Symposium : Q
|09:00||Novel biosensor approaches for biomedical applications|
Authors : Kohji Mitsubayashi
Affiliations : Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University
Resume : Rapid increasing of diabetes mellitus is now global problem and development of a safe and non-invasive and continuous method of blood sugar monitoring is strongly requested. We paid attention to the relationship between the tear glucose level and the blood sugar level. In this lecture, a soft contact lens type glucose sensor using biocompatible polymers will be introduced. The biosensor was designed for continuous glucose monitoring in tear fluids on eye site. In order to achieve flexibility and biocompatibility, the biosensor utilizes some functional polymers. Owing to the flexible laminar structure of the polymers, the sensor fits the rounded shape of human body and has good biocompatibility. The sensor measures the glucose concentration as a current change induced by enzyme reaction at the GOD immobilized polymer layer. In the MEMS fabrication process, film electrodes were formed on polymer substrate using sputtering method. The sensor showed linearity in glucose level of 0.05 – 3.00 mmol/l with a correlation coefficient of 0.998. The calibration range includes the reported concentration of tear glucose in normal human subject. The sensor also showed high flexibility and was soft and comfort to the touch. The sensor was attached on the rabbit eye as mentioned before and tear glucose level of the rabbit eye was monitored continuously. I will also show other novel biosensors for medical applications in this lecture.
|09:30||Electrochemical Impedance Spectroscopy analysis for a flexible Micro-Lab-on-Chip: Application for health care|
Authors : A. Baraket 1, M. Lee 1, N. Zine 1, N. Yaakoubi 2, M. G. Trivella 3, J. Bausells 4, N. Jaffrezic- Renault 1, A. Errachid 1.
Affiliations : 1; Université Claude Bernard Lyon 1, UMR 5180, 43 Bd. 11 Novembre 1918, Laboratoire des Sciences Analytiques (LSA), CPE, 69622, Villeurbanne, France. 2 ; Université du Maine UMR CNRS 6613, Bd. Olivier Messiaen 72085 LE MANS Cedex9, France. 3 ; CNR (Consiglio Nazionale Ricerche) Clinical Physiology Institute, Pisa, Italy. 4 ; Centre Nacional of Microelectronic (IMB-CSIC) Campus UAB, 08193 Bellaterra, Barcelona, Spain.
Resume : Heart failure (HF) is the most increasing cause of death in Western Countries. For that reason, together with the difficulty of having a sufficient number of donor organs, it is recognized that the device-based therapeutic approaches will assume an increasingly important role in treating the growing number of patients with advanced HF. An increasing need for a fast, real-time, and reliable medical diagnosis has led to growing interest in new point-of-care biological sensors capable of sensitive and specific detection of biomolecules . For this interest, a large study was investigated to evaluate the early stage detection of inflammation and/or sepsis markers using biosensors for HF monitoring in patients with left ventricle assisted device (LVADs). We report in the present work an original and simple method to manufacture a micro-lab-on-chip able to study electrochemical measurements for biomedical applications This micro-lab-on-chip contains eight gold micro-electrodes on a polyimide substrate (PI) which is a biocompatible and flexible polymer. The micro-electrodes were manufactured on PI by a combination of soft lithography tools  such as replica molding, micro-contact printing (µCP) and self-assembled monolayers (SAMs). To make this micro-lab-on-chip functional, a micro-fluidic system based on polydimethylsiloxane (PDMS) was sealed onto the PI substrate by chemical treatment of both PDMS micro-fluidic device and PI substrate with (3-aminopropyl)triethoxysilane (APTES). Time and cost of fabrication for this micro-lab-on-chip was very low compared to those fabricated by clean room technology. Besides the high control that can be induced during electrochemical measurements, significant benefits can be achieved using this micro-lab-on-chip regarding the small sample and reagent volumes utilized within this micro-system. Electrochemical impedance spectroscopy (EIS) was used for human IL-10 detection in this micro-lab-on-chip. This cytokine is one of many biomarkers secreted in the human body during an acute inflammation due to the implantation of a transplanted organ . EIS was chosen for this detection due to its high sensitivity towards small surface variations e.g. resistance. Cyclic voltammetry (CV) also characterized the gold micro-electrode surface properties during each micro-electrode fabrication process. Keywords: Micro-lab-on-chip, heart failure, LVAD, polymers, µCP, EIS. References:  K.M. Ainslie and T.A. Desai, Lab Chip, 8, (2008) 1864.  Y. Xia and G.M. Whitesides, Angew Chem. Int. Ed. Engl., 37, (1998) 550-575.  R. Caruso, S Trunfio, F. Milazzo, J. Campolo, R. de Maria, T. Colombo, M. Parolini, A. Cannata, C. Russo, R. Paino, M. Frigerio, L. Martinelli and O. Parodi, ASAIO Journal (2010) DOI: 10.1097/MAT.0b013e3181de3049.
