Day 2 :
- Nano Materials and Sensors & Synthesis of Smart Materials
Location: Flamingo-2
Chair
Mogens Brøndsted Nielsen
University of Copenhagen, Denmark.
Session Introduction
Mogens Brøndsted Nielsen
University of Copenhagen, Denmark
Title: From light-controlled molecular electronics devices to solar energy storage materials
Time : 10:00-10:30
Biography:
MOGENS BRØNDSTED NIELSEN, PhD, is Professor of Organic Chemistry Department of Chemistry at the University of Copenhagen, where he teaches courses in advanced organic chemistry, heterocyclic chemistry, and supramolecular chemistry. He has published more than 100 peer-reviewed papers, monographs, and book chapters.
Abstract:
Molecular switches that can be converted between high- and low-conducting states play a central role for information storage and logic operations at the molecular level and hence for the development of molecular electronics. The 1,8a-dihydroazulene-1,1-dicarbonitrile (DHA) molecule presents an example of such a light-sensitive molecule [1]. Thus, by irradiation with light, DHA undergoes a ring-opening reaction to form a vinylheptafulvene (VHF) which in turn can return to DHA by a thermally induced ring-closure. By suitable functionalization in either the five- or seven-membered rings of DHA, the switching behavior can be finely tuned as well as the optical properties of both the DHA and VHF isomers [1]. By incorporation of sulfur end-capping groups [2], DHA molecules can be anchored to silver or gold electrodes and hence be used as molecular wires / switches for molecular electronics. This talk will present how light-controlled conductance switching has been established in different junctions [3, 4]. In addition, the higher energy of the metastable VHF isomer renders the DHA-VHF pair interesting for solar thermal energy storage systems (”solar-heat batteries”) [5]. Such systems should harvest sunlight, store the energy, and ultimately release the energy when triggered. Challenges in regard to controlled release of the energy as well as energy storage capacities will be presented.
Shingjiang Jessie Lue
Chang Gung University, Taiwan
Title: Electrospun quaternized polyvinyl alcohol nanofibers with core-shell structure and their composite in alkaline fuel cell application
Time : 10:30-11:00
Biography:
Prof. Lue obtained a B.S. and M.S. degrees from National Taiwan University, and a Ph.D. degree of Biotechnology Engineering from University of Missouri-Columbia, USA, in 1990. She joined Chang Gung University in 1996 and was promoted to a full professor in 2007. She is now the department chair of Department of Chemical and Materials Engineering at CGU. Her research interest focuses on the development of high-performance materials for separation, energy, and biotechnology applications. Prof. Lue has published nearly 65 SCI papers and 2 book chapters, given 140 conference presentations, and applied 2 patents.
Abstract:
Electrospun quaternized polyvinyl alcohol (Q-PVA) nanofibers were prepared and characterized. The as-spun nanofibers exhibited lower crystallinity than the pristine Q-PVA. The core of the fibers exhibited a more amorphous region and the outer shell contained more polymer crystals. The core-shell structure of the nanofibers provided unique ionic conduction functionality after doping with potassium hydroxide (KOH) solution. A composite consisting of 5.98% electrospun Q-PVA nanofiber mat and Q-PVA polymer matrix demonstrated enhanced ionic conductivity and suppressed methanol permeability when compared to a pristine dense Q-PVA film. Both the high conductivity and suppressed permeability were attributed to the quasi-coaxial structure of the electrospun nanofibers. The soft core of the fibers formed super ionic conductive paths, while the outer shell served as a hard sheath surrounding the amorphous core. This shell induced mass transfer resistance and created a tortuous fuel pathway that suppressed methanol permeation. Such Q-PVA composite is an effective solid electrolyte and validated using alkaline fuel cell. In a direct methanol alkaline fuel cell operated at 60°C, a peak power density of 54 mw cm–2 was obtained using the electrospun Q-PVA composite, a 12% increase compared to a cell employing a pristine Q-PVA film. These results demonstrate that super-conductive coaxial electrospun nanofibers can be prepared through a single-opening spinneret and provide an elective approach for high-performance electrolyte fabrication.
