving direction is realized by a specific arrangement of the SMA elements. Those are designed regarding geometry, applied load, and control aspects. Furthermore, a sample actuator is built to investigate the capabilities to serve as miniaturized feed axis in small machines.
Functional Fatigue of NiTi Shape Memory Wires under Assorted Loading Conditions
Authors: Scire' Mammano Giovanni , Dragoni Eugenio
Published: September 2012

The rational design of shape memory alloy (SMA) actuators requires reliable data on the fatigue strength of the material under cyclic thermal activation (functional fatigue). Test results on SMAs under functional fatigue are scarce in the technical literature and the few data available are mainly limited to constant-stress loading. Since the SMA elements used within actuators are normally biased by elastic springs or by another SMA element, their stress state is far from constant in operation. The mismatch between actual working conditions and laboratory arrangements leads to suboptimal designs and undermines the prediction of the actuator lifetime. This paper aims at bridging the gap between experiment and reality. Four test procedures are planned, covering most of the typical situations occurring in practice: constant-stress, constant-strain, constant-stress with limited maximum strain and linear stress-strain variation. The paper describes the experimental apparatus specifically designed to implement the four loading conditions and presents fatigue results obtained from commercial NiTi wires tested under three of the four protocols.
Modelling of Shape Memory Alloy Negator Springs for Long-Stroke Constant-Force Actuators
Authors: Spaggiari Andrea , Dragoni Eugenio
Published: September 2012

The paper deals with the analytical modelling of a shape memory alloy Negator spring. Negator springs are spiral springs made of strip metal wound on the flat with an inherent curvature such that, in repose, each coil wraps tightly on its inner neighbour. This configuration allows a constant force mechanical response and very long strokes, limited mainly from the total length of the spring. The authors investigate the behaviour of the spring made of a shape memory alloy (SMA). The intrinsic characteristic of SMA is to have two different elastic moduli at different temperatures. This difference can be exploited in order to have a net actuation force for the entire very long stroke, overcoming the two major drawbacks of the SMA actuators, short strokes and output force which varies linearly during the travel.
Theoretical Study of Magnetic Properties and Twin Boundary Motion in Heusler Ni-Mn-X Shape Memory Alloys Using First Principles and Monte Carlo Method
Authors: Kostromitin Konstantin I. , Buchelnikov Vasiliy D. , Sokolovskiy Vladimir V. , Entel Peter
Published: September 2012

In this paper we firstly propose and study a microscopic model of twin boundary motion in the Heusler Ni-Mn-X (X= Ga, In, Sb, Sn) alloys on real tetragonal lattice using the first principles and Monte Carlo simulations. The two variants of the low temperature martensite which divided by twin boundary are considered. The Heisenberg model for magnetic subsystem and the Blume-Emery-Griffiths (BEG) one for structural subsystem with magnetostructural interaction between these subsystems are used. The influence of external magnetic field and anisotropy on the twin boundary motion is studied. It is shown that proposed model gives the picture of twin boundary motion as in experiments.
Low Temperature Crystallization of Sputter-Deposited TiNi Films
Authors: Kishi Yoichi , Ikenaga Noriaki , Sakudo Noriyuki , Yajima Zenjiro
Published: September 2012

We have found that deposited film can be crystallized without the post-annealing treatment but with the simultaneous ion-irradiation during sputter-deposition at very low substrate temperature. The present paper reviews the low temperature crystallized TiNi films deposited by the above technique. An RF magnetron sputtering apparatus equipped with separate confocal sources as well as with a heating and ion-irradiating system for substrates was used to make the films crystalline. Without using the ion-irradiating system, the films deposited on ambient-temperature substrate have been amorphous. However, crystallized film is deposited even at 353 K of substrate temperature with using the system. Appropriate ion-irradiation is considered to be help to crystallize the film at low substrate temperature. Broad and doublet X-ray diffraction profile of the film, which was diffracted from B19’ and/or R phase, was recorded between 42 degree to 45 degree in 2 theta. The crystallized film deposited on a polyimide sheet was cut into the shape of a double-beam cantilever and the ends of the two beams were connected to an electrical power supply. The cantilever shows a repeatable two-way motion by electrical cycle of 0.1 Hz at room temperature.
Synthesis of Crystallized TiNi Films by Ion Irradiation
Authors: Ikenaga Noriaki , Kishi Yoichi , Yajima Zenjiro , Sakudo Noriyuki
Published: September 2012

