Micro-CAT with redundant electrodes (CATER)

International Nuclear Information System (INIS)

Berg, F.D. van den; Eijk, C.W.E. van; Hollander, R.W.; Sarro, P.M.

2000-01-01

High-rate X-ray or neutron counting introduces the problem of hit multiplicity when 2D position reconstruction is demanded. Implementation of a third readout electrode having a different angle than the anode or cathode allows to eliminate multiplicity problems. We present experimental results of a new type of gas-filled micro-patterned radiation detector, called 'Compteur a Trous a Electrodes Redondantes (CATER)', that disposes of such an extra readout channel in the form of a ring-shaped electrode that is positioned between the anode and the cathode. The ionic signal is shared between the ring-electrode and the cathode strip in a way that can be controlled by their potential difference. We observe a strong signal dependence on the drift field, which can be understood by the reduced transparency for the primary charge at high drift fields

Solvent-Assisted Gel Printing for Micropatterning Thin Organic-Inorganic Hybrid Perovskite Films.

Science.gov (United States)

Jeong, Beomjin; Hwang, Ihn; Cho, Sung Hwan; Kim, Eui Hyuk; Cha, Soonyoung; Lee, Jinseong; Kang, Han Sol; Cho, Suk Man; Choi, Hyunyong; Park, Cheolmin

2016-09-27

While tremendous efforts have been made for developing thin perovskite films suitable for a variety of potential photoelectric applications such as solar cells, field-effect transistors, and photodetectors, only a few works focus on the micropatterning of a perovskite film which is one of the most critical issues for large area and uniform microarrays of perovskite-based devices. Here we demonstrate a simple but robust method of micropatterning a thin perovskite film with controlled crystalline structure which guarantees to preserve its intrinsic photoelectric properties. A variety of micropatterns of a perovskite film are fabricated by either microimprinting or transfer-printing a thin spin-coated precursor film in soft-gel state with a topographically prepatterned elastomeric poly(dimethylsiloxane) (PDMS) mold, followed by thermal treatment for complete conversion of the precursor film to a perovskite one. The key materials development of our solvent-assisted gel printing is to prepare a thin precursor film with a high-boiling temperature solvent, dimethyl sulfoxide. The residual solvent in the precursor gel film makes the film moldable upon microprinting with a patterned PDMS mold, leading to various perovskite micropatterns in resolution of a few micrometers over a large area. Our nondestructive micropatterning process does not harm the intrinsic photoelectric properties of a perovskite film, which allows for realizing arrays of parallel-type photodetectors containing micropatterns of a perovskite film with reliable photoconduction performance. The facile transfer of a micropatterned soft-gel precursor film on other substrates including mechanically flexible plastics can further broaden its applications to flexible photoelectric systems.

Micropatterning of Functional Conductive Polymers with Multiple Surface Chemistries in Register

DEFF Research Database (Denmark)

Lind, Johan Ulrik; Acikgöz, Canet; Daugaard, Anders Egede

2012-01-01

A versatile procedure is presented for fast and efficient micropatterning of multiple types of covalently bound surface chemistry in perfect register on and between conductive polymer microcircuits. The micropatterning principle is applied to several types of native and functionalized PEDOT (poly(3...... functionalized conjugated polymer systems....

Micropatterned Carbon-on-Quartz Electrode Chips for Photocurrent Generation from Thylakoid Membranes

DEFF Research Database (Denmark)

Bunea, Ada-Ioana; Heiskanen, Arto R.; Pankratova, Galina

2018-01-01

Harvesting the energy generated by photosynthetic organisms through light-dependent reactions is a significant step towards a sustainable future energy supply. Thylakoid membranes are the site of photosynthesis, and thus particularly suited for developing photo-bioelectrochemical cells. Novel ele......]+/2+) are used for evaluating photocurrent generation from thylakoid membranes with different electrode geometries. Current densities up to 71 µA cm-2 are measured upon illumination through the transparent electrode chip with solar simulated irradiance (1000 W m-2)....... electrode materials and geometries could potentially improve the efficiency of energy harvesting using thylakoid membranes. For commercial applications, electrodes with large surface areas are needed. Photolithographic patterning of a photoresist, followed by pyrolysis, is a flexible and fast approach...

Elsevier R&D on a new type of micropattern gaseous detector: The Fast Timing Micropattern detector

CERN Document Server

Abbaneo, D; Abbrescia, M; Abi Akl, M; Aboamer, O; Acosta, D; Ahmad, A; Ahmed, W; Aleksandrov, A; Altieri, P; Asawatangtrakuldee, C; Aspell, P; Assran, Y; Awan, I; Bally, S; Ban, Y; Banerjee, S; Barashko, V; Barria, P; Bencze, G; Beni, N; Benussi, L; Bhopatkar, V; Bianco, S; Bos, J; Bouhali, O; Braghieri, A; Braibant, S; Buontempo, S; Calabria, C; Caponero, M; Caputo, C; Cassese, F; Castaneda, A; Cauwenbergh, S; Cavallo, F R; Celik, A; Choi, M; Choi, S; Christiansen, J; Cimmino, A; Colafranceschi, S; Colaleo, A; Conde Garcia, A; Czellar, S; Dabrowski, M M; De Lentdecker, G; Oliveira, R De; De Robertis, G; Dildick, S; Dorney, B; Endroczi, G; Errico, F; Fallavollita, F; Fenyvesi, A; Ferry, S; Furic, I; Giacomelli, P; Gilmore, J; Golovtsov, V; Guiducci, L; Guilloux, F; Gutierrez, A; Hadjiiska, R M; Hauser, J; Hoepfner, K; Hohlmann, M; Hoorani, H; Iaydjiev, P; Jeng, Y G; Kamon, T; Karchin, P; Korytov, A; Krutelyov, S; Kumar, A; Kim, H; Lee, J; Lenzi, T; Litov, L; Loddo, F; Madorsky, A; Maerschalk, T; Maggi, M; Magnani, A; Mal, P K; Mandal, K; Marchioro, A; Marinov, A; Majumdar, N; Merlin, J A; Mitselmakher, G; Mohanty, A K; Mohapatra, A; Molnar, J; Muhammad, S; Mukhopadhyay, S; Naimuddin, M; Nuzzo, S; Oliveri, E; Pant, L M; Paolucci, P; Park, I; Passeggio, G; Pavlov, B; Philipps, B; Piccolo, D; Postema, H; Puig Baranac, A; Radi, A; Radogna, R; Raffone, G; Ranieri, A; Rashevski, G; Ressegotti, M; Riccardi, C; Rodozov, M; Rodrigues, A; Ropelewski, L; RoyChowdhury, S; Ryu, G; Ryu, M S; Safonov, A; Salva, S; Saviano, G; Sharma, A; Sharma, A; Sharma, R; Shah, A H; Shopova, M; Sturdy, J; Sultanov, G; Swain, S K; Szillasi, Z; Talvitie, J; Tatarinov, A; Tuuva, T; Tytgat, M; Vai, I; Van Stenis, M; Venditti, R; Verhagen, E; Verwilligen, P; Vitulo, P; Volkov, S; Vorobyev, A; Wang, D; Wang, M; Yang, U; Yang, Y; Yonamine, R; Zaganidis, N; Zenoni, F; Zhang, A

2017-01-01

Micropattern gaseous detectors (MPGD) underwent significant upgrades in recent years, introducing resistive materials to build compact spark-protected devices. Exploiting this technology further, various features such as space and time resolution, rate capability, sensitive area, operational stability and radiation hardness can be improved. This contribution introduces a new type of MPGD, namely the Fast Timing Micropattern (FTM) detector, utilizing a fully resistive WELL structure. It consists of a stack of several coupled layers where drift and WELL multiplication stages alternate in the structure, yielding a significant improvement in timing properties due to competing ionization processes in the different drift regions. Two FTM prototypes have been developed so far. The first one is uWELL-like, where multiplication takes place in the holes of a kapton foil covered on both sides with resistive material. The second one has a resistive Micromegas-like structure, with multiplication developing in a region del...

Nanotopography enhanced mobility determines mesenchymal stem cell distribution on micropatterned semiconductors bearing nanorough areas.

Science.gov (United States)

Gallach Pérez, Darío; Punzón Quijorna, Esther; Sanz, Ruy; Torres-Costa, Vicente; García Ruiz, Josefa P; Manso Silván, Miguel

2015-02-01

Surface micropatterns are relevant instruments for the in vitro analysis of cell cultures in non-conventional planar conditions. In this work, two semiconductors (Si and TiO2) have been micropatterned by combined ion-beam/chemical-etching processes leading to selective areas bearing nanorough features. A preferential affinity of human mesenchymal stem cells (hMSCs) for planar areas versus nanotopographic ones is observed. Fluorescence microscopy after β-catenin staining suggests that hMSCs adhesion is inhibited on nanostructured porous silicon areas. This has a direct impact in the development of actin fibers and suggests different cell migration mechanisms on the materials of a micropattern. hMSCs organization on nanotopographic micropatterns has been modeled by using a simplified random walk approach. The model attributes preferential cell mobilities on the nanotopographic areas with respect to the planar and considers purely stochastic movement with no inertial term. Simulations of the cell distribution have been run on 1D and 2D micropatterns and compared with the real hMSC cultures. The simulations allow defining two regimes for cell organization as a function of cell density. hMSCs ordering on planar areas is diffusion-induced in most micropatterns but constriction forced disorder appears for high cell densities. The relative mobility on the planar versus nanotopographic areas can be used as a quality indicator of the nanotopography contrasts in the diffusion induced ordering regime. It is shown that the relative mobility is favorable for the TiO2 versus the Si based system, and allows envisaging its use for the calibrated design of nanotopography based micropatterned materials. Copyright © 2014 Elsevier B.V. All rights reserved.

Delineating fibronectin bioadhesive micropatterns by photochemical immobilization of polystyrene and poly(vinylpyrrolidone).

Science.gov (United States)

Sterner, Olof; Giazzon, Marta; Zürcher, Stefan; Tosatti, Samuele; Liley, Martha; Spencer, Nicholas D

2014-01-01

Bioadhesive micropatterns, capable of laterally confining cells to a 2D lattice, have proven effective in simulating the in vivo tissue environment. They reveal fundamental aspects of the role of adhesion in cell mechanics, proliferation, and differentiation. Here we present an approach based on photochemistry for the fabrication of synthetic polymer micropatterns. Perfluorophenyl azide (PFPA), upon deep-UV exposure, forms a reactive nitrene capable of covalently linking to a molecule that is in close proximity. PFPA has been grafted onto a backbone of poly(allyl amine), which readily forms a self-assembled monolayer on silicon wafers or glass. A film of polystyrene was applied by spin-coating, and by laterally confining the UV exposure through a chromium-on-quartz photomask, monolayers of polymers could be immobilized in circular microdomains. Poly(vinylpyrrolidone) (PVP) was attached to the background to form a barrier to nonspecific protein adsorption and cell adhesion. Micropatterns were characterized with high-lateral-resolution time-of-flight secondary ion mass spectrometry (TOF-SIMS), which confirmed the formation of polystyrene domains within a PVP background. Fluorescence-microscopy adsorption assays with rhodamine-labeled bovine serum albumin demonstrated the nonfouling efficiency of PVP and, combined with TOF-SIMS, allowed for a comprehensive characterization of the pattern geometry. The applicability of the micropatterned platform in single-cell assays was tested by culturing two cell types, WM 239 melanoma cells and SaOs-2 osteoblasts, on micropatterned glass, either with or without backfilling of the patterns with fibronectin. It was demonstrated that the platform was efficient in confining cells to the fibronectin-backfilled micropatterns for at least 48 h. PVP is thus proposed as a viable, highly stable alternative to poly(ethylene glycol) for nonfouling applications. Due to the versatility of the nitrene-insertion reaction, the platform could be

R and D on a New Technology of Micro-pattern Gaseous Detectors Fast Timing Micro-pattern Detector

CERN Document Server

Salva Diblen, Sinem

2016-01-01

After the upgrades of the Large Hadron Collider (LHC) planned for the second and the third Long Shutdown (LS), the LHC luminosity will approach very high values. Such conditions will affect the performance of the CMS muon system, especially in the very forward region, due to the harsh expected background environment and high pile-up conditions. The CMS collaboration considers upgrading the muon forward region to take advantage of the pixel tracking coverage extension a new detector, ME0 station, possibly behind the new forward calorimeter. New resistive micro-pattern gaseous detectors that are able to handle the very demanding spatial, time resolution and rate capability, are being considered. In this contribution we introduce a new type of MPGD technology the Fast Timing Micro-pattern (FTM) detector, utilizing a fully resistive WELL structure. It consists of a stack of several coupled layers where drift and WELL multiplication stages alternate in the structure, yielding a significant improvement in timing p...

Reprogramming hMSCs morphology with silicon/porous silicon geometric micro-patterns.

Science.gov (United States)

Ynsa, M D; Dang, Z Y; Manso-Silvan, M; Song, J; Azimi, S; Wu, J F; Liang, H D; Torres-Costa, V; Punzon-Quijorna, E; Breese, M B H; Garcia-Ruiz, J P

2014-04-01

Geometric micro-patterned surfaces of silicon combined with porous silicon (Si/PSi) have been manufactured to study the behaviour of human Mesenchymal Stem Cells (hMSCs). These micro-patterns consist of regular silicon hexagons surrounded by spaced columns of silicon equilateral triangles separated by PSi. The results show that, at an early culture stage, the hMSCs resemble quiescent cells on the central hexagons with centered nuclei and actin/β-catenin and a microtubules network denoting cell adhesion. After 2 days, hMSCs adapted their morphology and cytoskeleton proteins from cell-cell dominant interactions at the center of the hexagonal surface. This was followed by an intermediate zone with some external actin fibres/β-catenin interactions and an outer zone where the dominant interactions are cell-silicon. Cells move into silicon columns to divide, migrate and communicate. Furthermore, results show that Runx2 and vitamin D receptors, both specific transcription factors for skeleton-derived cells, are expressed in cells grown on micropatterned silicon under all observed circumstances. On the other hand, non-phenotypic alterations are under cell growth and migration on Si/PSi substrates. The former consideration strongly supports the use of micro-patterned silicon surfaces to address pending questions about the mechanisms of human bone biogenesis/pathogenesis and the study of bone scaffolds.

The study and fabrication of DLC micropattern on roll mold

Science.gov (United States)

Kwon, Young Woo; Lee, Tae Dong; Park, Yeong Min; Cho, Hyun; Kim, Jin Kon; Kim, Tae Gyu

2015-03-01

Diamond-like carbon (DLC) coating is becoming a promising protective coating layers due to its superior properties. In this study, instead of protective coating, DLC film was applied as the only component for micropattern then etched with lithography and lift-off process selectively. Furthermore, DLC film has been fabricated on aluminum roll mold. Then UV curing resin was applied to form the pattern on the polyethylene terephthalate (PET) film. The dimension and formation of the DLC micropattern on roll mold were analyzed. Moreover, the Raman spectroscopic of nitrogen-doped DLC film was analyzed.

Preparation and regulating cell adhesion of anion-exchangeable layered double hydroxide micropatterned arrays.

Science.gov (United States)

Yao, Feng; Hu, Hao; Xu, Sailong; Huo, Ruijie; Zhao, Zhiping; Zhang, Fazhi; Xu, Fujian

2015-02-25

We describe a reliable preparation of MgAl-layered double hydroxide (MgAl-LDH) micropatterned arrays on gold substrate by combining SO3(-)-terminated self-assembly monolayer and photolithography. The synthesis route is readily extended to prepare LDH arrays on the SO3(-)-terminated polymer-bonded glass substrate amenable for cell imaging. The anion-exchangeable MgAl-LDH micropattern can act both as bioadhesive region for selective cell adhesion and as nanocarrier for drug molecules to regulate cell behaviors. Quantitative analysis of cell adhesion shows that selective HepG2 cell adhesion and spreading are promoted by the micropatterned MgAl-LDH, and also suppressed by methotrexate drug released from the LDH interlayer galleries.

Cell behaviors on micro-patterned porous thin films

International Nuclear Information System (INIS)

Phong, Ho Quoc; Wang Shuling; Wang, Meng-Jiy

2010-01-01

Thin polymer films with patterned surfaces have drawn tremendous attention in manufacturing advanced electronic, mechanical devices and in biomaterials due to the advantageous properties such as mechanical strength, chemical resistance and optic transparency. The applications can be extended to the fields such as catalysts, antireflection coatings, template for inorganic growth masks, and substrates for cell culturing providing the patterned surface containing micron-sized features. Various methods have been used to fabricate polymers with micro-patterned surfaces such as photolithographic, ink-jet printing, nonsolvent, spin coating in a dry environment, self-organization, and the condensation of monodisperse water droplet on the polymer solution. The physiological functions of mature cells depend on the microenvironment/niche surrounding which can provide proper factors to regulate cell proliferation and differentiation. While designing appropriate scaffolds for tissue engineering, the microstructure is one of the most important factors to be considered. In this work, a facile single-step phase separation method was used to create micro-patterned polymer thin films with concaves or convexes with sizes ranged from 7 to 70 μm. The effects of water content, casting volume and the addition of surfactant on the distribution of pores and substrate morphology were examined. Moreover, detailed observations of fibroblast cells on the micro-patterned thin films were presented to compare and elucidate the roles of surface micro-features and chemical functionalities.

Micropatterning on cylindrical surfaces via electrochemical etching using laser masking

International Nuclear Information System (INIS)

Cho, Chull Hee; Shin, Hong Shik; Chu, Chong Nam

2014-01-01

Highlights: • Various micropatterns were fabricated on the cylindrical surface of a stainless steel shaft. • Selective electrochemical dissolution was achieved via a series process of laser masking and electrochemical etching. • Laser masking characteristics on the non-planar surface were investigated. • A uniform mask layer was formed on the cylindrical surface via synchronized laser line scanning with a rotary system. • The characteristics of electrochemical etching on the non-planar surface were investigated. - Abstract: This paper proposes a method of selective electrochemical dissolution on the cylindrical surfaces of stainless steel shafts. Selective electrochemical dissolution was achieved via electrochemical etching using laser masking. A micropatterned recast layer was formed on the surface via ytterbium-doped pulsed fiber laser irradiation. The micropatterned recast layer could be used as a mask layer during the electrochemical etching process. Laser masking condition to form adequate mask layer on the planar surface for etching cannot be used directly on the non-planar surface. Laser masking condition changes depending on the morphological surface. The laser masking characteristics were investigated in order to form a uniform mask layer on the cylindrical surface. To minimize factors causing non-uniformity in the mask layer on the cylindrical surface, synchronized laser line scanning with a rotary system was applied during the laser masking process. Electrochemical etching characteristics were also investigated to achieve deeper etched depth, without collapsing the recast layer. Consequently, through a series process of laser masking and electrochemical etching, various micropatternings were successfully performed on the cylindrical surfaces

Facile approach to the fabrication of a micropattern possessing nanoscale substructure.

Science.gov (United States)

Ji, Qiang; Jiang, Xuesong; Yin, Jie

2007-12-04

On the basis of the combined technologies of photolithography and reaction-induced phase separation (RIPS), a facile approach has been successfully developed for the fabrication of a micropattern possessing nanoscale substructure on the thin film surface. This approach involves three steps. In the first step, a thin film was prepared by spin coating from a solution of a commercial random copolymer, polystyrene-r-poly(methyl methacrylate) (PS-r-PMMA) and a commercial crosslinker, trimethylolpropane triacrylate (TMPTA). In the second step, photolithograph was performed with the thin film using a 250 W high-pressure mercury lamp to produce the micropattern. Finally, the resulting micropattern was annealed at 200 degrees C for a certain time, and reaction-induced phase separation occurred. After soaking in chloroform for 4 h, nanoscale substructure was obtained. The whole processes were traced by atomic force microscopy (AFM), X-ray photoelectron spectrometry (XPS), and Fourier transform infrared (FTIR) spectroscopy, and the results supported the proposed structure.

Direct writing of conductive silver micropatterns on flexible polyimide film by laser-induced pyrolysis of silver nanoparticle-dispersed film

International Nuclear Information System (INIS)

Aminuzzaman, Mohammod; Watanabe, Akira; Miyashita, Tokuji

2010-01-01

This article describes fabrication of Ag micropatterns on a flexible polyimide (PI) film by laser direct writing using an Ag nanoparticle-dispersed film as a precursor. Ag micropatterns are characterized by optical microscopy, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), surface profilometry, and resistivity measurements. The line width of Ag micropatterns can be effectively controlled by altering the experimental parameters of laser direct writing especially laser intensity, objective lens, and laser beam scanning speed etc. Using an objective lens of 100x and laser intensity of 170.50 kW/cm 2 , Ag micropatterns with a line width of about 6 μm have been achieved. The Ag micropatterns show strong adhesion to polyimide surface as evaluated by Scotch-tape test. The resistivity of the Ag micropatterns is determined to be 4.1 x 10 -6 Ω cm using two-point probe method. This value is comparable with the resistivity of bulk Ag (1.6 x 10 -6 Ω cm).

Biomimicking micropatterned surfaces and their effect on marine biofouling.

Science.gov (United States)

Brzozowska, Agata M; Parra-Velandia, Fernando J; Quintana, Robert; Xiaoying, Zhu; Lee, Serina S C; Chin-Sing, Lim; Jańczewski, Dominik; Teo, Serena L-M; Vancso, Julius G

2014-08-05

When synthetic materials are submerged in marine environments, dissolved matter and marine organisms attach to their surfaces by a process known as marine fouling. This phenomenon may lead to diminished material performance with detrimental consequences. Bioinspired surface patterning and chemical surface modifications present promising approaches to the design of novel functional surfaces that can prevent biofouling phenomena. In this study, we report the synergistic effects of surface patterns, inspired by the marine decapod crab Myomenippe hardwickii in combination with chemical surface modifications toward suppressing marine fouling. M. hardwickii is known to maintain a relatively clean carapace although the species occurs in biofouling communities of tropical shallow subtidal coastal waters. Following the surface analysis of selected specimens, we designed hierarchical surface microtopographies that replicate the critical features observed on the crustacean surface. The micropatterned surfaces were modified with zwitterionic polymer brushes or with layer-by-layer deposited polyelectrolyte multilayers to enhance their antifouling and/or fouling-release potential. Chemically modified and unmodified micropatterned surfaces were subjected to extensive fouling tests, including laboratory assays against barnacle settlement and algae adhesion, and field static immersion tests. The results show a statistically significant reduction in settlement on the micropatterned surfaces as well as a synergistic effect when the microtopographies are combined with grafted polymer chains.

Cell micro-patterning by atom beam exposure

International Nuclear Information System (INIS)

Adachi, Taiji; Kajita, Fumiaki; Sato, Katsuya; Matsumoto, Koshi; Tagawa, Masahiro

2003-01-01

This study aimed to develop a new cell micro-patterning method by controlling material surface affinity of the cell using atomic oxygen beam exposure. Surfaces of low-density polyethylene (LDPE) and tetrafluoroethylene-hexafluoropropylene (FEP) were exposed to the atomic oxygen beam. On the LDPE surface, the roughness measured by atomic force microscopy (AFM) did not change much, however, the oxygen concentration on the surface measured by X-ray photoelectron spectroscopy (XPS) significantly increased that resulted in increase in wettability. Contrary to this, on the FEP surface, the oxygen concentration showed no significant change, but roughness of the surface remarkably increased and the wettability decreased. As a result of the surface modification, affinity of the osteoblastic cells on the FEP surface increased, which was also confirmed by increase in the cell area. Finally, cell micro-patterning on the FEP surface was carried out based on difference in the affinity between modified and unmodified surfaces patterned by masking method. (author)

MAPLE deposition of 3D micropatterned polymeric substrates for cell culture

Energy Technology Data Exchange (ETDEWEB)

Paun, Irina Alexandra, E-mail: irina.paun@physics.pub.ro [National Institute for Laser, Plasma and Radiation Physics, RO-077125, Magurele, Bucharest (Romania); Faculty of Applied Sciences, University Politehnica of Bucharest, RO-060042, Bucharest (Romania); Mihailescu, Mona [Faculty of Applied Sciences, University Politehnica of Bucharest, RO-060042, Bucharest (Romania); Calenic, Bogdan [Department of Biochemistry, Faculty of Dentistry, UMF Carol Davila, Bucharest (Romania); Luculescu, Catalin Romeo [National Institute for Laser, Plasma and Radiation Physics, RO-077125, Magurele, Bucharest (Romania); Greabu, Maria [Department of Biochemistry, Faculty of Dentistry, UMF Carol Davila, Bucharest (Romania); Dinescu, Maria, E-mail: dinescum@nipne.ro [National Institute for Laser, Plasma and Radiation Physics, RO-077125, Magurele, Bucharest (Romania)

2013-08-01

3D micropatterned poly(lactide-co-glycolide)/polyurethane (PLGA/PU) substrates were produced by MAPLE deposition through masks and used for regulating the behavior of oral keratinocyte stem cells in response to topography. Flat PLGA/PU substrates were produced for comparison. 3D imaging of the PLGA/PU substrates and of the cultured cells was performed by Digital Holographic Microscopy. The micropatterns were in the shape of squares of 50 × 50 and 80 × 80 μm{sup 2} areas, ∼1.8 μm in height and separated by 20 μm wide channels. It was found that substrate topography guided the adhesion of the cultured cells: on the smooth substrates the cells adhered randomly and showed no preferred orientation; in contrast, on the micropatterned substrates the cells adhered preferentially onto the squares and not in the separating channels. Furthermore, key properties of the cells (size, viability, proliferation rate and stem cell marker expression) did not show any dependence on substrate topography. The size of the cultured cells, their viability, the proportions of actively/slow proliferating cells, as well as the stem cell markers expressions, were similar for both flat and micropatterned substrates. Finally, it was found that the cells cultured on the PLGA/PU substrates deposited by MAPLE exhibited similar properties as the controls (i.e. cells cultured on glass slides), indicating the capability of the former to preserve the properties of the keratinocyte stem cells.

Fabrication of Pillar Shaped Electrode Arrays for Artificial Retinal Implants

Directory of Open Access Journals (Sweden)

Sung June Kim

2008-09-01

Full Text Available Polyimide has been widely applied to neural prosthetic devices, such as the retinal implants, due to its well-known biocompatibility and ability to be micropatterned. However, planar films of polyimide that are typically employed show a limited ability in reducing the distance between electrodes and targeting cell layers, which limits site resolution for effective multi-channel stimulation. In this paper, we report a newly designed device with a pillar structure that more effectively interfaces with the target. Electrode arrays were successfully fabricated and safely implanted inside the rabbit eye in suprachoroidal space. Optical Coherence Tomography (OCT showed well-preserved pillar structures of the electrode without damage. Bipolar stimulation was applied through paired sites (6:1 and the neural responses were successfully recorded from several regions in the visual cortex. Electrically evoked cortical potential by the pillar electrode array stimulation were compared to visual evoked potential under full-field light stimulation.

Micropattern printing of adhesion, spreading, and migration peptides on poly(tetrafluoroethylene) films to promote endothelialization.

Science.gov (United States)

Gauvreau, Virginie; Laroche, Gaétan

2005-01-01

We report here the development of an original multistep micropatterning technique for printing peptides on surfaces, based on the ink-jet printer technology. Contrary to most micropatterning methods used nowadays, this technique is advantageous because it allows displaying 2D-arrays of multiple biomolecules. Moreover, this low cost procedure allies the advantages of computer-aided design with high flexibility and reproducibility. A Hewlett-Packard printer was modified to print peptide solutions, and Adobe Illustrator was used as the graphic-editing software to design high-resolution checkerboard-like micropatterns. In a first step, PTFE films were treated with ammonia plasma to introduce amino groups on the surface. These chemical functionalities were reacted with heterobifunctional cross-linker sulfo-succinimidyl 4-(N-maleimidomethyl)cycloexane-1-carboxylate (S-SMCC) to allow the subsequent surface covalent conjugation of various cysteine-modified peptides to the polymer substrate. These peptidic molecules containing RGD and WQPPRARI sequences were selected for their adhesive, spreading, and migrational properties toward endothelial cells. On one hand, our data demonstrated that the initial cell adhesion does not depend on the chemical structure and combination of the peptides covalently bonded either through conventional conjugation or micropatterning. On the other hand, spreading and migration of endothelial cells is clearly enhanced while coconjugating the GRGDS peptide in conjunction with WQPPRARI. This behavior is further improved by micropatterning these peptides on specific areas of the polymer surface.

Inkjet printing for direct micropatterning of a superhydrophobic surface: Toward biomimetic fog harvesting surfaces

KAUST Repository

Zhang, Lianbin

2015-01-01

The preparation of biomimetic superhydrophobic surfaces with hydrophilic micro-sized patterns is highly desirable, but a one-step, mask-free method to produce such surfaces has not previously been reported. We have developed a direct method to produce superhydrophilic micropatterns on superhydrophobic surfaces based on inkjet printing technology. This work was inspired by the efficient fog-harvesting behavior of Stenocara beetles in the Namib Desert. A mussel-inspired ink consisting of an optimized solution of dopamine was applied directly by inkjet printing to superhydrophobic surfaces. Stable Wenzel\\'s microdroplets of the dopamine solution with well-defined micropatterns were obtained on these surfaces. Superhydrophilic micropatterns with well-controlled dimensions were then readily achieved on the superhydrophobic surfaces by the formation of polydopamine via in situ polymerization. The micropatterned superhydrophobic surfaces prepared by this inkjet printing method showed enhanced water collection efficiency compared with uniform superhydrophilic and superhydrophobic surfaces. This method can be used for the facile large-scale patterning of superhydrophobic surfaces with high precision and superior pattern stability and is therefore a key step toward patterning superhydrophobic surfaces for practical applications. This journal is

Micropatterning on glass with deep UV

OpenAIRE

sprotocols

2015-01-01

Authors: Nicolas CARPI, Matthieu PIEL, Ammar Azioune & Jenny Fink ### Abstract This protocol describes a method to print micropatterns on glass with extra-cellular matrix proteins to promote cell adhesion. The non-adhesive part is made with polylysine grafted polyethyleneglycol (PLL-g-PEG). This technique is reproducible, cheap, fast and can achieve high resolution (~1 µm). ### Introduction This protocol explains how to make high resolution adhesive micropattens of protein...

Morphology and intrinsic excitability of regenerating sensory and motor neurons grown on a line micropattern.

Directory of Open Access Journals (Sweden)

Ouafa Benzina

Full Text Available Axonal regeneration is one of the greatest challenges in severe injuries of peripheral nerve. To provide the bridge needed for regeneration, biological or synthetic tubular nerve constructs with aligned architecture have been developed. A key point for improving axonal regeneration is assessing the effects of substrate geometry on neuronal behavior. In the present study, we used an extracellular matrix-micropatterned substrate comprising 3 µm wide lines aimed to physically mimic the in vivo longitudinal axonal growth of mice peripheral sensory and motor neurons. Adult sensory neurons or embryonic motoneurons were seeded and processed for morphological and electrical activity analyses after two days in vitro. We show that micropattern-guided sensory neurons grow one or two axons without secondary branching. Motoneurons polarity was kept on micropattern with a long axon and small dendrites. The micro-patterned substrate maintains the growth promoting effects of conditioning injury and demonstrates, for the first time, that neurite initiation and extension could be differentially regulated by conditioning injury among DRG sensory neuron subpopulations. The micro-patterned substrate impacts the excitability of sensory neurons and promotes the apparition of firing action potentials characteristic for a subclass of mechanosensitive neurons. The line pattern is quite relevant for assessing the regenerative and developmental growth of sensory and motoneurons and offers a unique model for the analysis of the impact of geometry on the expression and the activity of mechanosensitive channels in DRG sensory neurons.

Precise micropatterning of silver nanoparticles on plastic substrates

International Nuclear Information System (INIS)

Ammosova, Lena; Jiang, Yu; Suvanto, Mika; Pakkanen, Tapani A.

2017-01-01

Highlights: • Silver ink has been deposited on plastic substrate and silver nanoparticles have been produced. • 3D control allows both ink superimposing and deposition on complicated surfaces. • Polyol method ensures the formation of metallic mircopatterns with high uniformity. • Substrate wettability, ink volume, and sintering temperature influences deposited patterns. - Abstract: Conventional fabrication methods to obtain metal patterns on polymer substrates are restricted by high operating temperature and complex preparation steps. The present study demonstrates a simple yet versatile method for preparation of silver nanoparticle micropatterns on polymer substrates with various surface geometry. With the microworking robot technique, we were able not only to directly structure the surface, but also precisely deposit silver nanoparticle ink on the desired surface location with the minimum usage of ink material. The prepared silver nanoparticle ink, containing silver cations and polyethylene glycol (PEG) as a reducing agent, yields silver nanoparticle micropatterns on plastic substrates at low sintering temperature without any contamination. The influence of the ink behaviour was studied, such as substrate wettability, ink volume, and sintering temperature. The ultraviolet visible (UV–vis), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) measurements revealed the formation of micropatterns with uniformly distributed silver nanoparticles. The prepared patterns are expected to have a broad range of applications in optics, medicine, and sensor devices owing to the unique properties of silver. Furthermore, the deposition of a chemical compound, which is different from the substrate material, not only adds a fourth dimension to the prestructured three-dimensional (3D) surfaces, but also opens new application areas to the conventional surface structures.

Precise micropatterning of silver nanoparticles on plastic substrates

Energy Technology Data Exchange (ETDEWEB)

Ammosova, Lena; Jiang, Yu; Suvanto, Mika; Pakkanen, Tapani A., E-mail: tapani.pakkanen@uef.fi

2017-04-15

Highlights: • Silver ink has been deposited on plastic substrate and silver nanoparticles have been produced. • 3D control allows both ink superimposing and deposition on complicated surfaces. • Polyol method ensures the formation of metallic mircopatterns with high uniformity. • Substrate wettability, ink volume, and sintering temperature influences deposited patterns. - Abstract: Conventional fabrication methods to obtain metal patterns on polymer substrates are restricted by high operating temperature and complex preparation steps. The present study demonstrates a simple yet versatile method for preparation of silver nanoparticle micropatterns on polymer substrates with various surface geometry. With the microworking robot technique, we were able not only to directly structure the surface, but also precisely deposit silver nanoparticle ink on the desired surface location with the minimum usage of ink material. The prepared silver nanoparticle ink, containing silver cations and polyethylene glycol (PEG) as a reducing agent, yields silver nanoparticle micropatterns on plastic substrates at low sintering temperature without any contamination. The influence of the ink behaviour was studied, such as substrate wettability, ink volume, and sintering temperature. The ultraviolet visible (UV–vis), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) measurements revealed the formation of micropatterns with uniformly distributed silver nanoparticles. The prepared patterns are expected to have a broad range of applications in optics, medicine, and sensor devices owing to the unique properties of silver. Furthermore, the deposition of a chemical compound, which is different from the substrate material, not only adds a fourth dimension to the prestructured three-dimensional (3D) surfaces, but also opens new application areas to the conventional surface structures.

Micropatterning of biomolecules on a glass substrate in fused silica microchannels by using photolabile linker-based surface activation

International Nuclear Information System (INIS)

Jang, K.; Mawatari, K.; Kitamori, T.; Xu, Y.; Sato, K.; Tanaka, Y.

2012-01-01

We report on a straightforward method for creating micropatterns of multiple biomolecules. The anti-fouling agent 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer and a photolabile linker (PL) were covalently linked to an amino-terminated silane surface. Patterns were generated by selective removal of the MPC polymer via UV irradiation. Multiple micropatterns of fluorescein isothiocyanate (FITC)-labeled bovine serum albumin (BSA) and rhodamine-labeled goat fragment antigen-binding fragments (FAB) were deposited on a same glass substrate. We also employed micropatterning of multiple biomolecules in that Texas red-labeled BSA and FITC-labeled rabbit anti-mouse IgG were placed inside a microchannel. (author)

Multifunctional surfaces with biomimetic nanofibres and drug-eluting micro-patterns for infection control and bone tissue formation

Directory of Open Access Journals (Sweden)

XN Chen

2012-09-01

Full Text Available For long-term orthopaedic implants, the creation of a surface that is repulsive to bacteria while adhesive to tissue cells represents a promising strategy to control infection. To obtain such multifunctional surfaces, two possible approaches were explored to incorporate a model antibiotic, rifampicin (Rf, into the osteogenic polycaprolactone (PCL/chitosan (CHS biomimetic nanofibre meshes by (1 blending Rf into the electrospinning solutions and then electrospinning into nanofibres (i.e., Rf-incorporating fibres, or (2 depositing Rf-containing poly(D,L-lactic-co-glycolic acid (PLGA micro-patterns onto the PCL/chitosan nanofibre meshes via ink-jet printing (i.e., Rf-eluting micro-pattern/fibre. Rapid release of Rf from both meshes was measured even though a relatively slower release rate was obtained from the Rf-eluting micro-pattern ones. Antibacterial assay with Staphylococcus epidermidis showed that both mesh surfaces could effectively kill bacteria and prevent biofilm formation. However, only Rf-eluting micro-pattern meshes favoured the attachment, spreading and metabolic activity of preosteoblasts in the cell culture study. Furthermore, the Rf-eluting micro-pattern meshes could better support the osteogenic differentiation of preosteoblasts by up-regulating the gene expression of bone markers (type I collagen and alkaline phosphatase. Clearly, compared to Rf-incorporating nanofibre meshes, Rf-eluting micro-patterns could effectively prevent biofilm formation without sacrificing the osteogenic properties of PCL/chitosan nanofibre surfaces. This finding provides an innovative avenue to design multifunctional surfaces for enhancing bone tissue formation while controlling infection.

Adhesive Micropatterns for Cells: A Microcontact Printing Protocol

OpenAIRE

sprotocols

2014-01-01

Authors: Manuel Théry and Matthieu Piel Corresponding authors ([](); []()) ### INTRODUCTION This protocol describes a simple, fast, and efficient method for making adhesive micropatterns that can be used to control individual cell shape and adhesion patterns. It is based on the use of an elastomeric stamp containing microfeatures to print proteins on the substrate of choice. The process can be subdiv...

Continuous droplet removal upon dropwise condensation of humid air on a hydrophobic micropatterned surface.

Science.gov (United States)

Zamuruyev, Konstantin O; Bardaweel, Hamzeh K; Carron, Christopher J; Kenyon, Nicholas J; Brand, Oliver; Delplanque, Jean-Pierre; Davis, Cristina E

2014-08-26

Combination of two physical phenomena, capillary pressure gradient and wettability gradient, allows a simple two-step fabrication process that yields a reliable hydrophobic self-cleaning condenser surface. The surface is fabricated with specific microscopic topography and further treatment with a chemically inert low-surface-energy material. This process does not require growth of nanofeatures (nanotubes) or hydrophilic-hydrophobic patterning of the surface. Trapezoidal geometry of the microfeatures facilitates droplet transfer from the Wenzel to the Cassie state and reduces droplet critical diameter. The geometry of the micropatterns enhances local coalescence and directional movement for droplets with diameter much smaller than the radial length of the micropatterns. The hydrophobic self-cleaning micropatterned condenser surface prevents liquid film formation and promotes continuous dropwise condensation cycle. Upon dropwise condensation, droplets follow a designed wettability gradient created with micropatterns from the most hydrophobic to the least hydrophobic end of the surface. The surface has higher condensation efficiency, due to its directional self-cleaning property, than a plain hydrophobic surface. We explain the self-actuated droplet collection mechanism on the condenser surface and demonstrate experimentally the creation of an effective wettability gradient over a 6 mm radial distance. In spite of its fabrication simplicity, the fabricated surface demonstrates self-cleaning property, enhanced condensation performance, and reliability over time. Our work enables creation of a hydrophobic condenser surface with the directional self-cleaning property that can be used for collection of biological (chemical, environmental) aerosol samples or for condensation enhancement.

Involvement of flocculin in negative potential-applied ITO electrode adhesion of yeast cells

Science.gov (United States)

Koyama, Sumihiro; Tsubouchi, Taishi; Usui, Keiko; Uematsu, Katsuyuki; Tame, Akihiro; Nogi, Yuichi; Ohta, Yukari; Hatada, Yuji; Kato, Chiaki; Miwa, Tetsuya; Toyofuku, Takashi; Nagahama, Takehiko; Konishi, Masaaki; Nagano, Yuriko; Abe, Fumiyoshi

2015-01-01

The purpose of this study was to develop novel methods for attachment and cultivation of specifically positioned single yeast cells on a microelectrode surface with the application of a weak electrical potential. Saccharomyces cerevisiae diploid strains attached to an indium tin oxide/glass (ITO) electrode to which a negative potential between −0.2 and −0.4 V vs. Ag/AgCl was applied, while they did not adhere to a gallium-doped zinc oxide/glass electrode surface. The yeast cells attached to the negative potential-applied ITO electrodes showed normal cell proliferation. We found that the flocculin FLO10 gene-disrupted diploid BY4743 mutant strain (flo10Δ /flo10Δ) almost completely lost the ability to adhere to the negative potential-applied ITO electrode. Our results indicate that the mechanisms of diploid BY4743 S. cerevisiae adhesion involve interaction between the negative potential-applied ITO electrode and the Flo10 protein on the cell wall surface. A combination of micropatterning techniques of living single yeast cell on the ITO electrode and omics technologies holds potential of novel, highly parallelized, microchip-based single-cell analysis that will contribute to new screening concepts and applications. PMID:26187908

Micropatterning of nanocomposite polymer scaffolds using sacrificial phosphate glass fibers for tendon tissue engineering applications.

Science.gov (United States)

Alshomer, Feras; Chaves, Camilo; Serra, Tiziano; Ahmed, Ifty; Kalaskar, Deepak M

2017-04-01

This study presents a simple and reproducible method of micropatterning the novel nanocomposite polymer (POSS-PCU) using a sacrificial phosphate glass fiber template for tendon tissue engineering applications. The diameters of the patterned scaffolds produced were dependent on the diameter of the glass fibers (15 μm) used. Scaffolds were tested for their physical properties and reproducibility using various microscopy techniques. For the first time, we show that POSS-PCU supports growth of human tenocytes cells. Furthermore, we show that cellular alignment, their biological function and expression of various tendon related proteins such as scleraxis, collagen I and III, tenascin-C are significantly elevated on the micropatterned polymer surfaces compared to flat samples. This study demonstrated a simple, reproducible method of micropatterning POSS-PCU nanocomposite polymer for novel tendon repair applications, which when provided with physical cues could help mimic the microenvironment of tenocytes cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Scanning electron microscopical observation of an osteoblast/osteoclast co-culture on micropatterned orthopaedic ceramics.

Science.gov (United States)

Halai, Mansur; Ker, Andrew; Meek, Rm Dominic; Nadeem, Danish; Sjostrom, Terje; Su, Bo; McNamara, Laura E; Dalby, Matthew J; Young, Peter S

2014-01-01

In biomaterial engineering, the surface of an implant can influence cell differentiation, adhesion and affinity towards the implant. On contact with an implant, bone marrow-derived mesenchymal stromal cells demonstrate differentiation towards bone forming osteoblasts, which can improve osteointegration. The process of micropatterning has been shown to improve osteointegration in polymers, but there are few reports surrounding ceramics. The purpose of this study was to establish a co-culture of bone marrow-derived mesenchymal stromal cells with osteoclast progenitor cells and to observe the response to micropatterned zirconia toughened alumina ceramics with 30 µm diameter pits. The aim was to establish whether the pits were specifically bioactive towards osteogenesis or were generally bioactive and would also stimulate osteoclastogenesis that could potentially lead to osteolysis. We demonstrate specific bioactivity of micropatterns towards osteogenesis, with more nodule formation and less osteoclastogenesis compared to planar controls. In addition, we found that that macrophage and osteoclast-like cells did not interact with the pits and formed fewer full-size osteoclast-like cells on the pitted surfaces. This may have a role when designing ceramic orthopaedic implants.

Stick-Jump (SJ) Evaporation of Strongly Pinned Nanoliter Volume Sessile Water Droplets on Quick Drying, Micropatterned Surfaces.

Science.gov (United States)

Debuisson, Damien; Merlen, Alain; Senez, Vincent; Arscott, Steve

2016-03-22

We present an experimental study of stick-jump (SJ) evaporation of strongly pinned nanoliter volume sessile water droplets drying on micropatterned surfaces. The evaporation is studied on surfaces composed of photolithographically micropatterned negative photoresist (SU-8). The micropatterning of the SU-8 enables circular, smooth, trough-like features to be formed which causes a very strong pinning of the three phase (liquid-vapor-solid) contact line of an evaporating droplet. This is ideal for studying SJ evaporation as it contains sequential constant contact radius (CCR) evaporation phases during droplet evaporation. The evaporation was studied in nonconfined conditions, and forced convection was not used. Micropatterned concentric circles were defined having an initial radius of 1000 μm decreasing by a spacing ranging from 500 to 50 μm. The droplet evaporates, successively pinning and depinning from circle to circle. For each pinning radius, the droplet contact angle and volume are observed to decrease quasi-linearly with time. The experimental average evaporation rates were found to decrease with decreasing pining radii. In contrast, the experimental average evaporation flux is found to increase with decreasing droplet radii. The data also demonstrate the influence of the initial contact angle on evaporation rate and flux. The data indicate that the total evaporation time of a droplet depends on the specific micropattern spacing and that the total evaporation time on micropatterned surfaces is always less than on flat, homogeneous surfaces. Although the surface patterning is observed to have little effect on the average droplet flux-indicating that the underlying evaporation physics is not significantly changed by the patterning-the total evaporation time is considerably modified by patterning, up to a factor or almost 2 compared to evaporation on a flat, homogeneous surface. The closely spaced concentric circle pinning maintains a large droplet radius and

Construction of Modular Hydrogel Sheets for Micropatterned Macro-scaled 3D Cellular Architecture.

Science.gov (United States)

Son, Jaejung; Bae, Chae Yun; Park, Je-Kyun

2016-01-11

Hydrogels can be patterned at the micro-scale using microfluidic or micropatterning technologies to provide an in vivo-like three-dimensional (3D) tissue geometry. The resulting 3D hydrogel-based cellular constructs have been introduced as an alternative to animal experiments for advanced biological studies, pharmacological assays and organ transplant applications. Although hydrogel-based particles and fibers can be easily fabricated, it is difficult to manipulate them for tissue reconstruction. In this video, we describe a fabrication method for micropatterned alginate hydrogel sheets, together with their assembly to form a macro-scale 3D cell culture system with a controlled cellular microenvironment. Using a mist form of the calcium gelling agent, thin hydrogel sheets are easily generated with a thickness in the range of 100 - 200 µm, and with precise micropatterns. Cells can then be cultured with the geometric guidance of the hydrogel sheets in freestanding conditions. Furthermore, the hydrogel sheets can be readily manipulated using a micropipette with an end-cut tip, and can be assembled into multi-layered structures by stacking them using a patterned polydimethylsiloxane (PDMS) frame. These modular hydrogel sheets, which can be fabricated using a facile process, have potential applications of in vitro drug assays and biological studies, including functional studies of micro- and macrostructure and tissue reconstruction.

Micro-patterned Nafion membranes for direct methanol fuel cell applications

NARCIS (Netherlands)

Yildirim, M.H.; te Braake, J.; Aran, H.C.; Stamatialis, Dimitrios; Wessling, Matthias

2010-01-01

In this work, we report the direct methanol fuel cell (DMFC) performance of micro-patterned (μp) Nafion® 117 (N117) membranes prepared by hot embossing and compare them with that of normal N117 and heat and pressure treated (hp) N117 non-patterned (smooth) membranes. Our results suggest that the

Spontaneous decoration of Au nanoparticles on micro-patterned reduced graphene oxide shaped by focused laser beam

International Nuclear Information System (INIS)

Wan, Y. C.; Tok, E. S.; Teoh, H. F.; Sow, C. H.

2015-01-01

We report a facile, two-step method for the micro-landscaping of Au nanoparticles(NPs) on reduced graphene oxide (rGO) film en route to micro-patterned Au(NPs)-rGO hybrid functional materials. This method employs a focused laser beam to first locally convert GO to rGO before immersing the micro-patterned GO-rGO film into HAuCl 4 solution. The rGO micro-pattern, shaped by the focused laser beam, serves as nucleation sites for the reduction of Au ions. The reduction mechanism that governs the decoration of Au NPs on rGO films is akin to electroless deposition process. In this instance, surface charges that are formed during laser reduction of GO to rGO provide active nucleation sites for Au 3+ ions to form Au NPs when HAuCl 4 solution is introduced. The number density, the size, and size distribution of the Au NPs can thus be directly tuned and preferentially anchored onto the rGO micro-pattern by varying the incident laser power, the scanning speed of the laser, or the concentration of HAuCl 4 . The resulting hybrid materials can be used as a substrate for Surface Enhanced Raman Spectroscopy (SERS). Using Rhodamine 6G as the test subject, we found an improvement of SERS enhancement over bare rGO of up to four times, depending on the size of the Au NPs

Spontaneous decoration of Au nanoparticles on micro-patterned reduced graphene oxide shaped by focused laser beam

Energy Technology Data Exchange (ETDEWEB)

Wan, Y. C.; Tok, E. S. [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Teoh, H. F. [Graduate School of Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456 (Singapore); Sow, C. H. [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Graduate School of Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456 (Singapore)

2015-02-07

We report a facile, two-step method for the micro-landscaping of Au nanoparticles(NPs) on reduced graphene oxide (rGO) film en route to micro-patterned Au(NPs)-rGO hybrid functional materials. This method employs a focused laser beam to first locally convert GO to rGO before immersing the micro-patterned GO-rGO film into HAuCl{sub 4} solution. The rGO micro-pattern, shaped by the focused laser beam, serves as nucleation sites for the reduction of Au ions. The reduction mechanism that governs the decoration of Au NPs on rGO films is akin to electroless deposition process. In this instance, surface charges that are formed during laser reduction of GO to rGO provide active nucleation sites for Au{sup 3+} ions to form Au NPs when HAuCl{sub 4} solution is introduced. The number density, the size, and size distribution of the Au NPs can thus be directly tuned and preferentially anchored onto the rGO micro-pattern by varying the incident laser power, the scanning speed of the laser, or the concentration of HAuCl{sub 4}. The resulting hybrid materials can be used as a substrate for Surface Enhanced Raman Spectroscopy (SERS). Using Rhodamine 6G as the test subject, we found an improvement of SERS enhancement over bare rGO of up to four times, depending on the size of the Au NPs.