|09:45||Use of biofunctionalised gold nanoparticles for enhancing enzymatic IDE biosensor response.|
Authors : W. Nouira1,2, A. Maaref2, F. Vocanson3, M. Siadat4, A. Errachid1, N. Jaffrezic-Renault1*
Affiliations : 1 Université de Lyon, Laboratoire des Sciences Analytiques : Université Claude Bernard, Lyon 1, 43 Boulevard du 11 novembre 1918, 69622 Villeurbanne, France ; 2 Laboratoire de physique et chimie des interfaces, Faculté des Sciences de Monastir, Avenue de l’Environnement, 5019 Monastir, Tunisia ; 3 Université de Lyon, F-42023 Saint-Etienne, France; CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne, France; Université de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne, France ; 4 LASC – ISEA - Université de Metz, 7 Rue Marconi, 57070 Metz, France
Resume : Conductometric biosensors based on interdigitated electrodes (IDEs) have largely been used for the detection of enzymatic substrates or enzymatic inhibitors for biomedical applications  or for environmental applications . The geometry of the IDEs takes advantage of the changing conditions on the current flow which occurs mainly very near the surface and thus shows a much higher sensitivity towards surface change compared to the conventional flat design of electrodes. The sensitivity of detection of these biosensors can be increased by using metallic nanoparticles that behaves as nanoelectrodes. Gold nanoparticles have been considered to have a wide range of potential applications including biomarkers , biosensors , molecular recognition systems  and nanoscale electronics , .… Moreover the functionalization of gold nanoparticles  may facilitate biomolecule immobilization, such as Liu who describes the layer-by-layer assembly (LbL) of ferrocene poly(ethylenimine) and gold nanoparticles . In this presentation, we have studied the possibility of using a simple conductometric transducer to elaborate the biosensor for enzyme detection. The use of functionalized gold nanoparticles allows us to immobilise the enzyme through LbL method, to amplify the conductivity variation and to enlarge the domain of detected concentrations. For example the detection limit of 2µM and the linear range from 0 to 600 μM were obtained for the urease coated nanoparticles, instead of a detection limit of 100µM without nanoparticles. The elaborated conductometric sensor can be considered as specific and can be used for other biomarker detection. The combination of biocompatible gold NPs and polyelectrolytes provides an interesting platform for sensitivity. 1 A.S. Jdanova, S. Poyard, A.P. Soldatkin, N. Jaffrezic-Renault, C. Martelet, Anal. Chim. Acta 321 (1996) 35. 2 N. Jaffrezic-Renault, S. V. Dzyadevych, Sensors 8 (2008) 2569. 3 X. Liu, Q. Dai, L. Austin, J. Coutts, G. Knowles, J. Zou, H. Chen, Q. Huo, J. Am. Chem. Soc. 130 (2008) 2780. 4 Y. Bai, H. Yang, W. Yang, Y. Li, C. Sun, Sens. Actuators B, Chem. 124 (2007) 179. 5 A. Labande, D. Astruc, Chem. Commun. (2000) 1007. 6 T. Sato, H. Ahmed, D. Brown, B. F. G. Johnson, J. Appl. Phys. 82 (1997) 696. 7 S. M. Chabane Sari, P. J. Debouttiere, R. Lamartine, F. Vocanson, C. Dujardin, G. Ledoux, S. Roux, O. Tillement, P. Perriat, J. Mater. Chem. 14 (2004) 402. 8 X. Liu, F. Wang, S. Han, L. Shi, G. Xua, Electroanalysis 22 (2010) 963.