TiNi is well known as a typical shape-memory alloy, and is expected to be a promising material for micro actuators. In order to realize micro electro mechanical systems (MEMS) with this material, we have to get thin crystal film of the material, since the shape-memory property appears only when the structure is crystalline. In our previous studies we developed a new apparatus as well as a new deposition process for lowering the crystallization temperature by using ion irradiation. In addition, we have found that the deposited film by the process can be crystallized at very low temperature (below 473 K) without annealing but with simultaneous irradiation of Ar ions during sputter-deposition. In this study, we aim for the realization of crystallized TiNi film, which is deposited on Si substrate below 373 K substrate temperature. In order to realization the purpose, we have revealed the effect of Ar ion energy on lowering the crystallization temperature. The ion energy is measured with a quadrupole mass spectrometer (QMS) having an ion energy analyzer. The deposited TiNi films are examined with an X-ray diffraction (XRD). We found the plasma potential against the reactor chamber is important to be considered in the ion irradiation energy. The effects of ion energy for the crystallization of TiNi film are discussed.
Characteristic Electrical Actuation of Plasticized Poly(vinyl chloride): Various Electrical Functions in Relation with the Dielectric Plasticizers
Authors: Hirai Toshihiro , Ali Mohammad , Ogiwara Takafumi , Tsurumi Daijiro , Yamamoto Keiichi , Ueki Takamitsu , Xia Hong , Hashimoto Minoru
Published: September 2012

Poly(vinyl chloride) (PVC) has been found to be actuated by applying dc electric field, accompanying colossal strain on the anode surface, particularly when plasticized with large amount of plasticizer [1]. We call the plasticized PVC as PVC gel for convenience in this paper. The deformation has been explained only phenomenologically. However, impedance spectroscopy revealed recently the some fundamental mechanism of the actuation, that is, the deformation depends on the dielectric nature of the materials. The colossal increase of dielectric constant was induced in the gel in the low frequency range. The dependency is strongly depends on the nature of the plasticizer and its content. The phenomena observed as electrical actuation of the PVC gels were (1) Creep deformation on the anode surface, (2) Creep induced bending motion, (3) Tacking to the anode, (4) Contractile deformation, and (5) Vibrational motion by dc electric field application. Creep deformation and the excellent transparency of the gel can be utilized for focus controllable lens. Tacking force can be applied various in combination with bending deformation. Bending actuator has been successfully applied micro-finger actuator and passed for hundreds thousands times continuous operation. In this paper, we will introduce not only the various features of the actuation, but also will get into the some detailed mechanism of the deformation.
One Actuator and Several Sensors in One Device with only Two Connecting Wires: Mimicking Muscle/Brain Feedback
Authors: Otero Toribio F. , Martinez Jose Gabriel , Valero Laura , Asaka Kinji , Ismail Yahya A.
Published: September 2012

Artificial muscles based on conducting polymers, fullerene derivatives, carbon nanotubes, graphenes or other carbon derivative molecular structures are electrochemomechanical actuators. Electrochemical reactions drive most of the volume variation and the concomitant actuation. So under flow of a constant current, any working or surrounding variable influencing the reaction rate will be sensed by the muscle potential, or by the consumed energy, evolution during actuation. Experimental results and full theoretical description will be presented. The muscle potential is a well defined function of: driving current, volume variation (external pressure or hanged masses), temperature and electrolyte concentration. While working artificial muscles detect any change of whatever of those variables by changing either its potential or its consumed energy evolution. Experimental changes fit those predicted by the theoretical description. Only two connecting wires contain, simultaneously, actuating (current) and sensing (potential) signals. Those constitute new feedback intelligent and biomimetic devices opening new technological borders and mimicking natural muscles/brain communication.
Effect of Crack Formation on Stretchable Silver Electrode for Dielectric Elastomer Actuators
Authors: Low Sze Hsien , Lau Gih Keong
Published: September 2012