Micro-patterned ZnO semiconductors for high performance thin film transistors via chemical imprinting with a PDMS stamp.

Science.gov (United States)

Seong, Kieun; Kim, Kyongjun; Park, Si Yun; Kim, Youn Sang

2013-04-07

Chemical imprinting was conducted on ZnO semiconductor films via a chemical reaction at the contact regions between a micro-patterned PDMS stamp and ZnO films. In addition, we applied the chemical imprinting on Li doped ZnO thin films for high performance TFTs fabrication. The representative micro-patterned Li doped ZnO TFTs showed a field effect mobility of 4.2 cm(2) V(-1) s(-1) after sintering at 300 °C.

Micropatterned 2D Hybrid Perovskite Thin Films with Enhanced Photoluminescence Lifetimes

NARCIS (Netherlands)

Kamminga, Machteld E.; Fang, Hong Hua; Loi, Maria Antonietta; Ten Brink, Gert H.; Blake, Graeme R.; Palstra, Thomas T.M.; Ten Elshof, Johan E.

2018-01-01

The application of luminescent materials in display screens and devices requires micropatterned structures. In this work, we have successfully printed microstructures of a two-dimensional (2D), orange-colored organic/inorganic hybrid perovskite ((C6H5CH2NH3)2PbI4) using two different soft

Development of innovative micro-pattern gaseous detectors with resistive electrodes and first results of their applications

CERN Document Server

Di Mauro, A; Martinengo, P; Nappi, E; Oliveira, R; Peskov, Vladimir; Periale, L; Picchi, P; Pietropaolo, F; Rodionov, I; Santiard, Jean-Claude

2007-01-01

The paper summarizes our latest progress in the development of newly introduced micro pattern gaseous detectors with resistive electrodes. These resistive electrodes protect the detector and the front-end electronics in case of occasional discharges and thus make the detectors very robust and reliable in operation. As an example, we describe in greater detail a new recently developed GEM-like detector, fully spark-protected with electrodes made of resistive kapton. We discovered that all resistive layers used in these studies (including kapton), that are coated with photosensitive layers, such as CsI, can be used as efficient photo cathodes for detectors operating in a pulse counting mode. We describe the first applications of such detectors combined with CsI or SbCs photo cathodes for the detection of UV photons at room and cryogenic temperatures.

Optimization of micropatterned poly(lactic-co-glycolic acid films for enhancing dorsal root ganglion cell orientation and extension

Directory of Open Access Journals (Sweden)

Ching-Wen Li

2018-01-01

Full Text Available Nerve conduits have been a viable alternative to the ‘gold standard’ autograft for treating small peripheral nerve gap injuries. However, they often produce inadequate functional recovery outcomes and are ineffective in large gap injuries. Ridge/groove surface micropatterning has been shown to promote neural cell orientation and guide growth. However, optimization of the ratio of ridge/groove parameters to promote orientation and extension for dorsal root ganglion (DRG cells on poly(lactic-co-glycolic acid (PLGA films has not been previously conducted. Photolithography and micro-molding were used to define various combinations of ridge/groove dimensions on PLGA films. The DRG cells obtained from chicken embryos were cultured on micropatterned PLGA films for cell orientation and migration evaluation. Biodegradation of the films occurred during the test period, however, this did not cause deformation or distortion of the micropatterns. Results from the DRG cell orientation test suggest that when the ridge/groove ratio equals 1 (ridge/groove width parameters are equal, i.e., 10 μm/10 μm (even, the degree of alignment depends on the size of the ridges and grooves, when the ratio is smaller than 1 (groove controlled the alignment increases as the ridge size decreases, and when the ratio is larger than 1 (ridge controlled, the alignment is reduced as the width of the grooves decreases. The migration rate and neurite extension of DRG neurons were greatest on 10 μm/10 μm and 30 μm/30 μm micropatterned PLGA films. Based on the data, the 10 μm/10 μm and 30 μm/30 μm micropatterned PLGA films are the optimized ridge/groove surface patterns for the construction of nerve repair devices.

Self-organization of human embryonic stem cells on micropatterns

Science.gov (United States)

Deglincerti, Alessia; Etoc, Fred; Guerra, M. Cecilia; Martyn, Iain; Metzger, Jakob; Ruzo, Albert; Simunovic, Mijo; Yoney, Anna; Brivanlou, Ali H.; Siggia, Eric; Warmflash, Aryeh

2018-01-01

Fate allocation in the gastrulating embryo is spatially organized as cells differentiate to specialized cell types depending on their positions with respect to the body axes. There is a need for in vitro protocols that allow the study of spatial organization associated with this developmental transition. While embryoid bodies and organoids can exhibit some spatial organization of differentiated cells, these methods do not yield consistent and fully reproducible results. Here, we describe a micropatterning approach where human embryonic stem cells are confined to disk-shaped, sub-millimeter colonies. After 42 hours of BMP4 stimulation, cells form self-organized differentiation patterns in concentric radial domains, which express specific markers associated with the embryonic germ layers, reminiscent of gastrulating embryos. Our protocol takes 3 days; it uses commercial microfabricated slides (CYTOO), human laminin-521 (LN-521) as extra-cellular matrix coating, and either conditioned or chemically-defined medium (mTeSR). Differentiation patterns within individual colonies can be determined by immunofluorescence and analyzed with cellular resolution. Both the size of the micropattern and the type of medium affect the patterning outcome. The protocol is appropriate for personnel with basic stem cell culture training. This protocol describes a robust platform for quantitative analysis of the mechanisms associated with pattern formation at the onset of gastrulation. PMID:27735934

New technologies for large-scale micropatterning of functional nanocomposite polymers

Science.gov (United States)

Khosla, A.; Gray, B. L.

2012-04-01

We present a review of different micropatterning technologies for flexible elastomeric functional nanocomposites with a particular emphasis on mold material and processes for production of large size substrates. The functional polymers include electrically conducting and magnetic materials developed at the Micro-instrumentation Laboratory at Simon Fraser University, Canada. We present a chart that compares many of these different conductive and magnetic functional nanocomposites and their measured characteristics. Furthermore, we have previously reported hybrid processes for nanocomposite polymers micromolded against SU-8 photoepoxy masters. However, SU-8 is typically limited to substrate sizes that are compatible with microelectronics processing as a microelectronics uv-patterning step is typically involved, and de-molding problems are observed. Recently, we have developed new processes that address the problems faced with SU-8 molds. These new technologies for micropatterning nanocomposites involve new substrate materials. A low cost Poly(methyl methacrylate) (PMMA) microfabrication technology has been developed, which involves fabrication of micromold via either CO2 laser ablation or deep UV. We have previously reported this large-scale patterning technique using laser ablation. Finally, we compare the two processes for PMMA producing micromolds for nanocomposites.

Effect of micropatterning induced surface hydrophobicity on drug release from electrospun cellulose acetate nanofibers

Science.gov (United States)

Adepu, Shivakalyani; Gaydhane, Mrunalini K.; Kakunuri, Manohar; Sharma, Chandra S.; Khandelwal, Mudrika; Eichhorn, Stephen J.

2017-12-01

Sustained release and prevention of burst release for low half-life drugs like Diclofenac sodium is crucial to prevent drug related toxicity. Electrospun nanofibers have emerged recently as potential carrier materials for controlled and sustained drug release. Here, we present a facile method to prevent burst release by tuning the surface wettability through template assisted micropatterning of drug loaded electrospun cellulose acetate (CA) nanofibers. A known amount of drug (Diclofenac sodium) was first mixed with CA and then electrospun in the form of a nanofabric. This as-spun network was hydrophilic in nature. However, when electrospinning was carried out through non-conducting templates, viz nylon meshes with 50 and 100 μm size openings, two kinds of hydrophobic micro-patterned CA nanofabrics were produced. In vitro transdermal testing of our nanofibrous mats was carried out; these tests were able to show that it would be possible to create a patch for transdermal drug release. Further, our results show that with optimized micro-patterned dimensions, a zero order sustained drug release of up to 12 h may be achieved for the transdermal system when compared to non-patterned samples. This patterning caused a change in the surface wettability, to a hydrophobic surface, resulting in a controlled diffusion of the hydrophilic drug. Patterning assisted in controlling the initial burst release, which is a significant finding especially for low half-life drugs.

Adhesion and migration of CHO cells on micropatterned single layer graphene

Science.gov (United States)

Keshavan, S.; Oropesa-Nuñez, R.; Diaspro, A.; Canale, C.; Dante, S.

2017-06-01

Cell patterning technology on single layer graphene (SLG) is a fairly new field that can find applications in tissue engineering and biomaterial/biosensors development. Recently, we have developed a simple and effective approach for the fabrication of patterned SLG substrates by laser micromachining, and we have successfully applied it for the obtainment of geometrically ordered neural networks. Here, we exploit the same approach to investigate the generalization of the cell response to the surface cues of the fabricated substrates and, contextually, to quantify cell adhesion on the different areas of the patterns. To attain this goal, we tested Chinese hamster ovary (CHO) cells on PDL-coated micropatterned SLG substrates and quantified the adhesion by using single cell force spectroscopy (SCFS). Our results indicate higher cell adhesion on PDL-SLG, and, consequently, an initial CHO cell accumulation on the graphene areas, confirming the neuronal behaviour observed previously; interestingly, at later time point in culture, cell migration was observed towards the adjacent SLG ablated regions, which resulted more favourable for cell proliferation. Therefore, our findings indicate that the mechanism of interaction with the surface cues offered by the micropatterned substrates is strictly cell-type dependent.

Subsurface oxidation for micropatterning silicon (SOMS).

Science.gov (United States)

Zhang, Feng; Sautter, Ken; Davis, Robert C; Linford, Matthew R

2009-02-03

Here we present a straightforward patterning technique for silicon: subsurface oxidation for micropatterning silicon (SOMS). In this method, a stencil mask is placed above a silicon surface. Radio-frequency plasma oxidation of the substrate creates a pattern of thicker oxide in the exposed regions. Etching with HF or KOH produces very shallow or much higher aspect ratio features on silicon, respectively, where patterning is confirmed by atomic force microscopy, scanning electron microscopy, and optical microscopy. The oxidation process itself is studied under a variety of reaction conditions, including higher and lower oxygen pressures (2 and 0.5 Torr), a variety of powers (50-400 W), different times and as a function of reagent purity (99.5 or 99.994% oxygen). SOMS can be easily executed in any normal chemistry laboratory with a plasma generator. Because of its simplicity, it may have industrial viability.

Novel micro-patterning processes for thin film NiTi vascular devices

International Nuclear Information System (INIS)

Chun, Y J; Mohanchandra, K P; Carman, G P; Levi, D S; Fishbein, M C

2010-01-01

In order to create microscale features in thin film NiTi for use in vascular endografts, a novel 'lift-off process' was developed for use with deep reactive ion etching. A wet etching approach is compared to two variations of this new 'lift-off' process. The first lift-off process (lift-off I) used Si posts to define the features of NiTi film deposited on the Si substrate. This method produced fractures in the NiTi when the film was released. The lift-off II process used Si islands as substrate for the film while the Si wafer defined the specific geometric features. Lift-off II process allowed for the creation of various shape patterns (i.e., ellipse, diamond, circle, square, etc) in the range of 5–180 µm. The lift-off II process produced smooth and well aligned micro-patterns in thin film NiTi without the undercutting found in wet etching techniques. The micro-patterned thin film NiTi formed from the lift-off II process was used to cover a stent. In vivo tests were performed to evaluate the endothelialization though patterned thin films. Angiography, histopathology and SEM showed patency of the artery and uniformly promoted endothelial layer covering without thrombosis in both a medium and small artery

Live-Cell, Label-Free Identification of GABAergic and Non-GABAergic Neurons in Primary Cortical Cultures Using Micropatterned Surface

Science.gov (United States)

Kono, Sho; Kushida, Takatoshi; Hirano-Iwata, Ayumi; Niwano, Michio; Tanii, Takashi

2016-01-01

Excitatory and inhibitory neurons have distinct roles in cortical dynamics. Here we present a novel method for identifying inhibitory GABAergic neurons from non-GABAergic neurons, which are mostly excitatory glutamatergic neurons, in primary cortical cultures. This was achieved using an asymmetrically designed micropattern that directs an axonal process to the longest pathway. In the current work, we first modified the micropattern geometry to improve cell viability and then studied the axon length from 2 to 7 days in vitro (DIV). The cell types of neurons were evaluated retrospectively based on immunoreactivity against GAD67, a marker for inhibitory GABAergic neurons. We found that axons of non-GABAergic neurons grow significantly longer than those of GABAergic neurons in the early stages of development. The optimal threshold for identifying GABAergic and non-GABAergic neurons was evaluated to be 110 μm at 6 DIV. The method does not require any fluorescence labelling and can be carried out on live cells. The accuracy of identification was 98.2%. We confirmed that the high accuracy was due to the use of a micropattern, which standardized the development of cultured neurons. The method promises to be beneficial both for engineering neuronal networks in vitro and for basic cellular neuroscience research. PMID:27513933

Monte Carlo simulations of protein micropatterning in biomembranes: effects of immobile sticky obstacles

International Nuclear Information System (INIS)

Arnold, Andreas M; Sevcsik, Eva; Schütz, Gerhard J

2016-01-01

Single molecule trajectories of lipids and proteins can yield valuable information about the nanoscopic organization of the plasma membrane itself. The interpretation of such trajectories, however, is complicated, as the mobility of molecules can be affected by the presence of immobile obstacles, and the transient binding of the tracers to these obstacles. We have previously developed a micropatterning approach that allows for immobilizing a plasma membrane protein and probing the diffusional behavior of a putative interaction partner in living cells. Here, we provide guidelines on how this micropatterning approach can be extended to quantify interaction parameters between plasma membrane constituents in their natural environment. We simulated a patterned membrane system and evaluated the effect of different surface densities of patterned immobile obstacles on the relative mobility as well as the surface density of diffusing tracers. In the case of inert obstacles, the size of the obstacle can be assessed from its surface density at the percolation threshold, which in turn can be extracted from the diffusion behavior of the tracer. For sticky obstacles, 2D dissociation constants can be determined from the tracer diffusion or surface density. (paper)

Innovative applications and developments of micro-pattern gaseous detectors

CERN Document Server

Francke, Tom

2014-01-01

Study of nature and the world around us has been a primary motivation for scientists and researchers for centuries. Advanced methods in the study of elementary particles have led to even greater discoveries in recent years. "Innovative Applications and Developments of Micro-Pattern Gaseous Detectors" focuses on the analysis and use of various gas detection systems, providing a detailed description of some of the most commonly used gas detectors and the science behind them. From early detectors to modern tools and techniques, this book will be of particular use to practitioners and researchers in chemical engineering and materials science, in addition to students and academicians concentrating in the field.

Semiconductor micropattern pixel detectors a review of the beginnings

CERN Document Server

Heijne, Erik H M

2001-01-01

The innovation in monolithic and hybrid semiconductor 'micropattern' or 'reactive' pixel detectors for tracking in particle physics was actually to fit logic and pulse processing electronics with µW power on a pixel area of less than 0.04 mm2, retaining the characteristics of a traditional nuclear amplifier chain. The ns timing precision in conjunction with local memory and logic operations allowed event selection at > 10 MHz rates with unambiguous track reconstruction even at particle multiplicities > 10 cm-2. The noise in a channel was ~100 e- r.m.s. and enabled binary operation with random noise 'hits' at a level 30 Mrad, respectively.

Fabrication of micropatterned alginate-gelatin and k-carrageenan hydrogels of defined shapes using simple wax mould method as a platform for stem cell/induced Pluripotent Stem Cells (iPSC) culture.

Science.gov (United States)

Vignesh, S; Gopalakrishnan, Aswathi; M R, Poorna; Nair, Shantikumar V; Jayakumar, R; Mony, Ullas

2018-06-01

Micropatterning techniques involve soft lithography, which is laborious, expensive and restricted to a narrow spectrum of biomaterials. In this work we report, first time employment of patterned wax moulds for generation of micropatterned alginate-gelatin and κ-carrageenan (κ-CRG) hydrogel systems by a novel, simple and cost effective method. We generated and characterized uniform and reproducible micropatterned hydrogels of varying sizes and shapes such as square projections, square grooves, and circular grids and crisscrossed hillocks. The rheological analysis showed that κ-carrageenan hydrogels had higher gel strength when compared to alginate-gelatin hydrogels. Human Mesenchymal stem cells (hMSCs) and Human Induced Pluripotent Stem Cells (hiPSCs) were found to be cytocompatible with these hydrogels. This micropatterned hydrogel system may have potential application in tissue engineering and also in understanding the basic biology behind the stem cell/iPSC fate. Copyright © 2018 Elsevier B.V. All rights reserved.

Micropatterned substrates for studying astrocytes in culture

Directory of Open Access Journals (Sweden)

William Lee

2009-12-01

Full Text Available Recent studies of the physiological roles of astrocytes have ignited renewed interest in the functional significance of these glial cells in the central nervous system. Many of the newly discovered astrocytic functions were initially demonstrated and characterized in cell culture systems. We discuss the use of microculture techniques and micropatterning of cell-adhesive substrates in studies of astrocytic Ca2+ excitability and bidirectional neuron-astrocyte signaling. This culturing approach aims to reduce the level of complexity of the system by limiting the interacting partners and by controlling the localization of cells. It provides tight control over experimental conditions allowing detailed characterization of cellular functions and intercellular communication. Although such a reductionist approach yields some difference in observations between astrocytic properties in culture and in situ, general phenomena discovered in cell culture systems, however, have also been found in vivo.

Scalable fabrication of strongly textured organic semiconductor micropatterns by capillary force lithography.

Science.gov (United States)

Jo, Pil Sung; Vailionis, Arturas; Park, Young Min; Salleo, Alberto

2012-06-26

Strongly textured organic semiconductor micropatterns made of the small molecule dioctylbenzothienobenzothiophene (C(8)-BTBT) are fabricated by using a method based on capillary force lithography (CFL). This technique provides the C(8)-BTBT solution with nucleation sites for directional growth, and can be used as a scalable way to produce high quality crystalline arrays in desired regions of a substrate for OFET applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Micropatterned co-culture of hepatocyte spheroids layered on non-parenchymal cells to understand heterotypic cellular interactions

International Nuclear Information System (INIS)

Otsuka, Hidenori; Sasaki, Kohei; Okimura, Saya; Nagamura, Masako; Nakasone, Yuichi

2013-01-01

Microfabrication and micropatterning techniques in tissue engineering offer great potential for creating and controlling cellular microenvironments including cell–matrix interactions, soluble stimuli and cell–cell interactions. Here, we present a novel approach to generate layered patterning of hepatocyte spheroids on micropatterned non-parenchymal feeder cells using microfabricated poly(ethylene glycol) (PEG) hydrogels. Micropatterned PEG-hydrogel-treated substrates with two-dimensional arrays of gelatin circular domains (ϕ = 100 μm) were prepared by photolithographic method. Only on the critical structure of PEG hydrogel with perfect protein rejection, hepatocytes were co-cultured with non-parenchymal cells to be led to enhanced hepatocyte functions. Then, we investigated the mechanism of the functional enhancement in co-culture with respect to the contributions of soluble factors and direct cell–cell interactions. In particular, to elucidate the influence of soluble factors on hepatocyte function, hepatocyte spheroids underlaid with fibroblasts (NIH/3T3 mouse fibroblasts) or endothelial cells (BAECs: bovine aortic endothelial cells) were compared with physically separated co-culture of hepatocyte monospheroids with NIH3T3 or BAEC using trans-well culture systems. Our results suggested that direct heterotypic cell-to-cell contact and soluble factors, both of these between hepatocytes and fibroblasts, significantly enhanced hepatocyte functions. In contrast, direct heterotypic cell-to-cell contact between hepatocytes and endothelial cells only contributed to enhance hepatocyte functions. This patterning technique can be a useful experimental tool for applications in basic science, drug screening and tissue engineering, as well as in the design of artificial liver devices. (paper)

Profuse and Selective Growth in vitro of Rat Spinal Axons on a Micro-Patterned Poly (ethylene imine) Grid

National Research Council Canada - National Science Library

Mouveroux, J

2001-01-01

To distribute neurites (axons) along a surface and to guide them towards specific point targets we cultured spinal cord explants on coverslips printed with a micro-patterned grid of poly (ethylene imine) (PEI) lanes...

Conformal ZnO nanocomposite coatings on micro-patterned surfaces for superhydrophobicity

International Nuclear Information System (INIS)

Steele, Adam; Bayer, Ilker; Moran, Stephen; Cannon, Andrew; King, William P.; Loth, Eric

2010-01-01

A conformal coating process is presented to transform surfaces with inherent micro-morphology into superhydrophobic surfaces with hierarchical surface structure using wet chemical spray casting. Nanocomposite coatings composed of zinc oxide nanoparticles and organosilane quaternary nitrogen compound are dispersed in solution for application. The coating is applied to a micro-patterned polydimethylsiloxane substrate with a regular array of cylindrical microposts as well as a surface with random micro-structure for the purpose of demonstrating improved non-wettability and a superhydrophobic state for water droplets. Coating surface morphology is investigated with an environmental scanning electron microscope and surface wettability performance is characterized by static and dynamic contact angle measurements.

High-throughput creation of micropatterned PDMS surfaces using microscale dual roller casting

International Nuclear Information System (INIS)

DiBartolomeo, Franklin J; Ge, Ning; Trinkle, Christine A

2012-01-01

This work introduces microscale dual roller casting (MDRC), a novel high-throughput fabrication method for creating continuous micropatterned surfaces using thermosetting polymers. MDRC utilizes a pair of rotating, heated cylindrical molds with microscale surface patterns to cure a continuous microstructured film. Using unmodified polydimethylsiloxane as the thermosetting polymer, we were able to create optically transparent, biocompatible surfaces with submicron patterning fidelity. Compared to other roll-to-roll fabrication processes, this method offers increased flexibility in the types of materials and topography that can be generated, including dual-sided patterning, embedded materials and tunable film thickness. (paper)

Methods of Micropatterning and Manipulation of Cells for Biomedical Applications

Directory of Open Access Journals (Sweden)

Adrian Martinez-Rivas

2017-11-01

Full Text Available Micropatterning and manipulation of mammalian and bacterial cells are important in biomedical studies to perform in vitro assays and to evaluate biochemical processes accurately, establishing the basis for implementing biomedical microelectromechanical systems (bioMEMS, point-of-care (POC devices, or organs-on-chips (OOC, which impact on neurological, oncological, dermatologic, or tissue engineering issues as part of personalized medicine. Cell patterning represents a crucial step in fundamental and applied biological studies in vitro, hence today there are a myriad of materials and techniques that allow one to immobilize and manipulate cells, imitating the 3D in vivo milieu. This review focuses on current physical cell patterning, plus chemical and a combination of them both that utilizes different materials and cutting-edge micro-nanofabrication methodologies.

Development of Hybrid and Monolithic Silicon Micropattern Detectors

CERN Multimedia

Beker, H; Snoeys, W; Campbell, M; Lemeilleur, F; Ropotar, I

2002-01-01

%RD-19 \\\\ \\\\ In a collaborative effort between particle physics institutes and microelectronics industry we are undertaking the development of true 2-dimensional semiconductor particle detectors with on-chip signal processing and information extraction: the so-called micropattern detector. This detector is able to cope in a robust way with high multiplicity events at high rates, while allowing for a longer detector lifetime under irradiation and a thinner sensitive depletion region. Therefore, it will be ideally suited for the complicated events in the LHC p-p collider experiments. Following a $^{\\prime}$stepping stone$^{\\prime}$ approach several telescopes of pixel planes, totalling now 600 cm$^{2}$ with \\(>\\)~1~M elements have been used in the WA97, NA50 and NA57 lead ion experiments. This new technology has facilitated the tracking considerably (see Fig.1). Not only Si but also GaAs and possibly diamond matrices can be connected to the readout matrix. Tests with GaAs pixel detectors with the RD-19 readout ...

A novel fast timing micropattern gaseous detector: FTM

CERN Document Server

De Oliveira, Rui; Sharma, Archana

2015-01-01

In recent years important progress in micropattern gaseous detectors has been achieved in the use of resistive material to build compact spark-protected devices. The novel idea presented here consists of the polarisation of WELL structures using only resistive coating. This allows a new device to be built with an architecture based on a stack of several coupled layers where drift and WELL multiplication stages alternate in the structure. The signals from each multiplication stage can be read out from any external readout boards through the capacitive couplings. Each layer provides a signal with a gain of 10^4-10^5. The main advantage of this new device is the dramatic improvement of the timing provided by the competition of the ionisation processes in the different drift regions, which can be exploited for fast timing at the high luminosity accelerators (e.g. HL-LHC upgrade) as well as far applications like medical imaging.

Micro-patterned agarose gel devices for single-cell high-throughput microscopy of E. coli cells.

Science.gov (United States)

Priest, David G; Tanaka, Nobuyuki; Tanaka, Yo; Taniguchi, Yuichi

2017-12-21

High-throughput microscopy of bacterial cells elucidated fundamental cellular processes including cellular heterogeneity and cell division homeostasis. Polydimethylsiloxane (PDMS)-based microfluidic devices provide advantages including precise positioning of cells and throughput, however device fabrication is time-consuming and requires specialised skills. Agarose pads are a popular alternative, however cells often clump together, which hinders single cell quantitation. Here, we imprint agarose pads with micro-patterned 'capsules', to trap individual cells and 'lines', to direct cellular growth outwards in a straight line. We implement this micro-patterning into multi-pad devices called CapsuleHotel and LineHotel for high-throughput imaging. CapsuleHotel provides ~65,000 capsule structures per mm 2 that isolate individual Escherichia coli cells. In contrast, LineHotel provides ~300 line structures per mm that direct growth of micro-colonies. With CapsuleHotel, a quantitative single cell dataset of ~10,000 cells across 24 samples can be acquired and analysed in under 1 hour. LineHotel allows tracking growth of > 10 micro-colonies across 24 samples simultaneously for up to 4 generations. These easy-to-use devices can be provided in kit format, and will accelerate discoveries in diverse fields ranging from microbiology to systems and synthetic biology.

Micropatterned Silica Films with Nanohydroxyapatite for Y-TZP Implants.

Science.gov (United States)

Miranda, R B P; Grenho, L; Carvalho, A; Fernandes, M H; Monteiro, F J; Cesar, P F

2018-03-01

This investigation aimed at developing micropatterned silica thin films (MSTFs) containing nanohydroxyapatite (nano-HA) microaggregates that were not completely covered by silica so that they could directly interact with the surrounding cells. The objectives were 1) to evaluate the effect of the presence of 2 films (MSTF with or without nano-HA addition) on the characteristic strength (σ 0 ) and Weibull modulus ( m) of a yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and 2) to evaluate the effect of these 2 films, as applied onto the Y-TZP surface, on the morphology, orientation, and proliferation of MG63 cells. Sol-gel process and soft lithography were used to apply the MSTF onto the Y-TZP specimens. Three experimental groups were produced: Y-TZP, Y-TZP + MSTF, and Y-TZP + MSTF + sprayed nano-HA. All surfaces were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy and tested for 4-point flexural strength ( n = 30) in water at 37 °C. Weibull analysis was used to determine m and σ 0 (maximum likelihood method). In vitro biological behavior was performed with human osteoblast-like cells (MG63). Y-TZP was successfully coated with MSFT and MSFT + nano-HA. Scanning electron microscopy micrographs indicated that the microaggregates of nano-HA were not entirely covered by the silica. There was no statistically significant difference among the experimental groups for σ 0 and m. In the groups containing the films, the cells were elongated and aligned along the lines. The MSFT + nano-HA group showed significantly higher cell metabolic activity than that obtained for the Y-TZP group at day 7. This investigation was successful in producing an MSTF containing nano-HA microaggregates that remained exposed to the environment. The developed films did not jeopardize the structural reliability of a commercial Y-TZP, as confirmed by the Weibull statistics. The MG63 cells seeded over the films became elongated and aligned along the

Modulation of human dermal microvascular endothelial cell and human gingival fibroblast behavior by micropatterned silica coating surfaces for zirconia dental implant applications

International Nuclear Information System (INIS)

Laranjeira, Marta S; Carvalho, Ângela; Ferraz, Maria Pia; Monteiro, Fernando Jorge; Pelaez-Vargas, Alejandro; Hansford, Derek; Coimbra, Susana; Costa, Elísio; Santos-Silva, Alice; Fernandes, Maria Helena

2014-01-01

Dental ceramic implants have shown superior esthetic behavior and the absence of induced allergic disorders when compared to titanium implants. Zirconia may become a potential candidate to be used as an alternative to titanium dental implants if surface modifications are introduced. In this work, bioactive micropatterned silica coatings were produced on zirconia substrates, using a combined methodology of sol–gel processing and soft lithography. The aim of the work was to compare the in vitro behavior of human gingival fibroblasts (HGFs) and human dermal microvascular endothelial cells (HDMECs) on three types of silica-coated zirconia surfaces: flat and micropatterned (with pillars and with parallel grooves). Our results showed that cells had a higher metabolic activity (HGF, HDMEC) and increased gene expression levels of fibroblast-specific protein-1 (FSP-1) and collagen type I (COL I) on surfaces with pillars. Nevertheless, parallel grooved surfaces were able to guide cell growth. Even capillary tube-like networks of HDMEC were oriented according to the surface geometry. Zirconia and silica with different topographies have shown to be blood compatible and silica coating reduced bacteria adhesion. All together, the results indicated that microstructured bioactive coating seems to be an efficient strategy to improve soft tissue integration on zirconia implants, protecting implants from peri-implant inflammation and improving long-term implant stabilization. This new approach of micropatterned silica coating on zirconia substrates can generate promising novel dental implants, with surfaces that provide physical cues to guide cells and enhance their behavior. (paper)

Tribological improvement of moving microparts by application of thin films and micropatterning

International Nuclear Information System (INIS)

Bandorf, R; Paulkowski, D M; Schiffmann, K I; Kuester, R L A

2008-01-01

The relevance of active microsystems continually increases and with the expansion of applications also aspects of reliability and durability of the moving microparts. In particular, the microtribological improvement of active MEMS therefore was investigated and improved. On the one hand, the influence of different thin films was investigated; on the other hand, improvement by micropatterning of the tribological surfaces in combination with coatings was studied. Most promising results were gained using thin carbon-based films. The typical film thickness of the coatings was in a range of several tens up to a few hundred nanometres. The films were deposited by plasma processes varying different process parameters, mainly the applied bias voltage. Different doping elements (Si, Au and W) were added to the diamond-like carbon (DLC) films (a-C, a-C:H, a-C:H:Si, a-C:H:Au, and a-C:H:W). Different methods were used for characterizing the thin films. Under single asperity contact indentation and scratch tests were performed to determine microhardness, microwear and microfriction. An influence of the applied bias voltage on the micromechanical and microtribological properties was found. At low constant loads of 100 μN the more brittle a-C films showed an initially higher microwear volume than the more elastic a-C:H films. With increasing load the microwear of the a-C films showed less increase of microwear compared to a-C:H films. At low load in the range from 50 μN to a few 100 μN the friction coefficient in single-asperity contact decreased with increasing load. Reaching a critical load the behaviour changed and due to inelastic effects, the friction coefficient increased with further increasing load. For investigation of microabrasive wear under multi-asperity contact a specifically developed tester was used. Besides a ranking of different materials regarding their abrasive microwear resistance the influence of the substrate material on the resulting wear behaviour was

Manganese oxide micro-supercapacitors with ultra-high areal capacitance

Science.gov (United States)

Wang, Xu; Myers, Benjamin D.; Yan, Jian; Shekhawat, Gajendra; Dravid, Vinayak; Lee, Pooi See

2013-05-01

A symmetric micro-supercapacitor is constructed by electrochemically depositing manganese oxide onto micro-patterned current collectors. High surface-to-volume ratio of manganese oxide and short diffusion distance between electrodes give an ultra-high areal capacitance of 56.3 mF cm-2 at a current density of 27.2 μA cm-2.A symmetric micro-supercapacitor is constructed by electrochemically depositing manganese oxide onto micro-patterned current collectors. High surface-to-volume ratio of manganese oxide and short diffusion distance between electrodes give an ultra-high areal capacitance of 56.3 mF cm-2 at a current density of 27.2 μA cm-2. Electronic supplementary information (ESI) available: Experimental procedures; optical images of micro-supercapacitors; areal capacitances of samples M-0.3C, M-0.6C and M-0.9C; illustration of interdigital finger electrodes; Nyquist plot of Co(OH)2 deposited on micro-electrodes. See DOI: 10.1039/c3nr00210a

Directing functional chemistries on micropatterned conducting polymers for all-polymer cell analysis microsystems

DEFF Research Database (Denmark)

Lind, Johan Ulrik; Daugaard, Anders Egede; Andresen, Thomas Lars

Micrometer scale electrical circuits of PEDOT (poly(3,4-dioxythiophene)) were created by locally oxidizing PEDOT thin films with an agarose stamp containing the oxidizing agent NaOCl. The oxidized PEDOT was removed completely by applying detergents. The process was sufficiently mild that chemical...... groups on the underlying substrate, such as azides or alkynes, were preserved for subsequent specific functionalization. Moreover entire PMOXA (poly(2-methyl-2-oxazoline)) films preventing cell binding could be hidden below the PEDOT and be re-exposed upon stamping, allowing for cell capturing...... microelectrodes on a cell non-adhesive background. Chemically functionalized PEDOT types permitted the introduction of multiple additional types of micropatterned chemistry....

Polymeric Shape-Memory Micro-Patterned Surface for Switching Wettability with Temperature

Directory of Open Access Journals (Sweden)

Nuria García-Huete

2015-09-01

Full Text Available An innovative method to switch the wettability of a micropatterned polymeric surface by thermally induced shape memory effect is presented. For this purpose, first polycyclooctene (PCO is crosslinked with dycumil peroxide (DCP and its melting temperature, which corresponds with the switching transition temperature (Ttrans, is measured by Dynamic Mechanical Thermal Analysis (DMTA in tension mode. Later, the shape memory behavior of the bulk material is analyzed under different experimental conditions employing a cyclic thermomechanical analysis (TMA. Finally, after creating shape memory micropillars by laser ablation of crosslinked thermo-active polycyclooctene (PCO, shape memory response and associated effect on water contact angle is analyzed. Thus, deformed micropillars cause lower contact angle on the surface from reduced roughness, but the original hydrophobicity is restored by thermally induced recovery of the original surface structure.

FGLD A novel and compact micro-pattern gas detector

CERN Document Server

Dick, Louis; Watts, David

2004-01-01

A new gas detector which combines in the same structure the gas amplification mechanism and the position sensitive readout, named the field gradient lattice detector (FGLD), is being developed at CERN. The detector, reminiscent in geometry of a multi-wire proportional chamber but with a different field configuration can be fabricated as two or more layers of micro-patterned parallel tracks on a variety of substrate materials. Two preliminary proof-of-concept designs without position sensitivity have been fabricated as copper tracks of 50 mum width and 150 mum pitch on polyimide in a 3D geometry and on epoxy in a 2D geometry. They have been shown to detect the 5.9 keV X-rays of an $^{55}Fe$ source with a stable gain ranging from 500 to 5000 in a 3 mm drift chamber containing an argon carbon-dioxide gas mixture. The elegance and compactness of the FGLD design make it a very attractive gas detector solution both economically and mechanically. Most interestingly, the 3D FGLD design on flexible polyimide should gr...

Soft-Matter Printed Circuit Board with UV Laser Micropatterning.

Science.gov (United States)

Lu, Tong; Markvicka, Eric J; Jin, Yichu; Majidi, Carmel

2017-07-05

When encapsulated in elastomer, micropatterned traces of Ga-based liquid metal (LM) can function as elastically deformable circuit wiring that provides mechanically robust electrical connectivity between solid-state elements (e.g., transistors, processors, and sensor nodes). However, LM-microelectronics integration is currently limited by challenges in rapid fabrication of LM circuits and the creation of vias between circuit terminals and the I/O pins of packaged electronics. In this study, we address both with a unique layup for soft-matter electronics in which traces of liquid-phase Ga-In eutectic (EGaIn) are patterned with UV laser micromachining (UVLM). The terminals of the elastomer-sealed LM circuit connect to the surface mounted chips through vertically aligned columns of EGaIn-coated Ag-Fe 2 O 3 microparticles that are embedded within an interfacial elastomer layer. The processing technique is compatible with conventional UVLM printed circuit board (PCB) prototyping and exploits the photophysical ablation of EGaIn on an elastomer substrate. Potential applications to wearable computing and biosensing are demonstrated with functional implementations in which soft-matter PCBs are populated with surface-mounted microelectronics.

Integration of 3D Printed and Micropatterned Polycaprolactone Scaffolds for Guidance of Oriented Collagenous Tissue Formation In Vivo.

Science.gov (United States)

Pilipchuk, Sophia P; Monje, Alberto; Jiao, Yizu; Hao, Jie; Kruger, Laura; Flanagan, Colleen L; Hollister, Scott J; Giannobile, William V

2016-03-01

Scaffold design incorporating multiscale cues for clinically relevant, aligned tissue regeneration has potential to improve structural and functional integrity of multitissue interfaces. The objective of this preclinical study is to develop poly(ε-caprolactone) (PCL) scaffolds with mesoscale and microscale architectural cues specific to human ligament progenitor cells and assess their ability to form aligned bone-ligament-cementum complexes in vivo. PCL scaffolds are designed to integrate a 3D printed bone region with a micropatterned PCL thin film consisting of grooved pillars. The patterned film region is seeded with human ligament cells, fibroblasts transduced with bone morphogenetic protein-7 genes seeded within the bone region, and a tooth dentin segment positioned on the ligament region prior to subcutaneous implantation into a murine model. Results indicate increased tissue alignment in vivo using micropatterned PCL films, compared to random-porous PCL. At week 6, 30 μm groove depth significantly enhances oriented collagen fiber thickness, overall cell alignment, and nuclear elongation relative to 10 μm groove depth. This study demonstrates for the first time that scaffolds with combined hierarchical mesoscale and microscale features can align cells in vivo for oral tissue repair with potential for improving the regenerative response of other bone-ligament complexes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High rate behavior and discharge limits in micro-pattern detectors

CERN Document Server

Bressan, A; Pagano, P; Ropelewski, Leszek; Sauli, Fabio; Biagi, S F; Buzulutskov, A F; Gruwé, M; De Lentdecker, G; Mörmann, D; Sharma, A

1999-01-01

We present and discuss a set of systematic measurements, carried out with gaseous proportional micro-pattern detectors, in order to assess their maximum gain when irradiated with high-rate soft X-rays and heavily ionizing alpha particles. The inventory of detectors tested includes: micro-strip micromegas, micro-dot, gas electron multiplier, CAT (compteur à trous), trench (or groove), micro-CAT (or WELL) detectors, as well as systems with two elements of gaseous amplification in cascade. We confirm the general trend of all single-stage detectors to follow Raether's criterion, i.e. a spontaneous transition from avalanche to streamer, followed by a discharge, when the avalanche size reaches a value of a few 10 7 ; a noticeable exception is the micro-dot counter holding more than 10 8. In multiple structures, where the gain under irradiation is increased by at least one order of magnitude; we speculate this to be a consequence of a voltage dependence of Raether's limit, larger for low operating potentials. Our c...

Fabrication of poly(ethylene glycol) hydrogel micropatterns with osteoinductive growth factors and evaluation of the effects on osteoblast activity and function

Energy Technology Data Exchange (ETDEWEB)

Subramani, K [Institute for Nanoscale Science and Technology (INSAT), University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7AR (United Kingdom); Birch, M A [Institute for Nanoscale Science and Technology (INSAT), University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7AR (United Kingdom)

2006-09-15

The aims of this study were to fabricate poly(ethylene glycol) (PEG) hydrogel micropatterns on a biomaterial surface to guide osteoblast behaviour and to study how incorporating vascular endothelial growth factor (VEGF) within the adhered hydrogel influenced cell morphology. Standard photolithographic procedures or photopolymerization through a poly(dimethyl siloxane) (PDMS) mould were used to fabricate patterned PEG hydrogels on the surface of silanized silicon wafers. Hydrogel patterns were evaluated by light microscopy and surface profilometry. Rat osteoblasts were cultured on these surfaces and cell morphology investigated by fluorescence microscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Release of protein trapped in the polymerized PEG was evaluated and VEGF-PEG surfaces were characterized for their ability to support cell growth. These studies show that photopolymerized PEG can be used to create anti-adhesive structures on the surface of silicon that completely control where cell interaction with the substrate takes place. Using conventional lithography, structures down to 50 {mu}m were routinely fabricated with the boundaries exhibiting sloping sides. Using the PDMS mould approach, structures were fabricated as small as 10 {mu}m and boundaries were very sharp and vertical. Osteoblasts exhibiting typical morphology only grew on the silicon wafer surface that was not coated with PEG. Adding BSA to the monomer solution showed that protein could be released from the hydrogel for up to 7 days in vitro. Incorporating VEGF in the hydrogel produced micropatterns that dramatically altered osteoblast behaviour. At boundaries with the VEGF-PEG hydrogel, there was striking formation of cellular processes and membrane ruffling indicative of a change in cell morphology. This study has explored the morphogenetic properties of VEGF and the applications of nano/microfabrication techniques for guided tissue (bone) regeneration in dental and

172 nm excimer VUV-triggered photodegradation and micropatterning of aminosilane films

International Nuclear Information System (INIS)

Elsner, Christian; Naumov, Sergej; Zajadacz, Joachim; Buchmeiser, Michael R.

2009-01-01

Emission from Xe 2 * excimers exhibiting photon energies between 7 and 10 eV can be used to induce strong surface modification effects on polymeric materials in the top 100 nm layer. In order to identify suitable monomers for this VUV-based process, the photodegradation mechanism of different organosilanes of the general structure R-CH 2 -Si(OCH 3 ) 3 was elucidated by quantum chemical calculations. Herein, the photodegradation of 3-aminopropyltrimethoxysilane films by the use of a 172 nm excimer lamp under different irradiation conditions is described and completed by micropatterning experiments. The presence of 1000-5000 ppm oxygen was found to promote the transformation process to an inorganic-like surface. The films obtained were analyzed by X-ray photoelectron spectroscopy, contact angle measurements and fluorescence microscopy after covalent attachment of a fluorescent dye to the remaining amino groups. Complementary, silver staining was used to visualize photopatterning.

Development and characterization of micro-pattern gas detectors for intense beams of hadrons

Energy Technology Data Exchange (ETDEWEB)

Vandenbroucke, Maxence

2012-07-02

This thesis work is dedicated to the design, development and characterization of Micro-Pattern Gas Detectors. The performances of a Time Projection Chamber (TPC) equipped with a triple Gas Electron Multiplier (GEM) amplification structure are reported. The intrinsic ion backflow suppression of GEM foils drastically reduces the space charge produced by wire readout in traditional TPC. The GEM solution allows the operation of a TPC at much higher event rate. The second part of this thesis describes the development of a 40 x 40 cm{sup 2} Micromegas detector with a highly segmented central area. A reduction of discharges compared to conventional Micromegas detectors is needed for stable operation in intense beams of hadrons. Spark reduction technologies have been successfully studied and results are presented.

Performance test of a micro-pattern stereo detector with two gas electron multipliers

International Nuclear Information System (INIS)

Barvich, T.; Bluem, P.; Erdmann, M.; Fahrer, M.; Kaercher, K.; Kuehn, F.; Moermann, D.; Mueller, Th.; Neuberger, D.; Roederer, F.; Simonis, H.J.; Skiba, A.; Thuemmel, W.H.; Weiler, Th.; Weseler, S.

2002-01-01

We report on the performance of a large micro-pattern detector with two gas electron multiplier foils and a two-layer readout structure at ground potential. The two readout layers each have a 406 μm pitch and cross at an effective angle of 6.7 deg. . This structure allows for two orthogonal coordinates to be determined. Using a muon beam at CERN together with a silicon tracking system, the position resolutions of the two coordinates are measured to be 50 μm and 1 mm respectively (1 standard deviation). The muon detection efficiency for the two-dimensional space points reaches 96%. The detector was found to be well operational over a wide range in the settings of the different electrical fields

Nano-structured micropatterns by combination of block copolymer self-assembly and UV photolithography

International Nuclear Information System (INIS)

Gorzolnik, B; Mela, P; Moeller, M

2006-01-01

A procedure for the fabrication of nano-structured micropatterns by direct UV photo-patterning of a monolayer of a self-assembled block copolymer/transition metal hybrid structure is described. The method exploits the selective photochemical modification of a self-assembled monolayer of hexagonally ordered block copolymer micelles loaded with a metal precursor salt. Solvent development of the monolayer after irradiation results in the desired pattern of micelles on the surface. Subsequent plasma treatment of the pattern leaves ordered metal nanodots. The presented technique is a simple and low-cost combination of 'top-down' and 'bottom-up' approaches that allows decoration of large areas with periodic and aperiodic patterns of nano-objects, with good control over two different length scales: nano- and micrometres

Development and characterization of micro-pattern gas detectors for intense beams of hadrons

International Nuclear Information System (INIS)

Vandenbroucke, Maxence

2012-01-01

This thesis work is dedicated to the design, development and characterization of Micro-Pattern Gas Detectors. The performances of a Time Projection Chamber (TPC) equipped with a triple Gas Electron Multiplier (GEM) amplification structure are reported. The intrinsic ion backflow suppression of GEM foils drastically reduces the space charge produced by wire readout in traditional TPC. The GEM solution allows the operation of a TPC at much higher event rate. The second part of this thesis describes the development of a 40 x 40 cm 2 Micromegas detector with a highly segmented central area. A reduction of discharges compared to conventional Micromegas detectors is needed for stable operation in intense beams of hadrons. Spark reduction technologies have been successfully studied and results are presented.

Reconstruction of Micropattern Detector Signals using Convolutional Neural Networks

Science.gov (United States)

Flekova, L.; Schott, M.

2017-10-01

Micropattern gaseous detector (MPGD) technologies, such as GEMs or MicroMegas, are particularly suitable for precision tracking and triggering in high rate environments. Given their relatively low production costs, MPGDs are an exemplary candidate for the next generation of particle detectors. Having acknowledged these advantages, both the ATLAS and CMS collaborations at the LHC are exploiting these new technologies for their detector upgrade programs in the coming years. When MPGDs are utilized for triggering purposes, the measured signals need to be precisely reconstructed within less than 200 ns, which can be achieved by the usage of FPGAs. In this work, we present a novel approach to identify reconstructed signals, their timing and the corresponding spatial position on the detector. In particular, we study the effect of noise and dead readout strips on the reconstruction performance. Our approach leverages the potential of convolutional neural network (CNNs), which have recently manifested an outstanding performance in a range of modeling tasks. The proposed neural network architecture of our CNN is designed simply enough, so that it can be modeled directly by an FPGA and thus provide precise information on reconstructed signals already in trigger level.

Design and Characterization of the VMM1 ASIC for Micropattern Gas Detectors

CERN Document Server

Metcalfe, J; The ATLAS collaboration; Fried, J; Li, S; Nambiar, N; Polychronakos, V; Vernon, E

2013-01-01

We present here the measurements of the first prototype VMM1 ASIC designed at Brookhaven National Laboratory in 130 nm CMOS and fabricated in spring 2012. The 64-channel ASIC features a novel design for use with several types of micropattern gas detectors. The data driven system measures peak amplitude and timing information in tracking mode and first channel hit address in trigger mode. Several programmable gain and integration times allows the flexibility to work with Micromegas, Thin Gap Chambers (TGCs), and Gas Electron Multiplier (GEM) detectors. The IC design architecture and features will be presented along with measurements characterizing the performance of the VMM1 such as noise, linearity of the response, time walk, and calibration range. The concept for use with Micromegas in ATLAS Upgrade will also be covered including characterization under test beam conditions.

Fast formation of hydrophilic and reactive polymer micropatterns by photocatalytic lithography method

International Nuclear Information System (INIS)

Chang, Chi-Jung; Wang, Chih-Feng; Chen, Jem-Kun; Hsieh, Chih-Chiao; Chen, Po-An

2013-01-01

An approach is developed for the fast formation of a hydrophilic pattern on superhydrophobic substrates with good contrast due to the large wettability contrast between superhydrophobic and superhydrophilic areas. It can be used for forming a polymer pattern with reactive functional groups. TiO 2 nanoparticles were grafted with long alkyl chains and then coated on substrates to produce superhydrophobic films. Photocatalytic degradation of the grafted alkyl chains was effected with UV light irradiation and resulted in transition from superhydrophobicity to superhydrophilicity. After UV light irradiation through a mask for 30 s, dyes or polymers were adsorbed on the photoinduced superhydrophilic areas to make micropatterns. The photoinduced superhydrophilic switching properties can be tuned by changing the alkyl chain length. The ninhydrin assay was adapted to identify free amino groups of polymers on the patterned area. Polymer patterns with free amino groups can be achieved.