Umadevi Kandalam
Nova Southeastern University, USA
Title: A nanofibrous hydrogel for bone tissue engineering
Time : 11:15-11:45
Biography:
Umadevi Kandalam is an Assistant Professor in Department of Pediatric Dentistry, College of Dental Medicine, Nova Southeastern University, Fort-Lauderdale, FL. She obtained her Doctoral degree in biology and has been pursuing her research in the niche areas of stem cell biology, signaling mechanisms and tissue engineering. Recipient of several internal and external grants, she is currently engaged in establishing an injectable cell-scaffold system for the repair of the craniofacial defects
Abstract:
Therapeutic management of bone loss in craniofacial region as a consequence of trauma, tumor surgery or congenital malformation presents clinical challenge. Biomaterials play a role in interacting with cells in the formation of tissue. PuraMatrixTM is a commercially available self-assembled synthetic peptide hydrogel that is amphiphilic in nature. Under physiological conditions PuraMatrixTM, can instantly polymerize forming matrices providing three-dimensional architecture that facilitate cells growth.The objective of the study is to investigate the ability of this hydrogel to support the cell growth and osteogenic differentiation of human gingiva derived stem cells. Mesenchymal stem cells obtained from human gingival tissue were culture expanded. Proliferation of the cells encapsulated in PuraMatrixTM scaffold was observed at 1- 7 days. In vitro osteogenic differentiation of these cells was investigated at 1 and 2 weeks. The in vivo bone regeneration ability was analyzed by using anectopic bone formation in a rat model. PuraMatrixTM embedded cells were viable during the entire period of study. Significant increase in osteogenic marker-alkaline phosphatase (ALP) activity was observed in cell- gel constructs when compared with monolayer cultures. Notably cells in PuraMatrixTM showed significant up regulation of other marker genes such as collagen type 1 and osteopontin at 2 weeks of culture. Within four weeks after implantation, osteoid like structures were observed in rats. The study revealed that PuraMatrixTM scaffold enhances the ability of HGMSCs for bone regeneration
Shiquan Tao
West Texas A&M University, United States.
Title: Sol-gel derived nanomaterials for designing fiber optic gas sensors
Time : 11:45-12:15
Biography:
Dr. Shiquan Tao completed his PhD in chemistry from Hiroshima University, Japan. He is an associate professor of chemistry at West Texas A&M University with research interest in the development of fiber optic chemical/biochemical sensors for monitoring industrial processes, environmental monitoring as well as for quick detecting foodborne pathogens. Before joining the faculty at WTAMU, he was a research faculty at the Diagnostic Instrumentation and Analysis Laboratory of Mississippi State University in charge of the institute’s fiber optic sensor research program for US DOE’ Office of Science’s Environmental Management Program.
Abstract:
Sol-gel methods and sol-gel combined with micelle techniques have been developed for synthesizing nanostructured materials, including porous silica, porous tin oxide, silver nanoparticles immobilized porous silica and palladium nanoparticles immobilized porous silica. These nanostructured materials have been used in the development of fiber optic gas sensors. The sol-gel derived porous silica has been coated on surface of optical fiber core for the development of a moisture sensor. Sol-gel derived tin oxide nanoparticles have been coated on surface of a silica optical fiber having a gold jacket for sensing reducing gases (H2, CH4, CO) at elevated temperatures (300-800oC). Silver nanoparticles have been immobilized in sol-gel derived porous silica by using a thiol stabilizer. The silver nanoparticle immobilized porous silica has been coated on surface of silica optical fiber core. The exposure of such a nanomaterial coating to an ammonia-containing gas sample causes a decrease of light intensity guided through the fiber, which can be used as a sensing signal for monitoring ammonia concentration in gas samples. Palladium nanoparticles have been synthesized by using a micelle technique with Triton X-100. The formed palladium nanoparticles have been immobilized to sol-gel derived silica. The palladium nanoparticle immobilized sol-gel silica has been made into the form of an optical fiber by using a patented fiber fabrication method. This porous fiber has been tested for sensing trace hydrogen gas in air for applications at ambient temperature. This paper reports the methodologies of making the above mentioned nanomaterials, the structure of the fiber optic sensors and test results of using the sensors for monitoring trace gases in different gas samples.
Yongmei Zheng
Beihang University, China
Title: Bioinspired multi-gradient surface materials for water-collection/repellency
Time : 12:15-12:45
Biography:
Yongmei Zheng, is a professor at School of Chemistry and Environment, and Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, in Beihang University. Research interests are focused on biological surfaces and bioinspired surface materials with gradient multi-structures to realize the dynamic wetting-controlled functions. The integrating methods of physical, chemical, and nanotechnology are used to develop novel technique into fabrication of bioinspired surfaces. Wetting mechanisms, including water repellency or water collecting, droplet driving, ice-phobic, anti-icing and anti-frosting, are revealed at micro- and nano-level.