Thin metal films are not commonly used electrodes for dielectric elastomer actuators as it is a common presumption that they are too stiff to allow large actuated strains. However, using thin metal film electrodes can improve reliability due to their ability to self heal, as shown from their use in metalized plastic film capacitors. Typically, from literature, actuated area strains do not exceed 10% when using thin, un-patterned, metal films formed by sputtering. However, in this present work, large actuated area strains of up to 50% have been demonstrated. This was accomplished by using thin silver film electrodes formed by electroless deposition, and it has been noticed that micro-cracks were present in such electrodes. In this paper, micro-cracks in thin silver electrodes are studied and compared against sputtered silver electrodes. This includes the study of the manner in which they affect the magnitude of actuated strain and the repeatability of the actuator. It has been found that the cracks have helped to improve actuated strain, yet did not affect repeatability, as the cracks did not propagate in subsequent activations. Instead, the cracked electrodes had reached a sort of “steady-state”
Adhesion between Polydimethylsiloxane Layers by Crosslinking
Authors: Yu Li Yun , Daugaard Anders Egede , Skov Anne Ladegaard
Published: September 2012

Adhesion between two surfaces may be strongly improved by chemical crosslinking of the interfaces. Polydimethylsiloxane (PDMS) is a widely used polymer that has received considerable attention due to its unique properties, such as relatively low price, biocompatibility, flexibility, high thermal stability, and outstanding dielectric properties. The excellent performances of PDMS elastomers enable the realization of pneumatic, electromagnetic, and thermal actuators. In this work, two-layered PDMS films were adhered together by different mixtures of crosslinkers. The double-layered films were investigated by rheology and microscopy. The objective of this work was to create adhesion of two layers without destroying the original viscoelastic properties of the PDMS films.
PEDOT Based Conducting IPN Actuators: Effects of Electrolyte on Actuation
Authors: Plesse Cedric , Khaldi Alexandre , Soyer Caroline , Cattan Eric , Teyssié Dominique , Chevrot Claude , Vidal Frédéric
Published: September 2012

Actuators from conducting IPNs architecture are described. The electroactive materials are based on several PEO/elastomer IPNs as solid polymer electrolytes in which the conducting polymer Poly(3,4-ethylenedioxythiophene) (PEDOT) is gradually dispersed, i.e. its content decreases from the outside towards the centre of the film. Influence of the electrolyte on the actuation properties has been studied. Moreover, the effect of actuator thickness has been investigated. It is shown that the decrease of the thickness leads to fast response systems presenting large deformations at frequencies above 100 Hz.
EAP-Actuators with Improved Actuation Capabilities for Construction Elements with Controllable Stiffness
Authors: Henke Markus , Sorber Jörg , Gerlach Gerald
Published: September 2012

This contribution considers an actuator based on Electroactive Polymers (EAPs) which is used for constructional elements with controllable stiffness. The actuator consists of a Danfoss PolyPower EAP-foil and a supporting structure which applies the necessary pre-straining force to the foil. Usually, such structures have a constant spring stiffness which strongly limits the actuation range. The novel actuator shows a highly nonlinear spring stiffness for pre-straining the foil. Therefore, the pre-straining force is nearly constant all over the entire actuation range. This behavior can be used to double the possible actuation range. Such structures are suitable to be used in construction elements with variable stiffness. The contribution shows the basic function of this actuator and its capabilities for the application in new smart, self-sensing and self-controlling composite materials for lightweight constructions. The theoretical background of highly nonlinear spring stiffness is discussed and transferred to the developed structures. The theoretical calculations are based on analytic calculations and finite element analyses and are verified by experimental set-ups consisting of different actuators both with constant and highly nonlinear pre-straining spring constant.
Organic Robotics Based on Conducting Polymers
Authors: Okuzaki Hidenori
Published: September 2012