Fast formation of hydrophilic and reactive polymer micropatterns by photocatalytic lithography method

Energy Technology Data Exchange (ETDEWEB)

Chang, Chi-Jung, E-mail: changcj@fcu.edu.tw [Department of Chemical Engineering, Feng Chia University, 100, Wenhwa Road, Seatwen, Taichung 407, Taiwan (China); Wang, Chih-Feng [Department of Materials Science and Engineering, I-Shou University, 1, Syuecheng Road, Dashu District, Kaohsiung 840, Taiwan (China); Chen, Jem-Kun [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Road, Taipei 106, Taiwan (China); Hsieh, Chih-Chiao; Chen, Po-An [Department of Chemical Engineering, Feng Chia University, 100, Wenhwa Road, Seatwen, Taichung 407, Taiwan (China)

2013-12-01

An approach is developed for the fast formation of a hydrophilic pattern on superhydrophobic substrates with good contrast due to the large wettability contrast between superhydrophobic and superhydrophilic areas. It can be used for forming a polymer pattern with reactive functional groups. TiO{sub 2} nanoparticles were grafted with long alkyl chains and then coated on substrates to produce superhydrophobic films. Photocatalytic degradation of the grafted alkyl chains was effected with UV light irradiation and resulted in transition from superhydrophobicity to superhydrophilicity. After UV light irradiation through a mask for 30 s, dyes or polymers were adsorbed on the photoinduced superhydrophilic areas to make micropatterns. The photoinduced superhydrophilic switching properties can be tuned by changing the alkyl chain length. The ninhydrin assay was adapted to identify free amino groups of polymers on the patterned area. Polymer patterns with free amino groups can be achieved.

Heat Transfer and Cooling in Gas Turbines (Le Transfert Thermique et le Refroidissement dans les Turbines a Gaz)

Science.gov (United States)

1993-02-01

Chan. H. W.; Scesa. S. Heat Tranfer to a Turbulent Boundary Lay-r Down- stream of an Injection Slot ASME-Paper 57-A-36, 1957 [18 Papell , S. S. Effect on...0.60 intermediate section of the lateral wall. 0.50 f 6. CONCLUSIONS 40 60 80100 fta "LP a"Pl" S (WThe comparison between predicted and actual test

Capability of Sputtered Micro-patterned NiTi Thick Films

Science.gov (United States)

Bechtold, Christoph; Lima de Miranda, Rodrigo; Quandt, Eckhard

2015-09-01

Today, most NiTi devices are manufactured by a combination of conventional metal fabrication steps, e.g., melting, extrusion, cold working, etc., and are subsequently structured by high accuracy laser cutting. This combination has been proven to be very successful; however, there are several limitations to this fabrication route, e.g., in respect to the fabrication of more complex device designs, device miniaturization or the combination of different materials for the integration of further functionality. These issues have to be addressed in order to develop new devices and applications. The fabrication of micro-patterned films using magnetron sputtering, UV lithography, and wet etching has great potential to overcome limitations of conventional device manufacturing. Due to its fabrication characteristics, this method allows the production of devices with complex designs, high structural accuracy, smooth edge profile, at layer thicknesses up to 75 µm. The aim of this study is to present recent developments in the field of NiTi thin film technology, its advantages and limitations, as well as new possible applications in the medical and in non-medical fields. These developments include among others NiTi scaffold structures covered with NiTi membranes for their potential use as filters, heart valve components or aneurysm treatments, as well as micro-actuators for consumable electronics or automotive applications.

Manipulation of self-assembly amyloid peptide nanotubes by dielectrophoresis (DEP)

DEFF Research Database (Denmark)

Castillo, Jaime; Tanzi, Simone; Dimaki, Maria

2008-01-01

Self-assembled amyloid peptide nanotubes (SAPNT) were manipulated and immobilized using dielectrophoresis. Micro-patterned electrodes of Au were fabricated by photolithography and lifted off on a silicon dioxide layer. SAPNT were manipulated by adjusting the amplitude and frequency of the applied...

High rate behavior and discharge limits in micro-pattern detectors

International Nuclear Information System (INIS)

Bressan, A.; Hoch, M.; Pagano, P.; Ropelewski, L.; Sauli, F.; Biagi, S.; Buzulutskov, A.; Gruwe, M.; De Lentdecker, G.; Moermann, D.; Sharma, A.

1999-01-01

We present and discuss a set of systematic measurements, carried out with gaseous proportional micro-pattern detectors, in order to assess their maximum gain when irradiated with high-rate soft X-rays and heavily ionizing alpha particles. The inventory of detectors tested includes: micro-strips, micromegas, micro-dot, gas electron multiplier, CAT (compteur a trous), trench (or groove), micro-CAT (or WELL) detectors, as well as systems with two elements of gaseous amplification in cascade. We confirm the general trend of all single-stage detectors to follow Raether's criterion, i.e. a spontaneous transition from avalanche to streamer, followed by a discharge, when the avalanche size reaches a value of a few 10 7 ; a noticeable exception is the micro-dot counter holding more than 10 8 . In multiple structures, where the gain is shared between two devices in cascade, the maximum overall gain under irradiation is increased by at least one order of magnitude; we speculate this to be a consequence of a voltage dependence of Raether's limit, larger for low operating potentials. Our conclusion is that only multiple devices can guarantee a sufficient margin of reliability for operation in harsh LHC running conditions

Cubic Gallium Nitride on Micropatterned Si (001) for Longer Wavelength LEDs

Energy Technology Data Exchange (ETDEWEB)

Durniak, Mark T. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Materials Science and Engineering; Chaudhuri, Anabil [Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials; Smith, Michael L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Material Sciences; Allerman, Andrew A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Material Sciences; Lee, S. C. [Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials; Brueck, S. R. J. [Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials; Wetzel, Christian [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Physics, Applied Physics, and Astronomy and Dept. of Materials Science and Engineering

2016-03-01

GaInN/GaN heterostructures of cubic phase have the potential to overcome the limitations of wurtzite structures commonly used for light emitting and laser diodes. Wurtzite GaInN suffers from large internal polarization fields, which force design compromises ( 0001 ) towards ultra-narrow quantum wells and reduce recombination volume and efficiency. Cubic GaInN microstripes grown at Rensselaer Polytechnic Institute by metal organic vapor phase epitaxy on micropatterned Si , with {111} v-grooves oriented along Si ( 001 ) , offer a system free of internal polarization fields, wider quantum wells, and smaller <00$\\bar1$> bandgap energy. We prepared 6 and 9 nm Ga _x In _1-x N/GaN single quantum well structures with peak wavelength ranges from 520 to 570 nm with photons predominately polarized perpendicular to the grooves. We estimate a cubic InN composition range of 0 < x < 0.5 and an upper limit of the internal quantum efficiency of 50%. Stripe geometry and polarization may be suitable for mode confinement and reduced threshold stimulated emission.

Electrode-electrolyte interface model of tripolar concentric ring electrode and electrode paste.

Science.gov (United States)

Nasrollaholhosseini, Seyed Hadi; Steele, Preston; Besio, Walter G

2016-08-01

Electrodes are used to transform ionic currents to electrical currents in biological systems. Modeling the electrode-electrolyte interface could help to optimize the performance of the electrode interface to achieve higher signal to noise ratios. There are previous reports of accurate models for single-element biomedical electrodes. In this paper we develop a model for the electrode-electrolyte interface for tripolar concentric ring electrodes (TCRE) that are used to record brain signals.

Semiconductor micropattern pixel detectors: a review of the beginnings

International Nuclear Information System (INIS)

Heijne, E.H.M.

2001-01-01

The innovation in monolithic and hybrid semiconductor 'micropattern' or 'reactive' pixel detectors for tracking in particle physics was actually to fit logic and pulse processing electronics with μW power on a pixel area of less than 0.04 mm 2 , retaining the characteristics of a traditional nuclear amplifier chain. The ns timing precision in conjunction with local memory and logic operations allowed event selection at >10 MHz rates with unambiguous track reconstruction even at particle multiplicities >10 cm -2 . The noise in a channel was ∼100e - rms and enabled binary operation with random noise 'hits' at a level -8 . Rectangular pixels from 75 μmx500 μm down to 34 μmx125 μm have been used by different teams. In binary mode a tracking precision from 6 to 14 μm was obtained, and using analog interpolation one came close to 1 μm. Earlier work, still based on charge integrating imaging circuits, provided a starting point. Two systems each with more than 1 million sensor + readout channels have been built, for WA97-NA57 and for the Delphi very forward tracker. The use of 0.5 μm and 0.25 μm CMOS and enclosed geometry for the transistors in the pixel readout chips resulted in radiation hardness of ∼2 Mrad, respectively, >30 Mrad

All-solid-state flexible ultrathin micro-supercapacitors based on graphene.

Science.gov (United States)

Niu, Zhiqiang; Zhang, Li; Liu, Lili; Zhu, Bowen; Dong, Haibo; Chen, Xiaodong

2013-08-07

Flexible, compact, ultrathin and all-solid-state micro-supercapacitors are prepared by coating H₃PO₄/PVA gel electrolyte onto micro-patterned rGO interdigitated electrodes prepared by combining photolithography with selective electrophoretic deposition. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Topologically Micropatterned Collagen and Poly(ε-caprolactone) Struts Fabricated Using the Poly(vinyl alcohol) Fibrillation/Leaching Process To Develop Efficiently Engineered Skeletal Muscle Tissue.

Science.gov (United States)

Kim, Minseong; Kim, WonJin; Kim, GeunHyung

2017-12-20

Optimally designed three-dimensional (3D) biomedical scaffolds for skeletal muscle tissue regeneration pose significant research challenges. Currently, most studies on scaffolds focus on the two-dimensional (2D) surface structures that are patterned in the micro-/nanoscales with various repeating sizes and shapes to induce the alignment of myoblasts and myotube formation. The 2D patterned surface clearly provides effective analytical results of pattern size and shape of the myoblast alignment and differentiation. However, it is inconvenient in terms of the direct application for clinical usage due to the limited thickness and 3D shapeability. Hence, the present study suggests an innovative hydrogel or synthetic structure that consists of uniaxially surface-patterned cylindrical struts for skeleton muscle regeneration. The alignment of the pattern on the hydrogel (collagen) and poly(ε-caprolactone) struts was attained with the fibrillation of poly(vinyl alcohol) and the leaching process. Various cell culture results indicate that the C2C12 cells on the micropatterned collagen structure were fully aligned, and that a significantly high level of myotube formation was achieved when compared to the collagen structures that were not treated with the micropatterning process.

Engineering connectivity by multiscale micropatterning of individual populations of neurons.

Science.gov (United States)

Albers, Jonas; Toma, Koji; Offenhäusser, Andreas

2015-02-01

Functional networks are the basis of information processing in the central nervous system. Essential for their formation are guided neuronal growth as well as controlled connectivity and information flow. The basis of neuronal development is generated by guiding cues and geometric constraints. To investigate the neuronal growth and connectivity of adjacent neuronal networks, two-dimensional protein patterns were created. A mixture of poly-L-lysine and laminin was transferred onto a silanized glass surface by microcontact printing. The structures were populated with dissociated primary cortical embryonic rat neurons. Triangular structures with diverse opening angles, height, and design were chosen as two-dimensional structures to allow network formation with constricted gateways. Neuronal development was observed by immunohistochemistry to pursue the influence of the chosen structures on the neuronal outgrowth. Neurons were stained for MAP2, while poly-L-lysine was FITC labeled. With this study we present an easy-to-use technique to engineer two-dimensional networks in vitro with defined gateways. The presented micropatterning method is used to generate daisy-chained neuronal networks with predefined connectivity. Signal propagation among geometrically constrained networks can easily be monitored by calcium-sensitive dyes, providing insights into network communication in vitro. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Virtual electrodes for high-density electrode arrays

Science.gov (United States)

Cela, Carlos J.; Lazzi, Gianluca

2015-10-13

The present embodiments are directed to implantable electrode arrays having virtual electrodes. The virtual electrodes may improve the resolution of the implantable electrode array without the burden of corresponding complexity of electronic circuitry and wiring. In a particular embodiment, a virtual electrode may include one or more passive elements to help steer current to a specific location between the active electrodes. For example, a passive element may be a metalized layer on a substrate that is adjacent to, but not directly connected to an active electrode. In certain embodiments, an active electrode may be directly coupled to a power source via a conductive connection. Beneficially, the passive elements may help to increase the overall resolution of the implantable array by providing additional stimulation points without requiring additional wiring or driver circuitry for the passive elements.

Micropatterned 2D Hybrid Perovskite Thin Films with Enhanced Photoluminescence Lifetimes.

Science.gov (United States)

Kamminga, Machteld E; Fang, Hong-Hua; Loi, Maria Antonietta; Ten Brink, Gert H; Blake, Graeme R; Palstra, Thomas T M; Ten Elshof, Johan E

2018-04-18

The application of luminescent materials in display screens and devices requires micropatterned structures. In this work, we have successfully printed microstructures of a two-dimensional (2D), orange-colored organic/inorganic hybrid perovskite ((C 6 H 5 CH 2 NH 3 ) 2 PbI 4 ) using two different soft lithography techniques. Notably, both techniques yield microstructures with very high aspect ratios in the range of 1.5-1.8. X-ray diffraction reveals a strong preferential orientation of the crystallites along the c-axis in both patterned structures, when compared to nonpatterned, drop-casted thin films. Furthermore, (time-resolved) photoluminescence (PL) measurements reveal that the optical properties of (C 6 H 5 CH 2 NH 3 ) 2 PbI 4 are conserved upon patterning. We find that the larger grain sizes of the patterned films with respect to the nonpatterned film give rise to an enhanced PL lifetime. Thus, our results demonstrate easy and cost-effective ways to manufacture patterns of 2D organic/inorganic hybrid perovskites, while even improving their optical properties. This demonstrates the potential use of color-tunable 2D hybrids in optoelectronic devices.

Cell adhesion and spreading on polymer surfaces micropatterned by ion beams

International Nuclear Information System (INIS)

Satriano, C.; Carnazza, S.; Licciardello, A.; Guglielmino, S.; Marletta, G.

2003-01-01

The cell adhesion and spreading behavior on surfaces of poly(ethyleneterephtalate) and poly(hydroxymethylsiloxane) micropatterned by focused 15 keV Ga + beams has been studied. It has been found that while no modification in the cell adhesion process could be observed for unirradiated and irradiated areas on the patterned surfaces, in the case of polyhydroxymethylsiloxane the cell adhesion process is basically confined within the irradiated areas and a clear dependence of the cell ordering on the lateral size of the irradiated areas is observed. The results are discussed in terms of the specific spatially resolved chemical modification induced by Ga + irradiation onto the two different polymers. Thus, the irradiation-induced modification of composition, functional groups concentration, surface free energy, and nanoscale morphology have been studied by means of x-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, contact angle, and atomic force microscopy. The cell adhesion and spreading behavior was found to nicely correlate with the increase of the acid-base component γ AB of the surface free energy and more particularly with the dramatic increase of the Lewis basic electron-donor term

Micro-patterning of resin-bonded NdFeB magnet for a fully integrated electromagnetic actuator

Science.gov (United States)

Tao, Kai; Wu, Jin; Kottapalli, Ajay Giri Prakash; Chen, Di; Yang, Zhuoqing; Ding, Guifu; Lye, Sun Woh; Miao, Jianmin

2017-12-01

This paper reports a fully-integrated, batch-fabricated electromagnetic actuator which features micro-patterned NdFeB magnets. The entire actuator is fabricated through MEMS-compatible laminated surface micromachining technology, eliminating the requirement for further component assembly processes. The fabrication strategy allowed the entire volume of the actuator to be reduced to a small size of 2.5 × 2.5 × 2 mm3, which is one of the smallest NdFeB-based electromagnetic actuators demonstrated to date. The magnetic properties of NdFeB thin films are further investigated and optimized using different types of lithographically-defined micromolds. By altering the direction of the input current, actuating displacements of approximately ±10 μm are achieved during both the attraction and the repulsion operations. This work demonstrates the viability and compatibility of using polymer-bonded magnets for magnetic MEMS applications.

A Flexible and Highly Sensitive Piezoresistive Pressure Sensor Based on Micropatterned Films Coated with Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Jia-lin Yao

2016-01-01

Full Text Available Excellent flexibility, high sensitivity, and low consumption are essential characteristics in flexible microtube pressure sensing occasion, for example, implantable medical devices, industrial pipeline, and microfluidic chip. This paper reports a flexible, highly sensitive, and ultrathin piezoresistive pressure sensor for fluid pressure sensing, whose sensing element is micropatterned films with conductive carbon nanotube layer. The flexible pressure sensor, the thickness of which is 40 ± 10 μm, could be economically fabricated by using biocompatible polydimethylsiloxane (PDMS. Experimental results show that the flexible pressure sensor has high sensitivity (0.047 kPa−1 in gas sensing and 5.6 × 10−3 kPa−1 in liquid sensing and low consumption (<180 μW, and the sensor could be used to measure the pressure in curved microtubes.

Direct writing and electro-mechanical characterization of Ag micro-patterns on polymer substrates for flexible electronics

International Nuclear Information System (INIS)

Torres Arango, Maria A.; Cokeley, Anna M.; Beard, Jared J.; Sierros, Konstantinos A.

2015-01-01

There is currently a great interest in developing flexible electrodes. Such components are used in most electronic devices from displays to solar cells to flexible sensors. To date most of them are fabricated using expensive vacuum techniques, and are based on transparent conducting oxides. These oxides are not entirely compatible with flexible substrates under the application of mechanical stresses, due to their brittle nature. Therefore, there is a need to explore novel low-cost, large-area fabrication methods to deposit alternative conducting materials with enhanced electro-mechanical performance. This work focuses on Ag patterns fabricated at low temperatures (below 150 °C) on flexible polyethylene naphthalate utilizing a robotic printing approach. Such lithography-free method minimizes material waste by printing exact amounts of inks on digitally predefined locations. Additionally, it allows a broad feature size range, from a few μm to a few mm, and a variety of ink viscosities for better pattern control. We investigate the synthesis and direct writing of Ag particle-based inks, patterned-on-flex as lines and grids in the μm scale. We report on a high-yield ink synthesis method (~ 61.6%) with controlled particle size. It is found that the electrical resistivity (1.75 ∗ 10"−"4 Ω cm) of the patterns is in the same range with similar particle-based conductive components. The correlation between annealing temperature, microstructural evolution, and electrical performance is established. Also, the optical transmittance of the patterns can be controlled to meet specific application requirements by regulating the substrate surface area covered. Finally, the mechanical behavior under both monotonic and cyclic conditions shows a superior performance compared to brittle counterparts and underlines the potential of such metallic micro-patterns to be utilized in a wide range of flexible electronic applications. It is believed that direct writing of Ag patterns on

Direct writing and electro-mechanical characterization of Ag micro-patterns on polymer substrates for flexible electronics

Energy Technology Data Exchange (ETDEWEB)

Torres Arango, Maria A.; Cokeley, Anna M.; Beard, Jared J.; Sierros, Konstantinos A., E-mail: kostas.sierros@mail.wvu.edu

2015-12-01

There is currently a great interest in developing flexible electrodes. Such components are used in most electronic devices from displays to solar cells to flexible sensors. To date most of them are fabricated using expensive vacuum techniques, and are based on transparent conducting oxides. These oxides are not entirely compatible with flexible substrates under the application of mechanical stresses, due to their brittle nature. Therefore, there is a need to explore novel low-cost, large-area fabrication methods to deposit alternative conducting materials with enhanced electro-mechanical performance. This work focuses on Ag patterns fabricated at low temperatures (below 150 °C) on flexible polyethylene naphthalate utilizing a robotic printing approach. Such lithography-free method minimizes material waste by printing exact amounts of inks on digitally predefined locations. Additionally, it allows a broad feature size range, from a few μm to a few mm, and a variety of ink viscosities for better pattern control. We investigate the synthesis and direct writing of Ag particle-based inks, patterned-on-flex as lines and grids in the μm scale. We report on a high-yield ink synthesis method (~ 61.6%) with controlled particle size. It is found that the electrical resistivity (1.75 ∗ 10{sup −4} Ω cm) of the patterns is in the same range with similar particle-based conductive components. The correlation between annealing temperature, microstructural evolution, and electrical performance is established. Also, the optical transmittance of the patterns can be controlled to meet specific application requirements by regulating the substrate surface area covered. Finally, the mechanical behavior under both monotonic and cyclic conditions shows a superior performance compared to brittle counterparts and underlines the potential of such metallic micro-patterns to be utilized in a wide range of flexible electronic applications. It is believed that direct writing of Ag patterns

Micropatterning of poly(4-hydroxystyrene) by ion beam contact lithography for the control of cell adhesion

International Nuclear Information System (INIS)

Hwang, In Tae; Jung, Chan Hee; Choi, Jae Hak; Nho, Young Chang; Lee, Byoung Min; Hong, Sung Kwon

2009-01-01

In this study, we report on a simple method of micropatterning of cells by using ion beam contact lithography. Thin poly(4-hydroxystyrene) (Phds) films spin-coated on a silicon wafer were irradiated through a pattern mask in a contact mode with proton ions and then developed to generate the patterns of the Phds. Well-defined 50 μm line (pitch 150 μm) patterns were obtained without using any additives. The remaining thickness after development was increased with an increasing fluence up to 3 x 10 14 ions cm -2 after which it leveled off. The in-vitro cell culture test revealed that the cells were preferentially adhered to and proliferated only on the space regions between the Phds line patterns. Inhibition of cell adhesion on the Phds patterns could be due to antifouling property of the irradiated PHS

Micro-patterning of self-supporting layers with conducting polymer wires for 3D-chip interconnection applications

International Nuclear Information System (INIS)

Ackermann, J.; Videlot, C.; Nguyen, T.N.; Wang, L.; Sarro, P.M.; Crawley, D.; Nikolic, K.; Forshaw, M.

2003-01-01

Highly conducting polymers have attracted much interest because of their potential applications in sensors and electronic devices. By the use of templates like porous membranes during polymerization conducting molecular wires can be formed with highly anisotropic properties which can be used as interconnecting layers in a three-dimensional (3D)-chip stacking. We focussed on two electrochemical polymerization (ECP) techniques to produce molecular wires based on polypyrrole (PPy) embedded in isolating porous polycarbonate membranes as self-supporting layers. The growth of the polymer through the membrane pores was investigated in order to achieve a good conductivity through the pores, but with a small cross-talk between them. A new polymerization technique based on a structured cathode has been developed in order to control the polymerization locally. By that technique micro-patterned membranes with separated conducting polymer wires could be produced

Enhancement of silicon using micro-patterned surfaces of thin films

Directory of Open Access Journals (Sweden)

E Kaivosoja

2010-04-01

Full Text Available Micro-textured biomaterials might enhance cytocompatibility of silicon-based micro-electro-mechanical system (bio-MEMS dummies. Photolithography-physical vapour deposition was used to produce diamond-like carbon (DLC or Ti squares and circles on silicon, and also their inverse replicas; then DLC and Ti were compared for their guiding potential, using a SaOS-2 cell model. Scanning electron microscopy at 48 hours indicated cells were well-spread on large-sized patterns (several cells on one pattern and assumed the geometrical architecture of underlying features. Medium-sized patterns (slightly smaller than solitary indicator cells were inhabited by singular cells, which stretched from one island to another, assuming longitudinal or branching morphologies. On small-sized patterns (much smaller than individual cells cells covered large micro-textured areas, but cellular filopodia bypassed the bare silicon. Immunofluorescence and confocal laser scanning microscopy indicated that the actin cytoskeleton and vinculin-containing adhesion junctions were present on the patterned areas, but not on the bare silicon. Cell density/coverage disclosed a 3.4-3.7-fold preference for the biomaterial patterns over silicon substrate (p < 0.001. Differences in the cellular response between materials were lost at 120 hours when cells were confluent. The working hypothesis was proven; enhancement by micro-patterning depends on the pattern size, shape and material and can be used to improve biocompatibility during the initial integration phase of the device.

Flexible electrode belt for EIT using nanofiber web dry electrodes.

Science.gov (United States)

Oh, Tong In; Kim, Tae Eui; Yoon, Sun; Kim, Kap Jin; Woo, Eung Je; Sadleir, Rosalind J

2012-10-01

Efficient connection of multiple electrodes to the body for impedance measurement and voltage monitoring applications is of critical importance to measurement quality and practicality. Electrical impedance tomography (EIT) experiments have generally required a cumbersome procedure to attach the multiple electrodes needed in EIT. Once placed, these electrodes must then maintain good contact with the skin during measurements that may last several hours. There is usually also the need to manage the wires that run between the electrodes and the EIT system. These problems become more severe as the number of electrodes increases, and may limit the practicality and portability of this imaging method. There have been several trials describing human-electrode interfaces using configurations such as electrode belts, helmets or rings. In this paper, we describe an electrode belt we developed for long-term EIT monitoring of human lung ventilation. The belt included 16 embossed electrodes that were designed to make good contact with the skin. The electrodes were fabricated using an Ag-plated PVDF nanofiber web and metallic threads. A large contact area and padding were used behind each electrode to improve subject comfort and reduce contact impedances. The electrodes were incorporated, equally spaced, into an elasticated fabric belt. We tested the electrode belt in conjunction with the KHU Mark1 multi-frequency EIT system, and demonstrate time-difference images of phantoms and human subjects during normal breathing and running. We found that the Ag-plated PVDF nanofiber web electrodes were suitable for long-term measurement because of their flexibility and durability. Moreover, the contact impedance and stability of the Ag-plated PVDF nanofiber web electrodes were found to be comparable to similarly tested Ag/AgCl electrodes.

Effect of Flow on Cultured Cell at Micro-Pattern of Ridge Lines

Directory of Open Access Journals (Sweden)

Haruka Hino

2017-10-01

Full Text Available A flow channel with a micro-pattern of ridge lines of a scaffold has been designed to study quantitatively the effect of flow on an oriented cell in vitro. The lines of parallel micro ridges (0.001 mm height, 0.003 mm width, and 0.003 mm interval are made by the lithography technique on the lower surface of the channel as the scaffold to make orientation of each cell. Variation is made about the angle between the longitudinal direction of the ridge line and the direction of the flow: zero, 0.79 and 1.6 rad. The suspension of C2C12 (mouse myoblast cell line was injected to the channel, and incubated for two hours on the micro ridges before the flow test for four hours. The flow rate of 3/hour is controlled by a syringe pump to make variation of the wall shear stress of < 3 Pa. The action of each cell adhered on the micro pattern was analyzed at the time lapse images. The experimental results show that both the migration and the deformation of each myoblast along the micro ridge are restricted by the wall shear stress higher than 3 Pa.

Microfluidic impact printer with interchangeable cartridges for versatile non-contact multiplexed micropatterning.

Science.gov (United States)

Ding, Yuzhe; Huang, Eric; Lam, Kit S; Pan, Tingrui

2013-05-21

Biopatterning has been increasingly used for well-defined cellular microenvironment, patterned surface topology, and guided biological cues; however, it meets challenges on biocompatibility, thermal and chemical sensitivity, as well as limited availability of reagents. In this paper, we aim at combining the desired features from non-contact inkjet printing and dot-matrix impact printing to establish a versatile multiplexed micropatterning platform, referred to as Microfluidic Impact Printer (MI-Printer), for emerging biomedical applications. Using this platform, we can achieve the distinct features of no cross-contamination, sub-microliter ink loading with a minimal dead volume, high-throughput printing, biocompatible non-contact processing, sequential patterning with self-alignment, wide adaptability for complex media (e.g., cell suspension or colloidal solutions), interchangeable/disposable cartridge design, and simple assembly and configuration, all highly desirable towards laboratory-based research and development. Specifically, the printing resolution of the MI-printer platform has been experimentally characterized and theoretically analysed. Optimal printing resolution of 80 μm has been repeatedly obtained. Furthermore, two useful functions of the MI-printer, multiplexed printing and combinatorial printing, have been experimentally demonstrated with less than 10 μm misalignment. Moreover, molecular and biological patterning, utilizing the multiplexed and combinatorial printing, has been implemented to illustrate the utility of this versatile printing technique for emerging biomedical applications.

Catoptric electrodes: transparent metal electrodes using shaped surfaces.

Science.gov (United States)

Kik, Pieter G

2014-09-01

An optical electrode design is presented that theoretically allows 100% optical transmission through an interdigitated metallic electrode at 50% metal areal coverage. This is achieved by redirection of light incident on embedded metal electrode lines to an angle beyond that required for total internal reflection. Full-field electromagnetic simulations using realistic material parameters demonstrate 84% frequency-averaged transmission for unpolarized illumination across the entire visible spectral range using a silver interdigitated electrode at 50% areal coverage. The redirection is achieved through specular reflection, making it nonresonant and arbitrarily broadband, provided the electrode width exceeds the optical wavelength. These findings could significantly improve the performance of photovoltaic devices and optical detectors that require high-conductivity top contacts.

Cobalt phthalocyanine modified electrodes utilised in electroanalysis: nano-structured modified electrodes vs. bulk modified screen-printed electrodes.

Science.gov (United States)

Foster, Christopher W; Pillay, Jeseelan; Metters, Jonathan P; Banks, Craig E

2014-11-19

Cobalt phthalocyanine (CoPC) compounds have been reported to provide electrocatalytic performances towards a substantial number of analytes. In these configurations, electrodes are typically constructed via drop casting the CoPC onto a supporting electrode substrate, while in other cases the CoPC complex is incorporated within the ink of a screen-printed sensor, providing a one-shot economical and disposable electrode configuration. In this paper we critically compare CoPC modified electrodes prepared by drop casting CoPC nanoparticles (nano-CoPC) onto a range of carbon based electrode substrates with that of CoPC bulk modified screen-printed electrodes in the sensing of the model analytes L-ascorbic acid, oxygen and hydrazine. It is found that no "electrocatalysis" is observed towards L-ascorbic acid using either of these CoPC modified electrode configurations and that the bare underlying carbon electrode is the origin of the obtained voltammetric signal, which gives rise to useful electroanalytical signatures, providing new insights into literature reports where "electrocatalysis" has been reported with no clear control experiments undertaken. On the other hand true electrocatalysis is observed towards hydrazine, where no such voltammetric features are witnessed on the bare underlying electrode substrate.

Cobalt Phthalocyanine Modified Electrodes Utilised in Electroanalysis: Nano-Structured Modified Electrodes vs. Bulk Modified Screen-Printed Electrodes

Directory of Open Access Journals (Sweden)

Christopher W. Foster

2014-11-01

Full Text Available Cobalt phthalocyanine (CoPC compounds have been reported to provide electrocatalytic performances towards a substantial number of analytes. In these configurations, electrodes are typically constructed via drop casting the CoPC onto a supporting electrode substrate, while in other cases the CoPC complex is incorporated within the ink of a screen-printed sensor, providing a one-shot economical and disposable electrode configuration. In this paper we critically compare CoPC modified electrodes prepared by drop casting CoPC nanoparticles (nano-CoPC onto a range of carbon based electrode substrates with that of CoPC bulk modified screen-printed electrodes in the sensing of the model analytes L-ascorbic acid, oxygen and hydrazine. It is found that no “electrocatalysis” is observed towards L-ascorbic acid using either of these CoPC modified electrode configurations and that the bare underlying carbon electrode is the origin of the obtained voltammetric signal, which gives rise to useful electroanalytical signatures, providing new insights into literature reports where “electrocatalysis” has been reported with no clear control experiments undertaken. On the other hand true electrocatalysis is observed towards hydrazine, where no such voltammetric features are witnessed on the bare underlying electrode substrate.

Micro-supercapacitors based on interdigital electrodes of reduced graphene oxide and carbon nanotube composites with ultrahigh power handling performance

Energy Technology Data Exchange (ETDEWEB)

Beidaghi, Majid; Wang, Chunlei [Department of Mechanical and Materials Engineering, Florida International University, 10555 W. Flagler St., EC 3463, FL 33174 (United States)

2012-11-07

A novel method for fabricating micro-patterned interdigitated electrodes based on reduced graphene oxide (rGO) and carbon nanotube (CNT) composites for ultra-high power handling micro-supercapacitor application is reported. The binder-free microelectrodes were developed by combining electrostatic spray deposition (ESD) and photolithography lift-off methods. Without typically used thermal or chemical reduction, GO sheets are readily reduced to rGO during the ESD deposition. Electrochemical measurements show that the in-plane interdigital design of the microelectrodes is effective in increasing accessibility of electrolyte ions in-between stacked rGO sheets through an electro-activation process. Addition of CNTs results in reduced restacking of rGO sheets and improved energy and power density. Cyclic voltammetry (CV) measurements show that the specific capacitance of the micro-supercapacitor based on rGO-CNT composites is 6.1 mF cm{sup -2} at 0.01 V s{sup -1}. At a very high scan rate of 50 V s{sup -1}, a specific capacitance of 2.8 mF cm{sup -2} (stack capacitance of 3.1 F cm{sup -3}) is recorded, which is an unprecedented performance for supercapacitors. The addition of CNT, electrolyte-accessible and binder-free microelectrodes, as well as an interdigitated in-plane design result in a high-frequency response of the micro-supercapacitors with resistive-capacitive time constants as low as 4.8 ms. These characteristics suggest that interdigitated rGO-CNT composite electrodes are promising for on-chip energy storage application with high power demands. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Entropy Generation Analysis of Power-Law Non-Newtonian Fluid Flow Caused by Micropatterned Moving Surface

Directory of Open Access Journals (Sweden)

M. H. Yazdi

2014-01-01

Full Text Available In the present study, the first and second law analyses of power-law non-Newtonian flow over embedded open parallel microchannels within micropatterned permeable continuous moving surface are examined at prescribed surface temperature. A similarity transformation is used to reduce the governing equations to a set of nonlinear ordinary differential equations. The dimensionless entropy generation number is formulated by an integral of the local rate of entropy generation along the width of the surface based on an equal number of microchannels and no-slip gaps interspersed between those microchannels. The velocity, the temperature, the velocity gradient, and the temperature gradient adjacent to the wall are substituted into this equation resulting from the momentum and energy equations obtained numerically by Dormand-Prince pair and shooting method. Finally, the entropy generation numbers, as well as the Bejan number, are evaluated. It is noted that the presence of the shear thinning (pseudoplastic fluids creates entropy along the surface, with an opposite effect resulting from shear thickening (dilatant fluids.

Effects of UV laser micropatterning on frictional performance of diamond-like nanocomposite films

Science.gov (United States)

Zavedeev, Evgeny V.; Zilova, Olga S.; Shupegin, Mikhail L.; Barinov, Alexej D.; Arutyunyan, Natalia R.; Roch, Teja; Pimenov, Sergei M.

2016-11-01

We report on UV laser modification and micropatterning of diamond-like nanocomposite (DLN) films (a-C:H,Si:O) with nanosecond pulses and effects of laser surface microstructuring on the frictional performance of DLN films on the nano- and macroscale. A technique of direct laser interference patterning was applied to produce arrays of periodic linear microstructures on the DLN films. The UV laser irradiation was performed at low fluences corresponding to the regime of surface graphitization and incipient ablation. At the initial stage of the thin film modification, the laser-induced spallation and graphitization in the surface layers were found to strongly influence the nanoscale topography and mechanical properties of the DLN surface. Frictional properties of the laser-patterned DLN films were studied using (1) atomic force microscopy in lateral force mode and (2) a ball-on-flat tribometer under linear reciprocating sliding against a 100Cr6 steel ball. The lateral force microscopy measurements revealed that the laser-irradiated regions were characterized by increased friction forces due to microspallation effects and enhanced surface roughness, correlating with tribotests at the initial stage of sliding. During prolonged sliding in ambient air, both the original and laser-patterned DLN surfaces exhibited low-friction performance at the friction coefficient of 0.07-0.08.

Controlled Growth of Carbon Nanotubes on Micropatterned Au/Cr Composite Film and Field Emission from Their Arrays

Science.gov (United States)

Kamide, Koichi; Araki, Hisashi; Yoshino, Katsumi

2003-12-01

Carbon nanotube (CNT) arrays with a controlled density are prepared on a micropatterned Au/Cr composite film formed on a quartz glass plate by pyrolysis of Ni-phthalocyanine at 800°C. It is clarified from characteristic X-ray analyses for those samples that a catalytic Ni nanoparticle is not contained within the base of the whisker-like CNT in contrast to that of the bamboo-like CNT, suggesting that the growth process of the present novel CNT is incompatible with that of the bamboo-like CNT. In the Au/Cr composite film, both the Cr atomic content of approximately 30% and the presence of the Ni catalyst devoid of a particle-like shape are important factors for the growth of CNTs. Field emission from the novel CNT arrays exhibits a lower turn-on voltage and a higher current density compared with that from the bamboo-like arrays formed on a quartz plate.

Using micro-patterned sensors and cell self-assembly for measuring the oxygen consumption rate of single cells

International Nuclear Information System (INIS)

Etzkorn, James R; Parviz, Babak A; Wu, Wen-Chung; Tian, Zhiyuan; Kim, Prince; Jang, Sei-Hum; Jen, Alex K-Y; Meldrum, Deirdre R

2010-01-01

We present a method for self-assembling arrays of live single cells on a glass chip using a photopatternable polymer to form micro-traps. We have studied the single-cell self-assembly method and optimized the process to obtain a 52% yield of single-trapped cells. We also report a method to measure the oxygen consumption rate of a single cell using micro-patterned sensors. These molecular oxygen sensors were fabricated around each micro-trap allowing optical interrogation of oxygen concentration in the immediate environment of the trapped cell. Micromachined micro-wells were then used to seal the trap, sensor and cell in order to determine the oxygen consumption rate of single cells. These techniques reported here add to the collection of tools for performing 'singe-cell' biology. An oxygen consumption rate of 1.05 ± 0.28 fmol min −1 was found for a data set consisting of 25 single A549 cells.

Long Life Nickel Electrodes for Nickel-Hydrogen Cells: Fiber Substrates Nickel Electrodes

Science.gov (United States)

Rogers, Howard H.

2000-01-01

Samples of nickel fiber mat electrodes were investigated over a wide range of fiber diameters, electrode thickness, porosity and active material loading levels. Thickness' were 0.040, 0.060 and 0.080 inches for the plaque: fiber diameters were primarily 2, 4, and 8 micron and porosity was 85, 90, and 95%. Capacities of 3.5 in. diameter electrodes were determined in the flooded condition with both 26 and 31% potassium hydroxide solution. These capacity tests indicated that the highest capacities per unit weight were obtained at the 90% porosity level with a 4 micron diameter fiber plaque. It appeared that the thinner electrodes had somewhat better performance, consistent with sintered electrode history. Limited testing with two-positive-electrode boiler plate cells was also carried out. Considerable difficulty with constructing the cells was encountered with short circuits the major problem. Nevertheless, four cells were tested. The cell with 95% porosity electrodes failed during conditioning cycling due to high voltage during charge. Discharge showed that this cell had lost nearly all of its capacity. The other three cells after 20 conditioning cycles showed capacities consistent with the flooded capacities of the electrodes. Positive electrodes made from fiber substrates may well show a weight advantage of standard sintered electrodes, but need considerably more work to prove this statement. A major problem to be investigated is the lower strength of the substrate compared to standard sintered electrodes. Problems with welding of leads were significant and implications that the electrodes would expand more than sintered electrodes need to be investigated. Loading levels were lower than had been expected based on sintered electrode experiences and the lower loading led to lower capacity values. However, lower loading causes less expansion and contraction during cycling so that stress on the substrate is reduced.

Improving LED CCT uniformity using micropatterned films optimized by combining ray tracing and FDTD methods.

Science.gov (United States)

Ding, Xinrui; Li, Jiasheng; Chen, Qiu; Tang, Yong; Li, Zongtao; Yu, Binhai

2015-02-09

Although the light-emitting diode (LED) has revolutionized lighting, the non-uniformity of its correlated color temperature (CCT) still remains a major concern. In this context, to improve the light distribution performance of remote phosphor LED lamps, we employ a micropatterned array (MPA) optical film fabricated using a low-cost molding process. The parameters of the MPA, including different installation configurations, positioning, and diameters, are optimized by combining the finite-difference time-domain and ray-tracing methods. Results show that the sample with the upward-facing convex-cone MPA film that has a diameter of half of that of the remote phosphor glass, and is tightly affixed to the inward surface of the remote phosphor glass renders a superior light distribution performance. When compared with the case in which no MPA film is used, the deviation of the CCT distribution decreases from 1033 K to 223 K, and the corresponding output power of the sample is an acceptable level of 85.6%. We perform experiments to verify our simulation results, and the two sets of results exhibit a close agreement. We believe that our approach can be used to optimize MPA films for various lighting applications.

Design, fabrication and skin-electrode contact analysis of polymer microneedle-based ECG electrodes

Science.gov (United States)

O'Mahony, Conor; Grygoryev, Konstantin; Ciarlone, Antonio; Giannoni, Giuseppe; Kenthao, Anan; Galvin, Paul

2016-08-01

Microneedle-based ‘dry’ electrodes have immense potential for use in diagnostic procedures such as electrocardiography (ECG) analysis, as they eliminate several of the drawbacks associated with the conventional ‘wet’ electrodes currently used for physiological signal recording. To be commercially successful in such a competitive market, it is essential that dry electrodes are manufacturable in high volumes and at low cost. In addition, the topographical nature of these emerging devices means that electrode performance is likely to be highly dependent on the quality of the skin-electrode contact. This paper presents a low-cost, wafer-level micromoulding technology for the fabrication of polymeric ECG electrodes that use microneedle structures to make a direct electrical contact to the body. The double-sided moulding process can be used to eliminate post-process via creation and wafer dicing steps. In addition, measurement techniques have been developed to characterize the skin-electrode contact force. We perform the first analysis of signal-to-noise ratio dependency on contact force, and show that although microneedle-based electrodes can outperform conventional gel electrodes, the quality of ECG recordings is significantly dependent on temporal and mechanical aspects of the skin-electrode interface.

Design, fabrication and skin-electrode contact analysis of polymer microneedle-based ECG electrodes

International Nuclear Information System (INIS)

O’Mahony, Conor; Grygoryev, Konstantin; Ciarlone, Antonio; Giannoni, Giuseppe; Kenthao, Anan; Galvin, Paul

2016-01-01

Microneedle-based ‘dry’ electrodes have immense potential for use in diagnostic procedures such as electrocardiography (ECG) analysis, as they eliminate several of the drawbacks associated with the conventional ‘wet’ electrodes currently used for physiological signal recording. To be commercially successful in such a competitive market, it is essential that dry electrodes are manufacturable in high volumes and at low cost. In addition, the topographical nature of these emerging devices means that electrode performance is likely to be highly dependent on the quality of the skin-electrode contact.This paper presents a low-cost, wafer-level micromoulding technology for the fabrication of polymeric ECG electrodes that use microneedle structures to make a direct electrical contact to the body. The double-sided moulding process can be used to eliminate post-process via creation and wafer dicing steps. In addition, measurement techniques have been developed to characterize the skin-electrode contact force. We perform the first analysis of signal-to-noise ratio dependency on contact force, and show that although microneedle-based electrodes can outperform conventional gel electrodes, the quality of ECG recordings is significantly dependent on temporal and mechanical aspects of the skin-electrode interface. (paper)

High performance cermet electrodes

Science.gov (United States)

Isenberg, Arnold O.; Zymboly, Gregory E.

1986-01-01

Disclosed is a method of increasing the operating cell voltage of a solid oxide electrochemical cell having metal electrode particles in contact with an oxygen-transporting ceramic electrolyte. The metal electrode is heated with the cell, and oxygen is passed through the oxygen-transporting ceramic electrolyte to the surface of the metal electrode particles so that the metal electrode particles are oxidized to form a metal oxide layer between the metal electrode particles and the electrolyte. The metal oxide layer is then reduced to form porous metal between the metal electrode particles and the ceramic electrolyte.

Characterization of poly(3,4-ethylenedioxythiophene):tosylate conductive polymer microelectrodes for transmitter detection

DEFF Research Database (Denmark)

Larsen, Simon T.; Vreeland, Richard F.; Heien, Michael L.

2012-01-01

applications such as capillary electrophoresis, high-performance liquid chromatography, and constant potential amperometry at living cells. Band electrodes with widths down to 3 μm were fabricated on polymer substrates using UV lithographic methods. The electrodes are electrochemically stable in a range......In this paper we investigate the physical and electrochemical properties of micropatterned poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:tosylate) microelectrodes for neurochemical detection. PEDOT:tosylate is a promising conductive polymer electrode material for chip-based bioanalytical...... between −200 mV and 700 mV vs. Ag/AgCl and show a relatively low resistance. A wide range of transmitters is shown to oxidize readily on the electrodes. Kinetic rate constants and half wave potentials are reported. The capacitance per area was found to be high (1670 ± 130 μF cm−2) compared to other thin...

Liquid electrode

Science.gov (United States)

Ekechukwu, A.A.

1994-07-05

A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

Ion-selective electrode reviews

CERN Document Server

Thomas, J D R

1983-01-01

Ion-Selective Electrode Reviews, Volume 5 is a collection of articles that covers ion-speciation. The book aims to present the advancements of the range and capabilities of selective ion-sensors. The topics covered in the selection are neutral carrier based ion-selective electrodes; reference electrodes and liquid junction effects in ion-selective electrode potentiometry; ion transfer across water/organic phase boundaries and analytical; and carbon substrate ion-selective electrodes. The text will be of great use to chemists and chemical engineers.

Characterisation of nano-interdigitated electrodes

Energy Technology Data Exchange (ETDEWEB)

Skjolding, L H D; Ribayrol, A; Montelius, L [Division of Solid State Physics, Lund University, Box 118, SE-221 00 Lund (Sweden); Spegel, C [Department of Analytical Chemistry Lund University, Box 124, SE-221 00 Lund (Sweden); Emneus, J [MIC - Department of Micro and Nanotechnology, DTU - Building 345 East, DK-2800 Kgs. Lyngby (Denmark)], E-mail: lars_henrik.daehli_skjolding@ftf.lth.se

2008-03-15

Interdigitated electrodes made up of two individually addressable interdigitated comb-like electrode structures have frequently been suggested as ultra sensitive electrochemical biosensors. Since the signal enhancement effects due to cycling of the reduced and oxidized species are strongly dependent on the inter electrode distances, since the nature of the enhancement is due to overlying diffusion layers, interdigitated electrodes with an electrode separation of less then one micrometer are desired for maximum signal amplification. Fabrication of submicron structures can only be made by advanced lithography techniques. By use of electron beam lithography we have fabricated arrays of interdigitated electrodes with an electrode separation distance of 200 nm and an electrode finger width of likewise 200 nm. The entire electrode structure is 100 micrometre times 100 micrometre, and the active electrode area is dictated by the opening in the passivation layer, that is defined by UV lithography. Here we report measurements of redox cycling of ferrocyanide by coupled cyclic voltammograms, where the potential at one of the working electrodes are varied and either an oxidising or reducing potential is applied to the complimentary interdigitated electrode. The measurements show fast conversion and high collection efficiency round 87% as expected for nano-interdigitated electrodes.

Electrode assemblies, plasma apparatuses and systems including electrode assemblies, and methods for generating plasma

Science.gov (United States)

Kong, Peter C; Grandy, Jon D; Detering, Brent A; Zuck, Larry D

2013-09-17

Electrode assemblies for plasma reactors include a structure or device for constraining an arc endpoint to a selected area or region on an electrode. In some embodiments, the structure or device may comprise one or more insulating members covering a portion of an electrode. In additional embodiments, the structure or device may provide a magnetic field configured to control a location of an arc endpoint on the electrode. Plasma generating modules, apparatus, and systems include such electrode assemblies. Methods for generating a plasma include covering at least a portion of a surface of an electrode with an electrically insulating member to constrain a location of an arc endpoint on the electrode. Additional methods for generating a plasma include generating a magnetic field to constrain a location of an arc endpoint on an electrode.

Near-Electrode Imager

Energy Technology Data Exchange (ETDEWEB)

Rathke, Jerome W.; Klingler, Robert J.; Woelk, Klaus; Gerald, Rex E.,II

1999-05-01

An apparatus, near-electrode imager, for employing nuclear magnetic resonance imaging to provide in situ measurements of electrochemical properties of a sample as a function of distance from a working electrode. The near-electrode imager use the radio frequency field gradient within a cylindrical toroid cavity resonator to provide high-resolution nuclear magnetic resonance spectral information on electrolyte materials.

Insulating electrodes: a review on biopotential front ends for dielectric skin–electrode interfaces

International Nuclear Information System (INIS)

Spinelli, Enrique; Haberman, Marcelo

2010-01-01

Insulating electrodes, also known as capacitive electrodes, allow acquiring biopotentials without galvanic contact with the body. They operate with displacement currents instead of real charge currents, and the electrolytic electrode–skin interface is replaced by a dielectric film. The use of insulating electrodes is not the end of electrode interface problems but the beginning of new ones: coupling capacitances are of the order of pF calling for ultra-high input impedance amplifiers and careful biasing, guarding and shielding techniques. In this work, the general requirements of front ends for capacitive electrodes are presented and the different contributions to the overall noise are discussed and estimated. This analysis yields that noise bounds depend on features of the available devices as current and voltage noise, but the final noise level also depends on parasitic capacitances, requiring a careful shield and printed circuit design. When the dielectric layer is placed on the skin, the present-day amplifiers allow achieving noise levels similar to those provided by wet electrodes. Furthermore, capacitive electrode technology allows acquiring high quality ECG signals through thin clothes. A prototype front end for capacitive electrodes was built and tested. ECG signals were acquired with these electrodes in direct contact with the skin and also through cotton clothes 350 µm thick. They were compared with simultaneously acquired signals by means of wet electrodes and no significant differences were observed between both output signals

Schiff Base modified on CPE electrode and PCB gold electrode for selective determination of silver ion

Science.gov (United States)

Leepheng, Piyawan; Suramitr, Songwut; Phromyothin, Darinee

2017-09-01

The schiff base was synthesized by 2,5-thiophenedicarboxaldehyde and 1,2,4-thiadiazole-3,5-diamine with condensation method. There was modified on carbon paste electrode (CPE) and Printed circuit board (PCB) gold electrode for determination silver ion. The schiff base modified electrodes was characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. The electrochemical study was reported by cyclic voltammetry method and impedance spectroscopy using modified electrode as working electrode, platinum wire and Ag/AgCl as counter electrode and reference electrode, respectively. The modified electrodes have suitable detection for Ag+. The determination of silver ions using the modified electrodes depended linearly on Ag+ concentration in the range 1×10-10 M to 1×10-7 M, with cyclic voltammetry sensitivity were 2.51×108 μAM-1 and 1.88×108 μAM-1 for PCB gold electrode and CPE electrode, respectively, limits of detection were 5.33×10-9 M and 1.99×10-8 M for PCB gold electrode and CPE electrode, respectively. The modified electrodes have high accuracy, inexpensive and can applied to detection Ag+ in real samples.