|10:30||Graphene-based high-performance surface plasmon resonance biosensors|
Authors : Edy Wijaya, Nazek Maalouli, Rabah Boukherroub, Sabine Szunerits, Jean-Pierre Vilcot
Affiliations : Institut d’Electronique, de Microélectronique et de Nanotechnologie; Institut de Recherche Interdisciplinaire; Institut de Recherche Interdisciplinaire; Institut de Recherche Interdisciplinaire; Institut d’Electronique, de Microélectronique et de Nanotechnologie
Resume : Since their successful commercialization in the 1990s, surface plasmon resonance (SPR) biosensors have become a central tool for the study of biomolecular interactions, chemical detection, and immunoassays in various fields thanks to unparalleled advantages such as label-free and real-time analysis with very high sensitivity. To further push the limits of SPR capabilities, novel SPR structures and approaches are being actively investigated. Here we experimentally demonstrate a graphene-based SPR biosensor. By incorporating a graphene layer to the conventional gold thin film SPR structure, its biosensing sensitivity is significantly increased. This is shown in a typical affinity biosensing experiment to measure the real-time binding kinetics of streptavidin-biotin. In addition to higher sensitivity, we also obtain a much higher signal-to-noise ratio without the slightest modification of the usual measurement setup. This implies that a considerably lower limit of detection can be made possible with the novel structure. Moreover, our graphene-based SPR biosensors do not require sophisticated surface functionalization schemes as in conventional SPR in order to function. Previous reports have also suggested that graphene might effectively prevent non-specific binding of biomolecules on the sensor surface. With relatively simple fabrication methods and large scalability, these combined distinctive advantages can enable future generation of high-performance SPR biosensors.
|10:45||Detection limits for fluorescent-core microcavity biosensors|
Authors : S. McFarlane, C.P.K. Manchee, J. W. Silverstone, J. Veinot, A. Meldrum
Affiliations : Department of Physics, University of Alberta; Department of Chemistry, University of Alberta
Resume : Optical fluidic microcavities exhibit many attractive properties for the development of a sensitive, label-free biosensor. These optical microcavities are inexpensive, non-toxic, reusable, and sensitive to low analyte concentrations, making them candidates for integration into Lab-on-a-Chip (LoC) devices. Here, a robust fluorescent-core microcapillary (FCM) sensor is demonstrated. It utilizes the whispering gallery mode (WGM) resonances in the fluorescence spectrum of a silicon quantum-dot-coated microcapillary channel. Well-defined WGMs with a visibility of 0.37 and Q-factors up to 400 were observed. The FCMs showed refractometric sensitivities of 10- 20 nm/RIU for methanol, ethanol, and sucrose solutions, and detection limits approaching 10-4 RIU. The FCMs were then functionalized for biotin and streptavidin detection, in order to demonstrate the feasibility of this microfluidic device for biosensing applications. Biotin molecules were immobilized on the inner surface of the FCMs using an aminopropyltrimethoxysilane linker. Buffer solutions were then pumped through the capillary channel and the fluorescence spectrum was monitored. Resonance shifts on the order of tens of pm were detected after the binding of biotin, and after the subsequent attachment of streptavidin molecules to the biotinylated surface.
|11:00||Assessment of Nafion polymer as immobilization matrix for formaldehyde dehydrogenase and its cofactor nicotinamide adenine dinucleotide. Application to the development of a conductometric biosensor for formaldehyde detection|
Authors : ThanThuy Nguyen-Boisse , Florence Lagarde, Nicole Jaffrezic-Renault
Affiliations : University of Lyon, Lyon1, Laboratory of Analytical Sciences, UMR 5280 CNRS-UCBL-ENS, 69622 Villeurbanne cedex, France
Resume : Formaldehyde is one of the most important commercialised chemical products. However, this compound is toxic, allergenic and considered as human carcinogen. Reliable analytical techniques are thus required for its environmental monitoring. In this work, a rapid, sensitive and miniaturized conductometric biosensor was developed for formaldehyde detection. The biosensor was prepared through immobilization of formaldehyde dehydrogenase (FDH) and its cofactor nicotinamide adenine dinucleotide (NAD+) on the surface of gold interdigitated microelectrodes. Formaldehyde oxidation catalyzed by FDH produces formate ions and protons detectable by conductometry. Three modes of immobilization were evaluated, including cross-linking of the enzyme, coating with Nafion sulfonated polymer and a combination of both methods. The latter protocol was the most efficient. The Nafion membrane was able to concentrate NAD+ cofactor in the vicinity of FDH enzyme, and to induce a local H+ concentration effect, allowing signal enhancement. In the optimal measurement conditions (phosphate buffer 5 mM, pH 7), the biosensor could detect 18 µM of formaldehyde, corresponding to 3 ppb atmospheric concentration. This value is far below the short-term (30-minute) guideline of 100 ppb recommended for in-door air quality by the World Health Organization. The signal was linear up to 10 mM and stable over a 20 days period when the biosensor was stored at 4°C in phosphate buffer 20 mM pH 7 between two measurements.