Free-standing films made of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) were prepared by casting water dispersion of its colloidal particles. Specific surface area, water vapor sorption, and electro-active polymer actuating behavior of the resulting films were investigated by means of sorption isotherm, and electromechanical analysis. It was found that the non-porous PEDOT/PSS film, having a specific surface area of 0.13 m2/g, sorbed water vapor of 1080 cm3(STP)/g, corresponding to 87 wt%, at relative water vapor pressure of 0.95. A temperature rise from 25 to 40 °C lowered sorption degree, indicative of an exothermic process, where isosteric heat of sorption decreased with increasing water vapor sorption and the value reached 43.9 kJ/mol, being consistent with the heat of water condensation (44 kJ/mol). Upon application of 10 V, the film underwent contraction of 2.4% in air at 50% relative humidity (RH) which significantly increased to 4.5% at 90% RH. The principle lay in desorption of water vapor sorbed in the film due to Joule heating, where electric field was capable of controlling the equilibrium of water vapor sorption.
Smart Textiles: A Strategic Perspective of Textile Industry
Authors: Affatato Lorena , Carfagna Cosimo
Published: September 2012

Comfort is a state of mind affected by many factors, and clothing has contributing to the well being of man, changing in some cases his customs. Since the origin, the primary functions of clothes have been of protection against cold or in general against environmental stimuli. New functions are required to modern textiles: wearing comfort, durability, cleaning properties, optimized functionality for specific applications (workwear, sportswear, medical wear). Smart and interactive textiles represent a budding interdisciplinary field that brings together specialists in information technology, micro systems, materials engineering, and production technology. The focus of this new area is on developing the enabling technologies and fabrication techniques for the economical production of flexible, conformable and large-area textile- based information systems that are expected to have more applications for different end users. The smart and interactive textiles will be highly applied in the next generation of fibres, fabrics and items produced from them. Application of smart textiles can be now found everywhere. The market and the business of wearable, interactive and smart textiles are presently changing the basis of the textile industry. The changes are dynamic knowledge transfer, innovative systems, new employment opportunities in the smart industries and others. Business possibilities are not limited to the textile industry, but they can be found in almost any line of business. The European textile sector is one of the mainstays of the European Manufacturing Industry. The market for smart textiles is one of the most dynamic and fast growing sectors and offers huge potential for companies.
Thigmo-Morphogenetic Fiber Composites Embedded with Shape Memory Alloys
Authors: Mingallon Maria , Ramaswamy Sakthivel
Published: September 2012

The premise of this research is to integrate sensing and actuation functions into a fibre composite material system. Fibre composites, which are anisotropic and heterogeneous, offer the possibility for local variations in their material properties. Embedded fibre optics are herein used to sense, while shape memory alloys provide actuation capabilities to the resulting composite. The definition of the geometry, inspired by the organization strategies found in biological composites, complements the functioning of the adaptive material system at both local and global levels, allowing it to display integrated functionality.
Research through Design: A Way to Drive Innovative Solutions in the Field of Smart Textiles
Authors: Toeters Marina , ten Bhömer Martijn , Bottenberg Eliza , Tomico Oscar , Brinks Ger
Published: September 2012

Research through design allows creating a dialogue with the material. It uses making and reflection on action as a generator of knowledge. Our aim is to explore the opportunities and challenges of smart textiles. The Fablab is our set up, a place that allows us to combine the hacking- scientific-, and design community. It stimulates collaboration and the knowledge exchange needed for the development of smart textile systems. A collaborative prototyping workshop for medical products combined two worlds. The textile world in Saxion aims at incorporating conductive materials into textile structures and functional- / 3D printing to create systems for applications such as flexible heating systems and wearable technology. We combined this with the world of Industrial Design at TU/e, focused on the design of intelligent products, systems and services by the research through design approach. The collaboration between these different disciplines speeded up the process by reducing the resistance to the new and skipped the frustration on failure.
Two Novel Techniques of Fabric Sensing Using Carbon Nanofibers
Authors: Santos Ana , Arquer Pablo , Prado Marta , Merino Maria Pilar , Ruiz Bernardino
Published: September 2012