Voltammetry at micro-mesh electrodes

Directory of Open Access Journals (Sweden)

Wadhawan Jay D.

2003-01-01

Full Text Available The voltammetry at three micro-mesh electrodes is explored. It is found that at sufficiently short experimental durations, the micro-mesh working electrode first behaves as an ensemble of microband electrodes, then follows the behaviour anticipated for an array of diffusion-independent micro-ring electrodes of the same perimeter as individual grid-squares within the mesh. During prolonged electrolysis, the micro-mesh electrode follows that behaviour anticipated theoretically for a cubically-packed partially-blocked electrode. Application of the micro-mesh electrode for the electrochemical determination of carbon dioxide in DMSO electrolyte solutions is further illustrated.

Electrode assembly for a lithium ion battery, process for the production of such electrode assembly, and lithium ion battery comprising such electrode assemblies

NARCIS (Netherlands)

Mulder, F.M.; Wagemaker, M.

2013-01-01

The invention provides an electrode assembly for a lithium ion battery, the electrode assembly comprising a lithium storage electrode layer on a current collector, wherein the lithium storage electrode layer is a porous layer having a porosity in the range of -35 %, with pores having pore widths in

Multi-electrode double layer capacitor having single electrolyte seal and aluminum-impregnated carbon cloth electrodes

Science.gov (United States)

Farahmandi, C. Joseph; Dispennette, John M.; Blank, Edward; Kolb, Alan C.

1999-01-19

A single cell, multi-electrode high performance double layer capacitor includes first and second flat stacks of electrodes adapted to be housed in a closeable two-part capacitor case which includes only a single electrolyte seal. Each electrode stack has a plurality of electrodes connected in parallel, with the electrodes of one stack being interleaved with the electrodes of the other stack to form an interleaved stack, and with the electrodes of each stack being electrically connected to respective capacitor terminals. A porous separator sleeve is inserted over the electrodes of one stack before interleaving to prevent electrical shorts between the electrodes. The electrodes are made by folding a compressible, low resistance, aluminum-impregnated carbon cloth, made from activated carbon fibers, around a current collector foil, with a tab of the foils of each electrode of each stack being connected in parallel and connected to the respective capacitor terminal. The height of the interleaved stack is somewhat greater than the inside height of the closed capacitor case, thereby requiring compression of the interleaved electrode stack when placed inside of the case, and thereby maintaining the interleaved electrode stack under modest constant pressure. The closed capacitor case is filled with an electrolytic solution and sealed. A preferred electrolytic solution is made by dissolving an appropriate salt into acetonitrile (CH.sub.3 CN). In one embodiment, the two parts of the capacitor case are conductive and function as the capacitor terminals.

Uncharged positive electrode composition

Science.gov (United States)

Kaun, Thomas D.; Vissers, Donald R.; Shimotake, Hiroshi

1977-03-08

An uncharged positive-electrode composition contains particulate lithium sulfide, another alkali metal or alkaline earth metal compound other than sulfide, e.g., lithium carbide, and a transition metal powder. The composition along with a binder, such as electrolytic salt or a thermosetting resin is applied onto an electrically conductive substrate to form a plaque. The plaque is assembled as a positive electrode within an electrochemical cell opposite to a negative electrode containing a material such as aluminum or silicon for alloying with lithium. During charging, lithium alloy is formed within the negative electrode and transition metal sulfide such as iron sulfide is produced within the positive electrode. Excess negative electrode capacity over that from the transition metal sulfide is provided due to the electrochemical reaction of the other than sulfide alkali metal or alkaline earth metal compound.

Recent advances with a hybrid micro-pattern gas detector operated in low pressure H2 and He, for AT-TPC applications

Directory of Open Access Journals (Sweden)

Cortesi Marco

2018-01-01

Full Text Available In view of a possible application as a charge-particle track readout for an Active-Target Time Projection Chamber (AT-TPC, the operational properties and performances of a hybrid Micro-Pattern Gaseous Detector (MPGD were investigated in pure low-pressure Hydrogen (H2 and Helium (He. The detector consists of a MICROMEsh GAseous Structure (MICROMEGAS coupled to a two-cascade THick Gaseous Electron Multiplier (THGEM as a pre-amplification stage. This study reports the effective gain dependence of the hybrid-MPGD at relevant pressure (in the range of 200-760 torr for different detector arrangements. The results of this work are relevant in the field of avalanche mechanism in low-pressure, low-mass noble gases, in particularly for applications of MPGD end-cap readout for active-target Time Projection Chambers (TPC in the field of nuclear physics and nuclear astrophysics.

Micropatterning stretched and aligned DNA for sequence-specific nanolithography

Science.gov (United States)

Petit, Cecilia Anna Paulette

Techniques for fabricating nanostructured materials can be categorized as either "top-down" or "bottom-up". Top-down techniques use lithography and contact printing to create patterned surfaces and microfluidic channels that can corral and organize nanoscale structures, such as molecules and nanorods in contrast; bottom-up techniques use self-assembly or molecular recognition to direct the organization of materials. A central goal in nanotechnology is the integration of bottom-up and top-down assembly strategies for materials development, device design; and process integration. With this goal in mind, we have developed strategies that will allow this integration by using DNA as a template for nanofabrication; two top-down approaches allow the placement of these templates, while the bottom-up technique uses the specific sequence of bases to pattern materials along each strand of DNA. Our first top-down approach, termed combing of molecules in microchannels (COMMIC), produces microscopic patterns of stretched and aligned molecules of DNA on surfaces. This process consists of passing an air-water interface over end adsorbed molecules inside microfabricated channels. The geometry of the microchannel directs the placement of the DNA molecules, while the geometry of the airwater interface directs the local orientation and curvature of the molecules. We developed another top-down strategy for creating micropatterns of stretched and aligned DNA using surface chemistry. Because DNA stretching occurs on hydrophobic surfaces, this technique uses photolithography to pattern vinyl-terminated silanes on glass When these surface-, are immersed in DNA solution, molecules adhere preferentially to the silanized areas. This approach has also proven useful in patterning protein for cell adhesion studies. Finally, we describe the use of these stretched and aligned molecules of DNA as templates for the subsequent bottom-up construction of hetero-structures through hybridization

The Composite Insertion Electrode

DEFF Research Database (Denmark)

Atlung, Sven; Zachau-Christiansen, Birgit; West, Keld

1984-01-01

The specific energy obtainable by discharge of porous insertion electrodes is limited by electrolyte depletion in thepores. This can be overcome using a solid ion conductor as electrolyte. The term "composite" is used to distinguishthese electrodes from porous electrodes with liquid electrolyte...

Ion-selective electrode reviews

CERN Document Server

Thomas, J D R

1985-01-01

Ion-Selective Electrode Reviews, Volume 7 is a collection of papers that covers the applications of electrochemical sensors, along with the versatility of ion-selective electrodes. The coverage of the text includes solid contact in membrane ion-selective electrodes; immobilized enzyme probes for determining inhibitors; potentiometric titrations based on ion-pair formation; and application of ion-selective electrodes in soil science, kinetics, and kinetic analysis. The text will be of great use to chemists and chemical engineers.

Studies of pyrrole black electrodes as possible battery positive electrodes

Energy Technology Data Exchange (ETDEWEB)

Mengoli, G.; Musiani, M.M.; Fleischmann, M.; Pletcher, D.

1984-05-01

It is shown that a polypyrrole, pyrrole black, may be formed anodically in several aqueous acids. The polypyrrole film shows a redox couple at less positive potentials than that required to form the film and the charge associated with these reduction and oxidation processes together with their stabilty to cycling varies with the anion in solution and the potential where the polypyrrole is formed; over-oxidation of the film caused by taking its potential too positive has a particularly disadvantageous affect. In the acids HBr and HI, the polypyrrole films can act as a storage medium for Br/sub 2/ or I/sub 2/ so that they may be used as a substrate for a X/sub 2//X/sup -/ electrode. Such electrodes may be charge/discharge cycled and the pyrrole/Br/sub 2/ electrode shows promise as a battery positive electrode.

Gas sensor with multiple internal reference electrodes and sensing electrodes

DEFF Research Database (Denmark)

2016-01-01

The invention relates to a potentiometric gas sensor, or potentiometric gas detection element, with multiple internal reference electrodes and multiple sensing electrodes for determining the concentrations of gas components in a gaseous mixture. The sensor for gas detection comprises: a solid...

An optical fiber-based flexible readout system for micro-pattern gas detectors

Science.gov (United States)

Li, C.; Feng, C. Q.; Zhu, D. Y.; Liu, S. B.; An, Q.

2018-04-01

This paper presents an optical fiber-based readout system that is intended to provide a general purpose multi-channel readout solution for various Micro-Pattern Gas Detectors (MPGDs). The proposed readout system is composed of several front-end cards (FECs) and a data collection module (DCM). The FEC exploits the capability of an existing 64-channel generic TPC readout ASIC chip, named AGET, to implement 256 channels readout. AGET offers FEC a large flexibility in gain range (4 options from 120 fC to 10 pC), peaking time (16 options from 50 ns to 1 us) and sampling freqency (100 MHz max.). The DCM contains multiple 1 Gbps optical fiber serial link interfaces that allow the system scaling up to 1536 channels with 6 FECs and 1 DCM. Further scaling up is possible through cascading of multiple DCMs, by configuring one DCM as a master while other DCMs in slave mode. This design offers a rapid readout solution for different application senario. Tests indicate that the nonlinearity of each channel is less than 1%, and the equivalent input noise charge is typically around 0.7 fC in RMS (root mean square), with a noise slope of about 0.01 fC/pF. The system level trigger rate limit is about 700 Hz in all channel readout mode. When in hit channel readout mode, supposing that typically 10 percent of channels are fired, trigger rate can go up to about 7 kHz. This system has been tested with Micromegas detector and GEM detector, confirming its capability in MPGD readout. Details of hardware and FPGA firmware design, as well as system performances, are described in the paper.

Handbook of reference electrodes

CERN Document Server

Inzelt, György; Scholz, Fritz

2013-01-01

Reference Electrodes are a crucial part of any electrochemical system, yet an up-to-date and comprehensive handbook is long overdue. Here, an experienced team of electrochemists provides an in-depth source of information and data for the proper choice and construction of reference electrodes. This includes all kinds of applications such as aqueous and non-aqueous solutions, ionic liquids, glass melts, solid electrolyte systems, and membrane electrodes. Advanced technologies such as miniaturized, conducting-polymer-based, screen-printed or disposable reference electrodes are also covered. Essen

Lithium-aluminum-magnesium electrode composition

Science.gov (United States)

Melendres, Carlos A.; Siegel, Stanley

1978-01-01

A negative electrode composition is presented for use in a secondary, high-temperature electrochemical cell. The cell also includes a molten salt electrolyte of alkali metal halides or alkaline earth metal halides and a positive electrode including a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent and a magnesium-aluminum alloy as a structural matrix. Various binary and ternary intermetallic phases of lithium, magnesium, and aluminum are formed but the electrode composition in both its charged and discharged state remains substantially free of the alpha lithium-aluminum phase and exhibits good structural integrity.

A Simple Hydrogen Electrode

Science.gov (United States)

Eggen, Per-Odd

2009-01-01

This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements…

Ion-selective electrode reviews

CERN Document Server

Thomas, J D R

1982-01-01

Ion-Selective Electrode Reviews, Volume 3, provides a review of articles on ion-selective electrodes (ISEs). The volume begins with an article on methods based on titration procedures for surfactant analysis, which have been developed for discrete batch operation and for continuous AutoAnalyser use. Separate chapters deal with detection limits of ion-selective electrodes; the possibility of using inorganic ion-exchange materials as ion-sensors; and the effect of solvent on potentials of cells with ion-selective electrodes. Also included is a chapter on advances in calibration procedures, the d

Analysis of oxidation of self-baking electrodes (Soederberg electrodes) by means of three-dimensional model

Science.gov (United States)

Pashnin, S. V.

2017-10-01

The paper presents the methodology and results of the development of the temperature dependence of the oxidation speed of the self-baking electrode (Soederberg Electrodes) in the ore-thermal furnaces. For the study of oxidation, the working ends of the self-baking electrodes, which were taken out from the ore-thermal furnaces after their scabbings, were used. The temperature of the electrode surface by its height was calculated with the help of the mathematical model of heat work of self-baking electrode. The comparison of electrode surface temperatures with the speed of oxidation of the electrode allowed one to obtain the temperature dependency of the oxidation of the lateral electrode surface. Comparison of the experimental data, obtained in the laboratory by various authors, showed their qualitative coincidence with results of calculations of the oxidation rate presented in this article. With the help of the mathematical model of temperatures fields of electrode, the calculations of the sizes of the cracks, appearing after burnout ribs, were performed. Calculations showed that the sizes of the cracks after the ribs burnout, calculated by means of the obtained temperature dependence, coincide with the experimental data with sufficient accuracy.

Manufacturing process and electrode properties of palladium-electroded ionic polymer–metal composite

International Nuclear Information System (INIS)

Chang, Longfei; Chen, Hualing; Zhu, Zicai; Li, Bo

2012-01-01

This paper primarily focuses on the manufacturing process of palladium-electroded ionic polymer–metal composite (IPMC). First, according to the special properties of Pd, many experiments were done to determine several specific procedures, including the addition of a reducing agent and the time consumed. Subsequently, the effects of the core manufacturing steps on the electrode morphology were revealed by scanning electron microscopy studies of 22 IPMC samples treated with different combinations of manufacturing steps. Finally, the effects of electrode characteristics on the electromechanical properties, including the sheet resistivity, the elastic modulus and the electro-active performance, of IPMCs were evaluated experimentally and analyzed according to the electrode morphology. (paper)

Time-dependent simulation of plasma and electrodes in high-intensity discharge lamps with different electrode shapes

CERN Document Server

Flesch, P

2003-01-01

The subject of this paper is the modelling of d.c. and a.c. high-intensity Hg-discharge lamps with differently shaped electrodes. Different arc attachments on the electrodes are studied and insight for the development of new electrodes is gained. The model includes the entire discharge plasma (plasma column, hot plasma spots in front of electrodes, near-electrode non-LTE-plasma) as well as anode and cathode. No subdivision of the discharge space into different regions is necessary (like space charge layer, ionization zone, plasma column). This is achieved by using a differential equation for a non-LTE electrical conductivity which is applicable for local thermal equilibrium (LTE-)regions as well as for non-LTE plasma regions close to the electrodes in a high pressure plasma. Modelling results for a 0.6 MPa mercury discharge considering six different electrode shapes (anode and cathode) are presented and compared with experimental results. The electrodes have different diameters and different electrode tips, s...

Robust high temperature oxygen sensor electrodes

DEFF Research Database (Denmark)

Lund, Anders

Platinum is the most widely used material in high temperature oxygen sensor electrodes. However, platinum is expensive and the platinum electrode may, under certain conditions, suffer from poisoning, which is detrimental for an oxygen sensor. The objective of this thesis is to evaluate electrode...... materials as candidates for robust oxygen sensor electrodes. The present work focuses on characterising the electrochemical properties of a few electrode materials to understand which oxygen electrode processes are limiting for the response time of the sensor electrode. Three types of porous platinum......-Dansensor. The electrochemical properties of the electrodes were characterised by electrochemical impedance spectroscopy (EIS), and the structures were characterised by x-ray diffraction and electron microscopy. At an oxygen partial pressures of 0.2 bar, the response time of the sensor electrode was determined by oxygen...

Sensor employing internal reference electrode

DEFF Research Database (Denmark)

2013-01-01

The present invention concerns a novel internal reference electrode as well as a novel sensing electrode for an improved internal reference oxygen sensor and the sensor employing same.......The present invention concerns a novel internal reference electrode as well as a novel sensing electrode for an improved internal reference oxygen sensor and the sensor employing same....

Microbial electrode sensor for alcohols

Energy Technology Data Exchange (ETDEWEB)

Hikuma, M [Ajinomoto Co., Inc., Kawasaki, Japan; Kubo, T; Yasuda, T; Karube, I; Suzuki, S

1979-10-01

A microbial electrode consisting of immobilized microorganisms, a gas permeable Teflon membrane, and an oxygen electrode was prepared for the continuous determination of methyl and ethyl alcohols. Immobilized Trichosporon brassicae was employed for a microbial electrode sensor for ethyl alcohol. When a sample solution containing ethyl alcohol was injected into a microbial electrode system, the current of the electrode decreased markedly with time until a steady state was reached. The response time was within 10 min by the steady state method and within 6 min by the pulse method. A linear relationship was observed between the current decrease and the concentration of ethyl alcohol below 22.5 mg/liter. The current was reproducible within +- 6% of the relative error when a sample solution containing 16.5 mg/liter ethyl alcohol. The standard deviation was 0.5 mg/liter in 40 experiments. The selectivity of the microbial electrode sensor for ethyl alcohol was satisfactory. The microbial electrode sensor was applied to a fermentation broth of yeasts and satisfactory comparative results were obtained (correlation coefficient 0.98). The current output of the microbial electrode sensor was almost constant for more than three weeks and 2100 assays. A microbial electrode sensor using immobilized bacteria for methyl alcohol was also described.

Effect of Particle Size on Electrode Potential and Thermodynamics of Nanoparticles Electrode in Theory and Experiment

International Nuclear Information System (INIS)

Yunfeng, Yang; Yongqiang, Xue; Zixiang, Cui; Miaozhi, Zhao

2014-01-01

The particle size of electrode materials has a significant influence on the standard electrode potential and the thermodynamic properties of electrode reactions. In this paper, the size-dependent electrochemical thermodynamics has been theoretically investigated and successfully deduced electrochemical thermodynamics equations for nanoparticles electrode. At the same time, the electrode potential and thermodynamical properties of Ag 2 O/Ag nanoparticles electrode constructed by the solid and spherical Ag 2 O nanoparticles with different sizes further testified that the particle size of nanoparticles has a significant effect on electrochemical thermodynamics. The results show that the electrode potential depends on that of the smallest nanoparticle in a nanoparticles electrode which consisted of different particle sizes of nano-Ag 2 O. When the size of Ag 2 O nanoparticles reduces, the standard electrode potentials and the equilibrium constants of the corresponding electrode reactions increase, and the temperature coefficient, the mole Gibbs energy change, the mole enthalpy change and the mole entropy change decrease. Moreover, these physical quantities are all linearly related with the reciprocal of average particle size (r > 10 nm). The experimental regularities coincide with the theoretical equations

Pitch ranking, electrode discrimination, and physiological spread-of-excitation using Cochlear's dual-electrode mode.

Science.gov (United States)

Goehring, Jenny L; Neff, Donna L; Baudhuin, Jacquelyn L; Hughes, Michelle L

2014-08-01

This study compared pitch ranking, electrode discrimination, and electrically evoked compound action potential (ECAP) spatial excitation patterns for adjacent physical electrodes (PEs) and the corresponding dual electrodes (DEs) for newer-generation Cochlear devices (Cochlear Ltd., Macquarie, New South Wales, Australia). The first goal was to determine whether pitch ranking and electrode discrimination yield similar outcomes for PEs and DEs. The second goal was to determine if the amount of spatial separation among ECAP excitation patterns (separation index, Σ) between adjacent PEs and the PE-DE pairs can predict performance on the psychophysical tasks. Using non-adaptive procedures, 13 subjects completed pitch ranking and electrode discrimination for adjacent PEs and the corresponding PE-DE pairs (DE versus each flanking PE) from the basal, middle, and apical electrode regions. Analysis of d' scores indicated that pitch-ranking and electrode-discrimination scores were not significantly different, but rather produced similar levels of performance. As expected, accuracy was significantly better for the PE-PE comparison than either PE-DE comparison. Correlations of the psychophysical versus ECAP Σ measures were positive; however, not all test/region correlations were significant across the array. Thus, the ECAP separation index is not sensitive enough to predict performance on behavioral tasks of pitch ranking or electrode discrimination for adjacent PEs or corresponding DEs.

Grid-texture mechanisms in human vision: Contrast detection of regular sparse micro-patterns requires specialist templates.

Science.gov (United States)

Baker, Daniel H; Meese, Tim S

2016-07-27

Previous work has shown that human vision performs spatial integration of luminance contrast energy, where signals are squared and summed (with internal noise) over area at detection threshold. We tested that model here in an experiment using arrays of micro-pattern textures that varied in overall stimulus area and sparseness of their target elements, where the contrast of each element was normalised for sensitivity across the visual field. We found a power-law improvement in performance with stimulus area, and a decrease in sensitivity with sparseness. While the contrast integrator model performed well when target elements constituted 50-100% of the target area (replicating previous results), observers outperformed the model when texture elements were sparser than this. This result required the inclusion of further templates in our model, selective for grids of various regular texture densities. By assuming a MAX operation across these noisy mechanisms the model also accounted for the increase in the slope of the psychometric function that occurred as texture density decreased. Thus, for the first time, mechanisms that are selective for texture density have been revealed at contrast detection threshold. We suggest that these mechanisms have a role to play in the perception of visual textures.

Electrode Conduction Processes Segmented Electrode-Insulator Ratio Effects in MHD Power Generation Experiments

Energy Technology Data Exchange (ETDEWEB)

Pain, H. J.; Fearn, D. G.; Distefano, E. [Imperial College. London (United Kingdom)

1966-10-15

(a) Electrode conduction processes have been investigated using a plasma produced in an electromagnetic shock tube operating with argon at 70 {mu}mHg pressure. Complete voltage-current characteristics were obtained by the variation of load and applied voltage. These indicated the existence of two conduction regimes with a complex transition region. In the first regime the current, controlled by ion mobility, rose linearly with voltage to saturate between 10 mA and 1 A depending on conditions. Electrode contamination was significant. The second regime involved large currents controlled by electron mobility and emission from the cathode. The current again increased linearly with voltage and reached 200 A. Observation of induced voltages in transverse magnetic fields and of plasma deceleration in non-uniform fields showed that in the electromagnetic shock tube the plasma was heated predominantly by the driver discharge. Its conductivity was calculated using properties measured by a Langmuir double probe. In both regimes the plasma conductivity was also found from the gradient of the voltage current characteristics using experimental electric field fringing factors and the experimental values were compared with theory. (b) Larger-scale experiments used a combustion-driven shock tube where argon plasma flow, magnetic field and induced current flow were mutually orthogonal. The supersonic flow velocity and thermodynamic parameters of the plasma were accurately known. The electrode channel consisted of a segmented system of 12 electrode pairs with an electrode insulator ratio ranging from 1 to 21, with electrode plus insulator length remaining constant, and with maximum Hall parameter values of unity. Different electrode load combinations (Faraday and Hall generators) have been studied in measuring the power generated and the flow of longitudinal currents between adjacent electrodes. A maximum power of 0,8 MW was obtained, the power output decreasing inversely with the

Electrode Conduction Processes Segmented Electrode-Insulator Ratio Effects in MHD Power Generation Experiments

International Nuclear Information System (INIS)

Pain, H.J.; Fearn, D.G.; Distefano, E.

1966-01-01

(a) Electrode conduction processes have been investigated using a plasma produced in an electromagnetic shock tube operating with argon at 70 μmHg pressure. Complete voltage-current characteristics were obtained by the variation of load and applied voltage. These indicated the existence of two conduction regimes with a complex transition region. In the first regime the current, controlled by ion mobility, rose linearly with voltage to saturate between 10 mA and 1 A depending on conditions. Electrode contamination was significant. The second regime involved large currents controlled by electron mobility and emission from the cathode. The current again increased linearly with voltage and reached 200 A. Observation of induced voltages in transverse magnetic fields and of plasma deceleration in non-uniform fields showed that in the electromagnetic shock tube the plasma was heated predominantly by the driver discharge. Its conductivity was calculated using properties measured by a Langmuir double probe. In both regimes the plasma conductivity was also found from the gradient of the voltage current characteristics using experimental electric field fringing factors and the experimental values were compared with theory. (b) Larger-scale experiments used a combustion-driven shock tube where argon plasma flow, magnetic field and induced current flow were mutually orthogonal. The supersonic flow velocity and thermodynamic parameters of the plasma were accurately known. The electrode channel consisted of a segmented system of 12 electrode pairs with an electrode insulator ratio ranging from 1 to 21, with electrode plus insulator length remaining constant, and with maximum Hall parameter values of unity. Different electrode load combinations (Faraday and Hall generators) have been studied in measuring the power generated and the flow of longitudinal currents between adjacent electrodes. A maximum power of 0,8 MW was obtained, the power output decreasing inversely with the

All-solid-state carbonate-selective electrode based on screen-printed carbon paste electrode

International Nuclear Information System (INIS)

Li, Guang; Lyu, Xiaofeng; Wang, Zhan; Rong, Yuanzhen; Hu, Ruifen; Wang, You; Luo, Zhiyuan

2017-01-01

A novel disposable all-solid-state carbonate-selective electrode based on a screen-printed carbon paste electrode using poly(3-octylthiophene-2,5-diyl) (POT) as an ion-to-electron transducer has been developed. The POT was dropped onto the reaction area of the carbon paste electrode covered by the poly(vinyl chloride) (PVC) membrane, which contains N,N-Dioctyl-3 α ,12 α -bis(4-trifluoroacetylbenzoyloxy)-5 β -cholan-24-amide as a carbonate ionophore. The electrode showed a near-Nernstian slope of  −27.5 mV/decade with a detection limit of 3.6 * 10 −5 mol l −1 . Generally, the detection time was 30 s. Because these electrodes are fast, convenient and low in cost, they have the potential to be mass produced and used in on-site testing as disposable sensors. Furthermore, the repeatability, reproducibility and stability have been studied to evaluate the properties of the electrodes. Measurement of the carbonate was also conducted in a human blood solution and achieved good performance. (paper)

Comparative investigation on electrochemical behavior of hydroquinone at carbon ionic liquid electrode, ionic liquid modified carbon paste electrode and carbon paste electrode

International Nuclear Information System (INIS)

Zhang, Ya; Zheng, Jian Bin

2007-01-01

Ionic liquid, 1-heptyl-3-methylimidazolium hexafluorophosphate (HMIMPF 6 ), has been used to fabricate two new electrodes, carbon ionic liquid electrode (CILE) and ionic liquid modified carbon paste electrode (IL/CPE), using graphite powder mixed with HMIMPF 6 or the mixture of HMIMPF 6 /paraffin liquid as the binder, respectively. The electrochemical behaviors of hydroquinone at the CILE, the IL/CPE and the CPE were investigated in phosphate buffer solution. At all these electrodes, hydroquinone showed a pair of redox peaks. The order of the current response and the standard rate constant of hydroquinone at these electrodes were as follows: CILE > IL/CPE > CPE, while the peak-to-peak potential separation was in an opposite sequence: CILE < IL/CPE < CPE. The results show the superiority of CILE to IL/CPE and CPE, and IL/CPE to CPE in terms of promoting electron transfer, improving reversibility and enhancing sensitivity. The CILE was chosen as working electrode to determine hydroquinone by differential pulse voltammetry, which can be used for sensitive, simple and rapid determination of hydroquinone in medicated skin cosmetic cream

The kinetics of porous insertion electrodes

Energy Technology Data Exchange (ETDEWEB)

Atlung, S; West, K [British Columbia Univ., Vancouver (Canada)

1989-05-01

The principles of porous electrodes are discussed as well as the discharge of the insertion compound, the working potential, transport in the electrolyte, the time dependence of the electrolyte concentration, and modeling of the porous electrode. The simulation of a TiS2 porous electrode and the composite insertion electrode are considered as well. The influence of electrode thickness and porosity in a typical porous TiS2 electrode is revealed. It is shown that the use of insertion compounds as battery electrodes is limited by the requirement that the inserted ion must be distributed in the interior of the insertion compound particle. 15 refs.

Beyond Slurry-Cast Supercapacitor Electrodes: PAN/MWNT Heteromat-Mediated Ultrahigh Capacitance Electrode Sheets

Science.gov (United States)

Lee, Jung Han; Kim, Jeong A.; Kim, Ju-Myung; Lee, Sun-Young; Yeon, Sun-Hwa; Lee, Sang-Young

2017-01-01

Supercapacitors (SCs) have garnered considerable attention as an appealing power source for forthcoming smart energy era. An ultimate challenge facing the SCs is the acquisition of higher energy density without impairing their other electrochemical properties. Herein, we demonstrate a new class of polyacrylonitrile (PAN)/multi-walled carbon tube (MWNT) heteromat-mediated ultrahigh capacitance electrode sheets as an unusual electrode architecture strategy to address the aforementioned issue. Vanadium pentoxide (V2O5) is chosen as a model electrode material to explore the feasibility of the suggested concept. The heteromat V2O5 electrode sheets are produced through one-pot fabrication based on concurrent electrospraying (for V2O5 precursor/MWNT) and electrospinning (for PAN nanofiber) followed by calcination, leading to compact packing of V2O5 materials in intimate contact with MWNTs and PAN nanofibers. As a consequence, the heteromat V2O5 electrode sheets offer three-dimensionally bicontinuous electron (arising from MWNT networks)/ion (from spatially reticulated interstitial voids to be filled with liquid electrolytes) conduction pathways, thereby facilitating redox reaction kinetics of V2O5 materials. In addition, elimination of heavy metallic foil current collectors, in combination with the dense packing of V2O5 materials, significantly increases (electrode sheet-based) specific capacitances far beyond those accessible with conventional slurry-cast electrodes.

Fabrication of Biomimetic Fog-Collecting Superhydrophilic-Superhydrophobic Surface Micropatterns Using Femtosecond Lasers.

Science.gov (United States)

Kostal, Elisabeth; Stroj, Sandra; Kasemann, Stephan; Matylitsky, Victor; Domke, Matthias

2018-03-06

The exciting functionalities of natural superhydrophilic and superhydrophobic surfaces served as inspiration for a variety of biomimetic designs. In particular, the combination of both extreme wetting states to micropatterns opens up interesting applications, as the example of the fog-collecting Namib Desert beetle shows. In this paper, the beetle's elytra were mimicked by a novel three-step fabrication method to increase the fog-collection efficiency of glasses. In the first step, a double-hierarchical surface structure was generated on Pyrex wafers using femtosecond laser structuring, which amplified the intrinsic wetting property of the surface and made it superhydrophilic (water contact angle 150°). In the last step, the Teflon-like coating was selectively removed by fs-laser ablation to uncover superhydrophilic spots below the superhydrophobic surface, following the example of the Namib Desert beetle's fog-collecting elytra. To investigate the influence on the fog-collection behavior, (super)hydrophilic, (super)hydrophobic, and low and high contrast wetting patterns were fabricated on glass wafers using selected combinations of these three processing steps and were exposed to fog in an artificial nebulizer setup. This experiment revealed that high-contrast wetting patterns collected the highest amount of fog and enhanced the fog-collection efficiency by nearly 60% compared to pristine Pyrex glass. The comparison of the fog-collection behavior of the six samples showed that the superior fog-collection efficiency of surface patterns with extreme wetting contrast is due to the combination of water attraction and water repellency: the superhydrophilic spots act as drop accumulation areas, whereas the surrounding superhydrophobic areas allow a fast water transportation caused by gravity. The presented method enables a fast and flexible surface functionalization of a broad range of materials including transparent substrates, which offers exciting possibilities for

Cold-electrode voltage fall for impulse arcs in argon between copper electrodes

Energy Technology Data Exchange (ETDEWEB)

Diaz, O; Cooray, V, E-mail: oscar.diaz@angstrom.uu.se [Lightning Research Group, Division for Electricity, Uppsala University Angstroemlaboratoriet Box 5234, 751 20, Uppsala (Sweden)

2011-06-23

The full electric arc discharge in gases for short gaps in homogeneous electric field and pressure{center_dot}distance (pd) below 150 Torr{center_dot}cm, can be described as a transition between different discharge mechanisms such as: Townsend, glow, and arc. Once the arc is achieved the measured voltage drops to some volts and the current density increases several orders of magnitude. Depending upon the type of gas used, the electrode surface characteristics and type of electrical excitation, the cathode and anode voltage fall might change. The present work is directed to study the electrode fall (sum of anode and cathode falls) during a current impulse arc discharge between copper electrodes in ceramic tubes filled with argon between 0.01 and 6.5 Torr{center_dot}cm. The copper electrodes were cleaned, degassed and hydrogen reduced. The arc voltages were measured with fast/slow rise times and short/long duration current impulses produced by a RLC circuit. An increasing variation of the electrode fall was found at the pressure{center_dot}distance range analyzed.

Durable fuel electrode

DEFF Research Database (Denmark)

2017-01-01

the composite. The invention also relates to the use of the composite as a fuel electrode, solid oxide fuel cell, and/or solid oxide electrolyser. The invention discloses a composite for an electrode, comprising a three-dimensional network of dispersed metal particles, stabilised zirconia particles and pores...

Built-in test of electrode degradation of multi-electrode array biosensors

NARCIS (Netherlands)

Liu, H.Y.; Dumas, N.; Richardson, A.; Heal, R.; Kerkhoff, Hans G.

2006-01-01

Micro-electrode array (MEA) is a widely used platform in biosensor systems, which provide a technology in communicating with micro chemical and biological world. This paper addresses hte topic of testing micro electrode degradation for MEAs, which is a common encountered damage during its

Extraction electrode geometry for a calutron

International Nuclear Information System (INIS)

Veach, A.M.; Bell, W.A. Jr.

1975-01-01

This patent relates to an improved geometry for the extraction electrode and the ground electrode utilized in the operation of a calutron. The improved electrodes are constructed in a partial-picture-frame fashion with the slits of both electrodes formed by two tungsten elongated rods. Additional parallel spaced-apart rods in each electrode are used to establish equipotential surfaces over the rest of the front of the ion source

Electromechanical properties of indium–tin–oxide/poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonate) hybrid electrodes for flexible transparent electrodes

International Nuclear Information System (INIS)

Jung, Sunghoon; Lim, Kyounga; Kang, Jae-Wook; Kim, Jong-Kuk; Oh, Se-In; Eun, Kyoungtae; Kim, Do-Geun; Choa, Sung-Hoon

2014-01-01

We investigated an indium–tin–oxide (ITO)/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) hybrid electrode as a potential flexible and transparent electrode. In particular, the mechanical integrity of an ITO/PEDOT:PSS hybrid electrode deposited onto a polyethylene terephthalate (PET) substrate was investigated via outer/inner bending, twisting, stretching, and adhesion tests. A PEDOT:PSS layer was inserted between ITO and PET substrate as a buffer layer to improve the flexibility and electrical properties. When a PEDOT:PSS layer was inserted, the sheet resistance of the 20 nm-thick ITO film decreased from 270 Ω/square to 57 Ω/square. Notably, the ITO/PEDOT:PSS hybrid electrode had a constant resistance change (ΔR/R 0 ) within an outer and inner bending radius of 3 mm. The bending fatigue test showed that the ITO/PEDOT:PSS hybrid electrode can withstand 10,000 bending cycles. Furthermore, the stretched ITO/PEDOT:PSS hybrid electrode showed a fairly constant resistance change up to 4%, which is more stable than the resistance change of the ITO electrode. The ITO/PEDOT:PSS electrode also shows good adhesion strength. The superior flexibility of the ITO/PEDOT:PSS hybrid electrode is attributed to the existence of a flexible PEDOT:PSS layer. This indicates that the hybridization of an ITO and PEDOT:PSS layer is a promising electrode scheme for next-generation flexible transparent electrodes. - Highlights: • We propose a hybrid electrode for flexible electronics. • Electrode made from In 2 O 3 :SnO 2 /poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) • PEDOT:PSS as a buffer layer increases flexibility and electrical conductivity. • Hybrid electrode has a superior flexibility. • Hybrid electrode can be a promising flexible transparent electrode scheme

Transparent Electrodes for Efficient Optoelectronics

KAUST Repository

Morales-Masis, Monica

2017-03-30

With the development of new generations of optoelectronic devices that combine high performance and novel functionalities (e.g., flexibility/bendability, adaptability, semi or full transparency), several classes of transparent electrodes have been developed in recent years. These range from optimized transparent conductive oxides (TCOs), which are historically the most commonly used transparent electrodes, to new electrodes made from nano- and 2D materials (e.g., metal nanowire networks and graphene), and to hybrid electrodes that integrate TCOs or dielectrics with nanowires, metal grids, or ultrathin metal films. Here, the most relevant transparent electrodes developed to date are introduced, their fundamental properties are described, and their materials are classified according to specific application requirements in high efficiency solar cells and flexible organic light-emitting diodes (OLEDs). This information serves as a guideline for selecting and developing appropriate transparent electrodes according to intended application requirements and functionality.

Transparent Electrodes for Efficient Optoelectronics

KAUST Repository

Morales-Masis, Monica; De Wolf, Stefaan; Woods-Robinson, Rachel; Ager, Joel W.; Ballif, Christophe

2017-01-01

With the development of new generations of optoelectronic devices that combine high performance and novel functionalities (e.g., flexibility/bendability, adaptability, semi or full transparency), several classes of transparent electrodes have been developed in recent years. These range from optimized transparent conductive oxides (TCOs), which are historically the most commonly used transparent electrodes, to new electrodes made from nano- and 2D materials (e.g., metal nanowire networks and graphene), and to hybrid electrodes that integrate TCOs or dielectrics with nanowires, metal grids, or ultrathin metal films. Here, the most relevant transparent electrodes developed to date are introduced, their fundamental properties are described, and their materials are classified according to specific application requirements in high efficiency solar cells and flexible organic light-emitting diodes (OLEDs). This information serves as a guideline for selecting and developing appropriate transparent electrodes according to intended application requirements and functionality.

Biopolymer-nanocarbon composite electrodes for use as high-energy high-power density electrodes

Science.gov (United States)

Karakaya, Mehmet; Roberts, Mark; Arcilla-Velez, Margarita; Zhu, Jingyi; Podila, Ramakrishna; Rao, Apparao

2014-03-01

Supercapacitors (SCs) address our current energy storage and delivery needs by combining the high power, rapid switching, and exceptional cycle life of a capacitor with the high energy density of a battery. Although activated carbon is extensively used as a supercapacitor electrode due to its inexpensive nature, its low specific capacitance (100-120 F/g) fundamentally limits the energy density of SCs. We demonstrate that a nano-carbon based mechanically robust, electrically conducting, free-standing buckypaper electrode modified with an inexpensive biorenewable polymer, viz., lignin increases the electrode's specific capacitance (~ 600-700 F/g) while maintaining rapid discharge rates. In these systems, the carbon nanomaterials provide the high surface area, electrical conductivity and porosity, while the redox polymers provide a mechanism for charge storage through Faradaic charge transfer. The design of redox polymers and their incorporation into nanomaterial electrodes will be discussed with a focus on enabling high power and high energy density electrodes. Research supported by US NSF CMMI Grant 1246800.

Gossipo-3 A prototype of a Front-End Pixel Chip for Read-Out of Micro-Pattern Gas Detectors

CERN Document Server

Brezina, Christpoh; van der Graaf, Haryy; Gromov, Vladimir; Kluit, Ruud; Kruth, Andre; Zappon, Francesco

2009-01-01

In a joint effort of Nikhef (Amsterdam) and the University of Bonn, the Gossipo-3 integrated circuit (IC) has been developed. This circuit is a prototype of a chip dedicated for read-out of various types of position sensitive Micro-Pattern Gas detectors (MPGD). The Gossipo-3 is defined as a set of building blocks to be used in a future highly granulated (60 μm) chip. The pixel circuit can operate in two modes. In Time mode every readout pixel measures the hit arrival time and the charge deposit. For this purpose it has been equipped with a high resolution TDC (1.7 ns) covering dynamic range up to 102 μs. Charge collected by the pixel will be measured using Time-over- Threshold method in the range from 400 e- to 28000 e- with accuracy of 200 e- (standard deviation). In Counting mode every pixel operates as a 24-bit counter, counting the number of incoming hits. The circuit is also optimized to operate at low power consumption (100 mW/cm2) that is required to avoid the need for massive power transport and coo...

Probing Electrode Heterogeneity Using Fourier-Transformed Alternating Current Voltammetry: Application to a Dual-Electrode Configuration.

Science.gov (United States)

Tan, Sze-Yin; Unwin, Patrick R; Macpherson, Julie V; Zhang, Jie; Bond, Alan M

2017-03-07

Quantitative studies of electron transfer processes at electrode/electrolyte interfaces, originally developed for homogeneous liquid mercury or metallic electrodes, are difficult to adapt to the spatially heterogeneous nanostructured electrode materials that are now commonly used in modern electrochemistry. In this study, the impact of surface heterogeneity on Fourier-transformed alternating current voltammetry (FTACV) has been investigated theoretically under the simplest possible conditions where no overlap of diffusion layers occurs and where numerical simulations based on a 1D diffusion model are sufficient to describe the mass transport problem. Experimental data that meet these requirements can be obtained with the aqueous [Ru(NH 3 ) 6 ] 3+/2+ redox process at a dual-electrode system comprised of electrically coupled but well-separated glassy carbon (GC) and boron-doped diamond (BDD) electrodes. Simulated and experimental FTACV data obtained with this electrode configuration, and where distinctly different heterogeneous charge transfer rate constants (k 0 values) apply at the individual GC and BDD electrode surfaces, are in excellent agreement. Principally, because of the far greater dependence of the AC current magnitude on k 0 , it is straightforward with the FTACV method to resolve electrochemical heterogeneities that are ∼1-2 orders of magnitude apart, as applies in the [Ru(NH 3 ) 6 ] 3+/2+ dual-electrode configuration experiments, without prior knowledge of the individual kinetic parameters (k 0 1 and k 0 2 ) or the electrode size ratio (θ 1 :θ 2 ). In direct current voltammetry, a difference in k 0 of >3 orders of magnitude is required to make this distinction.

3D Printed Dry EEG Electrodes.

Science.gov (United States)

Krachunov, Sammy; Casson, Alexander J

2016-10-02

Electroencephalography (EEG) is a procedure that records brain activity in a non-invasive manner. The cost and size of EEG devices has decreased in recent years, facilitating a growing interest in wearable EEG that can be used out-of-the-lab for a wide range of applications, from epilepsy diagnosis, to stroke rehabilitation, to Brain-Computer Interfaces (BCI). A major obstacle for these emerging applications is the wet electrodes, which are used as part of the EEG setup. These electrodes are attached to the human scalp using a conductive gel, which can be uncomfortable to the subject, causes skin irritation, and some gels have poor long-term stability. A solution to this problem is to use dry electrodes, which do not require conductive gel, but tend to have a higher noise floor. This paper presents a novel methodology for the design and manufacture of such dry electrodes. We manufacture the electrodes using low cost desktop 3D printers and off-the-shelf components for the first time. This allows quick and inexpensive electrode manufacturing and opens the possibility of creating electrodes that are customized for each individual user. Our 3D printed electrodes are compared against standard wet electrodes, and the performance of the proposed electrodes is suitable for BCI applications, despite the presence of additional noise.

3D Printed Dry EEG Electrodes

Directory of Open Access Journals (Sweden)

Sammy Krachunov

2016-10-01

Full Text Available Electroencephalography (EEG is a procedure that records brain activity in a non-invasive manner. The cost and size of EEG devices has decreased in recent years, facilitating a growing interest in wearable EEG that can be used out-of-the-lab for a wide range of applications, from epilepsy diagnosis, to stroke rehabilitation, to Brain-Computer Interfaces (BCI. A major obstacle for these emerging applications is the wet electrodes, which are used as part of the EEG setup. These electrodes are attached to the human scalp using a conductive gel, which can be uncomfortable to the subject, causes skin irritation, and some gels have poor long-term stability. A solution to this problem is to use dry electrodes, which do not require conductive gel, but tend to have a higher noise floor. This paper presents a novel methodology for the design and manufacture of such dry electrodes. We manufacture the electrodes using low cost desktop 3D printers and off-the-shelf components for the first time. This allows quick and inexpensive electrode manufacturing and opens the possibility of creating electrodes that are customized for each individual user. Our 3D printed electrodes are compared against standard wet electrodes, and the performance of the proposed electrodes is suitable for BCI applications, despite the presence of additional noise.

Capacitance enhancement via electrode patterning

International Nuclear Information System (INIS)

Ho, Tuan A.; Striolo, Alberto

2013-01-01

The necessity of increasing the energy density in electric double layer capacitors to meet current demand is fueling fundamental and applied research alike. We report here molecular dynamics simulation results for aqueous electrolytes near model electrodes. Particular focus is on the effect of electrode patterning on the structure of interfacial electrolytes, and on the potential drop between the solid electrodes and the bulk electrolytes. The latter is estimated by numerically integrating the Poisson equation using the charge densities due to water and ions accumulated near the interface as input. We considered uniform and patterned electrodes, both positively and negatively charged. The uniformly charged electrodes are modeled as graphite. The patterned ones are obtained by removing carbon atoms from the top-most graphene layer, yielding nanoscopic squares and stripes patterns. For simplicity, the patterned electrodes are effectively simulated as insulators (the charge remains localized on the top-most layer of carbon atoms). Our simulations show that the patterns alter the structure of water and the accumulation of ions at the liquid-solid interfaces. Using aqueous NaCl solutions, we found that while the capacitance calculated for three positively charged electrodes did not change much, that calculated for the negatively charged electrodes significantly increased upon patterning. We find that both water structure and orientation, as well as ion accumulation affect the capacitance. As electrode patterning affects differently water structure and ion accumulation, it might be possible to observe ion-specific effects. These results could be useful for advancing our understanding of electric double layer capacitors, capacitive desalination processes, as well as of fundamental interfacial electrolytes properties

Effect of oxidation of carbon material on suspension electrodes for flow electrode capacitive deionization.

Science.gov (United States)

Hatzell, Kelsey B; Hatzell, Marta C; Cook, Kevin M; Boota, Muhammad; Housel, Gabrielle M; McBride, Alexander; Kumbur, E Caglan; Gogotsi, Yury

2015-03-03

Flow electrode deionization (FCDI) is an emerging area for continuous and scalable deionization, but the electrochemical and flow properties of the flow electrode need to be improved to minimize energy consumption. Chemical oxidation of granular activated carbon (AC) was examined here to study the role of surface heteroatoms on rheology and electrochemical performance of a flow electrode (carbon slurry) for deionization processes. Moreover, it was demonstrated that higher mass densities could be used without increasing energy for pumping when using oxidized active material. High mass-loaded flow electrodes (28% carbon content) based on oxidized AC displayed similar viscosities (∼21 Pa s) to lower mass-loaded flow electrodes (20% carbon content) based on nonoxidized AC. The 40% increased mass loading (from 20% to 28%) resulted in a 25% increase in flow electrode gravimetric capacitance (from 65 to 83 F g(-1)) without sacrificing flowability (viscosity). The electrical energy required to remove ∼18% of the ions (desalt) from of the feed solution was observed to be significantly dependent on the mass loading and decreased (∼60%) from 92 ± 7 to 28 ± 2.7 J with increased mass densities from 5 to 23 wt %. It is shown that the surface chemistry of the active material in a flow electrode effects the electrical and pumping energy requirements of a FCDI system.

Electrode stabilizing materials

Science.gov (United States)

Amine, Khalil; Abouimrane, Ali; Moore, Jeffrey S.; Odom, Susan A.

2015-11-03

An electrolyte includes a polar aprotic solvent; an alkali metal salt; and an electrode stabilizing compound that is a monomer, which when polymerized forms an electrically conductive polymer. The electrode stabilizing compound is a thiophene, a imidazole, a anilines, a benzene, a azulene, a carbazole, or a thiol. Electrochemical devices may incorporate such electrolytes.

Cermet electrode

Science.gov (United States)

Maskalick, Nicholas J.

1988-08-30

Disclosed is a cermet electrode consisting of metal particles of nickel, cobalt, iron, or alloys or mixtures thereof immobilized by zirconia stabilized in cubic form which contains discrete deposits of about 0.1 to about 5% by weight of praseodymium, dysprosium, terbium, or a mixture thereof. The solid oxide electrode can be made by covering a substrate with particles of nickel, cobalt, iron, or mixtures thereof, growing a stabilized zirconia solid oxide skeleton around the particles thereby immobilizing them, contacting the skeleton with a compound of praseodymium, dysprosium, terbium, or a mixture thereof, and heating the skeleton to a temperature of at least 500.degree. C. The electrode can also be made by preparing a slurry of nickel, cobalt, iron, or mixture and a compound of praseodymium, dysprosium, terbium, or a mixture thereof, depositing the slurry on a substrate, heating the slurry to dryness, and growing a stabilized zirconia skeleton around the metal particles.

HVDC Ground Electrodes and Tectonic Setting

Science.gov (United States)

Freire, P. F.; Pereira, S. Y.

2017-12-01

Ground electrodes in HVDC transmission are huge grounding systems for the DC part of the converter substation, about 1 km wide, sized to inject in the ground DC currents up to 3.5 kA. This work presents an analysis of how the tectonic setting at converter substation location is determinant for the search of the best electrode location (Site Selection) and on its design and performance. It will briefly present the author experience on HVDC electrode design, summarized as follows: Itaipu - Foz do Iguaçu electrodes (transmitter side) located in the middle of Paraná Sedimentary Basin, and Ibiúna electrodes (receiving side) on the border of the basin, 6 km from the geological strike, where the crystalline basement outcrops in São Paulo state; Madeira River - North electrodes (transmitting side) located on the Northwest border of South Amazon Craton, where the crystalline basement is below a shallow sediments layer, and South electrodes (receiving side) located within Paraná Sedimentary Basin; Chile - electrodes located on the Andean forearc, where the Nazca Plate plunges under the South American Plate; Kenya - Ethiopia - electrodes located in the African Rift; Belo Monte - North electrodes (transmitter side) located within the Amazonian Sedimentary Basin, about 35 km of its South border, and South electrodes (receiving side) within Paraná Sedimentary Basin (bipole 1) and on crystalline metamorphic terrain "Brasília Belt" (bipole 2). This diversity of geological conditions results on ground electrodes of different topologies and dimensions, with quite different electrical and thermal performances. A brief study of the geology of the converter stations regions, the so-called Desktop Study, allows for the preview of several important parameters for the site selection and design of the electrodes, such as localization, type, size and estimate of the interference area, which are important predictors of the investment to be made and indications of the design to be

Conducting polymer coated neural recording electrodes

Science.gov (United States)

Harris, Alexander R.; Morgan, Simeon J.; Chen, Jun; Kapsa, Robert M. I.; Wallace, Gordon G.; Paolini, Antonio G.