|11:15||Selective chemical sensing of butterfly wing scales nanostructures|
Authors : K. Kertész1, G. Piszter1, E. Jakab2, Zs. Bálint3, Z. Vértesy1, L. P. Biró1
Affiliations : 1 Institute for Technical Physics and Materials Science, Research Centre for Natural Sciences, 1525 Budapest, PO Box 49, Hungary (http://www.nanotechnology.hu/) 2 Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, H-1525 Budapest, P O Box 17. Hungary 3 Hungarian Natural History Museum, Baross utca 13, H-1088 Budapest, Hungary
Resume : Photonic crystals are periodic dielectric nanocomposites which have photonic band gaps that forbid the propagation of light within certain frequency ranges. This property enables one to manipulate light with amazing facility. Such nanoarchitectures frequently occur in butterflies and beetles . The optical response on chemical changes in the environment of a biological photonic crystal type structure was first measured on Morpho butterflies . The spectral change of the reflected light depends on the composition of the ambient atmosphere and also on the wing nanostructure . In this work we show the results of recent measurements on nine Polyommatine species with dorsal blue coloration. Their color is generated by similar “pepper-pot” type nanoarchitectures which exhibit species specific characteristics , associated with species specific color . Experiments were carried out changing the concentration and nature of test vapors while monitoring the spectral variations in time. Proper data processing results gas-selective and concentration dependent signals. Our work shows a way to a prospective integrated biological - optical sensor combining light weight and low power with environmental friendly production.  LP Biró & JP Vigneron, Laser & Photonics Rev. 5, 27, 2011  RA Potyrailo et al. Nat. Phot. 1, 123, 2007  LP Biró et al. Proc. of SPIE 7057, 705706, 2008  Zs Bálint et al. Interface, in press  G Piszter et al. Analytical Methods 3, 78-83, 2011
|11:30||Biosensor array based platform for pesticides detection|
Authors : Carmen Moldovan, Rodica Iosub, Cecilia Codreanu, Daniel Necula, *Alina Ion, **Ion Stan
Affiliations : Natioanal Institute for R&D in Microtechnology, 126A Erou Iancu Nicolae, 077190 Bucharest, Romania, *Politehnica University of Bucharest, Faculty of Chemistry, 1-7 Gheorghe Polizu, Bucharest, **Romelgen SRL, 11 Ion Berindei, sector 2, Bucharest, Romania
Resume : The paper work has been focused on the technology development of an impedimetric microbiosensor array for pesticides detection. The microbiosensor array is containing seven biosensor chips integrated into a microfluidic system providing all fluids for biosensors activation and inhibition, electrically connected to electronic modules for signal processing and data acquisition. The overall pesticides detection platform is connected into a portable apparatus of small dimensions, low energy consumption, easy to be manipulated, providing independent functioning of biosensors with data acquisition from each one. The microcontroller will memorise the data and is able to discard them on the PC via USB. The biosensor is based on miniaturized interdigitated electrodes and immobilized acetylcholinesteraze on top of them, measuring the impedance of the layer adjacent to the electrodes surface. The acetylcholinesteraze based sensors are designed to detect the organophosphoric and carbamates compounds from pesticides. The pesticides detection measurements are realized under the strict control of temperature and pH using a Platinum temperature sensor and a pH electrode, both integrated on the same chip with the biosensor. The response time is about 10 minutes. The platform has been used for detection of Dichlorvos, Dichlopyrifos, Ethion and Coumaphos with a sensitivity in the area of 10-10M/l and the results will be presented.