Silver or copper coatings printed in fabric have shown good electrical conductivity, an essential property in wearable electronics, however they have problems when stretched due to their fragility. On the other hand, carbon nanofiber or nanofiber-silver nanocomposites dispersed in polymeric matrices can combine high electrical conductivity with exceptional stretching properties. The use of carbon nanofiber based ink as smart textile electrodes is demonstrated in this paper by using two novel sensing methods. The first method achieves wide range pressure measurements, being able to measure the pressure on the printed sensor from soft caress to hard press. This feature allows the implementation of an artificial skin that could be used in robots or in toys for children or disabled people. The second detection method has been designed for user distinction, allowing permission control. Technical prototypes have been developed to prove the above concepts.
Durable Self-Healing Super-Liquid-Repellent Fabrics
Authors: Wang Hong Xia , Zhou Hua , Lin Tong
Published: September 2012

In this study, fabrics having a superhydrophobic and superoleophobic surface were prepared by a wet-chemistry coating technique using a coating solution containing hydrolyzed fluorinated alkyl silane and fluorinated-alkyl polyhedral oligomeric silsesquioxane. The coating shows remarkable self-healing superhydrophobic and superoleophobic properties and excellent durability against UV light, acid, repeated machine washes, and severe abrasion.
The Concept of Mood Changing Garments Made from Luminescent Woven Fabrics and Flexible Photovoltaics “MoodWear”
Authors: Stylios George K. , Yang Dan Ying
Published: September 2012

In this project, solar harvesting and sound sensing are inputs for energy and mood, whilst power consumption for electronic devices and colour changing through lighting are the corresponding outputs. Between each set of input and output, there are key steps in processing, computing and testing which determine the working of the system. Purposed built printed-circuit boards (PCBs) are designed and made by integrating, programming and implementing ICs. For the energy system, a PCB is required for storing and conditioning the power from the PVs, and it uses a programmable microcontroller to decode the wearer’s mood intelligibly through a microphone in the information system. In this paper, the operation of the SMART clothing photonic system named “MoodWear” in energy harvesting and mood changing will be described, and the garment collection will be presented.
Integration of Small Diameter Wire Form SMA for the Creation of Dynamic Shape Memory Textiles
Authors: Dyer Patrick
Published: September 2012

The integration of Nitinol wire directly into flexible textile structures has seen limited successful research outcomes. This has mainly been due to issues with shape training and the accurate positioning of the Nitinol components. A new approach is investigated here, which utilises small diameter (0.15mm - 0.10mm) Nitinol components and the manipulation of the woven structure. This combined approach has the potential to improve the dynamic control of the resulting textiles, giving the textile designer further latitude to adapt a combination of functional and visual properties, as well as expanding application possibilities. This investigation focuses on the development of composite samples that integrate Nitinol directly into woven cotton, Kevlar, polyester and polypropylene textiles, demonstrating the potential for medical and healthcare applications. The prototype composite textiles developed, investigate a range of controlled surface manipulations as well as larger scale shape changes, including the creation of arced forms, pleating, expansion and compression. With supporting data, the evaluation of these samples explores the potential of integrating small diameter Nitinol wires into woven structures and the resultant levels of shape transfer, control and cyclic speed achievable.
Development of Paper Transistor Using Carbon-Nanotube-Composite Paper
Authors: Kawamura Yusuke , Hayashi Shunsuke , Shinde Yuya , Oya Takahide
Published: September 2012