2013-02-01

Objective. Neural recording electrodes suffer from poor signal to noise ratio, charge density, biostability and biocompatibility. This paper investigates the ability of conducting polymer coated electrodes to record acute neural response in a systematic manner, allowing in depth comparison of electrochemical and electrophysiological response. Approach. Polypyrrole (Ppy) and poly-3,4-ethylenedioxythiophene (PEDOT) doped with sulphate (SO4) or para-toluene sulfonate (pTS) were used to coat iridium neural recording electrodes. Detailed electrochemical and electrophysiological investigations were undertaken to compare the effect of these materials on acute in vivo recording. Main results. A range of charge density and impedance responses were seen with each respectively doped conducting polymer. All coatings produced greater charge density than uncoated electrodes, while PEDOT-pTS, PEDOT-SO4 and Ppy-SO4 possessed lower impedance values at 1 kHz than uncoated electrodes. Charge density increased with PEDOT-pTS thickness and impedance at 1 kHz was reduced with deposition times up to 45 s. Stable electrochemical response after acute implantation inferred biostability of PEDOT-pTS coated electrodes while other electrode materials had variable impedance and/or charge density after implantation indicative of a protein fouling layer forming on the electrode surface. Recording of neural response to white noise bursts after implantation of conducting polymer-coated electrodes into a rat model inferior colliculus showed a general decrease in background noise and increase in signal to noise ratio and spike count with reduced impedance at 1 kHz, regardless of the specific electrode coating, compared to uncoated electrodes. A 45 s PEDOT-pTS deposition time yielded the highest signal to noise ratio and spike count. Significance. A method for comparing recording electrode materials has been demonstrated with doped conducting polymers. PEDOT-pTS showed remarkable low fouling during

Tests of Micro-Pattern Gaseous Detectors for active target time projection chambers in nuclear physics

Energy Technology Data Exchange (ETDEWEB)

Pancin, J., E-mail: pancin@ganil.fr [GANIL, CEA/DSM-CNRS/IN2P3, Bvd H. Becquerel, Caen (France); Damoy, S.; Perez Loureiro, D. [GANIL, CEA/DSM-CNRS/IN2P3, Bvd H. Becquerel, Caen (France); Chambert, V.; Dorangeville, F. [IPNO, CNRS/IN2P3, Orsay (France); Druillole, F. [CEA, DSM/Irfu/SEDI, Gif-Sur-Yvette (France); Grinyer, G.F. [GANIL, CEA/DSM-CNRS/IN2P3, Bvd H. Becquerel, Caen (France); Lermitage, A.; Maroni, A.; Noël, G. [IPNO, CNRS/IN2P3, Orsay (France); Porte, C.; Roger, T. [GANIL, CEA/DSM-CNRS/IN2P3, Bvd H. Becquerel, Caen (France); Rosier, P. [IPNO, CNRS/IN2P3, Orsay (France); Suen, L. [GANIL, CEA/DSM-CNRS/IN2P3, Bvd H. Becquerel, Caen (France)

2014-01-21

Active target detection systems, where the gas used as the detection medium is also a target for nuclear reactions, have been used for a wide variety of nuclear physics applications since the eighties. Improvements in Micro-Pattern Gaseous Detectors (MPGDs) and in micro-electronics achieved in the last decade permit the development of a new generation of active targets with higher granularity pad planes that allow spatial and time information to be determined with unprecedented accuracy. A novel active target and time projection chamber (ACTAR TPC), that will be used to study reactions and decays of exotic nuclei at facilities such as SPIRAL2, is presently under development and will be based on MPGD technology. Several MPGDs (Micromegas and Thick GEM) coupled to a 2×2 mm{sup 2} pixelated pad plane have been tested and their performances have been determined with different gases over a wide range of pressures. Of particular interest for nuclear physics experiments are the angular and energy resolutions. The angular resolution has been determined to be better than 1° FWHM for short traces of about 4 cm in length and the energy resolution deduced from the particle range was found to be better than 5% for 5.5 MeV α particles. These performances have been compared to Geant4 simulations. These experimental results validate the use of these detectors for several applications in nuclear physics.

Tests of Micro-Pattern Gaseous Detectors for active target time projection chambers in nuclear physics

International Nuclear Information System (INIS)

Pancin, J.; Damoy, S.; Perez Loureiro, D.; Chambert, V.; Dorangeville, F.; Druillole, F.; Grinyer, G.F.; Lermitage, A.; Maroni, A.; Noël, G.; Porte, C.; Roger, T.; Rosier, P.; Suen, L.

2014-01-01

Active target detection systems, where the gas used as the detection medium is also a target for nuclear reactions, have been used for a wide variety of nuclear physics applications since the eighties. Improvements in Micro-Pattern Gaseous Detectors (MPGDs) and in micro-electronics achieved in the last decade permit the development of a new generation of active targets with higher granularity pad planes that allow spatial and time information to be determined with unprecedented accuracy. A novel active target and time projection chamber (ACTAR TPC), that will be used to study reactions and decays of exotic nuclei at facilities such as SPIRAL2, is presently under development and will be based on MPGD technology. Several MPGDs (Micromegas and Thick GEM) coupled to a 2×2 mm 2 pixelated pad plane have been tested and their performances have been determined with different gases over a wide range of pressures. Of particular interest for nuclear physics experiments are the angular and energy resolutions. The angular resolution has been determined to be better than 1° FWHM for short traces of about 4 cm in length and the energy resolution deduced from the particle range was found to be better than 5% for 5.5 MeV α particles. These performances have been compared to Geant4 simulations. These experimental results validate the use of these detectors for several applications in nuclear physics

Lithium-aluminum-iron electrode composition

Science.gov (United States)

Kaun, Thomas D.

1979-01-01

A negative electrode composition is presented for use in a secondary electrochemical cell. The cell also includes an electrolyte with lithium ions such as a molten salt of alkali metal halides or alkaline earth metal halides that can be used in high-temperature cells. The cell's positive electrode contains a a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent in an alloy of aluminum-iron. Various binary and ternary intermetallic phases of lithium, aluminum and iron are formed. The lithium within the intermetallic phase of Al.sub.5 Fe.sub.2 exhibits increased activity over that of lithium within a lithium-aluminum alloy to provide an increased cell potential of up to about 0.25 volt.

Stimulation and recording electrodes for neural prostheses

CERN Document Server

Pour Aryan, Naser; Rothermel, Albrecht

2015-01-01

This book provides readers with basic principles of the electrochemistry of the electrodes used in modern, implantable neural prostheses. The authors discuss the boundaries and conditions in which the electrodes continue to function properly for long time spans, which are required when designing neural stimulator devices for long-term in vivo applications. Two kinds of electrode materials, titanium nitride and iridium are discussed extensively, both qualitatively and quantitatively. The influence of the counter electrode on the safety margins and electrode lifetime in a two electrode system is explained. Electrode modeling is handled in a final chapter.

Depositing bulk or micro-scale electrodes

Science.gov (United States)

Shah, Kedar G.; Pannu, Satinderpall S.; Tolosa, Vanessa; Tooker, Angela C.; Sheth, Heeral J.; Felix, Sarah H.; Delima, Terri L.

2016-11-01

Thicker electrodes are provided on microelectronic device using thermo-compression bonding. A thin-film electrical conducting layer forms electrical conduits and bulk depositing provides an electrode layer on the thin-film electrical conducting layer. An insulating polymer layer encapsulates the electrically thin-film electrical conducting layer and the electrode layer. Some of the insulating layer is removed to expose the electrode layer.

Nickel hydrogen bipolar battery electrode design

Science.gov (United States)

Puglisi, V. J.; Russell, P.; Verrier, D.; Hall, A.

1985-01-01

The preferred approach of the NASA development effort in nickel hydrogen battery design utilizes a bipolar plate stacking arrangement to obtain the required voltage-capacity configuration. In a bipolar stack, component designs must take into account not only the typical design considerations such as voltage, capacity and gas management, but also conductivity to the bipolar (i.e., intercell) plate. The nickel and hydrogen electrode development specifically relevant to bipolar cell operation is discussed. Nickel oxide electrodes, having variable type grids and in thicknesses up to .085 inch are being fabricated and characterized to provide a data base. A selection will be made based upon a system level tradeoff. Negative (hydrpogen) electrodes are being screened to select a high performance electrode which can function as a bipolar electrode. Present nickel hydrogen negative electrodes are not capable of conducting current through their cross-section. An electrode was tested which exhibits low charge and discharge polarization voltages and at the same time is conductive. Test data is presented.

Method of making a multi-electrode double layer capacitor having single electrolyte seal and aluminum-impregnated carbon cloth electrodes

Science.gov (United States)

Farahmandi, C. Joseph; Dispennette, John M.; Blank, Edward; Kolb, Alan C.

2002-09-17

A single cell, multi-electrode high performance double layer capacitor includes first and second flat stacks of electrodes adapted to be housed in a closeable two-part capacitor case which includes only a single electrolyte seal. Each electrode stack has a plurality of electrodes connected in parallel, with the electrodes of one stack being interleaved with the electrodes of the other stack to form an interleaved stack, and with the electrodes of each stack being electrically connected to respective capacitor terminals. A porous separator is positioned against the electrodes of one stack before interleaving to prevent electrical shorts between the electrodes. The electrodes are made by folding a compressible, low resistance, aluminum-impregnated carbon cloth, made from activated carbon fibers, around a current collector foil, with a tab of the foils of each electrode of each stack being connected in parallel and connected to the respective capacitor terminal. The height of the interleaved stack is somewhat greater than the inside height of the closed capacitor case, thereby requiring compression of the interleaved electrode stack when placed inside of the case, and thereby maintaining the interleaved electrode stack under modest constant pressure. The closed capacitor case is filled with an electrolytic solution and sealed. A preferred electrolytic solution is made by dissolving an appropriate salt into acetonitrile (CH.sub.3 CN). In one embodiment, the two parts of the capacitor case are conductive and function as the capacitor terminals.

Coated carbon nanotube array electrodes

Science.gov (United States)

Ren, Zhifeng [Newton, MA; Wen, Jian [Newton, MA; Chen, Jinghua [Chestnut Hill, MA; Huang, Zhongping [Belmont, MA; Wang, Dezhi [Wellesley, MA

2008-10-28

The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

Ozone production by an atmospheric pulsed discharge with pre-ionization electrodes and partly covered electrode

International Nuclear Information System (INIS)

Kaneda, S.; Shimosaki, M.; Hayashi, N.; Ihara, S.; Satoh, S.; Yamabe, C.

2002-01-01

In this paper, results on ozone production by atmospheric pulsed discharge, are reported. In the research, two types of ozonizer (Type I and Type II) have been used to investigate improvements of ozone concentration and production efficiency. The ozonizer has plane-to-plane metal electrodes structure, and pre-ionization electrodes are placed on the high voltage electrodes (Type I). In Type II, the surface of grounded electrode with 20 mm of width is covered partly by dielectric (thin rubber) with 11 mm of width, while the geometry of both metal electrodes is same to Type I. In the case of Type I, maximum concentration of about 100 ppm and maximum yield of 70 g/kWh were obtained at input power of 0.3 W. On the other hands, in the case of Type II, 800 ppm and 100 g/kWh were obtained at input power of 1.5 W. It was found that the ozone concentration and production yield were improved by using electrode covered by dielectric. (author)

Electrode for a lithium cell

Science.gov (United States)

Thackeray, Michael M [Naperville, IL; Vaughey, John T [Elmhurst, IL; Dees, Dennis W [Downers Grove, IL

2008-10-14

This invention relates to a positive electrode for an electrochemical cell or battery, and to an electrochemical cell or battery; the invention relates more specifically to a positive electrode for a non-aqueous lithium cell or battery when the electrode is used therein. The positive electrode includes a composite metal oxide containing AgV.sub.3O.sub.8 as one component and one or more other components consisting of LiV.sub.3O.sub.8, Ag.sub.2V.sub.4O.sub.11, MnO.sub.2, CF.sub.x, AgF or Ag.sub.2O to increase the energy density of the cell, optionally in the presence of silver powder and/or silver foil to assist in current collection at the electrode and to improve the power capability of the cell or battery.

Electrochemical cell and negative electrode therefor

Science.gov (United States)

Kaun, Thomas D.

1982-01-01

A secondary electrochemical cell with the positive and negative electrodes separated by a molten salt electrolyte with the negative electrode comprising a particulate mixture of lithium-aluminum alloy and electrolyte and an additive selected from graphitized carbon, Raney iron or mixtures thereof. The lithium-aluminum alloy is present in the range of from about 45 to about 80 percent by volume of the negative electrode, and the electrolyte is present in an amount not less than about 10 percent by volume of the negative electrode. The additive of graphitized carbon is present in the range of from about 1 to about 10 percent by volume of the negative electrode, and the Raney iron additive is present in the range of from about 3 to about 10 percent by volume of the negative electrode.

Creating virtual electrodes with 2D current steering

Science.gov (United States)

Spencer, Thomas C.; Fallon, James B.; Shivdasani, Mohit N.

2018-06-01

Objective. Current steering techniques have shown promise in retinal prostheses as a way to increase the number of distinct percepts elicitable without increasing the number of implanted electrodes. Previously, it has been shown that ‘virtual’ electrodes can be created between simultaneously stimulated electrode pairs, producing unique cortical response patterns. This study investigated whether virtual electrodes could be created using 2D current steering, and whether these virtual electrodes can produce cortical responses with predictable spatial characteristics. Approach. Normally-sighted eyes of seven adult anaesthetised cats were implanted with a 42-channel electrode array in the suprachoroidal space and multi-unit neural activity was recorded from the visual cortex. Stimuli were delivered to individual physical electrodes, or electrodes grouped into triangular, rectangular, and hexagonal arrangements. Varying proportions of charge were applied to each electrode in a group to ‘steer’ current and create virtual electrodes. The centroids of cortical responses to stimulation of virtual electrodes were compared to those evoked by stimulation of single physical electrodes. Main results. Responses to stimulation of groups of up to six electrodes with equal ratios of charge on each electrode resulted in cortical activation patterns that were similar to those elicited by the central physical electrode (centroids: RM ANOVA on ranks, p  >  0.05 neural spread: one-way ANOVA on Ranks, p  >  0.05). We were also able to steer the centroid of activation towards the direction of any of the electrodes of the group by applying a greater charge to that electrode, but the movement in the centroid was not found to be significant. Significance. The results suggest that current steering is possible in two dimensions between up to at least six electrodes, indicating it may be possible to increase the number of percepts in patients without increasing the number

Direct Observation of Virtual Electrode Formation Through a Novel Electrolyte-to-Electrode Transition

Science.gov (United States)

Siegel, David; El Gabaly, Farid; Bartelt, Norman; McCarty, Kevin

2014-03-01

Novel electrochemical solutions to problems in energy storage and transportation can drive renewable energy to become an economically viable alternative to fossil fuels. In many electrochemical systems, the behavior of a device can be fundamentally limited by the surface area of a triple phase boundary, the boundary region where a gas-phase species, electrode, and electrolyte coincide. When the electrode is an ionic insulator the triple phase boundary is typically a one-dimensional boundary with nanometer-scale thickness: ions cannot transport through the electrode, while electrons cannot be transported through the electrolyte. Here we present direct experimental measurements of a novel electrolyte-to-electrode transition with photoemission electron microscopy, and observe that the surface of an ionically conductive, electronically insulative solid oxide electrolyte undergoes a transition into a mixed electron-ion conductor in the vicinity of a metal electrode. Our direct experimental measurements allow us to characterize this system and address the mechanisms of ionic reactions and transport through comparisons with theoretical modeling to provide us with a physical picture of the processes involved. Our results provide insight into one of the mechanisms of ion transport in an electrochemical cell that may be generalizable to other systems.

Laser printing of nanoparticle toner enables digital control of micropatterned carbon nanotube growth.

Science.gov (United States)

Polsen, Erik S; Stevens, Adam G; Hart, A John

2013-05-01

Commercialization of materials utilizing patterned carbon nanotube (CNT) forests, such as hierarchical composite structures, dry adhesives, and contact probe arrays, will require catalyst patterning techniques that do not rely on cleanroom photolithography. We demonstrate the large scale patterning of CNT growth catalyst via adaptation of a laser-based electrostatic printing process that uses magnetic ink character recognition (MICR) toner. The MICR toner contains iron oxide nanoparticles that serve as the catalyst for CNT growth, which are printed onto a flexible polymer (polyimide) and then transferred to a rigid substrate (silicon or alumina) under heat and mechanical pressure. Then, the substrate is processed for CNT growth under an atmospheric pressure chemical vapor deposition (CVD) recipe. This process enables digital control of patterned CNT growth via the laser intensity, which controls the CNT density; and via the grayscale level, which controls the pixelation of the image into arrays of micropillars. Moreover, virtually any pattern can be designed using standard software (e.g., MS Word, AutoCAD, etc.) and printed on demand. Using a standard office printer, we realize isolated CNT microstructures as small as 140 μm and isolated catalyst ″pixels″ as small as 70 μm (one grayscale dot) and determine that individual toner microparticles result in features of approximately 5-10 μm . We demonstrate that grayscale CNT patterns can function as dry adhesives and that large-area catalyst patterns can be printed directly onto metal foils or transferred to ceramic plates. Laser printing therefore shows promise to enable high-speed micropatterning of nanoparticle-containing thin films under ambient conditions, possibly for a wide variety of nanostructures by engineering of toners containing nanoparticles of desired composition, size, and shape.

Electrode Processes in Porous Electrodes.

Science.gov (United States)

1985-11-26

F104470 2.0 MASS SPECTROMETRY One part of activity for this year is an investigation of the behavior of silver electrodes through the distribution of...al. (2)). These, in some cases, involve tedious and time comsuming procedures and discrepencies of as much as 15% have been observed in the results. As

Field testing of sulphide electrodes

International Nuclear Information System (INIS)

Singh, P.R.; Gaonkar, K.B.; Gadiyar, H.S.

1993-01-01

Sulphide ion selective electrodes have been developed at BARC, for determination of Ag + and S - ions directly and Cl - and CN - ions indirectly. The electrodes were tested for their use in sulphide environments in the EAD (Effluent After Dilution) stream at the Heavy Water Plant, Kota. The electrodes are suitable in the concentration range of 16000 ppm to 0.002 ppm, with a slope of 29-31 mV per decade change in the sulphide ion concentration. The response time is less than 10 seconds. These electrodes are reliable for continuous on-line use for a long period. (author). 7 refs., 11 figs., 1 tab

Surface-modified electrodes (SME)

NARCIS (Netherlands)

Schreurs, J.P.G.M.; Barendrecht, E.

1984-01-01

This review deals with the literature (covered up to August 1983), the characterization and the applications of Surface-Modified Electrodes (SME). As a special class of SME's, the Enzyme-Modified Electrode (EME) is introduced. Three types of modification procedures are distinguished; i.e. covalent

Bifunctional electrodes for unitised regenerative fuel cells

International Nuclear Information System (INIS)

Altmann, Sebastian; Kaz, Till; Friedrich, Kaspar Andreas

2011-01-01

Research highlights: → Different oxygen electrode configurations for the operation in a unitised reversible fuel cell were tested. → Polarisation curves and EIS measurements were recorded. → The mixture of catalysts performs best for the present stage of electrode development. → Potential improvements for the different compositions are discussed. - Abstract: The effects of different configurations and compositions of platinum and iridium oxide electrodes for the oxygen reaction of unitised regenerative fuel cells (URFC) are reported. Bifunctional oxygen electrodes are important for URFC development because favourable properties for the fuel cell and the electrolysis modes must be combined into a single electrode. The bifunctional electrodes were studied under different combinations of catalyst mixtures, multilayer arrangements and segmented configurations with single catalyst areas. Distinct electrochemical behaviour was observed for both modes and can be explained on the basis of impedance spectroscopy. The mixture of both catalysts performs best for the present stage of electrode development. Also, the multilayer electrodes yielded good results with the potential for optimisation. The influence of ionic and electronic resistances on the relative performance is demonstrated. However, penalties due to cross currents in the heterogeneous electrodes were identified and explained by comparing the performance curves with electrodes composed of a single catalyst. Potential improvements for the different compositions are discussed.

Improvement in Electrode Performance of Novel SWCNT Loaded Three-Dimensional Porous RVC Composite Electrodes by Electrochemical Deposition Method

Science.gov (United States)

Almoigli, Mohammed; Meriey, Al Yahya; Alharbi, Khalid N.

2018-01-01

The three-dimensional (3D) composite electrodes were prepared by depositing different amounts of acid-functionalized single-walled carbon nanotubes (a-SWCNTs) on porous reticulated vitreous carbon (RVC) through the electrochemical deposition method. The SWCNT was functionalized by the reflux method in nitric acid and was proven by Raman and visible spectra. The optimum time for sonication to disperse the functionalized SWCNT (a-SWCNT) in dimethyl formamide (DMF) well was determined by UV spectra. The average pore size of RVC electrodes was calculated from scanning electron microscopy (SEM) images. Moreover, the surface morphology of composite electrodes was also examined by SEM study. All 3D electrodes were evaluated for their electrochemical properties by cyclic voltammetry. The result showed that the value of specific capacitance of the electrode increases with the increase in the amount of a-SWCNT in geometric volume. However, the value of specific capacitance per gram decreases with the increase in scan rate as well as the amount of a-SWCNT. The stability of the electrodes was also tested. This revealed that all the electrodes were stable; however, lower a-SWCNT-loaded electrodes had excellent cyclic stability. These results suggest that the a-SWCNT-coated RVC electrodes have promise as an effective technology for desalination. PMID:29301258

Ultrahigh PEMFC performance of a thin-film, dual-electrode assembly with tailored electrode morphology.

Science.gov (United States)

Jung, Chi-Young; Kim, Tae-Hyun; Yi, Sung-Chul

2014-02-01

A dual-electrode membrane electrode assembly (MEA) for proton exchange membrane fuel cells with enhanced polarization under zero relative humidity (RH) is fabricated by introducing a phase-separated morphology in an agglomerated catalyst layer of Pt/C (platinum on carbon black) and Nafion. In the catalyst layer, a sufficient level of phase separation is achieved by dispersing the Pt catalyst and the Nafion dispersion in a mixed-solvent system (propane-1,2,3-triol/1-methyl-2-pyrrolidinone).The high polymer chain mobility results in improved water uptake and regular pore-size distribution with small pore diameters. The electrochemical performance of the dual-film electrode assembly with different levels of phase separation is compared to conventional electrode assemblies. As a result, good performance at 0 % RH is obtained because self-humidification is dramatically improved by attaching this dense and phase-separated catalytic overlayer onto the conventional catalyst layer. A MEA prepared using the thin-film, dual-layered electrode exhibits 39-fold increased RH stability and 28-fold improved start-up recovery time during the on-off operation relative to the conventional device. We demonstrate the successful operation of the dual-layered electrode comprised of discriminatively phase-separated agglomerates with an ultrahigh zero RH fuel-cell performance reaching over 95 % performance of a fully humidified MEA. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Light-addressable amperometric electrodes for enzyme sensors based on direct quantum dot-electrode contacts

Science.gov (United States)

Riedel, M.; Göbel, G.; Parak, W. J.; Lisdat, F.

2014-03-01

Quantum dots allow the generation of charge carriers upon illumination. When these particles are attached to an electrode a photocurrent can be generated. This allows their use as a light-switchable layer on the surface. The QDs can not only exchange electronics with the electrode, but can also interact with donor or acceptor compounds in solution providing access to the construction of signal chains starting from an analytic molecule. The magnitude and the direction of the photocurrent depend on several factors such as electrode polarization, solution pH and composition. These defined dependencies have been evaluated with respect to the combination of QD-electrodes with enzyme reactions for sensorial purpose. CdSe/ZnS-QD-modified electrodes can be used to follow enzymatic reactions in solution based on the oxygen sensitivity. In order to develop a photoelectrochemical biosensor, e.g. glucose oxidase is immobilized on the CdSe/ZnS-electrode. One immobilization strategy applies the layer-by-layer-technique of GOD and a polyelectrolyte. Photocurrent measurements of such a sensor show a clear concentration dependent behavior. The principle of combing QD oxidase. The sensitivity of quantum dot electrodes can be influenced by additional nanoparticles, but also by multiple layers of the QDs. In another direction of research it can be influenced by additional nanoparticles, but also by multiple layers of the QDs. In another direction of research it can be demonstrated that direct electron transfer from excited quantum dots can be achieved with the redox protein cytochrome c. This allows the detection of the protein, but also interaction partners such as a enzymes or superoxide.

Nanofiber membrane-electrode-assembly and method of fabricating same

Energy Technology Data Exchange (ETDEWEB)

Pintauro, Peter N.; Ballengee, Jason; Brodt, Matthew

2018-01-23

In one aspect of the present invention, a method of fabricating a fuel cell membrane-electrode-assembly (MEA) having an anode electrode, a cathode electrode, and a membrane disposed between the anode electrode and the cathode electrode, includes fabricating each of the anode electrode, the cathode electrode, and the membrane separately by electrospinning; and placing the membrane between the anode electrode and the cathode electrode, and pressing then together to form the fuel cell MEA.

3D periodic multiscale TiO_2 architecture: a platform decorated with graphene quantum dots for enhanced photoelectrochemical water splitting

International Nuclear Information System (INIS)

Xu, Zhen; Yin, Min; Lu, Linfeng; Chen, Xiaoyuan; Li, Dongdong; Sun, Jing; Ding, Guqiao; Chang, Paichun

2016-01-01

Micropatterned TiO_2 nanorods (TiO_2NRs) via three-dimensional (3D) geometry engineering in both microscale and nanoscale decorated with graphene quantum dots (GQDs) have been demonstrated successfully. First, micropillar (MP) and microcave (MC) arrays of anatase TiO_2 films are obtained through the sol–gel based thermal nanoimprinting method. Then they are employed as seed layers in hydrothermal growth to fabricate the 3D micropillar/microcave arrays of rutile TiO_2NRs (NR), which show much-improved photoelectrochemical water-splitting performance than the TiO_2NRs grown on flat seed layer. The zero-dimensional GQDs are sequentially deposited onto the surfaces of the microscale patterned nanorods. Owing to the fast charge separation that resulted from the favorable band alignment of the GQDs and rutile TiO_2, the MP-NR-GQDs electrode achieves a photocurrent density up to 2.92 mA cm"−"2 under simulated one-sun illumination. The incident-photon-to-current-conversion efficiency (IPCE) value up to 72% at 370 nm was achieved on the MP-NR-GQDs electrode, which outperforms the flat-NR counterpart by 69%. The IPCE results also imply that the improved photocurrent mainly benefits from the distinctly enhanced ultraviolet response. The work provides a cost-effective and flexible pathway to develop periodic 3D micropatterned photoelectrodes and is promising for the future deployment of high performance optoelectronic devices. (paper)

Lithium battery electrodes with ultra-thin alumina coatings

Science.gov (United States)

Se-Hee, Lee; George, Steven M.; Cavanagh, Andrew S.; Yoon Seok, Jung; Dillon, Anne C.

2015-11-24

Electrodes for lithium batteries are coated via an atomic layer deposition process. The coatings can be applied to the assembled electrodes, or in some cases to particles of electrode material prior to assembling the particles into an electrode. The coatings can be as thin as 2 .ANG.ngstroms thick. The coating provides for a stable electrode. Batteries containing the electrodes tend to exhibit high cycling capacities.

Graphene electrodes for stimulation of neuronal cells

International Nuclear Information System (INIS)

Koerbitzer, Berit; Nick, Christoph; Thielemann, Christiane; Krauss, Peter; Yadav, Sandeep; Schneider, Joerg J

2016-01-01

Graphene has the ability to improve the electrical interface between neuronal cells and electrodes used for recording and stimulation purposes. It provides a biocompatible coating for common electrode materials such as gold and improves the electrode properties. Graphene electrodes are also prepared on SiO 2 substrate to benefit from its optical properties like transparency. We perform electrochemical and Raman characterization of gold electrodes with graphene coating and compare them with graphene on SiO 2 substrate. It was found that the substrate plays an important role in the performance of graphene and show that graphene on SiO 2 substrate is a very promising material combination for stimulation electrodes. (paper)

In-electrode vs. on-electrode: ultrasensitive Faraday cage-type electrochemiluminescence immunoassay.

Science.gov (United States)

Guo, Zhiyong; Sha, Yuhong; Hu, Yufang; Wang, Sui

2016-03-28

A new-concept of an "in-electrode" Faraday cage-type electrochemiluminescence immunoassay (ECLIA) method for the ultrasensitive detection of neurotensin (NT) was reported with capture antibody (Ab1)-nanoFe3O4@graphene (GO) and detector antibody (Ab2)&N-(4-aminobutyl)-N-ethylisoluminol (ABEI)@GO, which led to about 1000-fold improvement in sensitivity by extending the Helmholtz plane (OHP) of the proposed electrode assembly effectively.

Electrode systems for in situ vitrification

Science.gov (United States)

Buelt, James L.; Carter, John G.; Eschbach, Eugene A.; FitzPatrick, Vincent F.; Koehmstedt, Paul L.; Morgan, William C.; Oma, Kenton H.; Timmerman, Craig L.

1990-01-01

An electrode comprising a molybdenum rod is received within a conductive collar formed of graphite. The molybdenum rod and the graphite collar may be physically joined at the bottom. A pair of such electrodes are placed in soil containing buried waste material and an electric current is passed therebetween for vitrifying the soil. The graphite collar enhances the thermal conductivity of the combination, bringing heat to the surface, and preventing formation of a cold cap of material above the ground surface. The annulus between the molybdenum rod electrode and the graphite collar is suitably filled with a conductive ceramic powder that sinters upon the molybdenum rod, protecting the same from oxidation as graphite material is consumed, or a metal powder which liquefies at operating temperatures. The center of the molybdenum rod, used with a collar of separately, can be hollow and filled with a powdered metal, such as copper, which liquefies at operating temperatures. Connection to electrodes can be provided below ground level to avoid open circuit due to electrode deterioration, or sacrificial electrodes may be employed when operation is started. Outboard electrodes cna be utilized to square up a vitrified area.

Recovery of fluoride ion selective electrode

International Nuclear Information System (INIS)

Monteiro, R.P.G.

1988-01-01

A recovery procedure of fluoride ion selective electrode based upon the body radiography of inactive electrode and introduction of suitable internal regeneration solution, is developed. The recovered electrode was tested in standard solutions of fluoride ions (10 sup5) to 10 -1M showing as good performance as the new one. The fluor determination by potentiometric measurements with selective electrode is used in nuclear fuel cycle for quality control of thorium and uranium mixed oxide pellets and pellets of uranium dioxides. (author) [pt

Electrode for disintegrating metallic material

International Nuclear Information System (INIS)

Persang, J.C.

1985-01-01

A graphite electrode is provided for disintegrating and removing metallic material from a workpiece, e.g., such as portions of a nuclear reactor to be repaired while in an underwater and/or radioactive environment. The electrode is provided with a plurality of openings extending outwardly, and a manifold for supplying a mixture of water and compressed gas to be discharged through the openings for sweeping away the disintegrated metallic material during use of the electrode

Assessing the Electrode-Neuron Interface with the Electrically Evoked Compound Action Potential, Electrode Position, and Behavioral Thresholds.

Science.gov (United States)

DeVries, Lindsay; Scheperle, Rachel; Bierer, Julie Arenberg

2016-06-01

Variability in speech perception scores among cochlear implant listeners may largely reflect the variable efficacy of implant electrodes to convey stimulus information to the auditory nerve. In the present study, three metrics were applied to assess the quality of the electrode-neuron interface of individual cochlear implant channels: the electrically evoked compound action potential (ECAP), the estimation of electrode position using computerized tomography (CT), and behavioral thresholds using focused stimulation. The primary motivation of this approach is to evaluate the ECAP as a site-specific measure of the electrode-neuron interface in the context of two peripheral factors that likely contribute to degraded perception: large electrode-to-modiolus distance and reduced neural density. Ten unilaterally implanted adults with Advanced Bionics HiRes90k devices participated. ECAPs were elicited with monopolar stimulation within a forward-masking paradigm to construct channel interaction functions (CIF), behavioral thresholds were obtained with quadrupolar (sQP) stimulation, and data from imaging provided estimates of electrode-to-modiolus distance and scalar location (scala tympani (ST), intermediate, or scala vestibuli (SV)) for each electrode. The width of the ECAP CIF was positively correlated with electrode-to-modiolus distance; both of these measures were also influenced by scalar position. The ECAP peak amplitude was negatively correlated with behavioral thresholds. Moreover, subjects with low behavioral thresholds and large ECAP amplitudes, averaged across electrodes, tended to have higher speech perception scores. These results suggest a potential clinical role for the ECAP in the objective assessment of individual cochlear implant channels, with the potential to improve speech perception outcomes.

Electrochemical Oxidation of Glycerol Using Gold Electrode

International Nuclear Information System (INIS)

Mohamed Rozali Othman; Amirah Ahmad

2015-01-01

Cyclic voltammetry, potential linear V and chronocuolometry methods were carried out to gain electrochemical behavior of glycerol at a gold electrode. Potassium hydroxide and sulfuric acid were chosen to be the electrolyte for the electro-oxidation of this organic compound. Besides gold plate electrode, gold composite electrode (Au-PVC) was also used as the working electrode. The Au-PVC composite electrode was characterized by Scanning Electron Microscopy (SEM) to determine its morphological aspects before and after used in electrochemical oxidation of glycerol. In alkaline solution, the adsorption of hydroxide species onto the surface of both gold plate and composite Au-PVC electrodes occurs at potential around 500 mV vs SCE. However, at gold plate electrode, there was a small, broad peak before the drastic escalation of current densities which indicates the charge transfer of the chemisorbed OH - anion. In acidic media, the gold oxide was formed after potential 1.0 V. From the cyclic voltammogram glycerol undergo oxidation twice in potassium hydroxide at gold plate and Au-PVC composite electrodes, while in sulfuric acid, oxidation reaction happened once for glycerol on the gold plate electrode. Overall, electrochemical oxidation of glycerol was more effective in alkaline media. Tafel graph which plotted from potential linear V method shows that Au-PVC composite electrode is better than gold plate electrode for the electro-oxidation of glycerol in alkaline solution. Electrochemical oxidation of glycerol products as analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) produced several carboxylic acids and phenolic compounds. (author)

Doped graphene electrodes for organic solar cells

International Nuclear Information System (INIS)

Park, Hyesung; Kim, Ki Kang; Bulovic, Vladimir; Kong, Jing; Rowehl, Jill A

2010-01-01

In this work graphene sheets grown by chemical vapor deposition (CVD) with controlled numbers of layers were used as transparent electrodes in organic photovoltaic (OPV) devices. It was found that for devices with pristine graphene electrodes, the power conversion efficiency (PCE) is comparable to their counterparts with indium tin oxide (ITO) electrodes. Nevertheless, the chances for failure in OPVs with pristine graphene electrodes are higher than for those with ITO electrodes, due to the surface wetting challenge between the hole-transporting layer and the graphene electrodes. Various alternative routes were investigated and it was found that AuCl 3 doping on graphene can alter the graphene surface wetting properties such that a uniform coating of the hole-transporting layer can be achieved and device success rate can be increased. Furthermore, the doping both improves the conductivity and shifts the work function of the graphene electrode, resulting in improved overall PCE performance of the OPV devices. This work brings us one step further toward the future use of graphene transparent electrodes as a replacement for ITO.

Fluctuations at electrode-YSZ interfaces

DEFF Research Database (Denmark)

Jacobsen, Torben; Hansen, Karin Vels; Skou, Eivind

2005-01-01

Current fluctuations at potentiostatically controlled point electrodes of Pt, La$_{0.85}$Sr$_{0.15}$MnO$_3$ and Ni on YSZ surfaces are determined at 1000$^\\circ$C. For the oxygen reduction process on Pt electrodes characteristic sawtooth shaped low frequency fluctuations are observed. At temperat......Current fluctuations at potentiostatically controlled point electrodes of Pt, La$_{0.85}$Sr$_{0.15}$MnO$_3$ and Ni on YSZ surfaces are determined at 1000$^\\circ$C. For the oxygen reduction process on Pt electrodes characteristic sawtooth shaped low frequency fluctuations are observed....../water atmosphere are presented for discussion. The origin of the observations is not known at present but it appears likely that they are related to the activation/deactivation mechanism of SOFCs....

Polyaniline-deposited porous carbon electrode for supercapacitor

International Nuclear Information System (INIS)

Chen, W.-C.; Wen, T.-C.; Teng, H.

2003-01-01

Electrodes for supercapacitors were fabricated by depositing polyaniline (PANI) on high surface area carbons. The chemical composition of the PANI-deposited carbon electrode was determined by X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical properties of electrodes. An equivalent circuit was proposed to successfully fit the EIS data, and the significant contribution of pseudocapacitance from PANI was thus identified. A comparative analysis on the electrochemical properties of bare-carbon electrodes was also conducted under similar conditions. The performance of the capacitors equipped with the resulting electrodes in 1 M H 2 SO 4 was evaluated by constant current charge-discharge cycling within a potential range from 0 to 0.6 V. The PANI-deposited electrode exhibits high specific capacitance of 180 F/g, in comparison with a value of 92 F/g for the bare-carbon electrode

Study of electrochemical behavior of desatinib using hanging mercury drop electrode and gold disc electrode

Czech Academy of Sciences Publication Activity Database

Nováková, Kateřina; Navrátil, Tomáš; Jaklová Dytrtová, Jana; Jakl, M.

2015-01-01

Roč. 11, č. 1 (2015), s. 116-116 ISSN 1336-7242 Institutional support: RVO:61388955 ; RVO:61388963 Keywords : electrochemistry * hanging mercury drop electrode * gold electrode Subject RIV: CG - Electrochemistry

Silver manganese oxide electrodes for lithium batteries

Science.gov (United States)

Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

2006-05-09

This invention relates to electrodes for non-aqueous lithium cells and batteries with silver manganese oxide positive electrodes, denoted AgxMnOy, in which x and y are such that the manganese ions in the charged or partially charged electrodes cells have an average oxidation state greater than 3.5. The silver manganese oxide electrodes optionally contain silver powder and/or silver foil to assist in current collection at the electrodes and to improve the power capability of the cells or batteries. The invention relates also to a method for preparing AgxMnOy electrodes by decomposition of a permanganate salt, such as AgMnO4, or by the decomposition of KMnO4 or LiMnO4 in the presence of a silver salt.

Analysis of polypyrrole-coated stainless steel electrodes

Indian Academy of Sciences (India)

Analysis of polypyrrole-coated stainless steel electrodes - Estimation of specific ... is carried out on stainless steel electrodes using -toluene sulphonic acid. ... The feasibility of the electrode for supercapacitor applications is investigated.

Accuracy of Plantar Electrodes Compared with Hand and Foot Electrodes in Fat-free-mass Measurement

Directory of Open Access Journals (Sweden)

Michel Y. Jaffrin

2014-01-01

Full Text Available This paper investigates the measurement of fat-free mass (FFM by bioimpedance using foot-to-foot impedancemeters (FFI with plantar electrodes measuring the foot-to-foot resistance R34 and hand-to-foot medical impedancemeters. FFM measurements were compared with corresponding data using Dual X-ray absorptiometry (DXA. Equations giving FFM were established using linear multiple regression on DXA data in a first group of 170 subjects. For validation, these equations were used on a second group of 86 subjects, and FFM were compared with DXA data; no significant difference was observed. The same protocol was repeated, but using electrodes on the right hand and foot in standing position to measure the hand to-foot resistance R13. Mean differences with DXA were higher for R13 than for R34. Effect of electrode size and feet position on resistance was also investigated. R34 decreased when electrode area increased or if feet were moved forward. It decreased if feet were moved backward. A proper configuration of contact electrodes can improve measurement accuracy and reproducibility of FFI.

Nanofabrication strategies for advanced electrode materials

Directory of Open Access Journals (Sweden)

Chen Kunfeng

2017-09-01

Full Text Available The development of advanced electrode materials for high-performance energy storage devices becomes more and more important for growing demand of portable electronics and electrical vehicles. To speed up this process, rapid screening of exceptional materials among various morphologies, structures and sizes of materials is urgently needed. Benefitting from the advance of nanotechnology, tremendous efforts have been devoted to the development of various nanofabrication strategies for advanced electrode materials. This review focuses on the analysis of novel nanofabrication strategies and progress in the field of fast screening advanced electrode materials. The basic design principles for chemical reaction, crystallization, electrochemical reaction to control the composition and nanostructure of final electrodes are reviewed. Novel fast nanofabrication strategies, such as burning, electrochemical exfoliation, and their basic principles are also summarized. More importantly, colloid system served as one up-front design can skip over the materials synthesis, accelerating the screening rate of highperformance electrode. This work encourages us to create innovative design ideas for rapid screening high-active electrode materials for applications in energy-related fields and beyond.

Protected electrodes for plasma panels

International Nuclear Information System (INIS)

Hall, S.W.

1984-01-01

A metal oxide coating is applied between the conductive base and the magnesium oxide dielectric of the input and/or erase electrode(s) in a plasma display device to prevent break-down of the dielectric

Storage-battery electrodes. [preparation

Energy Technology Data Exchange (ETDEWEB)

1961-12-29

Two incompatible thermoplastic resins are mixed with a powdered electrochemical active substance. The substance may be, for example, an oxide of cadmium, iron, lead, or zinc or nickel hydroxide. After the mixture is shaped into elements which are inserted into conducting sheaths for an electrode, the one resin is washed out to form a porous electrode. (RWR)

Printed optically transparent graphene cellulose electrodes

Science.gov (United States)

Sinar, Dogan; Knopf, George K.; Nikumb, Suwas; Andrushchenko, Anatoly

2016-02-01

Optically transparent electrodes are a key component in variety of products including bioelectronics, touch screens, flexible displays, low emissivity windows, and photovoltaic cells. Although highly conductive indium tin oxide (ITO) films are often used in these electrode applications, the raw material is very expensive and the electrodes often fracture when mechanically stressed. An alternative low-cost material for inkjet printing transparent electrodes on glass and flexible polymer substrates is described in this paper. The water based ink is created by using a hydrophilic cellulose derivative, carboxymethyl cellulose (CMC), to help suspend the naturally hydrophobic graphene (G) sheets in a solvent composed of 70% DI water and 30% 2-butoxyethanol. The CMC chain has hydrophobic and hydrophilic functional sites which allow adsorption on G sheets and, therefore, permit the graphene to be stabilized in water by electrostatic and steric forces. Once deposited on the functionalized substrate the electrical conductivity of the printed films can be "tuned" by decomposing the cellulose stabilizer using thermal reduction. The entire electrode can be thermally reduced in an oven or portions of the electrode thermally modified using a laser annealing process. The thermal process can reduce the sheet resistance of G-CMC films to < 100 Ω/sq. Experimental studies show that the optical transmittance and sheet resistance of the G-CMC conductive electrode is a dependent on the film thickness (ie. superimposed printed layers). The printed electrodes have also been doped with AuCl3 to increase electrical conductivity without significantly increasing film thickness and, thereby, maintain high optical transparency.

[Verification of skin paste electrodes used in wireless polysomnography].

Science.gov (United States)

Ma, Y D; Huang, D; Chen, Y F; Jiang, H Y; Liu, J H; Sun, H Q; Li, Z H

2018-04-18

To explore an electrode suitable for wireless portable sleep monitoring equipment and analyze the result of the signals of electrooculogram (EOG) and electroencephalography (EEG) collected by this kind of flexible electrodes. The flexible electrodes were prepared by microelectromechanical systems (MEMS) technology. This kind of electrodes consisted parylene, chromium, and gold. Parylene, the flexible substrate of this kind of flexible electrodes, was of biocompatibility. Between parylene and gold there was an adhesion layer of chromium, which connected parylene and gold tightly. Then the flexible electrodes were stuck to medical adhesive tape. The electrodes were designed and made into a grid to make sure that the medical adhesive tape could tape on the skin tightly, so that the contact impedance between the electrodes and the skin would be reduced. Then the alternating current impedance of the electrode were tested by the CHI660E electrochemical workstation after the electrode was achieved. To make sure that this kind of electrodes could be used in EOG monitoring, the electrodes were connected to a wireless signal acquisition suite containing special biological signal acquisition and digital processing chip to gather different sites around the eyes and the electrical signals of different directions of the eye movements, then analyzed the signal-to-noise ratio of the EOG. At the end, the Philips A6 polysomnography was used to compare the noise amplitude of the EEG signals collected by the flexible electrode and the gold cup electrode. The electrodes stuck to the skin tightly, and these electrodes could collect signals that we wanted while the experiment was performed. The alternating current impedance of the flexible electrode was between 4 kΩ and 13 kΩ while with the frequency of alternating current under 100 Hz, most EEG signal frequencies were at this range. The EOG signals collected by the flexible electrodes were in line with the clinical requirements. The

Pulse-voltammetric glucose detection at gold junction electrodes.

Science.gov (United States)

Rassaei, Liza; Marken, Frank

2010-09-01

A novel glucose sensing concept based on the localized change or "modulation" in pH within a symmetric gold-gold junction electrode is proposed. A paired gold-gold junction electrode (average gap size ca. 500 nm) is prepared by simultaneous bipotentiostatic electrodeposition of gold onto two closely spaced platinum disk electrodes. For glucose detection in neutral aqueous solution, the potential of the "pH-modulator" electrode is set to -1.5 V vs saturated calomel reference electrode (SCE) to locally increase the pH, and simultaneously, either cyclic voltammetry or square wave voltammetry experiments are conducted at the sensor electrode. A considerable improvement in the sensor electrode response is observed when a normal pulse voltammetry sequence is applied to the modulator electrode (to generate "hydroxide pulses") and the glucose sensor electrode is operated with fixed bias at +0.5 V vs SCE (to eliminate capacitive charging currents). Preliminary data suggest good linearity for the glucose response in the medically relevant 1-10 mM concentration range (corresponding to 0.18-1.8 g L(-1)). Future electroanalytical applications of multidimensional pulse voltammetry in junction electrodes are discussed.

Diagnostics for the Biased Electrode Experiment on NSTX

International Nuclear Information System (INIS)

Roquemore, A.L.; Zweben, S.J.; Bush, C.E.; Kaita, R.; Marsalsa, R.J.; Maqueda, R.J.

2009-01-01

A linear array of four small biased electrodes was installed in NSTX in an attempt to control the width of the scrape-off layer (SOL) by creating a strong local poloidal electric field. The set of electrodes were separated poloidally by a 1 cm gap between electrodes and were located slightly below the midplane of NSTX, 1 cm behind the RF antenna and oriented so that each electrode is facing approximately normal to the magnetic field. Each electrode can be independently biased to ± 100 volts. Present power supplies limit the current on two electrodes to 30 amps the other two to 10 amps each. The effect of local biasing was measured with a set of Langmuir probes placed between the electrodes and another set extending radially outward from the electrodes, and also by the gas puff imaging diagnostic (GPI) located 1 m away along the magnetic field lines intersecting the electrodes. Two fast cameras were also aimed directly at the electrode array. The hardware and controls of the biasing experiment will be presented and the initial effects on local plasma parameters will be discussed

Long life lithium batteries with stabilized electrodes

Science.gov (United States)

Amine, Khalil [Downers Grove, IL; Liu, Jun [Naperville, IL; Vissers, Donald R [Naperville, IL; Lu, Wenquan [Darien, IL

2009-03-24

The present invention relates to non-aqueous electrolytes having electrode stabilizing additives, stabilized electrodes, and electrochemical devices containing the same. Thus the present invention provides electrolytes containing an alkali metal salt, a polar aprotic solvent, and an electrode stabilizing additive. In some embodiments the additives include a substituted or unsubstituted cyclic or spirocyclic hydrocarbon containing at least one oxygen atom and at least one alkenyl or alkynyl group. When used in electrochemical devices with, e.g., lithium manganese oxide spinel electrodes or olivine or carbon-coated olivine electrodes, the new electrolytes provide batteries with improved calendar and cycle life.

A survey of reference electrodes for high temperature waters

International Nuclear Information System (INIS)

Molander, A.; Eriksson, Sture; Pein, K.

2000-11-01

In nuclear power plants, corrosion potential measurements are used to follow the conditions for different corrosion types in reactor systems, particularly IGSCC in BWRs. The goal of this work has been to give a survey of reference electrodes for high temperature water, both those that are used for nuclear environments and those that are judged to possible future development. The reference electrodes that are used today in nuclear power plants for corrosion potential measurements are of three types. Silver chloride electrodes, membrane electrodes and platinum electrodes (hydrogen electrodes). The principals for their function is described as well as the conversion of measured potentials to the SHE scale (Standard Hydrogen Electrode). Silver chloride electrodes consist of an inner reference system of silver chloride in equilibrium with a chloride solution. The silver chloride electrode is the most common reference electrode and can be used in several different systems. Platinum electrodes are usually more robust and are particularly suitable to use in BWR environment to follow the hydrogen dosage, but have limitations at low and no hydrogen dosage. Ceramic membrane electrodes can be with different types of internal reference system. They were originally developed for pH measurements in high temperature water. If pH is constant, the membrane electrode can be used as reference electrode. A survey of ceramic reference electrodes for high temperature water is given. A ceramic membrane of the type used works as an oxygen conductor, so the potential and pH in surrounding medium is in equilibrium with the internal reference system. A survey of the lately development of electrodes is presented in order to explain why the different types of electrodes are developed as well as to give a background to the possibilities and limitations with the different electrodes. Possibilities of future development of electrodes are also given. For measurements at low or no hydrogen dosage

Reliable reference electrodes for lithium-ion batteries

KAUST Repository

La Mantia, F.