|11:45||Doped Biomolecules in Miniaturized Electric Junctions|
Authors : Elad D. Mentovich, Bogdan Belgorodsky, Michael Gozin, Hagai Cohen, Shachar Richter
Affiliations : School of Chemistry, Faculty of exact sciences, Tel-Aviv University
Resume : Control over molecular scale electrical properties within nano junctions is demonstrated, utilizing site-directed C60 targeting into protein macromolecules as a doping means. The protein molecules, self-assembled in a miniaturized transistor device, yield robust and reproducible operation. Their device signal is dominated by an activity center that inverts affinity upon guest incorporation and thus controls the properties of the entire macromolecule. We show how the leading routs of electron transport can be drawn, spatially and energetically, on the molecular level and, in particular, how the dopant effect is dictated by its 'strategic' binding site. Our findings propose the extension of microelectronic methodologies to the nanometer scale and further present a promising platform for ex-situ studies of biochemical processes.
|13:30||Nanostructured Dye-Sensitized Solar Cells for Enhanced Light Harvesting and Charge Collection|
Authors : Nicolas Tétreault‡, Philippe Labouchère‡, Jérémie Brillet, Aravind Kumar‡, Geoffrey. A. Ozin§ & Michael Grätzel‡
Affiliations : ‡ Laboratory of Photonics and Interfaces, Ecole Polytechnique Federale de Lausanne, Switzerland § Chemistry Department, University of Toronto, Canada
Resume : Dye-sensitized solar cells (DSCs) are one of the most promising photovoltaic technologies for production of renewable, clean, and affordable energy. 1,2 In DSCs, charge carrier generation takes place in a chemisorbed monolayer of photoactive dye that is sandwiched between a semiconducting oxide, usually anatase TiO2, and an electrolyte acting as electron and hole conducting materials, respectively. Because of the relatively low absorption cross-section of the molecular sensitizer, a high surface area mesoscopic photoanode is necessary to ensure high dye loading and efficient light harvesting in the visible part of the solar spectrum. This implies that the DSC has an exceedingly large, heterogeneous interface through which electrons may be (parasitically) intercepted as a result of the slow electron transport. The latter is governed by an ambipolar diffusion mechanism controlled by trap-limited hopping through a relatively long and tortuous path to the transparent conductive electrode. It is further hindered by the low electron mobility in anatase TiO2 nanoparticles and the multiple grain boundaries in the mesoporous film.3 We will present novel bottom-up 3D host-passivation-guest concepts enabling structural control on electron extraction and recombination as well as on the optical scattering in photovoltaic devices. Using this novel architecture combined with different passivation or tunneling layers, increases in photovoltage from 110 mV to about 400mV over state-of-t
|14:00||Engineered photoelectrodes for dye solar cells based on shape-tailored TiO2 nanocrystals|
Authors : Luisa De Marco (1), Michele Manca (1), Davide Cozzoli (2) and Giuseppe Gigli (1,2)
Affiliations : 1) CBN - Center for Biomolecular Nanotechnologies of Italian Institute of Technology Via Barsanti - 73010 Arnesano (LECCE) - ITALY 2) NNL - National Nanotechnology Laboratory– Nanoscience Institute of CNR – Distretto Tecnologico -Via Arnesano 16 – 73100 Lecce – ITALY
Resume : The ability to create photoanodes in which the structural and morphological features of TiO2 nanocrystal constituents provide tailored nanotexture with a higher degree of functionality represents an indispensible step towards boosting the ultimate light-to-electricity conversion. We have developed unconventional photoanodes that integrate different breeds of anisotropically shaped TiO2 nanocrystals synthesized by wet-chemical route, namely linear and branched nanorods. Our novel architecture embodies three layers of different materials: the bottom layer, 3-4 μm thick, neighboring to FTO, consist in 3x12 nm sized anatase nanorods which assure tremendous specific surface area and the highest transparency in the visible range; the 4-6 μm thick interlayer is constituted of 3x50 nm sized anatase nanorods which can profit from superior electron transport and good dye loading capability; finally, the upper layer, 5-7 μm thick, is made of 200 nm sized hyperbranched anatase nanocrystals in a peculiar bundle-like configuration, which offer adequate light scattering capacity and better interfacial charge-transfer properties. This approach represent a satisfactory combination between indispensable but often incompatible factors such as high specific surface area, fast electron transport and pronounced light-scattering and allows to maximize light harvesting capabilities and the charge collection efficiency of a DSSC, thus giving an has high power conversion efficiency as 10.1%.