Abstract:
Biological surfaces with the gradient features in micro- and nanostructures display smart wettability such as spider silk, beetle back, butterfly wings, and plant leaf, etc. Since spider silk collect water in mist, taking on scene of large pearly droplets, we have revealed the mechanism of the cooperation between surface energy gradient and difference of Laplace pressure. Recently series of bioinspired fibers have been designed at micro- and nano-level by the developing novel techniques such as dip-coating, fluid-coating, tilt-angle coating, electrospun and self-assembly, to combine the Rayleigh instability. These bioinspired fibers take on unique abilities such as the capturing of extreme hanging-drop; the directional driving of tiny condensed droplets on photo or temperature responsive spindle-knots and joint; the heterostructured bead-on-string fiber for humidity response; the controlling of condensed droplets in directional transport in long range gradient spindle-knots. By integrative gradient features of surfaces between spider silk and beetle back, a kind of wettable star-shape pattern surface also realizes the effect water repellency rather than others. To develop the functional surface, the wettable gradients in different modes are fabricated on the high adhesive surface, thus the high adhesive surface realize the controlling of droplet spreading in directions. Otherwise, butterfly wing and plant leaf display water repellency and low-temperature superhydrophobicity. So, bioinspired surfaces with optimal micro- and nanostructures display distinctly anti-icing, ice-phobic and de-ice abilities. It is also demonstrated further that the oriented or asymmetric features on geometries at micro- and nano-level can generate the driving of droplets that is resulted from the surface energy gradient, in addition to the trapped-air in multi-structures at Cassie’s state. Especially, the superhydrophilic oriented-nanohaired surface exhibits the directional transport of drop as the surface is at high temperature. These studies are greatly significant to help to design the novel functional engineering surfaces.
Jacek Przybylski
Czestochowa University of Technology, Poland
Title: The influence of structural parameters upon static control performance of a flextensional transducer
Time : 12:45-13:15
Biography:
Jacek Przybylski is a specialist in applied mechanics. At the early stages of his work for the Czestochowa University of Technology his scholarly research interests included the reliability theory of mechanical objects and the fatigue theory. Over the last thirty years he has been mainly concerned with the stability and vibration of mechanical systems. During that period he has published his doctoral and postdoctoral theses and many technical papers and articles. He has also been conducting research into other subject areas, such as the theoretical and experimental investigations of vibration of the divergence-pseudoflutter systems, computer aided design of mobile cranes and resonance boxes of musical instruments as well as the interaction problems between the supports of truck cranes and the ground of particular rheological properties. In the last ten years his investigation has been focused on the influence of the piezoelectric actuation on the static and dynamic behavior of mechanical systems, including the geometrically non-linear systems. His work in the above areas has been published in a large number of various Polish and international highly reputable journals. Moreover, he has published as an author or co-author seven research monographs in the field. He is the author of curriculum-oriented textbooks, laboratory instructions and concepts of many laboratory and didactic stands for graduate and postgraduate students at various stages of higher education. For his scientific and didactic activities Polish Ministry of Science and Higher Education has awarded him two individual and three collective prizes. He has also been awarded twelve prizes by the Rector of CUT.
Abstract:
Flextensional actuators belong to a group of piezoelectric transducers of great practical importance. A typical flextensional transducer consists of a piezoceramic connected to a flexible structure which amplifies and changes the direction of the generated piezoceramic displacement. The process of designing a flextensional actuator leads to the construction of such a flexible structure, coupled to a piezoceramic element or piezoceramic stack, which maximizes the output displacement and generative force as a result of piezoelectric actuation. Hence, two goals must be well balanced during the development of new actuators, i.e. high output displacement, which requires adequate high structure compliance, and high generative force, which is obtainable for high structure stiffness. Topology optimization is a technique used for designing flextensional actuators which ensures fulfilling those two opposing requirements. Piezoelectric actuators combined with a hinge lever mechanism and described by Uchino exemplify such structures. In this paper, the effects of hinge flexibility, material properties and dimensional changes on the output displacement and the generative axial force of the flextensional transducer have been investigated. The actuator is composed of two rectilinear or initially deflected beams placed equidistantly from a centrally located piezoceramic rod. A link with a hinge strengthened by a rotational spring placed symmetrically on both ends of the structure is adopted as a flexible joint. A simplified analytical mathematical model has been developed on the basis of the stationary value of the total potential energy principle with the application of Bernoulli-Euler theory and von Karman non-linear strain-displacement relations. The numerical calculations show that the output displacement and internal axial force generated by both the externally distributed load and the electric field application can be manipulated easily by changing the actuator material, the distance between the beams and the rod, the amplitude of beam initial displacement as well as the flexibility of the hinge. To keep the piezoelectric rod compressed during the operation, the application of structure prestressing has been considered in the model and computations. The obtained results may have applications in the design process of such actuators.
Mikk Antsov
University of Tartu, Estonia
Title: Observation of shape restoration effect in core-shell nanowire structures
Time : 14:15-14:30
Biography:
Mikk Antsov is a second year PhD student and is currently working in the University of Tartu, Institute of Physics in the Laboratory of Nanostructured Materials. His current research involves the study of the mechanisms of nanoscale friction and the mechanical properties of different nanostructures. He has published 9 papers on these topics in reputed journals.