2013-06-01

Despite the high attention drawn to the lithium-ion batteries by the scientific and industrial community, most of the electrochemical characterization is carried out using poor reference electrodes or even no reference electrode. In this case, the performances of the active material are inaccurate, especially at high current densities. In this work we show the error committed in neglecting the polarizability of lithium counter electrodes, and we propose two reference electrodes to use in organic electrolytes based on lithium salts, namely Li4Ti5O12 and LiFePO 4. In particular, it was observed that, the polarizability of the metallic lithium counter electrode has a relevant stochastic component, which renders measurements at high current densities (above 1 mA·cm - 2) in two electrode cells non reproducible.

Optimising carbon electrode materials for adsorptive stripping voltammetry

OpenAIRE

Chaisiwamongkhol, K; Batchelor-McAuley, C; Sokolov, S; Holter, J; Young, N; Compton, R

2017-01-01

Different types of carbon electrode materials for adsorptive stripping voltammetry are studied through the use of cyclic voltammetry. Capsaicin is utilised as a model compound for adsorptive stripping voltammetry using unmodified and modified basal plane pyrolytic graphite (BPPG) electrodes modified with multi-walled carbon nanotubes, carbon black or graphene nanoplatelets, screen printed carbon electrodes (SPE), carbon nanotube modified screen printed electrodes, and carbon paste electrodes....

Nanostructured Solid Oxide Fuel Cell Electrodes

Energy Technology Data Exchange (ETDEWEB)

Sholklapper, Tal Zvi [Univ. of California, Berkeley, CA (United States)

2007-01-01

The ability of Solid Oxide Fuel Cells (SOFC) to directly and efficiently convert the chemical energy in hydrocarbon fuels to electricity places the technology in a unique and exciting position to play a significant role in the clean energy revolution. In order to make SOFC technology cost competitive with existing technologies, the operating temperatures have been decreased to the range where costly ceramic components may be substituted with inexpensive metal components within the cell and stack design. However, a number of issues have arisen due to this decrease in temperature: decreased electrolyte ionic conductivity, cathode reaction rate limitations, and a decrease in anode contaminant tolerance. While the decrease in electrolyte ionic conductivities has been countered by decreasing the electrolyte thickness, the electrode limitations have remained a more difficult problem. Nanostructuring SOFC electrodes addresses the major electrode issues. The infiltration method used in this dissertation to produce nanostructure SOFC electrodes creates a connected network of nanoparticles; since the method allows for the incorporation of the nanoparticles after electrode backbone formation, previously incompatible advanced electrocatalysts can be infiltrated providing electronic conductivity and electrocatalysis within well-formed electrolyte backbones. Furthermore, the method is used to significantly enhance the conventional electrode design by adding secondary electrocatalysts. Performance enhancement and improved anode contamination tolerance are demonstrated in each of the electrodes. Additionally, cell processing and the infiltration method developed in conjunction with this dissertation are reviewed.

Excimer laser micropatterning of freestanding thermo-responsive hydrogel layers for cells-on-chip applications

International Nuclear Information System (INIS)

Santaniello, Tommaso; Milani, Paolo; Lenardi, Cristina; Martello, Federico; Tocchio, Alessandro; Gassa, Federico; Webb, Patrick

2012-01-01

We report a novel reliable and repeatable technologic manufacturing protocol for the realization of micro-patterned freestanding hydrogel layers based on thermo-responsive poly-(N-isopropyl)acrylamide (PNIPAAm), which have potential to be employed as temperature-triggered smart surfaces for cells-on-chip applications. PNIPAAm-based films with controlled mechanical properties and different thicknesses (100–300 µm thickness) were prepared by injection compression moulding at room temperature. A 9 × 9 array of 20 µm diameter through-holes is machined by means of the KrF excimer laser on dry PNIPAAm films which are physically attached to flat polyvinyl chloride (PVC) substrates. Machining parameters, such as fluence and number of shots, are optimized in order to achieve highly resolved features. Micro-structured freestanding films are then easily obtained after hydrogels are detached from PVC by gradually promoting the film swelling in ethanol. In the PNIPAAm water-swollen state, the machined holes’ diameter approaches a slight larger value (30 µm) according to the measured hydrogel swelling ratio. Thermo-responsive behaviour and through-hole tapering characterization are carried out by metrology measurements using an optical inverted and confocal microscope setup, respectively. After the temperature of freestanding films is raised above 32 °C, we observe that the shrinkage of the whole through-hole array occurs, thus reducing the holes’ diameter to less than a half its original size (about 15 µm) as a consequence of the film dehydration. Different holes’ diameters (10 and 30 µm) are also obtained on dry hydrogel employing suitable projection masks, showing similar shrinking behaviour when hydrated and undergone thermo-response tests. Thermo-responsive PNIPAAm-based freestanding layers could then be integrated with other suitable micro-fabricated thermoplastic components in order to preliminary test their feasibility in operating as temperature

Spinal cord electrophysiology II: extracellular suction electrode fabrication.

Science.gov (United States)

Garudadri, Suresh; Gallarda, Benjamin; Pfaff, Samuel; Alaynick, William

2011-02-20

Development of neural circuitries and locomotion can be studied using neonatal rodent spinal cord central pattern generator (CPG) behavior. We demonstrate a method to fabricate suction electrodes that are used to examine CPG activity, or fictive locomotion, in dissected rodent spinal cords. The rodent spinal cords are placed in artificial cerebrospinal fluid and the ventral roots are drawn into the suction electrode. The electrode is constructed by modifying a commercially available suction electrode. A heavier silver wire is used instead of the standard wire given by the commercially available electrode. The glass tip on the commercial electrode is replaced with a plastic tip for increased durability. We prepare hand drawn electrodes and electrodes made from specific sizes of tubing, allowing consistency and reproducibility. Data is collected using an amplifier and neurogram acquisition software. Recordings are performed on an air table within a Faraday cage to prevent mechanical and electrical interference, respectively.

Method for uniformly distributing carbon flakes in a positive electrode, the electrode made thereby and compositions. [Patent application

Science.gov (United States)

Mrazek, F.C.; Smaga, J.A.; Battles, J.E.

1981-01-19

A positive electrode for a secondary electrochemical cell is described wherein an electrically conductive current collector is in electrical contact with a particulate mixture of gray cast iron and an alkali metal sulfide and an electrolyte including alkali metal halides or alkaline earth metal halides. Also present may be a transition metal sulfide and graphite flakes from the conversion of gray cast iron to iron sulfide. Also disclosed is a method of distributing carbon flakes in a cell wherein there is formed an electrochemical cell of a positive electrode structure of the type described and a suitable electrolyte and a second electrode containing a material capable of alloying with alkali metal ions. The cell is connected to a source of electrical potential to electrochemically convert gray cast iron to an iron sulfide and uniformly to distribute carbon flakes formerly in the gray cast iron throughout the positive electrode while forming an alkali metal alloy in the negative electrode. Also disclosed are compositions useful in preparing positive electrodes.

Electrodes for 24 hours pH monitoring--a comparative study.

OpenAIRE

McLauchlan, G; Rawlings, J M; Lucas, M L; McCloy, R F; Crean, G P; McColl, K E

1987-01-01

Three pH electrodes in clinical use were examined--(1) antimony electrode with remote reference electrode (Synectics 0011), (2) glass electrode with remote reference electrode (Microelectrodes Inc. MI 506) and (3) combined glass electrode with integral reference electrode (Radiometer GK2801C). In vitro studies showed that both glass electrodes were similar and superior to the antimony electrode with respect to response time, drift, and sensitivity. The effect of the siting of the reference el...

Making EDM Electrodes By Stereolithography

Science.gov (United States)

Barlas, Philip A.

1988-01-01

Stereolithography is computer-aided manufacturing technique. Used to make models and molds of electrodes for electrical-discharge machining (EDM). Eliminates intermediate steps in fabrication of plastic model of object used in making EDM electrode to manufacture object or mold for object.

Update on Peripheral Nerve Electrodes for Closed-Loop Neuroprosthetics

Directory of Open Access Journals (Sweden)

Emil H. Rijnbeek

2018-05-01

Full Text Available In this paper various types of electrodes for stimulation and recording activity of peripheral nerves for the control of neuroprosthetic limbs are reviewed. First, an overview of interface devices for (feedback- controlled movement of a prosthetic device is given, after which the focus is on peripheral nervous system (PNS electrodes. Important electrode properties, i.e., longevity and spatial resolution, are defined based upon the usability for neuroprostheses. The cuff electrode, longitudinal intrafascicular electrodes (LIFE, transverse intrafascicular multichannel electrode (TIME, Utah slanted electrode array (USEA, and the regenerative electrode are discussed and assessed on their longevity and spatial resolution. The cuff electrode seems to be a promising electrode for the control of neuroprostheses in the near future, because it shows the best longevity and good spatial resolution and it has been used on human subjects in multiple studies. The other electrodes may be promising in the future, but further research on their longevity and spatial resolution is needed. A more quantitatively uniform study protocol used for all electrodes would allow for a proper comparison of recording and stimulation performance. For example, the discussed electrodes could be compared in a large in vivo study, using one uniform comparison protocol.

Detection of EEG electrodes in brain volumes.

Science.gov (United States)

Graffigna, Juan P; Gómez, M Eugenia; Bustos, José J

2010-01-01

This paper presents a method to detect 128 EEG electrodes in image study and to merge with the Nuclear Magnetic Resonance volume for better diagnosis. First we propose three hypotheses to define a specific acquisition protocol in order to recognize the electrodes and to avoid distortions in the image. In the second instance we describe a method for segmenting the electrodes. Finally, registration is performed between volume of the electrodes and NMR.

Ion-selective electrodes

CERN Document Server

Mikhelson, Konstantin N

2013-01-01

Ion-selective electrodes (ISEs) have a wide range of applications in clinical, environmental, food and pharmaceutical analysis as well as further uses in chemistry and life sciences. Based on his profound experience as a researcher in ISEs and a course instructor, the author summarizes current knowledge for advanced teaching and training purposes with a particular focus on ionophore-based ISEs. Coverage includes the basics of measuring with ISEs, essential membrane potential theory and a comprehensive overview of the various classes of ion-selective electrodes. The principles of constructing I

Electrochemical oxidation of p-nitrophenol using graphene-modified electrodes, and a comparison to the performance of MWNT-based electrodes

International Nuclear Information System (INIS)

Arvinte, A.; Pinteala, M.; Mahosenaho, M.; Sesay, A.M.; Virtanen, V.

2011-01-01

The electrochemical oxidation of p-nitrophenol (p-NP) has been studied comparatively on a graphene modified electrode and a multiwall carbon nanotube (MWNT) electrode by using cyclic and differential pulse voltammetry. The sensors were fabricated by modifying screen-printed electrodes with graphene and MWNT nanomaterials, respectively, both dispersed in Nafion polymer. p-NP is irreversibly oxidized at +0. 9 V (vs. the Ag/AgCl) in solutions of pH 7. The height and potential of the peaks depend on pH in the range from 5 to 11. In acidic media, p-NP yields a well-defined oxidation peak at +0. 96 V which gradually increases in height with the concentration of the analyte. In case of differential pulse voltammetry in sulfuric acid solution, the sensitivity is practically the same for both electrodes. The modified electrodes display an unusually wide linear response (from 10 μM to 0. 62 mM of p-NP), with a detection limit of 0. 6 μM in case of the graphene electrode, and of 1. 3 μM in case of the MWNT electrode. (author)

Minimizing electrode contamination in an electrochemical cell

Science.gov (United States)

Kim, Yu Seung; Zelenay, Piotr; Johnston, Christina

2014-12-09

An electrochemical cell assembly that is expected to prevent or at least minimize electrode contamination includes one or more getters that trap a component or components leached from a first electrode and prevents or at least minimizes them from contaminating a second electrode.

Fractals in several electrode materials

Energy Technology Data Exchange (ETDEWEB)

Zhang, Chunyong, E-mail: zhangchy@njau.edu.cn [Department of Chemistry, College of Science, Nanjing Agricultural University, Nanjing 210095 (China); Suzhou Key Laboratory of Environment and Biosafety, Suzhou Academy of Southeast University, Dushuhu lake higher education town, Suzhou 215123 (China); Wu, Jingyu [Department of Chemistry, College of Science, Nanjing Agricultural University, Nanjing 210095 (China); Fu, Degang [Suzhou Key Laboratory of Environment and Biosafety, Suzhou Academy of Southeast University, Dushuhu lake higher education town, Suzhou 215123 (China); State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210096 (China)

2014-09-15

Highlights: • Fractal geometry was employed to characterize three important electrode materials. • The surfaces of all studied electrodes were proved to be very rough. • The fractal dimensions of BDD and ACF were scale dependent. • MMO film was more uniform than BDD and ACF in terms of fractal structures. - Abstract: In the present paper, the fractal properties of boron-doped diamond (BDD), mixed metal oxide (MMO) and activated carbon fiber (ACF) electrode have been studied by SEM imaging at different scales. Three materials are self-similar with mean fractal dimension in the range of 2.6–2.8, confirming that they all exhibit very rough surfaces. Specifically, it is found that MMO film is more uniform in terms of fractal structure than BDD and ACF. As a result, the intriguing characteristics make these electrodes as ideal candidates for high-performance decontamination processes.

The effect of gamma radiation on reference electrodes and platinum and carbon steel bare metal electrodes in a simulated waste solution

International Nuclear Information System (INIS)

Danielson, M.J.

1993-09-01

Electrochemical potential measurements of materials in waste tanks are important in determining if the materials have a propensity for stress corrosion cracking and pitting. Potential measurement requires a reference electrode, but the effect of radiation on the potential generated by the reference electrode has been an unknown quantity. To determine the significance of the radiation effect, Pacific Northwest Laboratory conducted studies of five types of electrodes under gamma radiation at room temperature. The subjects were two types of silver/silver chloride reference electrodes (Fisher and Lazaran), a mercury/calomel reference electrode, a platinum ''flag,'' and a piece of A-537 carbon steel; the electrodes were exposed to a simulated caustic tank environment. The Fisher silver/silver chloride and mercury/calomel reference electrodes showed essentially no radiation effects up to a flux of 2.1E6 R/h and fluence of 9.4E8 R, indicating they would be useful reference electrodes for in-tank studies. The Lazaran reg-sign silver/silver chloride electrode showed serious potential deviations at fluences of 2.E8 R, but it would be the electrode of choice in many situations because it is simple to maintain. Radiation affected the open circuit potential of both the platinum and carbon steel electrodes. This effect indicates that corrosion studies without radiation may not duplicate the corrosion processes expected in a waste tank. Mixed-potential theory was used to explain the radiation effects

A new texture descriptor based on local micro-pattern for detection of architectural distortion in mammographic images

Science.gov (United States)

de Oliveira, Helder C. R.; Moraes, Diego R.; Reche, Gustavo A.; Borges, Lucas R.; Catani, Juliana H.; de Barros, Nestor; Melo, Carlos F. E.; Gonzaga, Adilson; Vieira, Marcelo A. C.

2017-03-01

This paper presents a new local micro-pattern texture descriptor for the detection of Architectural Distortion (AD) in digital mammography images. AD is a subtle contraction of breast parenchyma that may represent an early sign of breast cancer. Due to its subtlety and variability, AD is more difficult to detect compared to microcalcifications and masses, and is commonly found in retrospective evaluations of false-negative mammograms. Several computer-based systems have been proposed for automatic detection of AD, but their performance are still unsatisfactory. The proposed descriptor, Local Mapped Pattern (LMP), is a generalization of the Local Binary Pattern (LBP), which is considered one of the most powerful feature descriptor for texture classification in digital images. Compared to LBP, the LMP descriptor captures more effectively the minor differences between the local image pixels. Moreover, LMP is a parametric model which can be optimized for the desired application. In our work, the LMP performance was compared to the LBP and four Haralick's texture descriptors for the classification of 400 regions of interest (ROIs) extracted from clinical mammograms. ROIs were selected and divided into four classes: AD, normal tissue, microcalcifications and masses. Feature vectors were used as input to a multilayer perceptron neural network, with a single hidden layer. Results showed that LMP is a good descriptor to distinguish AD from other anomalies in digital mammography. LMP performance was slightly better than the LBP and comparable to Haralick's descriptors (mean classification accuracy = 83%).

An ionization chamber with magnetic levitated electrodes

CERN Document Server

Kawaguchi, T

1999-01-01

A new type of ionization chamber which has magnetically levitated electrodes has been developed. The electrodes are supplied voltages for the repelling of ions by a battery which is also levitated with the electrodes. The characteristics of this ionization chamber are investigated in this paper.

Low Energy Desalination Using Battery Electrode Deionization

KAUST Repository

Kim, Taeyoung

2017-09-21

New electrochemical technologies that use capacitive or battery electrodes are being developed to minimize energy requirements for desalinating brackish waters. When a pair of electrodes is charged in capacitive deionization (CDI) systems, cations bind to the cathode and anions bind to the anode, but high applied voltages (>1.2 V) result in parasitic reactions and irreversible electrode oxidation. In the battery electrode deionization (BDI) system developed here, two identical copper hexacyanoferrate (CuHCF) battery electrodes were used that release and bind cations, with anion separation occurring via an anion exchange membrane. The system used an applied voltage of 0.6 V, which avoided parasitic reactions, achieved high electrode desalination capacities (up to 100 mg-NaCl/g-electrode, 50 mM NaCl influent), and consumed less energy than CDI. Simultaneous production of desalinated and concentrated solutions in two channels avoided a two-cycle approach needed for CDI. Stacking additional membranes between CuHCF electrodes (up to three anion and two cation exchange membranes) reduced energy consumption to only 0.02 kWh/m3 (approximately an order of magnitude lower than values reported for CDI), for an influent desalination similar to CDI (25 mM decreased to 17 mM). These results show that BDI could be effective as a very low energy method for brackish water desalination.

Electrochemical photovoltaic cells and electrodes

Science.gov (United States)

Skotheim, Terje A.

1984-01-01

Improved electrochemical photovoltaic cells and electrodes for use therein, particularly electrodes employing amorphous silicon or polyacetylene coating are produced by a process which includes filling pinholes or porous openings in the coatings by electrochemical oxidation of selected monomers to deposit insulating polymer in the openings.

Improved photovoltaic cells and electrodes

Science.gov (United States)

Skotheim, T.A.

1983-06-29

Improved photovoltaic cells and electrodes for use therein, particularly electrodes employing amorphous silicon or polyacetylene coating are produced by a process which includes filling pinholes or porous openings in the coatings by electrochemical oxidation of selected monomers to deposit insulating polymer in the openings.

Graphene-based battery electrodes having continuous flow paths

Science.gov (United States)

Zhang, Jiguang; Xiao, Jie; Liu, Jun; Xu, Wu; Li, Xiaolin; Wang, Deyu

2014-05-24

Some batteries can exhibit greatly improved performance by utilizing electrodes having randomly arranged graphene nanosheets forming a network of channels defining continuous flow paths through the electrode. The network of channels can provide a diffusion pathway for the liquid electrolyte and/or for reactant gases. Metal-air batteries can benefit from such electrodes. In particular Li-air batteries show extremely high capacities, wherein the network of channels allow oxygen to diffuse through the electrode and mesopores in the electrode can store discharge products.

Alkali metal ion battery with bimetallic electrode

Science.gov (United States)

Boysen, Dane A; Bradwell, David J; Jiang, Kai; Kim, Hojong; Ortiz, Luis A; Sadoway, Donald R; Tomaszowska, Alina A; Wei, Weifeng; Wang, Kangli

2015-04-07

Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten the alkali metal and the electrode comprising the combined alkali/non-alkali metals.

electrode array

African Journals Online (AJOL)

PROF EKWUEME

A geoelectric investigation employing vertical electrical soundings (VES) using the Ajayi - Makinde Two-Electrode array and the ... arrangements used in electrical D.C. resistivity survey. These include ..... Refraction Tomography to Study the.

DNA-modified electrodes (Ⅶ)——Preparation and characterization of DNA-bonded and DNA-adsorbed SAM/Au electrodes

Institute of Scientific and Technical Information of China (English)

陆琪; 庞代文; 胡深; 程介克; 蔡雄伟; 施财辉; 毛秉伟; 戴鸿平

1999-01-01

Two kinds of DNA-modified electrodes were prepared by covalent and adsorptive immobilization of DNA onto self-assembled monolayers of 2, 2’-dithiodiethanol on gold electrodes and characterized by cyclic voltammetry, Xray photoelectron spectroscopy and scanning tunneling microscopy. The results suggest that the methods are satisfactory for the immobilization of DNA on electrodes.

Electroencephalogram measurement using polymer-based dry microneedle electrode

Science.gov (United States)

Arai, Miyako; Nishinaka, Yuya; Miki, Norihisa

2015-06-01

In this paper, we report a successful electroencephalogram (EEG) measurement using polymer-based dry microneedle electrodes. The electrodes consist of needle-shaped substrates of SU-8, a silver film, and a nanoporous parylene protective film. Differently from conventional wet electrodes, microneedle electrodes do not require skin preparation and a conductive gel. SU-8 is superior as a structural material to poly(dimethylsiloxane) (PDMS; Dow Corning Toray Sylgard 184) in terms of hardness, which was used in our previous work, and facilitates the penetration of needles through the stratum corneum. SU-8 microneedles can be successfully inserted into the skin without breaking and could maintain a sufficiently low skin-electrode contact impedance for EEG measurement. The electrodes successfully measured EEG from the frontal pole, and the quality of acquired signals was verified to be as high as those obtained using commercially available wet electrodes without any skin preparation or a conductive gel. The electrodes are readily applicable to record brain activities for a long period with little stress involved in skin preparation to the users.

Thermoelectric energy recovery at ionic-liquid/electrode interface

Energy Technology Data Exchange (ETDEWEB)

Bonetti, Marco; Nakamae, Sawako; Huang, Bo Tao; Wiertel-Gasquet, Cécile; Roger, Michel [Service de Physique de l’Etat Condensé, CEA-IRAMIS-SPEC, CNRS-UMR 3680, CEA Saclay, F-91191 Gif-sur-Yvette Cedex (France); Salez, Thomas J. [Service de Physique de l’Etat Condensé, CEA-IRAMIS-SPEC, CNRS-UMR 3680, CEA Saclay, F-91191 Gif-sur-Yvette Cedex (France); École des Ponts ParisTech, 6 et 8 avenue Blaise Pascal, Champs-sur-Marne, F-77455 Marne-la-Vallée (France)

2015-06-28

A thermally chargeable capacitor containing a binary solution of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide in acetonitrile is electrically charged by applying a temperature gradient to two ideally polarisable electrodes. The corresponding thermoelectric coefficient is −1.7 mV/K for platinum foil electrodes and −0.3 mV/K for nanoporous carbon electrodes. Stored electrical energy is extracted by discharging the capacitor through a resistor. The measured capacitance of the electrode/ionic-liquid interface is 5 μF for each platinum electrode while it becomes four orders of magnitude larger, ≈36 mF, for a single nanoporous carbon electrode. Reproducibility of the effect through repeated charging-discharging cycles under a steady-state temperature gradient demonstrates the robustness of the electrical charging process at the liquid/electrode interface. The acceleration of the charging by convective flows is also observed. This offers the possibility to convert waste-heat into electric energy without exchanging electrons between ions and electrodes, in contrast to what occurs in most thermogalvanic cells.

Electroretinography in dogs using a fiber electrode prototype

Directory of Open Access Journals (Sweden)

A.L. Pereira

2013-03-01

Full Text Available We compared two electroretinography (ERG electrodes in dogs using ERG standards of the International Society for Clinical Electrophysiology of Vision (ISCEV. Ten healthy Yorkshire terrier dogs (mean age, 2.80 ± 1.42 years; 6 females weighing 5.20 ± 1.56 kg were evaluated using an ERG system for veterinary use. Dark- and light-adapted ERG responses were recorded using an ERG-Jet electrode and a fiber electrode prototype. The examinations were performed during 2 visits, 3 weeks apart. Both electrodes (ERG-Jet or fiber prototype were used on each animal and the first eye to be recorded (OD × OS was selected randomly. Three weeks later the examination was repeated on the same animal switching the type of electrode to be used that day and the first eye to be examined. The magnitude and waveform quality obtained with the two electrode types were similar for all ERG responses. ERG amplitudes and implicit times obtained from dogs using the fiber electrode prototype were comparable to those obtained with the ERG-Jet electrode for rod, maximal rod-cone summed, cone, and 30-Hz flicker responses. The fiber electrode prototype is a low-cost device, available as an alternative instrument for clinical veterinary ERG recording for retinal function assessment.

Electroretinography in dogs using a fiber electrode prototype

Directory of Open Access Journals (Sweden)

A.L. Pereira

Full Text Available We compared two electroretinography (ERG electrodes in dogs using ERG standards of the International Society for Clinical Electrophysiology of Vision (ISCEV. Ten healthy Yorkshire terrier dogs (mean age, 2.80 ± 1.42 years; 6 females weighing 5.20 ± 1.56 kg were evaluated using an ERG system for veterinary use. Dark- and light-adapted ERG responses were recorded using an ERG-Jet electrode and a fiber electrode prototype. The examinations were performed during 2 visits, 3 weeks apart. Both electrodes (ERG-Jet or fiber prototype were used on each animal and the first eye to be recorded (OD × OS was selected randomly. Three weeks later the examination was repeated on the same animal switching the type of electrode to be used that day and the first eye to be examined. The magnitude and waveform quality obtained with the two electrode types were similar for all ERG responses. ERG amplitudes and implicit times obtained from dogs using the fiber electrode prototype were comparable to those obtained with the ERG-Jet electrode for rod, maximal rod-cone summed, cone, and 30-Hz flicker responses. The fiber electrode prototype is a low-cost device, available as an alternative instrument for clinical veterinary ERG recording for retinal function assessment.

Electroretinography in dogs using a fiber electrode prototype

International Nuclear Information System (INIS)

Pereira, A.L.; Montiani-Ferreira, F.; Santos, V.R.; Salomão, S.R.; Souza, C.; Berezovsky, A.

2013-01-01

We compared two electroretinography (ERG) electrodes in dogs using ERG standards of the International Society for Clinical Electrophysiology of Vision (ISCEV). Ten healthy Yorkshire terrier dogs (mean age, 2.80 ± 1.42 years; 6 females) weighing 5.20 ± 1.56 kg were evaluated using an ERG system for veterinary use. Dark- and light-adapted ERG responses were recorded using an ERG-Jet electrode and a fiber electrode prototype. The examinations were performed during 2 visits, 3 weeks apart. Both electrodes (ERG-Jet or fiber prototype) were used on each animal and the first eye to be recorded (OD × OS) was selected randomly. Three weeks later the examination was repeated on the same animal switching the type of electrode to be used that day and the first eye to be examined. The magnitude and waveform quality obtained with the two electrode types were similar for all ERG responses. ERG amplitudes and implicit times obtained from dogs using the fiber electrode prototype were comparable to those obtained with the ERG-Jet electrode for rod, maximal rod-cone summed, cone, and 30-Hz flicker responses. The fiber electrode prototype is a low-cost device, available as an alternative instrument for clinical veterinary ERG recording for retinal function assessment

Pierce electrodes for a multigap accelerating system

International Nuclear Information System (INIS)

Davydenko, V.I.; Ivanov, A.A.; Kotelnikov, I.A.; Tiunov, M.A.

2007-01-01

A well-known Pierce's solution that allows to focus a beam of charged particles using properly shaped electrodes outside the beam is generalized to the case of multigap accelerating system. Simple parametric formulae for Pierce electrodes are derived for an accelerating system with current density, limited either by space charge or by emitting property of the cathode. As an example of general approach, Pierce electrodes shape is analyzed for a system with two accelerating gaps. It is shown that precise Pierce's solution exists if acceleration rate within second gap is lower than within first gap. In the opposite case quasi-Pierce solution can be implemented using non-equipotential electrode between the gaps, and guidelines, based on numerical simulations, for the design of equipotential focusing electrodes are given

Radio frequency ablation in the rabbit lung using wet electrodes: comparison of monopolar and dual bipolar electrode mode

International Nuclear Information System (INIS)

Jin, Gong Yong; Park, Sang Hee; Han, Young Min; Chung, Gyung Ho; Kwak, Hyo Sung; Jeon, Soo Bin; Lee, Yong Chul

2006-01-01

To compare the effect of radio frequency ablation (RFA) on the dimensions of radio frequency coagulation necrosis in a rabbit lung using a wet electrode in monopolar mode with that in dual electrode bipolar mode at different infusion rates (15 mm/hr versus 30 ml/hr) and saline concentrations (0.9% normal versus 5.8% hypertonic saline. Fifty ablation zones (one ablation zone in each rabbit) were produced in 50 rabbit using one or two 16-guage wet electrodes with a 1- cm active tip. The RFA system used in the monopolar and dual electrode wet bipolar RFA consisted of a 375-kHz generator (Elektrotom HiTT 106, Berchtold, Medizinelektronik, Germany). The power used was 30 watts and the exposure time was 5 minutes. The rabbits were assigned to one of five groups. Group A (n = 10) was infused with 0.9% NaCl used at a rate of 30 ml/hr in a monopolar mode. Groups B (n=10) and C (n=10) were infused with 0.9% NaCl at a rate of 15 and 30ml/hr, respectively in dual electrode bipolar mode; groups D (n=10) and E (n=10) were infused with 5.8% NaCl at a rate of 15 and 30 ml/hr, respectively in a dual electrode bipolar mode. The dimensions of the ablation zones in the gross specimens from the groups were compared using one-way analysis of variance by means of the Scheffe test (post-hoc testing). The mean largest diameter of the ablation zones was larger in dual electrode bipolar mode (30.9 ± 4.4 mm) than in monopolar mode (22.5 ± 3.5 mm). The mean smallest diameter of the ablation zones was larger in dual electrode bipolar mode (22.3 ± 2.5 mm) than in monopolar mode (19.5 ± 3.5 mm). There were significant differences in the largest and smallest dimension between the monopolar (group A ) ana dual electrode wet bipolar mode (groups B-E). In dual electrode bipolar mode, the mean largest diameter of the ablation zones was larger at an infusion rate of 15 ml/hr (34.2 ± 4.0 mm) than at 30 ml/hr (27.6 ± 0.0 mm), and the mean smallest diameter of the ablation zones was larger at an

Hot electron-induced electrochemiluminescence at polyetherimide-carbon black-based electrodes

International Nuclear Information System (INIS)

Salminen, Kalle; Grönroos, Päivi; Johansson, Leena-Sisko; Campbell, Joseph; Kulmala, Sakari

2017-01-01

Highlights: • Generation of hydrated electrons at carbon paste electrodes. • Hydrated electrons are able to produce intense chemiluminescence. • Relationship between carbon black content in electrode and HECL studied. • Performance of composite electrodes is similar to aluminum electrodes. • The present electrodes are good alternative for disposable assay cartridges. - Abstract: Various luminophores produce strong electrogenerated chemiluminescence during cathodic pulse polarization of the present insulating film-covered carbon paste electrodes in fully aqueous solutions. First electrodes made of a commercial conductive carbon paste were successfully utilized as working electrodes and their surface was characterized by ESCA. Then custom in-laboratory made improved composite electrodes were manufactured from the same insulating polymer and conducting carbon black particles. The relationship between the amount of carbon present on the composite electrode, in the bulk and on the surface, and the intensity of electrogenerated chemiluminescence was studied further. The overall performance of these composite electrodes makes them viable low-cost replacements for metal/insulator type electrodes such as oxide-coated silicon electrodes.

Sandwich-type electrode

Science.gov (United States)

Lu, Wen-Tong P.; Garcia, Earl R.

1983-01-01

Disclosed is an improvement on a method of making an electrode wherein a suspension in a liquid is prepared of a powdered catalyst containing a noble metal, carbon powder and a binder, and the suspension is poured over a carbon substrate dried, compressed and sintered to form a solid catalyst layer bonded to the carbon substrate. The improvement is placing a carbon paper on the catalyst layer prior to compressing. The improved electrode can be used as either a cathode or an anode in a sulfur dioxide depolarized electrolyzer in a process for producing hydrogen from water.

Ion-selective electrodes

Energy Technology Data Exchange (ETDEWEB)

Mikhelson, Konstantin N. [St. Petersburg State Univ. (Russian Federation). Ion-Selective Electrode Laboratory

2013-06-01

Ion-selective electrodes (ISEs) have a wide range of applications in clinical, environmental, food and pharmaceutical analysis as well as further uses in chemistry and life sciences. Based on his profound experience as a researcher in ISEs and a course instructor, the author summarizes current knowledge for advanced teaching and training purposes with a particular focus on ionophore-based ISEs. Coverage includes the basics of measuring with ISEs, essential membrane potential theory and a comprehensive overview of the various classes of ion-selective electrodes. The principles of constructing ISEs are outlined, and the transfer of methods into routine analysis is considered.

Ionization detector, electrode configuration and single polarity charge detection method

Science.gov (United States)

He, Z.

1998-07-07

An ionization detector, an electrode configuration and a single polarity charge detection method each utilize a boundary electrode which symmetrically surrounds first and second central interlaced and symmetrical electrodes. All of the electrodes are held at a voltage potential of a first polarity type. The first central electrode is held at a higher potential than the second central or boundary electrodes. By forming the first and second central electrodes in a substantially interlaced and symmetrical pattern and forming the boundary electrode symmetrically about the first and second central electrodes, signals generated by charge carriers are substantially of equal strength with respect to both of the central electrodes. The only significant difference in measured signal strength occurs when the charge carriers move to within close proximity of the first central electrode and are received at the first central electrode. The measured signals are then subtracted and compared to quantitatively measure the magnitude of the charge. 10 figs.

Effect of electrode shape on grounding resistances - Part 1

DEFF Research Database (Denmark)

Ingeman-Nielsen, Thomas; Tomaskovicova, Sonia; Dahlin, Torleif

2016-01-01

Electrode grounding resistance is a major factor affecting measurement quality in electric resistivity tomography (ERT) measurements for cryospheric applications. Still, little information is available on grounding resistances in the geophysical literature, mainly because it is difficult to measure....... The focus-one protocol is a new method for estimating single electrode grounding resistances by measuring the resistance between a single electrode in an ERT array and all the remaining electrodes connected in parallel. For large arrays, the measured resistance is dominated by the grounding resistance...... of the electrode under test, the focus electrode. We have developed an equivalent circuit model formulation for the resistance measured when applying the focus-one protocol. Our model depends on the individual grounding resistances of the electrodes of the array, the mutual resistances between electrodes...

Fabricating solid carbon porous electrodes from powders

Science.gov (United States)

Kaschmitter, James L.; Tran, Tri D.; Feikert, John H.; Mayer, Steven T.

1997-01-01

Fabrication of conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive dionization, and waste treatment. Electrodes fabricated from low surface area (Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon compositives with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to be high surface area carbons, fuel cell electrodes can be produced.

Modiolus-Hugging Intracochlear Electrode Array with Shape Memory Alloy

Directory of Open Access Journals (Sweden)

Kyou Sik Min

2013-01-01

Full Text Available In the cochlear implant system, the distance between spiral ganglia and the electrodes within the volume of the scala tympani cavity significantly affects the efficiency of the electrical stimulation in terms of the threshold current level and spatial selectivity. Because the spiral ganglia are situated inside the modiolus, the central axis of the cochlea, it is desirable that the electrode array hugs the modiolus to minimize the distance between the electrodes and the ganglia. In the present study, we propose a shape-memory-alloy-(SMA- embedded intracochlear electrode which gives a straight electrode a curved modiolus-hugging shape using the restoration force of the SMA as triggered by resistive heating after insertion into the cochlea. An eight-channel ball-type electrode array is fabricated with an embedded titanium-nickel SMA backbone wire. It is demonstrated that the electrode array changes its shape in a transparent plastic human cochlear model. To verify the safe insertion of the electrode array into the human cochlea, the contact pressures during insertion at the electrode tip and the contact pressures over the electrode length after insertion were calculated using a 3D finite element analysis. The results indicate that the SMA-embedded electrode is functionally and mechanically feasible for clinical applications.

Carbon in bifunctional air electrodes in alkaline solution

International Nuclear Information System (INIS)

Tryk, D.; Aldred, W.; Yeager, E.

1983-01-01

Bifunctional O 2 electrodes can be used both to reduce and to generate O 2 in rechargeable metal-air batteries and fuel cells. The factors controlling the O 2 reduction and generation reactions in gas-diffusional bifunctional O 2 electrodes are discussed. The resistance of such electrodes, as established from voltammetry curves, has been found to increase markedly during anodic polarization and to be dependent upon the electrode fabrication technique. Carbon blacks with more graphitic structure than Shawinigan black have been found to be more resistant to electro-oxidation. The further extension of cycle life of bifunctional electrodes using carbon is critically dependent on finding more oxidation-resistant carbons that at the same time have other surface properties meeting the requirements for catalyzed gas-diffusion electrodes

EDM Electrode for Internal Grooves

Science.gov (United States)

Ramani, V.; Werner, A.

1985-01-01

Electroerosive process inexpensive alternative to broaching. Hollow brass electrodes, soldered at one end to stainless-steel holding ring, held in grooves in mandrel. These electrodes used to machine grooves electrically in stainless-steel tube three-eights inch (9.5 millimeters) in diameter. Tool used on tubes already in place in equipment.

Fast optoelectric printing of plasmonic nanoparticles into tailored circuits

Science.gov (United States)

Rodrigo, José A.

2017-04-01

Plasmonic nanoparticles are able to control light at nanometre-scale by coupling electromagnetic fields to the oscillations of free electrons in metals. Deposition of such nanoparticles onto substrates with tailored patterns is essential, for example, in fabricating plasmonic structures for enhanced sensing. This work presents an innovative micro-patterning technique, based on optoelectic printing, for fast and straightforward fabrication of curve-shaped circuits of plasmonic nanoparticles deposited onto a transparent electrode often used in optoelectronics, liquid crystal displays, touch screens, etc. We experimentally demonstrate that this kind of plasmonic structure, printed by using silver nanoparticles of 40 nm, works as a plasmonic enhanced optical device allowing for polarized-color-tunable light scattering in the visible. These findings have potential applications in biosensing and fabrication of future optoelectronic devices combining the benefits of plasmonic sensing and the functionality of transparent electrodes.

Development of a Micro Pixel Chamber for the ATLAS Upgrade

CERN Document Server

Ochi, Atsuhiko; Komai, Hidetoshi; Edo, Yuki; Yamaguchi, Takahiro

2012-01-01

The Micro Pixel Chamber (μ-PIC) is being developed a sacandidate for the muon system of the ATLAS detector for upgrading in LHC experiments. The μ-PIC is a micro-pattern gaseous detector that doesn’t have floating structure such as wires, mesh, or foil. This detector can be made by printed-circuit-board (PCB) technology, which is commercially available and suited for mass production. Operation tests have been performed under high flux neutrons under similar conditions to the ATLAS cavern. Spark rates are measured using several gas mixtures under 7 MeV neutron irradiation, and good properties were observed using neon, ethane, and CF4 mixture of gases.Using resistive materials as electrodes, we are also developing a new μ-PIC, which is not expected to damage the electrodes in the case of discharge sparks.

Dielectric elastomers with novel highly-conducting electrodes

Science.gov (United States)

Böse, Holger; Uhl, Detlev

2013-04-01

Beside the characteristics of the elastomer material itself, the performance of dielectric elastomers in actuator, sensor as well as generator applications depends also on the properties of the electrode material. Various electrode materials based on metallic particles dispersed in a silicone matrix were manufactured and investigated. Anisotropic particles such as silver-coated copper flakes and silver-coated glass flakes were used for the preparation of the electrodes. The concentration of the metallic particles and the thickness of the electrode layers were varied. Specific conductivities derived from resistance measurements reached about 100 S/cm and surmount those of the reference materials based on graphite and carbon black by up to three orders of magnitude. The high conductivities of the new electrode materials can be maintained even at very large stretch deformations up to 200 %.

Emerging Novel Metal Electrodes for Photovoltaic Applications.

Science.gov (United States)

Lu, Haifei; Ren, Xingang; Ouyang, Dan; Choy, Wallace C H

2018-04-01

Emerging novel metal electrodes not only serve as the collector of free charge carriers, but also function as light trapping designs in photovoltaics. As a potential alternative to commercial indium tin oxide, transparent electrodes composed of metal nanowire, metal mesh, and ultrathin metal film are intensively investigated and developed for achieving high optical transmittance and electrical conductivity. Moreover, light trapping designs via patterning of the back thick metal electrode into different nanostructures, which can deliver a considerable efficiency improvement of photovoltaic devices, contribute by the plasmon-enhanced light-mattering interactions. Therefore, here the recent works of metal-based transparent electrodes and patterned back electrodes in photovoltaics are reviewed, which may push the future development of this exciting field. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of Imbalanced Activated Carbon Electrode Supercapacitors

Directory of Open Access Journals (Sweden)

Tieshi He

2015-01-01

Full Text Available Imbalanced supercapacitor was constructed by using various ratio of activated carbon (AC of positive to negative electrode. The electrochemical behavior of imbalanced supercapacitor was investigated using 1.0 M spiro-(1,1′-bipyrrolidinium tetrafluoroborate electrolyte in propylene carbonate. The results showed that there are some factors that influenced the imbalanced supercapacitor with different AC ratio of positive to negative electrode, the utilization of AC, electrode potential distribution, and life cycle. The imbalanced supercapacitor with an AC weight ratio of 80 : 120 of positive to negative electrode has an average potential distribution in each electrode, and it revealed the best electrochemical performance: specific capacitor was 39.6 F·g−1, while the charge-discharge efficiency was 97.2% after 2000 life cycle tests.

Researches on Position Detection for Vacuum Switch Electrode

Science.gov (United States)

Dong, Huajun; Guo, Yingjie; Li, Jie; Kong, Yihan

2018-03-01

Form and transformation character of vacuum arc is important influencing factor on the vacuum switch performance, and the dynamic separations of electrode is the chief effecting factor on the transformation of vacuum arcs forms. Consequently, how to detect the position of electrode to calculate the separations in the arcs image is of great significance. However, gray level distribution of vacuum arcs image isn’t even, the gray level of burning arcs is high, but the gray level of electrode is low, meanwhile, the forms of vacuum arcs changes sharply, the problems above restrict electrode position detection precisely. In this paper, algorithm of detecting electrode position base on vacuum arcs image was proposed. The digital image processing technology was used in vacuum switch arcs image analysis, the upper edge and lower edge were detected respectively, then linear fitting was done using the result of edge detection, the fitting result was the position of electrode, thus, accurate position detection of electrode was realized. From the experimental results, we can see that: algorithm described in this paper detected upper and lower edge of arcs successfully and the position of electrode was obtained through calculation.

The industrial application of a uranium dioxide electrode

International Nuclear Information System (INIS)

Needes, C.R.S.; Nicol, M.J.; Finkelstein, N.P.; Ormrod, G.T.W.

1975-01-01

A correlation between the potential of a UO 2 electrode and the rate of recovery of uranium has been proved in laboratory and plant trials. When the recovery rates change because of variation in the concentrations of Fe(III), Fe(II), SO 2- 4 , and H + , a positive correlation is observed. However, an increase in the concentration of phosphate in solution produces an increase in the UO 2 electrode potential but a decrease in the rate of leaching of UO 2 . The correlation between the UO 2 electrode potential and the rate of leaching of UO 2 is then negative. It is concluded that, as a control device, the electrode cannot compete with the platinum electrode for use on certain plants. Nevertheless, the UO 2 electrode will act as a useful warning device if the total concentration of iron in solution decreases to below a level concomitant with the economic recovery of uranium. Furthermore, because of the positive correlation between the UO 2 electrode potential and the phosphate concentration, the electrode will also be of value in the detection of an increase in the phosphate level in solution. When it was incorporated in a suitable industrial probe, the electrode was found to be able to withstand the rigours of the leaching conditions in a large pilot-plant pachuca, and only failed after six weeks operation [af

Pt-graphene electrodes for dye-sensitized solar cells

International Nuclear Information System (INIS)

Hoshi, Hajime; Tanaka, Shumpei; Miyoshi, Takashi

2014-01-01

Highlights: • Graphene films with Pt nanoparticles were prepared from commercial graphene. • Pt consumption can be reduced by using Pt-graphene films. • The film showed improved catalytic activity for the reaction I 3 − /I − . • The film can be used as the counter electrode of dye-sensitized solar cells (DSSCs). • The performance of DSSC was superior to that of the Pt electrode. - Abstract: A simple paste method for fabricating graphene films with Pt nanoparticles was developed. First, graphene pastes with Pt nanoparticles were prepared from commercially available graphene. The resulting films of graphene nanoplatelet aggregates with Pt nanoparticles (Pt-GNA) contained Pt nanoparticles distributed over the entire three-dimensional surface of the GNA. Then, the catalytic activity for the I 3 − /I − redox reaction was evaluated by cyclic voltammetry. The GNA electrode exhibited higher activity than a graphene nanoplatelet electrode because of its higher effective surface area. Addition of Pt nanoparticles to the electrodes improved the catalytic activity. In particular, a large Faradaic current for the I 3 − /I − reaction was observed for the Pt-GNA electrode. As the counter electrodes of dye-sensitized solar cells (DSSCs), their performance was consistent with the cyclic voltammetry results. In particular, the DSSC performance of the Pt-GNA electrode was superior to that of the Pt electrodes commonly used in DSSCs

Basic electrochemical properties of sputtered gold film electrodes

International Nuclear Information System (INIS)

Libansky, Milan; Zima, Jiri; Barek, Jiri; Reznickova, Alena; Svorcik, Vaclav; Dejmkova, Hana

2017-01-01

Gold nanolayers made by sputtering of pure gold (physical vapour deposition) are commonly used for many biophysical and material applications. However, the use of sputtering method for fabrication of working electrodes for electroanalytical purposes is less common. This paper focuses on the testing and characterization of sputtered working roughened gold nanostructured film electrodes, which fall into category of upcoming desirable new generation of nanostructured gold working electrodes. Gold nanostructured films (80 nm thin) were sputtered onto 50 μm thin PTFE substrates with three different types of treatment: pristine, plasma treated, and plasma treated and subsequently spontaneously grafted with biphenyl-4,4′-dithiol. The characterization of gold nanostructured film electrodes was carried out by examination of the electrode reaction of standard redox probes (ferrocyanide/ferricyanide, hydroquinone/benzoquinone) in different types of supporting electrolytes (BR buffers of various pH, KCl, KNO 3 , H 2 SO 4 ), by exploration of the electrode surface by scanning electron microscopy, by atomic force microscopy accompanied by elementary analysis and contact angle measurements. The testing of electrodes was complemented by an attempt to calculate their real surface areas from Randles-Sevcik equation. All results were compared to conventional bulk gold electrode. The practical applicability of the nanostructured gold electrodes as sensors for the determination of environmental pollutants was verified by voltammetric determination of hydroquinone as a model electrochemically oxidisable organic environmental pollutant.

Strategies for the fabrication of porous platinum electrodes

Energy Technology Data Exchange (ETDEWEB)

Kloke, Arne; Stetten, Felix von; Kerzenmacher, Sven [Laboratory for MEMS Applications, Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg (Germany); Zengerle, Roland [Laboratory for MEMS Applications, Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg (Germany); BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universitaet Freiburg (Germany)

2011-11-16

Porous platinum is of high technological importance due to its various applications in fuel cells, sensors, stimulation electrodes, mechanical actuators and catalysis in general. Based on a discussion of the general principles behind the reduction of platinum salts and corresponding deposition processes this article discusses techniques available for platinum electrode fabrication. The numerous, different strategies available to fabricate platinum electrodes are reviewed and discussed in the context of their tuning parameters, strengths and weaknesses. These strategies comprise bottom-up approaches as well as top-down approaches. In bottom-up approaches nanoparticles are synthesized in a first step by chemical, photochemical or sonochemical means followed by an electrode formation step by e.g. thin film technology or network formation to create a contiguous and conducting solid electrode structure. In top-down approaches fabrication starts with an already conductive electrode substrate. Corresponding strategies enable the fabrication of substrate-based electrodes by e.g. electrodeposition or the fabrication of self-supporting electrodes by dealloying. As a further top-down strategy, this review describes methods to decorate porous metals other than platinum with a surface layer of platinum. This way, fabrication methods not performable with platinum can be applied to the fabrication of platinum electrodes with the special benefit of low platinum consumption. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Cyanex based uranyl sensitive polymeric membrane electrodes.

Science.gov (United States)

Badr, Ibrahim H A; Zidan, W I; Akl, Z F

2014-01-01

Novel uranyl selective polymeric membrane electrodes were prepared using three different low-cost and commercially available Cyanex extractants namely, bis(2,4,4-trimethylpentyl) phosphinic acid [L1], bis(2,4,4-trimethylpentyl) monothiophosphinic acid [L2] and bis(2,4,4-trimethylpentyl) dithiophosphinic acid [L3]. Optimization and performance characteristics of the developed Cyanex based polymer membrane electrodes were determined. The influence of membrane composition (e.g., amount and type of ionic sites, as well as type of plasticizer) on potentiometric responses of the prepared membrane electrodes was studied. Optimized Cyanex-based membrane electrodes exhibited Nernstian responses for UO₂(2+) ion over wide concentration ranges with fast response times. The optimized membrane electrodes based on L1, L2 and L3 exhibited Nernstian responses towards uranyl ion with slopes of 29.4, 28.0 and 29.3 mV decade(-1), respectively. The optimized membrane electrodes based on L1-L3 showed detection limits of 8.3 × 10(-5), 3.0 × 10(-5) and 3.3 × 10(-6) mol L(-1), respectively. The selectivity studies showed that the optimized membrane electrodes exhibited high selectivity towards UO₂(2+) ion over large number of other cations. Membrane electrodes based on L3 exhibited superior potentiometric response characteristics compared to those based on L1 and L2 (e.g., widest linear range and lowest detection limit). The analytical utility of uranyl membrane electrodes formulated with Cyanex extractant L3 was demonstrated by the analysis of uranyl ion in different real samples for nuclear safeguards verification purposes. The results obtained using direct potentiometry and flow-injection methods were compared with those measured using the standard UV-visible and inductively coupled plasma spectroscopic methods. © 2013 Published by Elsevier B.V.