We have developed a unique “paper transistor” comprised of carbon nanotube (CNT) composite papers. CNTs have recently attracted much research attention in the nanotechnology field due to their many excellent physical properties, including good electrical and heat conductivities, physical strength, and dual semiconducting- and metallic- characteristics. CNTs have great potential for use as many different functional materials. In a previous work, we developed a CNT-composite paper as a new functional material. A normal paper is flexible and can be fabricated and used easily, and we can easily fabricate the CNT-composite paper by mixing pulp with CNTs. The resulting CNT-composite paper has both CNT and normal paper characteristics. In this study, we focused primarily on the dual semiconducting- and metallic- characteristics exhibited by CNTs because we can create paper composites that are both semiconducting and metallic. Our main goal was to develop a field-effect-transistor (FET) using semiconducting- and metallic- CNT-composite papers. A conventional FET has metal, insulator, and semiconductor layers. Our FET also has three layers: the metallic CNT-composite paper is used for gate, source, and drain electrodes as the metal layer; the semiconducting CNT-composite paper is used for a semiconductor as the channel layer; and the normal paper is used as a gate insulator layer. The key point here is that we were able to design and develop an FET using only normal paper and two kinds of CNT-composite paper, without any silicon or semiconductors. After the construction, we measured the electrical conductivity of our FET to test its operation. A drain-to-source current of about 10μA was observed. Moreover, we could control the current flow by controlling the gate voltage. These results demonstrate that it is possible to fabricate a paper FET using only normal paper and two kinds of CNT-composite paper.
Textile Sensor Applications with Composite Monofilaments of Polymer / Carbon Nanotubes
Authors: Ferreira Alexandre , Ferreira Fernando , Paiva M. Conceição
Published: September 2012

Polymer/carbon nanotube (CNT) composite monofilaments were produced and tested for sensing activity. Polylactide (PLA) was the polymer selected for humidity sensing, while a mixture of polypropylene (PP) and poly(ε-caprolactone) (PCL) was used for temperature sensing. The PP/PCL/CNT composite filaments developed a co-continuous structure with CNT localized in the PCL phase. The filaments were characterized in terms of tensile properties and electrical resistivity. Textile fabrics were produced with both types of filaments. The electrical resistance of the fabrics subjected to humidity or temperature variations was measured in a climatic chamber.
New Viscosity Data for CuO-Water Nanofluid – The Hysteresis Phenomenon Revisited
Authors: Nguyen Cong Tam , Galanis Nicolas , Maré Thierry , Eveillard Erwan
Published: September 2012

In the present work, we have experimentally investigated the stability and hysteresis behaviors of CuO-water nanofluid when submitted to a repeated heating and cooling process. Data has shown that for a low particle volume concentration, 1.6% in particular, the hysteresis phenomenon did not occur for the temperature range considered. For a higher particle concentration, 5% in particular, the hysteresis behaviour was clearly observed when fluid temperature exceeded 52°C approximately. Beyond this critical temperature, the nanofluid viscosity has increased, and such an increase even continued with a decrease of temperature during the cooling phase. Subsequent measured viscosity and observations in laboratory after the first occurrence of the hysteresis phenomenon have confirmed that the alterations on the particle suspension and on the nanofluid stability appear indeed permanent. Such alterations were found to worsen with further heating/cooling cycles.
Novel Plasmonic Bio-Sensing System Based on Two-Dimensional Gold Patch Arrays for Linear and Nonlinear Regimes
Authors: Grande Marco , Vincenti Maria Antonietta , Stomeo Tiziana , Bianco Giuseppe Valerio , de Ceglia Domenico , Morea Giuseppe , Marani Roberto , Marrocco Valeria , Petruzzelli Vincenzo , de Vittorio Massimo , Bruno Giovanni , Scalora Michael , d'Orazio Antonella
Published: September 2012

We propose a novel bio-sensing platform based on the observation of the shift of the leaky surface plasmon mode that occurs at the edge of the plasmonic band gap of metal gratings based on two-dimensional gold nano-patch arrays when an analyte is deposited on the top of the metallic structure. We detail the numerical analysis, the fabrication and the characterization of these two-dimensional arrangements of gold patches in linear regime showing that sensitivity of our device approaches a value of 1000 nm/RIU with a corresponding Figure of Merit (FOM) of 222 RIU-1. We provide experimental proof of the sensing capabilities of the device by observing colour variations in the diffracted field when the air overlayer is replaced with a small quantity of Isopropyl Alcohol (IPA). Effects of technological tolerance such as rounded corners and surface imperfections are also discussed. We also report proof of changes in colour intensities as a function of the air/filling ratio ad periodicity and discuss how they can be obtained by diffracted spectra. Finally we report the numerical and experimental investigation of the non-linear behaviour of the device highlighting the Surface Enhanced Raman Scattering (SERS) performance.