Abstract:
The combination of two different nanostructured materials into a heterostructure can lead to completely new novel properties, which for both materials separately is missing. One of the most interesting and promising structures in this field are core-shell materials, for example nanowires (NWs), where the core material (metal, oxide) is covered by a other material (metal, oxide). In this work, Ag-SiO2 core-shell NWs were fabricated using a known sol-gel method, where Ag NWs were covered with a uniform SiO2 layer. The enhanced mechanical properties were demonstrated via the cantilevered beam bending technique carried out in a scanning electron microscope. The improved fracture strength and resistance to fatigue were shown and compared to the bare Ag NWs. Under electron beam radiation a novel shape restoration effect was demonstrated and studied. To fully understand this phenomenon the core and shell materials were analysed separately. Mechanical tests were conducted on the empty SiO2 shells and on Ag NWs. The experimental conditions were simulated using the finite element method and the mechanisms behind the shape restoration and fracture resistance were proposed.
Qiaoyun Xie
University of Pittsburgh, USA
Title: Dynamic fracture toughness of TAC/CNTS/SIC CMCS prepared by spark plasma sintering
Time : 14:30-14:45
Biography:
Qiaoyun Xie, PhD, is the graduate researcher in the department of Mechanical Engineering & Materials Science at University of Pittsburgh. Her R&D areas focus on the micro and thermo-mechanical property degradation of nano particle/fiber reinforced composites at high strain rate dynamic loading conditions, and material model development to characterize the dynamic profile of energy absorption, damage initiation and propagation. Her recent work involved in the design, manufacturing and characterization of a new hybrid system of carbon nanotubes (CNTs) and TaC reinforced SiC ceramic composites to resist oxidation, dynamic impact and fracture damage, that for the application in aerospace turbine engines and space vehicles.
Abstract:
This study focuses on the dynamic fracture toughness of TaC and carbon nanotubes (CNTs) reinforced SiC ceramic matrix composites (CMCs), that prepared by a two-stage spark plasma sintering (SPS) technique. A high densification of 98.4% was achieved under the sintering parameter of 133oC/min, 1800oC and 90 MPa pressure. Vickers indentation was employed to measure the static fracture toughness on the polished surface of ceramic samples; SEM was applied to directly observe the crack propagation after indentation; and split Hopkinson pressure bar (SHPB) was developed to determine the dynamic fracture toughness within the ceramic samples subjected to an impact in a three-point bending configuration. The result indicated that, the dynamic fracture toughness for SiC ceramics was 4.71-8.36 MPa∙m1/2, which was higher that the quasi-static toughness of 3.88 MPa∙m1/2. It was found that SiC ceramics exhibited a more strain rate dependent property for higher strain rate. Fracture toughening mechanisms of CNTs deflection and CNTs bridging were directly observed by SEM.
Md Mamun Bin Ibne
University Kebangsaan Malaysia, Malaysia
Title: A contactless capacitive biosensor for muscle activity measurement
Time : 14:45-15:15
Biography:
Mamun Bin Ibne Reaz was born in Bangladesh, in December 1963. He received his B.Sc. and M.Sc. degree in Applied Physics and Electronics, both from University of Rajshahi, Bangladesh, in 1985 and 1986, respectively. He received his D.Eng. degree in 2007 from Ibaraki University, Japan. He is currently a Professor in the Department of Electrical, Electronic and Systems Engineering, Universiti Kebangsaan Malaysia, Malaysia involving in teaching, research and industrial consultation. He is a regular associate of the Abdus Salam International Centre for Theoretical Physics since 2008. He is also a Senior Member of IEEE. He has vast research experiences in Japan, Italy and Malaysia. He has published extensively in the area of IC Design and Biomedical application IC. He is author and co-author of more than 200 research articles in design automation and IC design for biomedical applications. He is also the recipients of more than 50 research grants (national and international).
Abstract:
As elderly population grows globally, the percentage of people diagnosed with musculoskeletal disorder (MSD) increase proportionally. Electromyography (EMG) is an important biosignal that contributes to MSD’s clinical diagnose and recovery process. Conventional conductive electrode has many disadvantages in the continuous EMG measurement application. This research has design a new surface EMG biosensor based on the parallel-plate capacitive coupling principle. The biosensor is developed by using a double-sided PCB with having one side of the PCB use to construct high input impedance circuitry while the other side of the copper (CU) plate function as biosignal sensing metal plate. The metal plate is insulated using kapton tape for contactless application. The result implicates that capacitive biosensor is capable to constantly capture EMG signal without having galvanic contact to human skin surface. However, there are noticeable noise couple into the measured signal. Post signal processing is needed in order to present a clean and significant EMG signal. A complete design of single ended, non-contact, high input impedance, front end EMG biosensor is presented in this paper.