ORGANIC ELECTRODE COATINGS FOR NEXT-GENERATION NEURAL INTERFACES

Directory of Open Access Journals (Sweden)

Ulises A Aregueta-Robles

2014-05-01

Full Text Available Traditional neuronal interfaces utilize metallic electrodes which in recent years have reached a plateau in terms of the ability to provide safe stimulation at high resolution or rather with high densities of microelectrodes with improved spatial selectivity. To achieve higher resolution it has become clear that reducing the size of electrodes is required to enable higher electrode counts from the implant device. The limitations of interfacing electrodes including low charge injection limits, mechanical mismatch and foreign body response can be addressed through the use of organic electrode coatings which typically provide a softer, more roughened surface to enable both improved charge transfer and lower mechanical mismatch with neural tissue. Coating electrodes with conductive polymers or carbon nanotubes offers a substantial increase in charge transfer area compared to conventional platinum electrodes. These organic conductors provide safe electrical stimulation of tissue while avoiding undesirable chemical reactions and cell damage. However, the mechanical properties of conductive polymers are not ideal, as they are quite brittle. Hydrogel polymers present a versatile coating option for electrodes as they can be chemically modified to provide a soft and conductive scaffold. However, the in vivo chronic inflammatory response of these conductive hydrogels remains unknown. A more recent approach proposes tissue engineering the electrode interface through the use of encapsulated neurons within hydrogel coatings. This approach may provide a method for activating tissue at the cellular scale, however several technological challenges must be addressed to demonstrate feasibility of this innovative idea. The review focuses on the various organic coatings which have been investigated to improve neural interface electrodes.

Electrochemical Deposition of CdTe Semiconductor Thin Films for Solar Cell Application Using Two-Electrode and Three-Electrode Configurations: A Comparative Study

Directory of Open Access Journals (Sweden)

O. K. Echendu

2016-01-01

Full Text Available Thin films of CdTe semiconductor were electrochemically deposited using two-electrode and three-electrode configurations in potentiostatic mode for comparison. Cadmium sulphate and tellurium dioxide were used as cadmium and tellurium sources, respectively. The layers obtained using both configurations exhibit similar structural, optical, and electrical properties with no specific dependence on any particular electrode configuration used. These results indicate that electrochemical deposition (electrodeposition of CdTe and semiconductors in general can equally be carried out using two-electrode system as well as the conventional three-electrode system without compromising the essential qualities of the materials produced. The results also highlight the advantages of the two-electrode configuration in process simplification, cost reduction, and removal of a possible impurity source in the growth system, especially as the reference electrode ages.

Hybrid capacitor with activated carbon electrode, Ni(OH) 2 electrode and polymer hydrogel electrolyte

Science.gov (United States)

Nohara, Shinji; Asahina, Toshihide; Wada, Hajime; Furukawa, Naoji; Inoue, Hiroshi; Sugoh, Nozomu; Iwasaki, Hideharu; Iwakura, Chiaki

A new hybrid capacitor (HC) cell was assembled using an activated carbon (AC) negative electrode, an Ni(OH) 2 positive electrode and a polymer hydrogel electrolyte prepared from crosslinked potassium poly(acrylate) (PAAK) and KOH aqueous solution. The HC cell was characterized compared with an electric double layer capacitor (EDLC) using two AC electrodes and the polymer hydrogel electrolyte. It was found that the HC cell successfully worked in the larger voltage range and exhibited ca. 2.4 times higher capacitance than the EDLC cell. High-rate dischargeability of the HC cell was also superior to that of the EDLC cell. These improved characteristics strongly suggest that the HC cell can be a promising system of capacitors with high energy and power densities.

Substitution of thoriated tungsten electrodes in Switzerland

International Nuclear Information System (INIS)

Kunz, H.; Piller, G.

2006-01-01

Thoriated tungsten electrodes are frequently used for inert gas welding (TIG/WIG). The use of these electrodes can lead to doses which are well above the limit for the general population (1mSv/year). This has been shown by different investigations, for example from the ''Berufsgenossenschaft''. With these findings in mind, the regulatory authorities (Swiss Federal Office of Public Health (SFOPH) and Swiss National Accident Insurance Association (Suva)) started in 1999 to examine the justification of thoriated tungsten electrodes and a possible substitution with products containing no radioactive material. Up to this time, the use of thoriated tungsten electrodes could be justified since no thorium-free products leading to comparable results were available on the market. This was also the reason why the SFOPH approved several types of these electrodes. Discussions with formation centers for welding and inquiries made at welding shops, trading companies and producers showed that in the mean-time thorium-free products with comparable welding specifications and results became available on the market. Since the 1 January 2004, thoriated tungsten electrodes can only be used if the user has obtained the corresponding license from the SFOPH. The use of thoriated tungsten electrodes is thus not completely forbidden, but very strict conditions have to be fulfilled. Up to now and due to the involvement of the relevant partners, the substitution process has not met any problem. Neither trading companies nor users made any opposition and no request for obtaining a license for thoriated tungsten electrodes was made. (orig.)

Development of high temperature reference electrodes for in-pile application: Part I. Feasibility study of the external pressure balanced Ag/AgCl reference electrode (EPBRE) and the cathodically charged Palladium hydrogen electrode

International Nuclear Information System (INIS)

Bosch, R.W.; Van Nieuwenhove, R.

1998-10-01

The main problems connected with corrosion potential measurements at elevated temperatures and pressures are related to the stability and lifetime of the reference electrode and the correct estimation of the potential related to the Standard Hydrogen Scale (SHE). Under Pressurised Water Reactor (PWR) conditions of 300 degrees Celsius and 150 bar, the choice of materials is also a limiting factor due to the influence of radiation. Investigations on two reference electrodes that can be used under PWR conditions are reported: the cathodically charged palladium hydrogen electrode, and the external pressure balanced silver/silver chloride electrode. Preliminary investigations with the Pd-electrode were focused on the calculation of the required charging time and the influence of dissolved oxygen. High temperature applications are discussed on the basis of results reported in the literature. Investigations with the silver/silver chloride reference electrode mainly dealt with the salt bridge which is necessary to connect the reference electrode with the testing solution. It is shown that the thermal junction potential is independent of the length of the salt bridge. In addition, the high temperature contributes to an increase of the conductivity of the solution, which is beneficial for the salt bridge connection

Electrode Nanostructures in Lithium‐Based Batteries

Science.gov (United States)

Mahmood, Nasir

2014-01-01

Lithium‐based batteries possessing energy densities much higher than those of the conventional batteries belong to the most promising class of future energy devices. However, there are some fundamental issues related to their electrodes which are big roadblocks in their applications to electric vehicles (EVs). Nanochemistry has advantageous roles to overcome these problems by defining new nanostructures of electrode materials. This review article will highlight the challenges associated with these chemistries both to bring high performance and longevity upon considering the working principles of the various types of lithium‐based (Li‐ion, Li‐air and Li‐S) batteries. Further, the review discusses the advantages and challenges of nanomaterials in nanostructured electrodes of lithium‐based batteries, concerns with lithium metal anode and the recent advancement in electrode nanostructures. PMID:27980896

Low Impedance Carbon Adhesive Electrodes with Long Shelf Life.

Science.gov (United States)

Posada-Quintero, Hugo F; Reyes, Bersaín A; Burnham, Ken; Pennace, John; Chon, Ki H

2015-10-01

A novel electrocardiogram (ECG) electrode film is developed by mixing carbon black powder and a quaternary salt with a visco-elastic polymeric adhesive. Unlike traditional wet gel-based electrodes, carbon/salt/adhesive (CSA) electrodes should theoretically have an infinite shelf life as they do not dehydrate even after a prolonged period of storage. The CSA electrodes are electrically activated for use through the process of electrophoresis. Specifically, the activation procedure involves sending a high voltage and current through the electrode, which results in significant reduction of impedance so that high fidelity ECG signals can be obtained. Using the activation procedure, the ideal concentration of carbon black powder in the mixture with the adhesive was examined. It was determined that the optimum concentration of carbon black which minimized post-activation impedance was 10%. Once the optimal carbon black powder concentration was determined, extensive signal analysis was performed to compare the performance of the CSA electrodes to the standard silver-silver chloride (Ag/AgCl) electrodes. As a part of data analysis, electrode-skin contact impedance of the CSA was measured and compared to the standard Ag/AgCl electrodes; we found consistently lower impedance for CSA electrodes. For quantitative data analysis, we simultaneously collected ECG data with CSA and Ag/AgCl electrodes from 17 healthy subjects. Heart rate variability (HRV) indices and ECG morphological waveforms were calculated to compare CSA and Ag/AgCl electrodes. Non-significant differences for most of the HRV indices between CSA and Ag/AgCl electrodes were found. Of the morphological waveform metrics consisting of R-wave peak amplitude, ST-segment elevation and QT interval, only the first index was found to be significantly different between the two media. The response of CSA electrodes to motion artifacts was also tested, and we found in general no difference in the quality of the ECG signal

Composite carbon foam electrode

Science.gov (United States)

Mayer, Steven T.; Pekala, Richard W.; Kaschmitter, James L.

1997-01-01

Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivty and power to system energy.

Flexible transparent electrode

Science.gov (United States)

Demiryont, Hulya; Shannon, Kenneth C., III; Moorehead, David; Bratcher, Matthew

2011-06-01

This paper presents the properties of the EclipseTECTM transparent conductor. EclipseTECTM is a room temperature deposited nanostructured thin film coating system comprised of metal-oxide semiconductor elements. The system possesses metal-like conductivity and glass-like transparency in the visible region. These highly conductive TEC films exhibit high shielding efficiency (35dB at 1 to 100GHz). EclipseTECTM can be deposited on rigid or flexible substrates. For example, EclipseTECTM deposited on polyethylene terephthalate (PET) is extremely flexible that can be rolled around a 9mm diameter cylinder with little or no reduction in electrical conductivity and that can assume pre-extension states after an applied stress is relieved. The TEC is colorless and has been tailored to have high visible transmittance which matches the eye sensitivity curve and allows the viewing of true background colors through the coating. EclipseTECTM is flexible, durable and can be tailored at the interface for applications such as electron- or hole-injecting OLED electrodes as well as electrodes in flexible displays. Tunable work function and optical design flexibility also make EclipseTECTM well-suited as a candidate for grid electrode replacement in next-generation photovoltaic cells.

A facile electrode preparation method for accurate electrochemical measurements of double-side-coated electrode from commercial Li-ion batteries

Science.gov (United States)

Zhou, Ge; Wang, Qiyu; Wang, Shuo; Ling, Shigang; Zheng, Jieyun; Yu, Xiqian; Li, Hong

2018-04-01

The post mortem electrochemical analysis, including charge-discharge and electrochemical impedance spectroscopy (EIS) measurements, are critical steps for revealing the failure mechanisms of commercial lithium-ion batteries (LIBs). These post measurements usually require the reassembling of coin-cell with electrode which is often double-side-coated in commercial LIBs. It is difficult to use such double-side-coated electrode to perform accurate electrochemical measurements because the back side of the electrode is coated with active materials, rather than single-side-coated electrode that is often used in coin-cell measurements. In this study, we report a facile tape-covering sample preparation method, which can effectively suppress the influence of back side of the double-side-coated electrodes on capacity and EIS measurements in coin-cells. By tape-covering the unwanted side, the areal capacity of the desired investigated side of the electrode has been accurately measured with an experimental error of about 0.5% at various current densities, and accurate EIS measurements and analysis have been conducted as well.

Monitoring drilling mud composition using flowing liquid junction electrodes

Energy Technology Data Exchange (ETDEWEB)

Jasinski, R; Fletcher, P; Vercaemer, C

1990-06-27

The concentration of a chosen ionic component of a drilling mud is determined from the potential difference between an ion selective electrode, selective to the component and a reference electrode, the reference electrode being connected to the mud by a liquid junction through which reference electrolyte flows from the electrode to the mud. The system avoids errors due to undesirable interactions between the mud and the reference electrode materials. (author).

Recycling positive-electrode material of a lithium-ion battery

Science.gov (United States)

Sloop, Steven E.

2017-11-21

Examples are disclosed of methods to recycle positive-electrode material of a lithium-ion battery. In one example, the positive-electrode material is heated under pressure in a concentrated lithium hydroxide solution. After heating, the positive-electrode material is separated from the concentrated lithium hydroxide solution. After separating, the positive electrode material is rinsed in a basic liquid. After rinsing, the positive-electrode material is dried and sintered.

A comparison study of electrodes for neonate electrical impedance tomography

International Nuclear Information System (INIS)

Rahal, Mohamad; Demosthenous, Andreas; Khor, Joo Moy; Tizzard, Andrew; Bayford, Richard

2009-01-01

Electrical impedance tomography (EIT) is an imaging technique that has the potential to be used for studying neonate lung function. The properties of the electrodes are very important in multi-frequency EIT (MFEIT) systems, particularly for neonates, as the skin cannot be abraded to reduce contact impedance. In this work, the impedance of various clinical electrodes as a function of frequency is investigated to identify the optimum electrode type for this application. Six different types of self-adhesive electrodes commonly used in general and neonatal cardiology have been investigated. These electrodes are Ag/AgCl electrodes from the Ambu® Cardiology Blue sensors range (BR, NF and BRS), Kendall (KittyCat(TM) and ARBO®) and Philips 13953D electrodes. In addition, a textile electrode without gel from Textronics was tested on two subjects to allow comparison with the hydrogel-based electrodes. Two- and four-electrode measurements were made to determine the electrode-interface and tissue impedances, respectively. The measurements were made on the back of the forearm of six healthy adult volunteers without skin preparation with 2.5 cm electrode spacing. Impedance measurements were carried out using a Solartron SI 1260 impedance/gain-phase analyser with a frequency range from 10 Hz to 1 MHz. For the electrode-interface impedance, the average magnitude decreased with frequency, with an average value of 5 kΩ at 10 kHz and 337 Ω at 1 MHz; for the tissue impedance, the respective values were 987 Ω and 29 Ω. Overall, the Ambu BRS, Kendall ARBO® and Textronics textile electrodes gave the lowest electrode contact impedance at 1 MHz. Based on the results of the two-electrode measurements, simple RC models for the Ambu BRS and Kendall-ARBO and Textronics textile electrodes have been derived for MFEIT applications

Elastomeric binders for Li-SOCl2 cell carbon electrodes

Science.gov (United States)

Carter, B. J.; Jeffries, B.; Yen, S. P. S.

1987-01-01

Nonoptimized elastomer bonded carbon electrodes made with 100-percent compressed Gulf Acetylene Black have demonstrated performance comparable to that of optimized Teflon bonded carbon electrodes, made from the same carbon, when tested at 1-10 mA/sq cm, at 24 and -26 C. The enhanced performance of elastomer bonded carbon electrodes appears to be due to the more uniform utilization of the carbon electrode to store insoluble discharge products, as compared to Teflon bonded carbon electrodes. With even minimal optimization of elastomer bonded carbon electrodes, significant improvement in Li-SOCl2 cell performance can be expected.

Etching holes in graphene supercapacitor electrodes for faster performance.

Science.gov (United States)

Ervin, Matthew H

2015-06-12

Graphene is being widely investigated as a material to replace activated carbon in supercapacitor (electrochemical capacitor) electrodes. Supercapacitors have much higher energy density, but are typically slow devices (∼0.1 Hz) compared to other types of capacitors. Here, top-down semiconductor processing has been applied to graphene-based electrodes in order to fabricate ordered arrays of holes through the graphene electrodes. This is demonstrated to increase the speed of the electrodes by reducing the ionic impedance through the electrode thickness. This approach may also be applicable to speeding up other types of devices, such as batteries and sensors, that use porous electrodes.

Pt-graphene electrodes for dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Hoshi, Hajime, E-mail: hoshi@ed.tus.ac.jp; Tanaka, Shumpei; Miyoshi, Takashi

2014-12-15

Highlights: • Graphene films with Pt nanoparticles were prepared from commercial graphene. • Pt consumption can be reduced by using Pt-graphene films. • The film showed improved catalytic activity for the reaction I{sub 3}{sup −}/I{sup −}. • The film can be used as the counter electrode of dye-sensitized solar cells (DSSCs). • The performance of DSSC was superior to that of the Pt electrode. - Abstract: A simple paste method for fabricating graphene films with Pt nanoparticles was developed. First, graphene pastes with Pt nanoparticles were prepared from commercially available graphene. The resulting films of graphene nanoplatelet aggregates with Pt nanoparticles (Pt-GNA) contained Pt nanoparticles distributed over the entire three-dimensional surface of the GNA. Then, the catalytic activity for the I{sub 3}{sup −}/I{sup −} redox reaction was evaluated by cyclic voltammetry. The GNA electrode exhibited higher activity than a graphene nanoplatelet electrode because of its higher effective surface area. Addition of Pt nanoparticles to the electrodes improved the catalytic activity. In particular, a large Faradaic current for the I{sub 3}{sup −}/I{sup −} reaction was observed for the Pt-GNA electrode. As the counter electrodes of dye-sensitized solar cells (DSSCs), their performance was consistent with the cyclic voltammetry results. In particular, the DSSC performance of the Pt-GNA electrode was superior to that of the Pt electrodes commonly used in DSSCs.

Pseudocapacitive and hierarchically ordered porous electrode materials supercapacitors

Science.gov (United States)

Saruhan, B.; Gönüllü, Y.; Arndt, B.

2013-05-01

Commercially available double layer capacitors store energy in an electrostatic field. This forms in the form of a double layer by charged particles arranged on two electrodes consisting mostly of active carbon. Such double layer capacitors exhibit a low energy density, so that components with large capacity according to large electrode areas are required. Our research focuses on the development of new electrode materials to realize the production of electrical energy storage systems with high energy density and high power density. Metal oxide based electrodes increase the energy density and the capacitance by addition of pseudo capacitance to the static capacitance present by the double layer super-capacitor electrodes. The so-called hybrid asymmetric cell capacitors combine both types of energy storage in a single component. In this work, the production routes followed in our laboratories for synthesis of nano-porous and aligned metal oxide electrodes using the electrochemical and sputter deposition as well as anodization methods will be described. Our characterisation studies concentrate on electrodes having redox metal-oxides (e.g. MnOx and WOx) and hierarchically aligned nano-porous Li-doped TiO2-NTs. The material specific and electrochemical properties achieved with these electrodes will be presented.

Receivers for processing electron beam pick-up electrode signals

International Nuclear Information System (INIS)

Anon.

1991-01-01

There are several methods of determining the transverse position of the electron beam, based upon sensing either the electric field, the magnetic field, or both. At the NSLS the transverse beam position monitors each consist of a set of four circular electrodes. There are 48 sets of pick-up electrodes in the X-ray ring and 24 in the VUV storage ring for determining the electron orbit, and a few extra sets installed for specialized purposes. When the beam passes between the four electrodes, charge is induced on each electrode, the amount depending upon the distance of the beam from that electrode. If V a , V b , V c and V d given by a difference between pairs of electrodes normalized for variations in beam current by dividing by the sum of electrode voltages. The method of processing these signals depends upon their time structure. The electrons circulating around the vacuum chamber are concentrated in short bunches within stability buckets produced by the accelerating voltage in the RF cavities. The charges induced on the pickup electrodes then are narrow pulses, a fraction of a nanosecond long, and would result in a monopolar voltage pulses if it were not for the impedance of the cable connecting the electrode to the processing apparatus. The capacitance between each electrode and the chamber wall is only a few picofarads and is effectively in parallel with the cable impedance (50 ohms). Thus an appreciable amount of the charge flows off the electrode while the bunch is between the electrodes, resulting in potential of opposite sign as the bunch is leaving the vicinity of the electrode. The resulting signal consists of a series of bipolar pulses, each of less than one nanosecond duration

Electrochemical properties of polypyrrole/polyfuran polymer composite electrode

International Nuclear Information System (INIS)

Cha, Seong Keuck

1998-01-01

Poly pyrrole polymer(ppy) has an excellent electrical conductivity and can be easily polymerized on anode to give various morphology according to doped anion on electroactive sites. To improve the properties of brittleness, ageing and hydrophobicity, poly furan polymer(pfu) having a high initiation potential was anodically implanted in this porous ppy film matrix to get the Pt/ppy/pfu(x)type of polymer campsite electrode. Cyclic voltammetry and electrochemical impedance methods were used to these electrode, where PF 6 - , BF 4 - , and ClO 4 - ions were employed as dopants. The composition of the pfu(x) at the electrode was changed from 0 to 1.10, but the range was useful only at 0.1 to 0.2 as the redox electrode. The polymer composite electrode doped with PF 6 - was better in charge transfer resistance by a factor of 40 times and in double layer capacitance by a factor of 20 times than others. The charge transfer in the polymer film of the electrode was influenced on frequency change and equivalent circuit of this electrode had Warburg impedance including mass transfer

Chromatic aberrations of two-electrode transaxial mirrors

International Nuclear Information System (INIS)

Bejzina, L.G.; Karetskaya, S.P.

1991-01-01

Second order chromatic aberrations of electrostatic two-electrode transaxial mirrors in case the beam axial trajectory of charged particles is curvilinear are considered. Interrelations between coefficients of linear and angular chromatic aberrations are determined. Values of these coefficients for concave and convex transaxial mirrors with plane electrodes in dependence on potential ratio on electrodes by different onnular clearance radii are presented

Resistivity tomography using line electrode; Sendenryugen wo tsukatta hiteiko tomography

Energy Technology Data Exchange (ETDEWEB)

Sugimoto, Y [Dia Consultants Company, Tokyo (Japan)

1996-10-01

Resistivity tomography (RT) using line electrode was studied. Although line electrode is available even for RT, in casing line electrode, only one kind of electrode data is obtained. The calculation method of potential and sensitivity distributions based on line electrode is not yet established. Since various data in various measurement arrangements are required for analysis of RT, the new measurement method was devised which measures resistivities while successively changing the tip depth of line electrode. Until now, although potential has been calculated under the assumption that outflow current per unit length of line electrode is uniform, this assumption is incorrect. The new potential distribution calculation method was thus proposed. Sensitivity distribution calculation for inverse analysis is also described. RT using line electrode could precisely obtain deep information which couldn`t be obtained only by measurement along the surface measuring line. Although RT is poorer in accuracy than the previous point electrode method, it will be probably improved by 3-electrode arrangement. RT is also useful in the case difficult to apply point electrode method. 3 refs., 10 figs.

Structure and Modification of Electrode Materials for Protein Electrochemistry.

Science.gov (United States)

Jeuken, Lars J C

The interactions between proteins and electrode surfaces are of fundamental importance in bioelectrochemistry, including photobioelectrochemistry. In order to optimise the interaction between electrode and redox protein, either the electrode or the protein can be engineered, with the former being the most adopted approach. This tutorial review provides a basic description of the most commonly used electrode materials in bioelectrochemistry and discusses approaches to modify these surfaces. Carbon, gold and transparent electrodes (e.g. indium tin oxide) are covered, while approaches to form meso- and macroporous structured electrodes are also described. Electrode modifications include the chemical modification with (self-assembled) monolayers and the use of conducting polymers in which the protein is imbedded. The proteins themselves can either be in solution, electrostatically adsorbed on the surface or covalently bound to the electrode. Drawbacks and benefits of each material and its modifications are discussed. Where examples exist of applications in photobioelectrochemistry, these are highlighted.

The influence of electrode angle on the minimization of the aberration coefficients of the two electrodes electrostatic immersion lens

International Nuclear Information System (INIS)

Al-Khashab, M. A.; Ahmad, A. A.

2012-01-01

This paper deals with electron optical properties of a set asymmetrical electrostatic immersion lenses with two electrodes which have been designed using different angles (θ) of the outer lens electrodes as well as air gaps (S) between the electrodes of each lens. It was found that the angle of the outer electrode and the air gap have a clear effect on the electron optical performance of such lenses. In addition to that, it was noticed that the better electron optical properties occurred when the angle of the outer electrode equals (θ = O d egree) and the air gap equals (S = 11 mm). the results of the perferable design of the prsent work were compared with those in published papers in terms of the optical properties. It was found that results are in good agreement with each other. (authors).

Perovskite electrodes and method of making the same

Science.gov (United States)

Seabaugh, Matthew M.; Swartz, Scott L.

2005-09-20

The invention relates to perovskite oxide electrode materials in which one or more of the elements Mg, Ni, Cu, and Zn are present as minority components that enhance electrochemical performance, as well as electrode products with these compositions and methods of making the electrode materials. Such electrodes are useful in electrochemical system applications such as solid oxide fuel cells, ceramic oxygen generation systems, gas sensors, ceramic membrane reactors, and ceramic electrochemical gas separation systems.

Magnetohydrodynamic electrode

International Nuclear Information System (INIS)

1980-01-01

The object of the invention is the provision of a material capable of withstanding a high-temperature, corrosive and erosive environment for use as a ceramic-metal composite electrode current collector in the channel of a magnetohydrodynamic generator. (U.K.)

Assessing the degradation of compliant electrodes for soft actuators

Science.gov (United States)

Rosset, Samuel; de Saint-Aubin, Christine; Poulin, Alexandre; Shea, Herbert R.

2017-10-01

We present an automated system to measure the degradation of compliant electrodes used in dielectric elastomer actuators (DEAs) over millions of cycles. Electrodes for DEAs generally experience biaxial linear strains of more than 10%. The decrease in electrode conductivity induced by this repeated fast mechanical deformation impacts the bandwidth of the actuator and its strain homogeneity. Changes in the electrode mechanical properties lead to reduced actuation strain. Rather than using an external actuator to periodically deform the electrodes, our measurement method consists of measuring the properties of an electrode in an expanding circle DEA. A programmable high voltage power supply drives the actuator with a square signal up to 1 kHz, periodically actuating the DEA, and thus stretching the electrodes. The DEA strain is monitored with a universal serial bus camera, while the resistance of the ground electrode is measured with a multimeter. The system can be used for any type of electrode. We validated the test setup by characterising a carbon black/silicone composite that we commonly use as compliant electrode. Although the composite is well-suited for tens of millions of cycles of actuation below 5%, we observe important degradation for higher deformations. When activated at a 20% radial strain, the electrodes suffer from important damage after a few thousand cycles, and an inhomogeneous actuation is observed, with the strain localised in a sub-region of the actuator only.

Nanowire Electrodes for Advanced Lithium Batteries

Energy Technology Data Exchange (ETDEWEB)

Huang, Lei; Wei, Qiulong; Sun, Ruimin; Mai, Liqiang, E-mail: mlq518@whut.edu.cn [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, WUT-Harvard Joint Nano Key Laboratory, Wuhan University of Technology, Wuhan (China)

2014-10-27

Since the commercialization of lithium ion batteries (LIBs) in the past two decades, rechargeable LIBs have become widespread power sources for portable devices used in daily life. However, current demands require higher energy density and power density of batteries. The electrochemical energy storage performance of LIBs could be improved by applying nanomaterial electrodes, but their fast capacity fading is still one of the key limitations and the mechanism need to be clearly understood. Single nanowire electrode devices are considered as a versatile platform for in situ probing the direct relationship between electrical transport, structure change, and other properties of the single nanowire electrode along with the charge/discharge process. The results indicate that the conductivity decrease of the nanowire electrode and the structural disorder/destruction during electrochemical reaction limit the cycling performance of LIBs. Based on the in situ observations, some feasible optimization strategies, including prelithiation, coaxial structure, nanowire arrays, and hierarchical structure architecture, are proposed and utilized to restrain the conductivity decrease and structural disorder/destruction. Further, the applications of nanowire electrodes in some “beyond Li-ion” batteries, such as Li-S and Li-air batteries are also described.

FINAL REPORT: Transformational electrode drying process

Energy Technology Data Exchange (ETDEWEB)

Claus Daniel, C.; Wixom, M.(A123 Systems, Inc.)

2013-12-19

This report includes major findings and outlook from the transformational electrode drying project performance period from January 6, 2012 to August 1, 2012. Electrode drying before cell assembly is an operational bottleneck in battery manufacturing due to long drying times and batch processing. Water taken up during shipment and other manufacturing steps needs to be removed before final battery assembly. Conventional vacuum ovens are limited in drying speed due to a temperature threshold needed to avoid damaging polymer components in the composite electrode. Roll to roll operation and alternative treatments can increase the water desorption and removal rate without overheating and damaging other components in the composite electrode, thus considerably reducing drying time and energy use. The objective of this project was the development of an electrode drying procedure, and the demonstration of processes with no decrease in battery performance. The benchmark for all drying data was an 80°C vacuum furnace treatment with a residence time of 18 – 22 hours. This report demonstrates an alternative roll to roll drying process with a 500-fold improvement in drying time down to 2 minutes and consumption of only 30% of the energy compared to vacuum furnace treatment.

Colloidal paradigm in supercapattery electrode systems

Science.gov (United States)

Chen, Kunfeng; Xue, Dongfeng

2018-01-01

Among decades of development, electrochemical energy storage systems are now sorely in need of a new design paradigm at the nano size and ion level to satisfy the higher energy and power demands. In this review paper, we introduce a new colloidal electrode paradigm for supercapattery that integrates multiple-scale forms of matter, i.e. ion clusters, colloidal ions, and nanosized materials, into one colloid system, coupled with multiple interactions, i.e. electrostatic, van der Waals forces, and chemical bonding, thus leading to the formation of many redox reactive centers. This colloidal electrode not only keeps the original ionic nature in colloidal materials, but also creates a new attribute of high electroactivity. Colloidal supercapattery is a perfect application example of the novel colloidal electrode, leading to higher specific capacitance than traditional electrode materials. The high electroactivity of the colloidal electrode mainly comes from the contribution of exposed reactive centers, owing to the confinement effect of carbon and a binder matrix. Systematic and thorough research on the colloidal system will significantly promote the development of fundamental science and the progress of advanced energy storage technology.

Nanowire Electrodes for Advanced Lithium Batteries

Directory of Open Access Journals (Sweden)

Lei eHuang

2014-10-01

Full Text Available Since the commercialization of lithium ion batteries (LIBs in the past two decades, rechargeable LIBs have become widespread power sources for portable devices used in daily life. However, current demands require higher energy density and power density of batteries. The electrochemical energy storage performance of LIBs could be improved by applying nanomaterial electrodes, but their fast capacity fading is still one of the key limitations and the mechanism needs to be clearly understood. Single nanowire electrode devices are considered as a versatile platform for in situ probing the direct relationship between electrical transport, structure change, and other properties of the single nanowire electrode along with the charge/discharge process. The results indicate the conductivity decrease of the nanowire electrode and the structural disorder/destruction during electrochemical reactions which limit the cycling performance of LIBs. Based on the in situ observations, some feasible structure architecture strategies, including prelithiation, coaxial structure, nanowire arrays and hierarchical structure architecture, are proposed and utilized to restrain the conductivity decrease and structural disorder/destruction. Further, the applications of nanowire electrodes in some beyond Li-ion batteries, such as Li-S and Li-air battery, are also described.

Nanowire Electrodes for Advanced Lithium Batteries

International Nuclear Information System (INIS)

Huang, Lei; Wei, Qiulong; Sun, Ruimin; Mai, Liqiang

2014-01-01

Since the commercialization of lithium ion batteries (LIBs) in the past two decades, rechargeable LIBs have become widespread power sources for portable devices used in daily life. However, current demands require higher energy density and power density of batteries. The electrochemical energy storage performance of LIBs could be improved by applying nanomaterial electrodes, but their fast capacity fading is still one of the key limitations and the mechanism need to be clearly understood. Single nanowire electrode devices are considered as a versatile platform for in situ probing the direct relationship between electrical transport, structure change, and other properties of the single nanowire electrode along with the charge/discharge process. The results indicate that the conductivity decrease of the nanowire electrode and the structural disorder/destruction during electrochemical reaction limit the cycling performance of LIBs. Based on the in situ observations, some feasible optimization strategies, including prelithiation, coaxial structure, nanowire arrays, and hierarchical structure architecture, are proposed and utilized to restrain the conductivity decrease and structural disorder/destruction. Further, the applications of nanowire electrodes in some “beyond Li-ion” batteries, such as Li-S and Li-air batteries are also described.

Electrochemical surface plasmon resonance sensor based on two-electrode configuration

International Nuclear Information System (INIS)

Zhang, Bing; Dong, Wei; Wen, Yizhang; Pang, Kai; Wang, Xiaoping; Li, Yazhuo; Zhan, Shuyue

2016-01-01

To obtain detailed information about electrochemistry reactions, a two-electrode electrochemical surface plasmon resonance (EC-SPR) sensor has been proposed. We describe the theory of potential modulation for this novel sensor and determine the factors that can change the SPR resonance angle. The reference electrode in three-electrode configuration was eliminated, and comparing with several other electrode materials, activated carbon (AC) is employed as the suitable counter electrode for its potential stability. Just like three-electrode configuration, the simpler AC two-electrode system can also obtain detailed information about the electrochemical reactions. (paper)

A reciprocity-based formula for the capacitance with quadrupolar electrodes

Energy Technology Data Exchange (ETDEWEB)

Cho, Sungbo [Gachon University of Medicine and Science, Incheon (Korea, Republic of)

2011-11-15

A new capacitance formula for the practical design and characterization of quadrupolar electrode arrays with capacitive structures was derived based on the reciprocal theorem. The reciprocity-based capacitance formula agreed with the empirical equations established to estimate the capacitance of a single strip line or disk electrode compensating for the fringing field effect that occurs at the electrode edge. The reciprocity-based formula was applied to compute the capacitance measurable by using a quadrupolar square electrode array with a symmetric dipole-dipole configuration and was compared with the analytical equation established based on the image method assuming that the electrodes were points. The results showed that the capacitance of the quadrupolar electrodes was determined by the size of the quadrupolar electrodes relative to the separation distance between the electrodes and that the reciprocity-based capacitance formula was in agreement with the established analytical equation if the separated distance between the electrodes relative to the electrode size was large enough.

A reciprocity-based formula for the capacitance with quadrupolar electrodes

International Nuclear Information System (INIS)

Cho, Sungbo

2011-01-01

A new capacitance formula for the practical design and characterization of quadrupolar electrode arrays with capacitive structures was derived based on the reciprocal theorem. The reciprocity-based capacitance formula agreed with the empirical equations established to estimate the capacitance of a single strip line or disk electrode compensating for the fringing field effect that occurs at the electrode edge. The reciprocity-based formula was applied to compute the capacitance measurable by using a quadrupolar square electrode array with a symmetric dipole-dipole configuration and was compared with the analytical equation established based on the image method assuming that the electrodes were points. The results showed that the capacitance of the quadrupolar electrodes was determined by the size of the quadrupolar electrodes relative to the separation distance between the electrodes and that the reciprocity-based capacitance formula was in agreement with the established analytical equation if the separated distance between the electrodes relative to the electrode size was large enough.

Negative electrodes for Na-ion batteries.

Science.gov (United States)

Dahbi, Mouad; Yabuuchi, Naoaki; Kubota, Kei; Tokiwa, Kazuyasu; Komaba, Shinichi

2014-08-07

Research interest in Na-ion batteries has increased rapidly because of the environmental friendliness of sodium compared to lithium. Throughout this Perspective paper, we report and review recent scientific advances in the field of negative electrode materials used for Na-ion batteries. This paper sheds light on negative electrode materials for Na-ion batteries: carbonaceous materials, oxides/phosphates (as sodium insertion materials), sodium alloy/compounds and so on. These electrode materials have different reaction mechanisms for electrochemical sodiation/desodiation processes. Moreover, not only sodiation-active materials but also binders, current collectors, electrolytes and electrode/electrolyte interphase and its stabilization are essential for long cycle life Na-ion batteries. This paper also addresses the prospect of Na-ion batteries as low-cost and long-life batteries with relatively high-energy density as their potential competitive edge over the commercialized Li-ion batteries.

Electrode placement during electro-desalination of

DEFF Research Database (Denmark)

Ottosen, Lisbeth M.; Andersson, Lovisa C. H.

2017-01-01

Carved stone sculptures and ornaments can be severely damaged by salt induced decay. Often the irregular surfaces are decomposed, and the artwork is lost. The present paper is an experimental investigation on the possibility for using electro-desalination for treatment of stone with irregular shape....... Electro-desalination experiments were made with different duration to follow the progress. Successful desalination of the whole stone piece was obtained, showing that also parts not being placed directly between the electrodes were desalinated. This is important in case of salt damaged carved stones......, where the most fragile parts thus can be desalinated without physically placing electrodes on them. The Cl removal rate was higher in the areas closest to the electrodes and slowest in the part, which was not placed directly between the electrodes. This is important to incorporate in the monitoring...

Cu mesh for flexible transparent conductive electrodes.

Science.gov (United States)

Kim, Won-Kyung; Lee, Seunghun; Hee Lee, Duck; Hee Park, In; Seong Bae, Jong; Woo Lee, Tae; Kim, Ji-Young; Hun Park, Ji; Chan Cho, Yong; Ryong Cho, Chae; Jeong, Se-Young

2015-06-03

Copper electrodes with a micromesh/nanomesh structure were fabricated on a polyimide substrate using UV lithography and wet etching to produce flexible transparent conducting electrodes (TCEs). Well-defined mesh electrodes were realized through the use of high-quality Cu thin films. The films were fabricated using radio-frequency (RF) sputtering with a single-crystal Cu target--a simple but innovative approach that overcame the low oxidation resistance of ordinary Cu. Hybrid Cu mesh electrodes were fabricated by adding a capping layer of either ZnO or Al-doped ZnO. The sheet resistance and the transmittance of the electrode with an Al-doped ZnO capping layer were 6.197 ohm/sq and 90.657%, respectively, and the figure of merit was 60.502 × 10(-3)/ohm, which remained relatively unchanged after thermal annealing at 200 °C and 1,000 cycles of bending. This fabrication technique enables the mass production of large-area flexible TCEs, and the stability and high performance of Cu mesh hybrid electrodes in harsh environments suggests they have strong potential for application in smart displays and solar cells.

Removal of suspended solids and turbidity from marble processing wastewaters by electrocoagulation: Comparison of electrode materials and electrode connection systems

Energy Technology Data Exchange (ETDEWEB)

Solak, Murat [Duezce University, Kaynasli Vocational School, Environmental Protection and Control Department, 81900 Duezce (Turkey); Kilic, Mehmet, E-mail: kavi@mmf.sdu.edu.tr [Sueleyman Demirel University, Engineering and Architecture Faculty, Environmental Engineering Department, 32260 Isparta (Turkey); Hueseyin, Yazici; Sencan, Aziz [Sueleyman Demirel University, Engineering and Architecture Faculty, Environmental Engineering Department, 32260 Isparta (Turkey)

2009-12-15

In this study, removal of suspended solids (SS) and turbidity from marble processing wastewaters by electrocoagulation (EC) process were investigated by using aluminium (Al) and iron (Fe) electrodes which were run in serial and parallel connection systems. To remove these pollutants from the marble processing wastewater, an EC reactor including monopolar electrodes (Al/Fe) in parallel and serial connection system, was utilized. Optimization of differential operation parameters such as pH, current density, and electrolysis time on SS and turbidity removal were determined in this way. EC process with monopolar Al electrodes in parallel and serial connections carried out at the optimum conditions where the pH value was 9, current density was approximately 15 A/m{sup 2}, and electrolysis time was 2 min resulted in 100% SS removal. Removal efficiencies of EC process for SS with monopolar Fe electrodes in parallel and serial connection were found to be 99.86% and 99.94%, respectively. Optimum parameters for monopolar Fe electrodes in both of the connection types were found to be for pH value as 8, for electrolysis time as 2 min. The optimum current density value for Fe electrodes used in serial and parallel connections was also obtained at 10 and 20 A/m{sup 2}, respectively. Based on the results obtained, it was found that EC process running with each type of the electrodes and the connections was highly effective for the removal of SS and turbidity from marble processing wastewaters, and that operating costs with monopolar Al electrodes in parallel connection were the cheapest than that of the serial connection and all the configurations for Fe electrode.

Removal of suspended solids and turbidity from marble processing wastewaters by electrocoagulation: Comparison of electrode materials and electrode connection systems

International Nuclear Information System (INIS)

Solak, Murat; Kilic, Mehmet; Hueseyin, Yazici; Sencan, Aziz

2009-01-01

In this study, removal of suspended solids (SS) and turbidity from marble processing wastewaters by electrocoagulation (EC) process were investigated by using aluminium (Al) and iron (Fe) electrodes which were run in serial and parallel connection systems. To remove these pollutants from the marble processing wastewater, an EC reactor including monopolar electrodes (Al/Fe) in parallel and serial connection system, was utilized. Optimization of differential operation parameters such as pH, current density, and electrolysis time on SS and turbidity removal were determined in this way. EC process with monopolar Al electrodes in parallel and serial connections carried out at the optimum conditions where the pH value was 9, current density was approximately 15 A/m 2 , and electrolysis time was 2 min resulted in 100% SS removal. Removal efficiencies of EC process for SS with monopolar Fe electrodes in parallel and serial connection were found to be 99.86% and 99.94%, respectively. Optimum parameters for monopolar Fe electrodes in both of the connection types were found to be for pH value as 8, for electrolysis time as 2 min. The optimum current density value for Fe electrodes used in serial and parallel connections was also obtained at 10 and 20 A/m 2 , respectively. Based on the results obtained, it was found that EC process running with each type of the electrodes and the connections was highly effective for the removal of SS and turbidity from marble processing wastewaters, and that operating costs with monopolar Al electrodes in parallel connection were the cheapest than that of the serial connection and all the configurations for Fe electrode.

Removal of suspended solids and turbidity from marble processing wastewaters by electrocoagulation: comparison of electrode materials and electrode connection systems.

Science.gov (United States)

Solak, Murat; Kiliç, Mehmet; Hüseyin, Yazici; Sencan, Aziz

2009-12-15

In this study, removal of suspended solids (SS) and turbidity from marble processing wastewaters by electrocoagulation (EC) process were investigated by using aluminium (Al) and iron (Fe) electrodes which were run in serial and parallel connection systems. To remove these pollutants from the marble processing wastewater, an EC reactor including monopolar electrodes (Al/Fe) in parallel and serial connection system, was utilized. Optimization of differential operation parameters such as pH, current density, and electrolysis time on SS and turbidity removal were determined in this way. EC process with monopolar Al electrodes in parallel and serial connections carried out at the optimum conditions where the pH value was 9, current density was approximately 15 A/m(2), and electrolysis time was 2 min resulted in 100% SS removal. Removal efficiencies of EC process for SS with monopolar Fe electrodes in parallel and serial connection were found to be 99.86% and 99.94%, respectively. Optimum parameters for monopolar Fe electrodes in both of the connection types were found to be for pH value as 8, for electrolysis time as 2 min. The optimum current density value for Fe electrodes used in serial and parallel connections was also obtained at 10 and 20 A/m(2), respectively. Based on the results obtained, it was found that EC process running with each type of the electrodes and the connections was highly effective for the removal of SS and turbidity from marble processing wastewaters, and that operating costs with monopolar Al electrodes in parallel connection were the cheapest than that of the serial connection and all the configurations for Fe electrode.

Optically Transparent Thin-Film Electrode Chip for Spectroelectrochemical Sensing

Energy Technology Data Exchange (ETDEWEB)

Branch, Shirmir D.; Lines, Amanda M.; Lynch, John A.; Bello, Job M.; Heineman, William R.; Bryan, Samuel A.

2017-07-03

The electrochemical and spectroelectrochemical applications of an optically transparent thin film electrode chip are investigated. The working electrode is composed of indium tin oxide (ITO); the counter and quasi-reference electrodes are composed of platinum. The stability of the platinum quasi-reference electrode is modified by coating it with a planar, solid state Ag/AgCl layer. The Ag/AgCl reference is characterized with scanning electron microscopy and energy-dispersive X-ray spectroscopy. Open circuit potential measurements indicate that the potential of the planar Ag/AgCl electrode varies a maximum of 20 mV over four days. Cyclic voltammetry measurements show that the electrode chip is comparable to a standard electrochemical cell. Randles-Sevcik analysis of 10 mM K3[Fe(CN)6] in 0.1 M KCl using the electrode chip shows a diffusion coefficient of 1.59 × 10-6 cm2/s, in comparison to the standard electrochemical cell value of 2.38 × 10-6 cm2/s. By using the electrode chip in an optically transparent thin layer electrode (OTTLE), the spectroelectrochemical modulation of [Ru(bpy)3]2+ florescence was demonstrated, achieving a detection limit of 36 nM.

Carbon aerogel electrodes for direct energy conversion

Science.gov (United States)

Mayer, Steven T.; Kaschmitter, James L.; Pekala, Richard W.

1997-01-01

A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome.

High Speed, Low Cost Fabrication of Gas Diffusion Electrodes for Membrane Electrode Assemblies

Energy Technology Data Exchange (ETDEWEB)

DeCastro, Emory S.; Tsou, Yu-Min; Liu, Zhenyu

2013-09-20

Fabrication of membrane electrode assemblies (MEAs) depends on creating inks or pastes of catalyst and binder, and applying this suspension to either the membrane (catalyst coated membrane) or gas diffusion media (gas diffusion electrode) and respectively laminating either gas diffusion media or gas diffusion electrodes (GDEs) to the membrane. One barrier to cost effective fabrication for either of these approaches is the development of stable and consistent suspensions. This program investigated the fundamental forces that destabilize the suspensions and developed innovative approaches to create new, highly stable formulations. These more concentrated formulations needed fewer application passes, could be coated over longer and wider substrates, and resulted in significantly lower coating defects. In March of 2012 BASF Fuel Cell released a new high temperature product based on these advances, whereby our customers received higher performing, more uniform MEAs resulting in higher stack build yields. Furthermore, these new materials resulted in an “instant” increase in capacity due to higher product yields and material throughput. Although not part of the original scope of this program, these new formulations have also led us to materials that demonstrate equivalent performance with 30% less precious metal in the anode. This program has achieved two key milestones in DOE’s Manufacturing R&D program: demonstration of processes for direct coating of electrodes and continuous in-line measurement for component fabrication.

Porous electrode preparation method

Science.gov (United States)

Arons, R.M.; Dusek, J.T.

1983-10-18

A porous sintered plaque is provided with a bimodal porosity that is especially well suited for use as an electrode within a molten carbonate fuel cell. The coarse porosity is sufficient for admitting gases into contact with the reaction surfaces while the fine porosity is wetted with and retains molten electrolyte on the reaction sites. The electrode structure is prepared by providing a very fine powder of such as nickel oxide and blending the powder with a suitable decomposable binder to form a solid mass. The mass is comminuted into agglomerate size particles substantially larger than the fine oxide particles and formed into a cohesive compact for subsequent sintering. Sintering is carried out at sufficient conditions to bind the agglomerates together into a porous structure having both coarse and fine porosity. Where lithiated nickel oxide cathodes are prepared, the sintering conditions can be moderate enough to retain substantial quantities of lithium within the electrode for adequate conductivity. 2 figs.

Etching holes in graphene supercapacitor electrodes for faster performance

International Nuclear Information System (INIS)

Ervin, Matthew H

2015-01-01

Graphene is being widely investigated as a material to replace activated carbon in supercapacitor (electrochemical capacitor) electrodes. Supercapacitors have much higher energy density, but are typically slow devices (∼0.1 Hz) compared to other types of capacitors. Here, top-down semiconductor processing has been applied to graphene-based electrodes in order to fabricate ordered arrays of holes through the graphene electrodes. This is demonstrated to increase the speed of the electrodes by reducing the ionic impedance through the electrode thickness. This approach may also be applicable to speeding up other types of devices, such as batteries and sensors, that use porous electrodes. (special)

Organic light emitting diode with light extracting electrode

Energy Technology Data Exchange (ETDEWEB)

Bhandari, Abhinav; Buhay, Harry

2017-04-18

An organic light emitting diode (10) includes a substrate (20), a first electrode (12), an emissive active stack (14), and a second electrode (18). At least one of the first and second electrodes (12, 18) is a light extracting electrode (26) having a metallic layer (28). The metallic layer (28) includes light scattering features (29) on and/or in the metallic layer (28). The light extracting features (29) increase light extraction from the organic light emitting diode (10).

Dependence of hydrogen arcjet operation on electrode geometry

Science.gov (United States)

Pencil, Eric J.; Sankovic, John M.; Sarmiento, Charles J.; Hamley, John A.

1992-01-01

The dependence of 2kW hydrogen arcjet performance on cathode to anode electrode spacing was evaluated at specific impulses of 900 and 1000 s. Less than 2 absolute percent change in efficiency was measured for the spacings tested which did not repeat the 14 absolute percent variation reported in earlier work with similar electrode designs. A different nozzle configuration was used to quantify the variation in hydrogen arcjet performance over an extended range of electrode spacing. Electrode gap variation resulted in less than 3 absolute percent change in efficiency. These null results suggested that electrode spacing is decoupled from hydrogen arcjet ignition. The dependence of breakdown voltage on mass flow rate and electrode agreed with Paschen curves for hydrogen. Preliminary characterization of the dependence of hydrogen arcjet ignition on rates of pulse repetition and pulse voltage rise were also included for comparison with previous results obtained using simulated hydrazine.

EDTA modified glassy carbon electrode: Preparation and characterization

International Nuclear Information System (INIS)

Ustuendag, Zafer; Solak, Ali Osman

2009-01-01

EDTA-phenoxyamide modified glassy carbon electrode (EDTA-GC) was prepared at a glassy carbon electrode by surface synthesis. In the first step, nitrophenyl was grafted to the glassy carbon (GC) surface via the electrochemical reduction of its tetraflouroborate diazonium salt. In the second step, nitrophenyl-modified electrode (NP-GC) was subjected to the cathodic potential scan to reduce the nitro to amine group. p-Aminophenyl modified glassy carbon electrode (AP-GC) was dipped into a EDTA solution containing 1-ethyl-3(3-(dimethlyamino)propyl)-carbodiimide (EDC) as an activating agent. Thus formed ((2-anilino-2-oxoethyl){2-[bis(carboxymethyl)amino]-ethyl}amino)acetic acid modified GC electrode was denoted as EDTA-GC and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), ellipsometry and X-ray photoelectron spectroscopy (XPS). Complexation of the EDTA-GC surface with Pb 2+ ions was investigated if this electrode could be used as a metal sensor.