|14:15||Hierarchical TiO2-based materials for dye-sensitized solar cells and other applications|
Authors : MARKETA ZUKALOVA1, LADISLAV KAVAN1, MICHAEL GRAETZEL2
Affiliations : 1J. Heyrovský Institute of Physical Chemistry, v.v.i. Academy of Sciences of the Czech Republic, Dolejškova 3, CZ-18223 Prague 8, Czech Republic; 2Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland
Resume : Dye-sensitized solar cells (DSCs) have received great attention because of cost-effectiveness compared with silicon (Si)–based photovoltaic devices. DSC is the only solar cell that separates the two functions of light harvesting and charge-carrier transport. This imposes stringent demands upon the morphology, optical and electronic properties of the semiconductor, i.e., its band gap and band position, as well as charge-carrier mobility. Recently, we succeeded in optimization of synthetic procedure for DSC photoanodes with 2.3 m thick layers of highly organized mesoporous TiO2 films sensitized with the N945 dye exhibiting solar conversion efficiency of 5.05%. However, the solar conversion efficiency reaches plateau value for thicker layers despite an increase of their surface area. Problems with charge collection, recombination, and ohmic loses are assumed to account for this effect in the extremely open framework. Incorporation of nanofibrous TiO2 was selected to eliminate electron transport problem in this extremely porous structure. This hierarchical material consisting of two different TiO2 morphologies enabled to reach solar conversion efficiency of the respective DSC as high as 5.35% at 2.5m thick layer. Fibrous NanospiderTM TiO2 is a material of huge application potential due to enhanced surface reactivity facilitating its doping and chemical treatment (synthesis of nitride, oxynitride or Magnelli phases at mild conditions as compared to those of ordinary TiO2).
|14:30||Colloidal suspensions of perovskite solid-solution nanoparticles for energy conversion technologies|
Authors : R. P. Doherty , I. Dozov , P. Davidson , M-H. Berger , T. Delahaye , J-F. Hochepied 
Affiliations :  Systemes Colloidaux dans les Procedes Industriels, CEP, Mines ParisTech, ENSTA ParisTech, 32 Boulevard Victor, 75739 Paris cedex 15, France,  Laboratoire de Physique des Solides, Bat 510, Universite Paris-Sud, 91405 Orsay Cedex, France,  Centre des Materiaux, Mines ParisTech, BP 87, F-91003 Evry Cedex, France
Resume : Colloidal suspensions of perovskite solid-solution nanoparticles (SSNPs) are promising candidates for, amongst others, energy conversion technologies (patent: T. Delahaye, WO 2011/055065). However, most perovskite studies to date have focused on rigid ceramic materials. Colloidal systems can be exploited to create new applications where having a mobile liquid phase is advantageous. Mixing of two perovskites in a SSNP allows further control over the properties, notably the Curie temperature (Tc). KNbO3-BaTiO3, a lead-free ferroelectric with a relatively low Tc, has great potential for RAMs, sensors, actuators and pyroelectric energy conversion applications. Currently, KNbO3-based solid solutions are predominantly prepared by high temperature solid-state reactions that do not allow sufficient control over nanoparticle size and morphology. Here, we will show a simple, solution-based, calcination-free method to prepare KNbO3-BaTiO3 perovskite SSNPs (~10 nm), which are subsequently dispersed, forming a stable colloidal suspension by polymer addition. This solution-based method allows the investigation of homogeneous single-domain nanoparticles. The nanoparticle structure has been characterized by XRD, HRTEM, EDX, EFTEM, and the electronic properties by EELS. Current research in the laboratory aims at determining, by electric birefringence measurements, how the colloidal suspensions behave in an electric field, with the goal of developing a novel pyroelectric energy convertor.
|14:45||Facile Route to Fabricating Vertically Aligned High-Aspect Ratio Block-Copolymer Films for Organic Photovoltaics|
Authors : G. Singh, M. M. Kulkarni, K. Yager, D.-M. Smilgies, B. Berry, D. G. Bucknall, A. Karim
Affiliations : University of Akron; Brookhaven National Laboratory; Cornell University; University of Arkansas at Little Rock; Georgia Institute of Technology
Resume : Fabricating vertically ordered and etchable high aspect ratio nanodomains of block copolymer (BCP) thin films on diverse substrates via continuous processing dynamic cold zone annealing (CZA), is particularly attractive for nanomanufacturing of next generation electronics. Here, we report CZA utilizing a dynamic sharp thermal gradient (NablaT~ 45 oC/mm) (i.e. CZA-S). This method allows production of etchable and predominantly (~90%) vertically oriented cylindrical domains of poly(styrene-b-methylmethacrylate) in (100-1000) nm thick films on low thermal conductivity rigid (quartz) and flexible (PDMS, Kapton) substrates. Various factors affect BCP orientation in films below 100nm or thicker than 1000 nm leading to loss of vertical orientation. An optimal dynamic sweep rate (~ 3.5 um/s) produces the best vertical order. At too fast a sweep rate (> 10 um/s) the BCP film ordering is kinetically hindered, while at too slow a sweep rate (< 1 um/s), excessive polymer relaxation and preferential surface wetting dynamics favor parallel BCP orientation. The CZA-S orientation mechanism involves propagating a narrow vertically oriented BCP zone created at the maximum NablaT across the sample. Application of CZA-S to creating high density silica nanodots arrays is demonstrated.
|15:00||Electrodeposition of vanadium oxide on aluminium 3-D substrates for Li-ion batteries|
Authors : D. Rehnlund, M. Valvo, K. Edström, L. Nyholm
Affiliations : Department of Materials Chemistry, Ångström Advanced Battery Centre, Uppsala University.
Resume : Electrodeposition is a powerful tool in the fabrication of nanostructured electrodes due to its ability to yield high aspect ratios. The technique has therefore emerged as a particularly promising tool for low-cost manufacturing of 3D-microbattery (MB) devices . The developing field of Li-ion MBs shows great promise to meet the power and scalability needs of the microsystems market. Although, extensive work has been done on the synthesis of nanostructured anode materials, there is a need for a corresponding development of 3-D cathodes. Among the candidates for MB cathodes vanadium oxide is a good and viable choice for inclusion in future MBs . This study is focused on using electrodeposition to deposit VOx on aluminium nanorods thereby fabricating an inexpensive and versatile 3D-cathode. However, the corrosion of aluminium results in a challenging system. A detailed study has therefore been carried out and a new deposition approach has been designed enabling the manufacturing of vanadium oxide coated aluminium nanorods. 1. K. Edström, et. al., Electrodeposition as a Tool for 3D Microbattery Fabrication. Electrochem. Soc. Interphase, 20 (2011) 41-46. 2. T. Ripenbein, et. al., Novel porous-silicon structures for 3D-interlaced microbatteries. Electrochimica Acta, 2010. 56(1): p. 37-41. 3. E. Potiron, et. al., Electrochemically synthesized vanadium oxides as lithium insertion hosts. Electrochimica Acta, 1999. 45: p. 197-214.
|15:15||Template Free Electrodeposition of ZnSb Nanoflakes Structure for Li-Ion Battery Anodes|
Authors : Somaye Saadat, Alex Yan Qingyu
Affiliations : School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore; 1School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
Resume : One of the great challenges in the twenty-first century is energy. It is essential that new and improved energy conversion/storage devices are developed. In the present study, a simple, cheap single-step fabrication of ZnSb nanostructures using template free electrodeposition was established. Results indicate that ZnSb nanoflakes, nanowires or nanoparticles with controlled composition and phase could be grown by adjusting the deposition parameters. By application of deposition voltage Vd = -3 V in the ethylene glycol solution with IZnCl2-SbCl3 = 1.6, 60-120 nm ZnSb nanoparticles were grown on smooth Cu. Increase in voltage e.g. Vd =-7V led to formation of interconnected ZnSb nanoflakes under high over potential conditions. Application of rough Cu foils and further increase in applied voltage e.g. Vd = -9 V resulted in fabrication of vertically grown ZnSb nanowires with 70-150 nm diameter and 1-1.5 m length. Electrochemical analyses revealed that the carbon coated ZnSb nanoflakes depicted high discharge capacities and a stable performance with the initial discharge capacity of 735 mA h/g and an initial Columbic efficiency of 85%, while it maintained a discharge capacity of 500 mA h/g (0.18 C) after 70 cycles which were better than that of ZnSb/C nanowires and nanoparticles. The improved performance of the interconnected ZnSb nanoflakes is attributed to their open structure with a large surface area and small crystal grains which facilitates the Li intercalation process.
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