Cleaved-edge-overgrowth nanogap electrodes

Energy Technology Data Exchange (ETDEWEB)

Luber, Sebastian M; Bichler, Max; Abstreiter, Gerhard; Tornow, Marc, E-mail: m.tornow@tu-bs.de [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall, 85748 Garching (Germany)

2011-02-11

We present a method to fabricate multiple metal nanogap electrodes of tailored width and distance in parallel, on the cleaved plane of a GaAs/AlGaAs heterostructure. The three-dimensional patterned structures are obtained by a combination of molecular-beam-epitaxial regrowth on a crystal facet, using the cleaved-edge-overgrowth (CEO) method, and subsequent wet selective etching and metallization steps. SEM and AFM studies reveal smooth and co-planar electrodes of width and distance of the order of 10 nm. Preliminary electrical characterization indicates electrical gap insulation in the 100 M{Omega} range with k{Omega} lead resistance. We propose our methodology to realize multiple electrode geometries that would allow investigation of the electrical conductivity of complex nanoscale objects such as branched organic molecules.

Cleaved-edge-overgrowth nanogap electrodes.

Science.gov (United States)

Luber, Sebastian M; Bichler, Max; Abstreiter, Gerhard; Tornow, Marc

2011-02-11

We present a method to fabricate multiple metal nanogap electrodes of tailored width and distance in parallel, on the cleaved plane of a GaAs/AlGaAs heterostructure. The three-dimensional patterned structures are obtained by a combination of molecular-beam-epitaxial regrowth on a crystal facet, using the cleaved-edge-overgrowth (CEO) method, and subsequent wet selective etching and metallization steps. SEM and AFM studies reveal smooth and co-planar electrodes of width and distance of the order of 10 nm. Preliminary electrical characterization indicates electrical gap insulation in the 100 MΩ range with kΩ lead resistance. We propose our methodology to realize multiple electrode geometries that would allow investigation of the electrical conductivity of complex nanoscale objects such as branched organic molecules.

Graphene-based transparent electrodes for hybrid solar cells

Directory of Open Access Journals (Sweden)

Pengfei eLi

2014-11-01

Full Text Available The graphene-based transparent and conductive films were demonstrated to be cost-effective electrodes working in organic-inorganic hybrid Schottky solar cells. Large area graphene films were produced by chemical vapor deposition (CVD on copper foils and transferred onto glass as transparent electrodes. The hybrid solar cell devices consist of solution processed poly (3, 4-ethlenedioxythiophene: poly (styrenesulfonate (PEDOT: PSS which is sandwiched between silicon wafer and graphene electrode. The solar cells based on graphene electrodes, especially those doped with HNO3, has comparable performance to the reference devices using commercial indium tin oxide (ITO. Our work suggests that graphene-based transparent electrode is a promising candidate to replace ITO.

Ferrocene-functionalized graphene electrode for biosensing applications

Energy Technology Data Exchange (ETDEWEB)

Rabti, Amal [Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona (Spain); Université de Tunis El–Manar, Faculté des Sciences de Tunis, Laboratoire de Chimie Analytique et Electrochimie (LR99ES15), Campus universitaire de Tunis El–Manar, 2092, Tunis (Tunisia); Mayorga-Martinez, Carmen C.; Baptista-Pires, Luis [Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona (Spain); Raouafi, Noureddine, E-mail: n.raouafi@fst.rnu.tn [Université de Tunis El–Manar, Faculté des Sciences de Tunis, Laboratoire de Chimie Analytique et Electrochimie (LR99ES15), Campus universitaire de Tunis El–Manar, 2092, Tunis (Tunisia); Merkoçi, Arben, E-mail: arben.merkoci@icn2.cat [Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona (Spain); ICREA, Barcelona, Catalonia (Spain)

2016-07-05

A novel ferrocene-functionalized reduced graphene oxide (rGO)-based electrode is proposed. It was fabricated by the drop casting of ferrocene-functionalized graphene onto polyester substrate as the working electrode integrated within screen-printed reference and counter electrodes. The ferrocene-functionalized rGO has been fully characterized using FTIR, XPS, contact angle measurements, SEM and TEM microscopy, and cyclic voltammetry. The XPS and EDX analysis showed the presence of Fe element related to the introduced ferrocene groups, which is confirmed by a clear CV signal at ca. 0.25 V vs. Ag/AgCl (0.1 KCl). Mediated redox catalysis of H{sub 2}O{sub 2} and bio-functionalization with glucose oxidase for glucose detection were achieved by the bioelectrode providing a proof for potential biosensing applications. - Graphical abstract: An easy-to-prepare standalone graphene electrode was obtained by the drop-casting ferrocene-functionalized rGO on PET polymer. This electrode can be used as an enzymeless electrochemical sensor for the detection of hydrogen peroxide or as an amperometric enzyme-based biosensor for sensitive glucose detection. - Highlights: • A novel ferrocene-functionalized reduced graphene oxide based electrode. • Ease of preparation by drop-casting of Fc-modified graphene and chitosan mixture. • Well-defined and exploitable ferrocene CV signal for sensing purposes. • Sensitive enzymeless detection of hydrogen peroxide at low potentials. • Enzymatic Sensitive detection of glucose on GOx-modified graphene electrode.

Faradic resistance of the electrode/electrolyte interface.

Science.gov (United States)

Mayer, S; Geddes, L A; Bourland, J D; Ogborn, L

1992-09-01

A new method is used to measure the direct-current (Faradic) resistance of a single electrode/electrolyte interface. The method employs a constant-current pulse and a potential-sensing electrode. By choosing a sufficiently long pulse duration, the voltage between the test and potential-sensing electrode exhibits a three-phase response. In the steady-state phase, the voltage measured is equal to the current flowing through the electrode Faradic resistance and the resistance of the electrolyte between the test and potential-sensing electrode. By measuring this latter resistance with a high-frequency sinusoidal alternating current, the voltage drop in the electrolyte is calculated and subtracted from the voltage measured between the test and potential-sensing electrode, thereby allowing calculation of the Faradic resistance. By plotting the reciprocal of the Faradic resistance against current density and fitting the data points to a third-order polynomial, it is possible to determine the zero-current density (Faradic) resistance. This technique was used to determine the Faradic resistance of electrodes (0.1 cm2) of stainless-steel, platinum, platinum-iridium and rhodium in 0.9 per cent NaCl at 25 degrees. The zero current Faradic resistance is lowest for platinum (30.3 k omega), slightly higher for platinum-iridium (47.6k omega), much higher for rhodium (111k omega) and highest for type 316 stainless-steel (345k omega). In all cases, the Faradic resistance decreases dramatically with increasing current density.

Organic Photovoltaic Structures as Photo-active Electrodes

International Nuclear Information System (INIS)

Gustafson, Matthew P.; Clark, Noel; Winther-Jensen, Bjorn; MacFarlane, Douglas R.

2014-01-01

This study demonstrated the novel use of a bulk heterojunction (BHJ), as present in modern organic solar cells, as a light-assisted electrocatalyst for water electrolysis reactions. Two separate organic photo-voltaic electrode structures were designed for targeting both the reduction, (ITO-PET/PEDOT:PSS/P3HT:PCBM)* and oxidation, (ITO-PET/ZnO/P3HT:PCBM)* reactions of water, denoted as OPE-R and OPE-O respectively. The OPE-R electrode supported both the proton reduction reaction (PRR) and oxygen reduction reaction (ORR) achieving photocurrents of -0.04 mAcm −2 (ORR) and -0.03 mAcm −2 (PRR) and a photovoltage of 0.50 V (ORR) and onset photovoltage at -0.59 V (PRR). By comparison, the OPE-O electrode achieved photocurrents of 0.15 mAcm −2 and photovoltages of 0.35 V for the water oxidation reaction (WOR). Both BHJ designs confirmed evidence of photo-enhanced Bulk Heterojunction Electrode (BHE) activity. The stability and sources of electrode degradation were also studied, with the OPE-O electrode proving to be more stable than the OPE-R electrode, most likely due to the PEDOT:PSS layer and PSS migration in the presence of water. *Indium Tin Oxide (ITO), Polyethylene Terephthalate (PET), Poly(3,4-ethylenedioxythiophene) (PEDOT), Polystyrenesulfonate acid (PSS), Poly(3-hexylthiophene) (P3HT), Phenyl-C 61 -Butyric acid Methyl ester (PCBM), Zinc Oxide (ZnO)

Ferrocene-functionalized graphene electrode for biosensing applications

International Nuclear Information System (INIS)

Rabti, Amal; Mayorga-Martinez, Carmen C.; Baptista-Pires, Luis; Raouafi, Noureddine; Merkoçi, Arben

2016-01-01

A novel ferrocene-functionalized reduced graphene oxide (rGO)-based electrode is proposed. It was fabricated by the drop casting of ferrocene-functionalized graphene onto polyester substrate as the working electrode integrated within screen-printed reference and counter electrodes. The ferrocene-functionalized rGO has been fully characterized using FTIR, XPS, contact angle measurements, SEM and TEM microscopy, and cyclic voltammetry. The XPS and EDX analysis showed the presence of Fe element related to the introduced ferrocene groups, which is confirmed by a clear CV signal at ca. 0.25 V vs. Ag/AgCl (0.1 KCl). Mediated redox catalysis of H_2O_2 and bio-functionalization with glucose oxidase for glucose detection were achieved by the bioelectrode providing a proof for potential biosensing applications. - Graphical abstract: An easy-to-prepare standalone graphene electrode was obtained by the drop-casting ferrocene-functionalized rGO on PET polymer. This electrode can be used as an enzymeless electrochemical sensor for the detection of hydrogen peroxide or as an amperometric enzyme-based biosensor for sensitive glucose detection. - Highlights: • A novel ferrocene-functionalized reduced graphene oxide based electrode. • Ease of preparation by drop-casting of Fc-modified graphene and chitosan mixture. • Well-defined and exploitable ferrocene CV signal for sensing purposes. • Sensitive enzymeless detection of hydrogen peroxide at low potentials. • Enzymatic Sensitive detection of glucose on GOx-modified graphene electrode.

Diffuse charge and Faradaic reactions in porous electrodes

NARCIS (Netherlands)

Biesheuvel, P.M.; Yu, F.; Bazant, M.Z.

2011-01-01

Porous electrodes instead of flat electrodes are widely used in electrochemical systems to boost storage capacities for ions and electrons, to improve the transport of mass and charge, and to enhance reaction rates. Existing porous electrode theories make a number of simplifying assumptions: (i) The

21 CFR 870.3720 - Pacemaker electrode function tester.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker electrode function tester. 870.3720... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3720 Pacemaker electrode function tester. (a) Identification. A pacemaker electrode function tester is a device which is...

The standardized EEG electrode array of the IFCN.

Science.gov (United States)

Seeck, Margitta; Koessler, Laurent; Bast, Thomas; Leijten, Frans; Michel, Christoph; Baumgartner, Christoph; He, Bin; Beniczky, Sándor

2017-10-01

Standardized EEG electrode positions are essential for both clinical applications and research. The aim of this guideline is to update and expand the unifying nomenclature and standardized positioning for EEG scalp electrodes. Electrode positions were based on 20% and 10% of standardized measurements from anatomical landmarks on the skull. However, standard recordings do not cover the anterior and basal temporal lobes, which is the most frequent source of epileptogenic activity. Here, we propose a basic array of 25 electrodes including the inferior temporal chain, which should be used for all standard clinical recordings. The nomenclature in the basic array is consistent with the 10-10-system. High-density scalp EEG arrays (64-256 electrodes) allow source imaging with even sub-lobar precision. This supplementary exam should be requested whenever necessary, e.g. search for epileptogenic activity in negative standard EEG or for presurgical evaluation. In the near future, nomenclature for high density electrodes arrays beyond the 10-10 system needs to be defined, to allow comparison and standardized recordings across centers. Contrary to the established belief that smaller heads needs less electrodes, in young children at least as many electrodes as in adults should be applied due to smaller skull thickness and the risk of spatial aliasing. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Coaxial fiber supercapacitor using all-carbon material electrodes.

Science.gov (United States)

Le, Viet Thong; Kim, Heetae; Ghosh, Arunabha; Kim, Jaesu; Chang, Jian; Vu, Quoc An; Pham, Duy Tho; Lee, Ju-Hyuck; Kim, Sang-Woo; Lee, Young Hee

2013-07-23

We report a coaxial fiber supercapacitor, which consists of carbon microfiber bundles coated with multiwalled carbon nanotubes as a core electrode and carbon nanofiber paper as an outer electrode. The ratio of electrode volumes was determined by a half-cell test of each electrode. The capacitance reached 6.3 mF cm(-1) (86.8 mF cm(-2)) at a core electrode diameter of 230 μm and the measured energy density was 0.7 μWh cm(-1) (9.8 μWh cm(-2)) at a power density of 13.7 μW cm(-1) (189.4 μW cm(-2)), which were much higher than the previous reports. The change in the cyclic voltammetry characteristics was negligible at 180° bending, with excellent cycling performance. The high capacitance, high energy density, and power density of the coaxial fiber supercapacitor are attributed to not only high effective surface area due to its coaxial structure and bundle of the core electrode, but also all-carbon materials electrodes which have high conductivity. Our coaxial fiber supercapacitor can promote the development of textile electronics in near future.

Flexible Graphene Electrodes for Prolonged Dynamic ECG Monitoring

Directory of Open Access Journals (Sweden)

Cunguang Lou

2016-11-01

Full Text Available This paper describes the development of a graphene-based dry flexible electrocardiography (ECG electrode and a portable wireless ECG measurement system. First, graphene films on polyethylene terephthalate (PET substrates and graphene paper were used to construct the ECG electrode. Then, a graphene textile was synthesized for the fabrication of a wearable ECG monitoring system. The structure and the electrical properties of the graphene electrodes were evaluated using Raman spectroscopy, scanning electron microscopy (SEM, and alternating current impedance spectroscopy. ECG signals were then collected from healthy subjects using the developed graphene electrode and portable measurement system. The results show that the graphene electrode was able to acquire the typical characteristics and features of human ECG signals with a high signal-to-noise (SNR ratio in different states of motion. A week-long continuous wearability test showed no degradation in the ECG signal quality over time. The graphene-based flexible electrode demonstrates comfortability, good biocompatibility, and high electrophysiological detection sensitivity. The graphene electrode also combines the potential for use in long-term wearable dynamic cardiac activity monitoring systems with convenience and comfort for use in home health care of elderly and high-risk adults.

Low-cost electrodes for stable perovskite solar cells

Science.gov (United States)

Bastos, João P.; Manghooli, Sara; Jaysankar, Manoj; Tait, Jeffrey G.; Qiu, Weiming; Gehlhaar, Robert; De Volder, Michael; Uytterhoeven, Griet; Poortmans, Jef; Paetzold, Ulrich W.

2017-06-01

Cost-effective production of perovskite solar cells on an industrial scale requires the utilization of exclusively inexpensive materials. However, to date, highly efficient and stable perovskite solar cells rely on expensive gold electrodes since other metal electrodes are known to cause degradation of the devices. Finding a low-cost electrode that can replace gold and ensure both efficiency and long-term stability is essential for the success of the perovskite-based solar cell technology. In this work, we systematically compare three types of electrode materials: multi-walled carbon nanotubes (MWCNTs), alternative metals (silver, aluminum, and copper), and transparent oxides [indium tin oxide (ITO)] in terms of efficiency, stability, and cost. We show that multi-walled carbon nanotubes are the only electrode that is both more cost-effective and stable than gold. Devices with multi-walled carbon nanotube electrodes present remarkable shelf-life stability, with no decrease in the efficiency even after 180 h of storage in 77% relative humidity (RH). Furthermore, we demonstrate the potential of devices with multi-walled carbon nanotube electrodes to achieve high efficiencies. These developments are an important step forward to mass produce perovskite photovoltaics in a commercially viable way.

Nanometer-spaced electrodes with calibrated separation

NARCIS (Netherlands)

Kervennic, Y.V.; Van der Zant, H.S.J.; Morpurgo, A.F.; Gurevich, L.; Kouwenhoven, L.P.

2002-01-01

We have fabricated pairs of platinum electrodes with separation between 20 and 3.5 nm. Our technique combines electron beam lithography and chemical electrodeposition. We show that the measurement of the conductance between the two electrodes through the electrolyte provides an accurate and

Nanostructured ternary electrodes for energy-storage applications

KAUST Repository

Baby, Rakhi Raghavan

2012-02-13

A three-component, flexible electrode is developed for supercapacitors over graphitized carbon fabric, utilizing γ-MnO 2 nanoflowers anchored onto carbon nanotubes (γ-MnO 2/CNT) as spacers for graphene nanosheets (GNs). The three-component, composite electrode doubles the specific capacitance with respect to GN-only electrodes, giving the highest-reported specific capacitance (308 F g -1) for symmetric supercapacitors containing MnO 2 and GNs using a two-electrode configuration, at a scan rate of 20 mV s -1. A maximum energy density of 43 W h kg -1 is obtained for our symmetric supercapacitors at a constant discharge-current density of 2.5 A g -1 using GN-(γ-MnO 2/CNT)-nanocomposite electrodes. The fabricated supercapacitor device exhibits an excellent cycle life by retaining ≈90% of the initial specific capacitance after 5000 cycles. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thickness shear mode quartz crystal resonators with optimized elliptical electrodes

International Nuclear Information System (INIS)

Ma Ting-Feng; Feng Guan-Ping; Zhang Chao; Jiang Xiao-Ning

2011-01-01

Quartz crystal resonators (QCRs) with circular electrodes have been widely used for various liquid and gas sensing applications. In this work, quartz crystal resonators with elliptical electrodes were studied and tested for liquid property measurement. Mindlin's theory was used to optimize the dimension and geometry of the electrodes and a 5-MHz QCR with minimum series resistance and without any spurious modes was obtained. A series of AT-cut QCRs with elliptical electrodes of different sizes were fabricated and their sensing performances were compared to devices with circular electrodes. The experimental result shows that the device with elliptical electrodes can obtain lower resonance impedance and a higher Q factor, which results in a better loading capability. Even though the sensitivities of devices with elliptical and circular electrodes are found to be similar, the sensor with elliptical electrodes has much higher resolution due to a better frequency stability. The study indicates that the performance of QCRs with elliptical electrodes is superior to that of traditional QCRs with circular electrodes. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Investigation of Imbalanced Activated Carbon Electrode Supercapacitors

OpenAIRE

Tieshi He; Xue Ren; Junping Nie; Jun Ying; Kedi Cai

2015-01-01

Imbalanced supercapacitor was constructed by using various ratio of activated carbon (AC) of positive to negative electrode. The electrochemical behavior of imbalanced supercapacitor was investigated using 1.0 M spiro-(1,1′)-bipyrrolidinium tetrafluoroborate electrolyte in propylene carbonate. The results showed that there are some factors that influenced the imbalanced supercapacitor with different AC ratio of positive to negative electrode, the utilization of AC, electrode potential distrib...

Anodized Steel Electrodes for Supercapacitors.

Science.gov (United States)

Sagu, Jagdeep S; Wijayantha, K G Upul; Bohm, Mallika; Bohm, Siva; Kumar Rout, Tapan

2016-03-09

Steel was anodized in 10 M NaOH to enhance its surface texture and internal surface area for application as an electrode in supercapacitors. A mechanism was proposed for the anodization process. Field-emission gun scanning electron microscopy (FEGSEM) studies of anodized steel revealed that it contains a highly porous sponge like structure ideal for supercapacitor electrodes. X-ray photoelectron spectroscopy (XPS) measurements showed that the surface of the anodized steel was Fe2O3, whereas X-ray diffraction (XRD) measurements indicated that the bulk remained as metallic Fe. The supercapacitor performance of the anodized steel was tested in 1 M NaOH and a capacitance of 18 mF cm(-2) was obtained. Cyclic voltammetry measurements showed that there was a large psueudocapacitive contribution which was due to oxidation of Fe to Fe(OH)2 and then further oxidation to FeOOH, and the respective reduction of these species back to metallic Fe. These redox processes were found to be remarkably reversible as the electrode showed no loss in capacitance after 10000 cycles. The results demonstrate that anodization of steel is a suitable method to produce high-surface-area electrodes for supercapacitors with excellent cycling lifetime.

Tests of the presampler electrodes for module 0

CERN Document Server

Belymam, A; Hoummada, A; Lund-Jensen, B

2000-01-01

The ATLAS presampler will be composed of approximately 90000 printed circuit board electrodes. These electrodes need to be tested to verify that they are whithin the tight thickness and size tolerances required by the module production technique. For the 3-layer anode electrodes a measurement of the electrical properties is required. A testbench to automatize these electrical measurements has been developed at KTH. This note presents the results obtained from measurements of thickness, size and electrical properties of the electrodes for the first series produced sectors, "module 0" . The thickness requirements are well fulfiled on 2-layer cathode electrodes. A large fraction of the 3-layer anode electrodes did not meet the thickness specifications. The reasons for this are identified and several improvements of the manufacturing process are proposed. The quality of the contour cutting of the boards is examined on preseries cut by milling and preseries cut by punching. Measurements show that the precision of ...

EDTA modified glassy carbon electrode: Preparation and characterization

Energy Technology Data Exchange (ETDEWEB)

Ustuendag, Zafer [Dumlupinar University, Faculty of Arts and Sciences, Department of Chemistry, Kuetahya (Turkey); Solak, Ali Osman [Ankara University, Faculty of Science, Department of Chemistry, Degol Street, Tandogan, 06100 Ankara (Turkey)], E-mail: osolak@science.ankara.edu.tr

2009-11-01

EDTA-phenoxyamide modified glassy carbon electrode (EDTA-GC) was prepared at a glassy carbon electrode by surface synthesis. In the first step, nitrophenyl was grafted to the glassy carbon (GC) surface via the electrochemical reduction of its tetraflouroborate diazonium salt. In the second step, nitrophenyl-modified electrode (NP-GC) was subjected to the cathodic potential scan to reduce the nitro to amine group. p-Aminophenyl modified glassy carbon electrode (AP-GC) was dipped into a EDTA solution containing 1-ethyl-3(3-(dimethlyamino)propyl)-carbodiimide (EDC) as an activating agent. Thus formed ((2-anilino-2-oxoethyl){l_brace}2-[bis(carboxymethyl)amino]-ethyl{r_brace}amino)acetic acid modified GC electrode was denoted as EDTA-GC and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), ellipsometry and X-ray photoelectron spectroscopy (XPS). Complexation of the EDTA-GC surface with Pb{sup 2+} ions was investigated if this electrode could be used as a metal sensor.

Hybrid capacitor with activated carbon electrode, Ni(OH){sub 2} electrode and polymer hydrogel electrolyte

Energy Technology Data Exchange (ETDEWEB)

Nohara, Shinji; Asahina, Toshihide; Wada, Hajime; Furukawa, Naoji; Inoue, Hiroshi; Iwakura, Chiaki [Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531 (Japan); Sugoh, Nozomu; Iwasaki, Hideharu [Kurashiki Research Laboratory, Kuraray Co., Ltd., 2045-1 Sakazu, Kurashiki, Okayama 710-8691 (Japan)

2006-06-19

A new hybrid capacitor (HC) cell was assembled using an activated carbon (AC) negative electrode, an Ni(OH){sub 2} positive electrode and a polymer hydrogel electrolyte prepared from crosslinked potassium poly(acrylate) (PAAK) and KOH aqueous solution. The HC cell was characterized compared with an electric double layer capacitor (EDLC) using two AC electrodes and the polymer hydrogel electrolyte. It was found that the HC cell successfully worked in the larger voltage range and exhibited ca. 2.4 times higher capacitance than the EDLC cell. High-rate dischargeability of the HC cell was also superior to that of the EDLC cell. These improved characteristics strongly suggest that the HC cell can be a promising system of capacitors with high energy and power densities. (author)

Offset-electrode profile acquisition strategy for electrical resistivity tomography

Science.gov (United States)

Robbins, Austin R.; Plattner, Alain

2018-04-01

We present an electrode layout strategy that allows electrical resistivity profiles to image the third dimension close to the profile plane. This "offset-electrode profile" approach involves laterally displacing electrodes away from the profile line in an alternating fashion and then inverting the resulting data using three-dimensional electrical resistivity tomography software. In our synthetic and field surveys, the offset-electrode method succeeds in revealing three-dimensional structures in the vicinity of the profile plane, which we could not achieve using three-dimensional inversions of linear profiles. We confirm and explain the limits of linear electrode profiles through a discussion of the three-dimensional sensitivity patterns: For a homogeneous starting model together with a linear electrode layout, all sensitivities remain symmetric with respect to the profile plane through each inversion step. This limitation can be overcome with offset-electrode layouts by breaking the symmetry pattern among the sensitivities. Thanks to freely available powerful three-dimensional resistivity tomography software and cheap modern computing power, the requirement for full three-dimensional calculations does not create a significant burden and renders the offset-electrode approach a cost-effective method. By offsetting the electrodes in an alternating pattern, as opposed to laying the profile out in a U-shape, we minimize shortening the profile length.

Multi-component intermetallic electrodes for lithium batteries

Science.gov (United States)

Thackeray, Michael M; Trahey, Lynn; Vaughey, John T

2015-03-10

Multi-component intermetallic negative electrodes prepared by electrochemical deposition for non-aqueous lithium cells and batteries are disclosed. More specifically, the invention relates to composite intermetallic electrodes comprising two or more compounds containing metallic or metaloid elements, at least one element of which can react with lithium to form binary, ternary, quaternary or higher order compounds, these compounds being in combination with one or more other metals that are essentially inactive toward lithium and act predominantly, but not necessarily exclusively, to the electronic conductivity of, and as current collection agent for, the electrode. The invention relates more specifically to negative electrode materials that provide an operating potential between 0.05 and 2.0 V vs. metallic lithium.

A polyoxovanadate as an advanced electrode material for supercapacitors.

Science.gov (United States)

Chen, Han-Yi; Wee, Grace; Al-Oweini, Rami; Friedl, Jochen; Tan, Kim Soon; Wang, Yuxi; Wong, Chui Ling; Kortz, Ulrich; Stimming, Ulrich; Srinivasan, Madhavi

2014-07-21

Polyoxovanadate Na(6)V(10)O(28) is investigated for the first time as electrode material for supercapacitors (SCs). The electrochemical properties of Na(6)V(10)O(28) electrodes are studied in Li(+) -containing organic electrolyte (1 M LiClO(4) in propylene carbonate) by galvanostatic charge/discharge and cyclic voltammetry in a three-electrode configuration. Na(6)V(10)O(28) electrodes exhibit high specific capacitances of up to 354 F g(-1). An asymmetric SC with activated carbon as positive electrode and Na(6)V(10)O(28) as negative electrode is fabricated and exhibits a high energy density of 73 Wh kg(-1) with a power density of 312 W kg(-1), which successfully demonstrates that Na(6)V(10)O(28) is a promising electrode material for high-energy SC applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low Cost Electrode Assembly for EEG Recordings in Mice

Directory of Open Access Journals (Sweden)

Emily C. Vogler

2017-11-01

Full Text Available Wireless electroencephalography (EEG of small animal subjects typically utilizes miniaturized EEG devices which require a robust recording and electrode assembly that remains in place while also being well-tolerated by the animal so as not to impair the ability of the animal to perform normal living activities or experimental tasks. We developed simple and fast electrode assembly and method of electrode implantation using electrode wires and wire-wrap technology that provides both higher survival and success rates in obtaining recordings from the electrodes than methods using screws as electrodes. The new wire method results in a 51% improvement in the number of electrodes that successfully record EEG signal. Also, the electrode assembly remains affixed and provides EEG signal for at least a month after implantation. Screws often serve as recording electrodes, which require either drilling holes into the skull to insert screws or affixing screws to the surface of the skull with adhesive. Drilling holes large enough to insert screws can be invasive and damaging to brain tissue, using adhesives may interfere with conductance and result in a poor signal, and soldering screws to wire leads results in fragile connections. The methods presented in this article provide a robust implant that is minimally invasive and has a significantly higher success rate of electrode implantation. In addition, the implant remains affixed and produces good recordings for over a month, while using economical, easily obtained materials and skills readily available in most animal research laboratories.

Ni-Based Solid Oxide Cell Electrodes

DEFF Research Database (Denmark)

Mogensen, Mogens Bjerg; Holtappels, Peter

2013-01-01

This paper is a critical review of the literature on nickel-based electrodes for application in solid oxide cells at temperature from 500 to 1000 _C. The applications may be fuel cells or electrolyser cells. The reviewed literature is that of experimental results on both model electrodes...... and practical composite cermet electrodes. A substantially longer three-phase boundary (TPB) can be obtained per unit area of cell in such a composite of nickel and electrolyte material, provided that two interwoven solid networks of the two solid and one gaseous phases are obtained to provide a three...

Stimulating the Comfort of Textile Electrodes in Wearable Neuromuscular Electrical Stimulation

Science.gov (United States)

Zhou, Hui; Lu, Yi; Chen, Wanzhen; Wu, Zhen; Zou, Haiqing; Krundel, Ludovic; Li, Guanglin

2015-01-01

Textile electrodes are becoming an attractive means in the facilitation of surface electrical stimulation. However, the stimulation comfort of textile electrodes and the mechanism behind stimulation discomfort is still unknown. In this study, a textile stimulation electrode was developed using conductive fabrics and then its impedance spectroscopy, stimulation thresholds, and stimulation comfort were quantitatively assessed and compared with those of a wet textile electrode and a hydrogel electrode on healthy subjects. The equivalent circuit models and the finite element models of different types of electrode were built based on the measured impedance data of the electrodes to reveal the possible mechanism of electrical stimulation pain. Our results showed that the wet textile electrode could achieve similar stimulation performance as the hydrogel electrode in motor threshold and stimulation comfort. However, the dry textile electrode was found to have very low pain threshold and induced obvious cutaneous painful sensations during stimulation, in comparison to the wet and hydrogel electrodes. Indeed, the finite element modeling results showed that the activation function along the z direction at the depth of dermis epidermis junction of the dry textile electrode was significantly larger than that of the wet and hydrogel electrodes, thus resulting in stronger activation of pain sensing fibers. Future work will be done to make textile electrodes have similar stimulation performance and comfort as hydrogel electrodes. PMID:26193273

Stimulating the Comfort of Textile Electrodes in Wearable Neuromuscular Electrical Stimulation

Directory of Open Access Journals (Sweden)

Hui Zhou

2015-07-01

Full Text Available Textile electrodes are becoming an attractive means in the facilitation of surface electrical stimulation. However, the stimulation comfort of textile electrodes and the mechanism behind stimulation discomfort is still unknown. In this study, a textile stimulation electrode was developed using conductive fabrics and then its impedance spectroscopy, stimulation thresholds, and stimulation comfort were quantitatively assessed and compared with those of a wet textile electrode and a hydrogel electrode on healthy subjects. The equivalent circuit models and the finite element models of different types of electrode were built based on the measured impedance data of the electrodes to reveal the possible mechanism of electrical stimulation pain. Our results showed that the wet textile electrode could achieve similar stimulation performance as the hydrogel electrode in motor threshold and stimulation comfort. However, the dry textile electrode was found to have very low pain threshold and induced obvious cutaneous painful sensations during stimulation, in comparison to the wet and hydrogel electrodes. Indeed, the finite element modeling results showed that the activation function along the z direction at the depth of dermis epidermis junction of the dry textile electrode was significantly larger than that of the wet and hydrogel electrodes, thus resulting in stronger activation of pain sensing fibers. Future work will be done to make textile electrodes have similar stimulation performance and comfort as hydrogel electrodes.

Electrode redox reactions with polarizable molecules

Science.gov (United States)

Matyushov, Dmitry V.

2018-04-01

A theory of redox reactions involving electron transfer between a metal electrode and a polarizable molecule in solution is formulated. Both the existence of molecular polarizability and its ability to change due to electron transfer distinguish this problem from classical theories of interfacial electrochemistry. When the polarizability is different between the oxidized and reduced states, the statistics of thermal fluctuations driving the reactant over the activation barrier becomes non-Gaussian. The problem of electron transfer is formulated as crossing of two non-parabolic free energy surfaces. An analytical solution for these free energy surfaces is provided and the activation barrier of electrode electron transfer is given in terms of two reorganization energies corresponding to the oxidized and reduced states of the molecule in solution. The new non-Gaussian theory is, therefore, based on two theory parameters in contrast to one-parameter Marcus formulation for electrode reactions. The theory, which is consistent with the Nernst equation, predicts asymmetry between the cathodic and anodic branches of the electrode current. They show different slopes at small electrode overpotentials and become curved at larger overpotentials. However, the curvature of the Tafel plot is reduced compared to the Marcus-Hush model and approaches the empirical Butler-Volmer form with different transfer coefficients for the anodic and cathodic currents.

Real-time management of faulty electrodes in electrical impedance tomography.

Science.gov (United States)

Hartinger, Alzbeta E; Guardo, Robert; Adler, Andy; Gagnon, Hervé

2009-02-01

Completely or partially disconnected electrodes are a fairly common occurrence in many electrical impedance tomography (EIT) clinical applications. Several factors can contribute to electrode disconnection: patient movement, perspiration, manipulations by clinical staff, and defective electrode leads or electronics. By corrupting several measurements, faulty electrodes introduce significant image artifacts. In order to properly manage faulty electrodes, it is necessary to: 1) account for invalid data in image reconstruction algorithms and 2) automatically detect faulty electrodes. This paper presents a two-part approach for real-time management of faulty electrodes based on the principle of voltage-current reciprocity. The first part allows accounting for faulty electrodes in EIT image reconstruction without a priori knowledge of which electrodes are at fault. The method properly weights each measurement according to its compliance with the principle of voltage-current reciprocity. Results show that the algorithm is able to automatically determine the valid portion of the data and use it to calculate high-quality images. The second part of the approach allows automatic real-time detection of at least one faulty electrode with 100% sensitivity and two faulty electrodes with 80% sensitivity enabling the clinical staff to fix the problem as soon as possible to minimize data loss.

Sculptured platinum nanowire counter electrodes for dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Lee, Hyeonseok [Department of Electrical Engineering, Pennsylvania State University, University Park 16802 (United States); Horn, Mark W., E-mail: MHorn@engr.psu.edu [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park 16802-6812 (United States)

2013-07-01

Sculptured platinum nanowire thin films were formed by oblique angle electron beam evaporation with a 5° vapor incidence angle and incorporated as counter electrodes for dye-sensitized solar cells (DSSCs). For the comparison of the performance, bare fluorine doped tin oxide, planar Pt electrodes and counter electrodes treated with chloroplatinic acid were prepared. The sculptured Pt nanowire electrodes showed five times lower charge transfer resistance (0.121 [Ω∗cm{sup 2}]) than that of Pt planar electrode (0.578 [Ω∗cm{sup 2}]) and when the Pt nanowire electrodes are treated with an H{sub 2}PtCl{sub 6} solution have more than ten times lower charge transfer resistance (0.04025 [Ω∗cm{sup 2}]). Moreover, Pt nanowire films used as a counter electrode lead to enhancement in current density and efficiency in comparison with Pt planar counter electrodes. The conversion efficiency with planar electrodes was 5.1 [%] while the efficiency of DSSC with platinum nanowire counter electrodes reached to 5.63 [%] under AM 1.5 illumination. - Highlights: • Pt sculptured thin films (STFs) fabricated by electron beam evaporator. • The STFs featured higher roughness and lower charge transfer resistance. • Improved performance of dye-sensitized solar cells by Pt STFs counter electrodes.

All-Carbon Electrodes for Flexible Solar Cells

OpenAIRE

Zexia Zhang; Ruitao Lv; Yi Jia; Xin Gan; Hongwei Zhu; Feiyu Kang

2018-01-01

Transparent electrodes based on carbon nanomaterials have recently emerged as new alternatives to indium tin oxide (ITO) or noble metal in organic photovoltaics (OPVs) due to their attractive advantages, such as long-term stability, environmental friendliness, high conductivity, and low cost. However, it is still a challenge to apply all-carbon electrodes in OPVs. Here, we report our efforts to develop all-carbon electrodes in organic solar cells fabricated with different carbon-based materia...

Electrocatalytic activity of bismuth doped silver electrodes

CERN Document Server

Amjad, M

2002-01-01

Investigation of redox reactions on silver, and bismuth doped silver electrodes in aqueous KOH solutions, by using potentiostatic steady-state polarization technique, has been carried out. The redox wave potential and current displacements along with multiplicity of the latter have been examined. These electrodes were employed for the oxidation of organic molecules such as ethylamine in alkaline media. Subsequently, these electrodes were ranked with respect to their activity for the redox reactions. (author)

RETGEM with polyvinylchloride (PVC) electrodes

CERN Document Server

Razin, V I; Reshetin, A I; Filippov, S N

2009-01-01

This paper presents a new design of the RETGEM (Resistive Electrode Thick GEM) based on electrodes made of a polyvinylchloride material (PVC). Our device can operate with gains of 10E5 as a conventional TGEM at low counting rates and as RPC in the case of high counting rates without of the transit to the violent sparks. The distinct feature of present RETGEM is the absent of the metal coating and lithographic technology for manufacturing of the protective dielectric rms. The electrodes from PVC permit to do the holes by a simple drilling machine. Detectors on a RETGEM basis could be useful in many fields of an application requiring a more cheap manufacturing and safe operation, for example, in a large neutrino experiments, in TPC, RICH systems.

Rational design of new electrodes for electrochemotherapy.

Science.gov (United States)

Spugnini, E P; Citro, G; Porrello, A

2005-06-01

Electrochemotherapy associates the local delivery of anticancer drugs with the administration of permeabilizing electric pulses that support the antiblastic action. The basic instrumentation for this therapy is constituted by a pulse generator and various specific electrodes. While many efforts have been profuse by researchers in this field to obtain the standardization of the pulse generating equipment over the past 15 years, the delivery apparatus still needs refinements in order to reach most of the body districts, to control the homogeneity and stability of the electric fields and to further reduce morbidity. With the aim to develop innovative electrodes able to satisfy, at least partially, these requirements, extensive studies on pet patients with spontaneous neoplasms have been conducted, leading to the manufacturing of several different prototypes. In this paper we discuss the rationale of 11 different electrodes, briefly summarize the results obtained and their experimental validation, also presenting five paradigmatic clinical cases. In particular, it is shown that the caliper electrodes are more suited for the treatment of cutaneous and subcutaneous lesions, while the needle arrays are more efficacious in intraoperative settings. Furthermore, relevant peculiarities of unipolar electrodes are examined with a particular focus on the irregular current paths that they produce and on the potentialities of this feature. Remarkably, the decrease of the steric encumbrance turned out to be a stronger factor in electrode design than the containment of the total number of electric fields covered in serial ECT sessions. In the conclusions, perspectives and new challenges of electrode design for electrochemotherapy are illustrated.

Organic conductive films for semiconductor electrodes

Science.gov (United States)

Frank, Arthur J.

1984-01-01

According to the present invention, improved electrodes overcoated with conductive polymer films and preselected catalysts are provided. The electrodes typically comprise an inorganic semiconductor overcoated with a charge conductive polymer film comprising a charge conductive polymer in or on which is a catalyst or charge-relaying agent.

Wearable Textile Electrodes for ECG Measurement

Directory of Open Access Journals (Sweden)

Lukas Vojtech

2013-01-01

Full Text Available The electrocardiogram (ECG is one of the most important parameters for monitoring of the physiological state of a person. Currently available systems for ECG monitoring are both stationary and wearable, but the comfort of the monitored person is not at a satisfactory level because these systems are not part of standard clothing. This article is therefore devoted to the development and measurement of wearable textile electrodes for ECG measurement device with high comfort for the user. The electrode material is made of electrically conductive textile. This creates a textile composite that guarantees high comfort for the user while ensuring good quality of ECG measurements. The composite is implemented by a carrier (a T-shirt with flame retardant and sensing electrodes embroidered with yarn based on a mixture of polyester coated with silver nanoparticles and cotton. The electrodes not only provide great comfort but are also antibacterial and antiallergic due to silver nanoparticles.

Modeling the electrode-neuron interface of cochlear implants: effects of neural survival, electrode placement, and the partial tripolar configuration.

Science.gov (United States)

Goldwyn, Joshua H; Bierer, Steven M; Bierer, Julie Arenberg

2010-09-01

The partial tripolar electrode configuration is a relatively novel stimulation strategy that can generate more spatially focused electric fields than the commonly used monopolar configuration. Focused stimulation strategies should improve spectral resolution in cochlear implant users, but may also be more sensitive to local irregularities in the electrode-neuron interface. In this study, we develop a practical computer model of cochlear implant stimulation that can simulate neural activation in a simplified cochlear geometry and we relate the resulting patterns of neural activity to basic psychophysical measures. We examine how two types of local irregularities in the electrode-neuron interface, variations in spiral ganglion nerve density and electrode position within the scala tympani, affect the simulated neural activation patterns and how these patterns change with electrode configuration. The model shows that higher partial tripolar fractions activate more spatially restricted populations of neurons at all current levels and require higher current levels to excite a given number of neurons. We find that threshold levels are more sensitive at high partial tripolar fractions to both types of irregularities, but these effects are not independent. In particular, at close electrode-neuron distances, activation is typically more spatially localized which leads to a greater influence of neural dead regions. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Electron transfer reactions to probe the electrode/solution interface

Energy Technology Data Exchange (ETDEWEB)

Capitanio, F.; Guerrini, E.; Colombo, A.; Trasatti, S. [Milan Univ., Milan (Italy). Dept. of Physical Chemistry and Electrochemistry

2008-07-01

The reactions that occur at the interface between an electrode and an electrolyte were examined with particular reference to the interaction of different electrode surfaces with redox couples. A semi-integration or convolution technique was used to study the kinetics of electron transfer on different electrode materials with different hydrophilic behaviour, such as Boron-Doped-Diamond (BDD), Au and Pt. Standard reversible redox couples were also investigated, including (Fe3+/2+, Fe(CN)63-/4-, Ru(NH3)63+/2+, Co(NH3)63+/2+, Ir4+/3+, V4+/5+ and V3+/2+). The proposed method proved to be simple, straightforward and reliable since the obtained kinetic information was in good agreement with data in the literature. It was concluded that the kinetics of the electrode transfer reactions depend on the chemical nature of the redox couple and electrode material. The method should be further extended to irreversible couples and other electrode materials such as mixed oxide electrodes. 3 refs., 2 figs.

High-resolution spatiotemporal strain mapping reveals non-uniform deformation in micropatterned elastomers

Science.gov (United States)

Aksoy, B.; Rehman, A.; Bayraktar, H.; Alaca, B. E.

2017-04-01

Micropatterns are generated on a vast selection of polymeric substrates for various applications ranging from stretchable electronics to cellular mechanobiological systems. When these patterned substrates are exposed to external loading, strain field is primarily affected by the presence of microfabricated structures and similarly by fabrication-related defects. The capturing of such nonhomogeneous strain fields is of utmost importance in cases where study of the mechanical behavior with a high spatial resolution is necessary. Image-based non-contact strain measurement techniques are favorable and have recently been extended to scanning tunneling microscope and scanning electron microscope images for the characterization of mechanical properties of metallic materials, e.g. steel and aluminum, at the microscale. A similar real-time analysis of strain heterogeneity in elastomers is yet to be achieved during the entire loading sequence. The available measurement methods for polymeric materials mostly depend on cross-head displacement or precalibrated strain values. Thus, they suffer either from the lack of any real-time analysis, spatiotemporal distribution or high resolution in addition to a combination of these factors. In this work, these challenges are addressed by integrating a tensile stretcher with an inverted optical microscope and developing a subpixel particle tracking algorithm. As a proof of concept, the patterns with a critical dimension of 200 µm are generated on polydimethylsiloxane substrates and strain distribution in the vicinity of the patterns is captured with a high spatiotemporal resolution. In the field of strain measurement, there is always a tradeoff between minimum measurable strain value and spatial resolution. Current noncontact techniques on elastomers can deliver a strain resolution of 0.001% over a minimum length of 5 cm. More importantly, inhomogeneities within this quite large region cannot be captured. The proposed technique can

High-resolution spatiotemporal strain mapping reveals non-uniform deformation in micropatterned elastomers

International Nuclear Information System (INIS)

Aksoy, B; Alaca, B E; Rehman, A; Bayraktar, H

2017-01-01

Micropatterns are generated on a vast selection of polymeric substrates for various applications ranging from stretchable electronics to cellular mechanobiological systems. When these patterned substrates are exposed to external loading, strain field is primarily affected by the presence of microfabricated structures and similarly by fabrication-related defects. The capturing of such nonhomogeneous strain fields is of utmost importance in cases where study of the mechanical behavior with a high spatial resolution is necessary. Image-based non-contact strain measurement techniques are favorable and have recently been extended to scanning tunneling microscope and scanning electron microscope images for the characterization of mechanical properties of metallic materials, e.g. steel and aluminum, at the microscale. A similar real-time analysis of strain heterogeneity in elastomers is yet to be achieved during the entire loading sequence. The available measurement methods for polymeric materials mostly depend on cross-head displacement or precalibrated strain values. Thus, they suffer either from the lack of any real-time analysis, spatiotemporal distribution or high resolution in addition to a combination of these factors. In this work, these challenges are addressed by integrating a tensile stretcher with an inverted optical microscope and developing a subpixel particle tracking algorithm. As a proof of concept, the patterns with a critical dimension of 200 µ m are generated on polydimethylsiloxane substrates and strain distribution in the vicinity of the patterns is captured with a high spatiotemporal resolution. In the field of strain measurement, there is always a tradeoff between minimum measurable strain value and spatial resolution. Current noncontact techniques on elastomers can deliver a strain resolution of 0.001% over a minimum length of 5 cm. More importantly, inhomogeneities within this quite large region cannot be captured. The proposed technique can

Effects of Cable Sway, Electrode Surface Area, and Electrode Mass on Electroencephalography Signal Quality during Motion.

Science.gov (United States)

Symeonidou, Evangelia-Regkina; Nordin, Andrew D; Hairston, W David; Ferris, Daniel P

2018-04-03

More neuroscience researchers are using scalp electroencephalography (EEG) to measure electrocortical dynamics during human locomotion and other types of movement. Motion artifacts corrupt the EEG and mask underlying neural signals of interest. The cause of motion artifacts in EEG is often attributed to electrode motion relative to the skin, but few studies have examined EEG signals under head motion. In the current study, we tested how motion artifacts are affected by the overall mass and surface area of commercially available electrodes, as well as how cable sway contributes to motion artifacts. To provide a ground-truth signal, we used a gelatin head phantom with embedded antennas broadcasting electrical signals, and recorded EEG with a commercially available electrode system. A robotic platform moved the phantom head through sinusoidal displacements at different frequencies (0-2 Hz). Results showed that a larger electrode surface area can have a small but significant effect on improving EEG signal quality during motion and that cable sway is a major contributor to motion artifacts. These results have implications in the development of future hardware for mobile brain imaging with EEG.

New electrodes for hydrogen/oxygen solid polymer electrolyte fuel cell

Energy Technology Data Exchange (ETDEWEB)

Mosdale, R [CEA Centre d` Etudes de Grenoble, 38 (France). Dept. de Recherche Fondamentale sur la Matiere Condensee; Stevens, P [CEA Centre d` Etudes de Grenoble, 38 (France). Dept. de Thermohydraulique et de Physique

1993-12-31

A new method of preparation of Electrode/Membrane/Electrode (EME) assemblies for Proton Exchange Membrane Fuel Cells (PEMFC) has been developed. The electrodes are deposited directly onto a Nafion electrolyte membrane from a mixture of platinized carbon, Nafion solution, and PTFE by using a spray technique. By this technique, porous electrodes are obtained with an optimized gas/electrolyte/catalyst interface, and electrode/membrane interface.

The electrochemical impedance of metal hydride electrodes

DEFF Research Database (Denmark)

Valøen, Lars Ole; Lasia, Andrzej; Jensen, Jens Oluf

2002-01-01

The electrochemical impedance responses for different laboratory type metal hydride electrodes were successfully modeled and fitted to experimental data for AB5 type hydrogen storage alloys as well as one MgNi type electrode. The models fitted the experimental data remarkably well. Several AC......, explaining the experimental impedances in a wide frequency range for electrodes of hydride forming materials mixed with copper powder, were obtained. Both charge transfer and spherical diffusion of hydrogen in the particles are important sub processes that govern the total rate of the electrochemical...... hydrogen absorption/desorption reaction. To approximate the experimental data, equations describing the current distribution in porous electrodes were needed. Indications of one or more parallel reduction/oxidation processes competing with the electrochemical hydrogen absorption/desorption reaction were...

Chirality of magneto-electrodeposited metal film electrodes

International Nuclear Information System (INIS)

Mogi, Iwao; Watanabe, Kazuo

2008-01-01

The chiral electrode behaviors of magneto-electrodeposited (MED) Ag and Cu films were examined for the electrochemical reactions of D-glucose, L-glucose and L-cysteine. The Ag and Cu films were electrodeposited under a magnetic field of 2 T parallel (+2 T) or antiparallel (-2 T) to the faradaic current. For MED films of both Ag and Cu, the oxidation current of L-glucose was larger than that of D-glucose on the +2 T-film electrodes, and the results were opposite on the - 2 T-film electrodes. These facts demonstrate that the MED metal films possess the ability of chiral recognition for D- and L-glucoses. The MED Ag film electrodes also exhibited chiral behavior for the oxidation of L-cysteine

Methods for Specific Electrode Resistance Measurement during Transcranial Direct Current Stimulation

Science.gov (United States)

Khadka, Niranjan; Rahman, Asif; Sarantos, Chris; Truong, Dennis Q.; Bikson, Marom

2014-01-01

Background Transcranial Direct Current Stimulation (tDCS) is investigated to treat a wide range of neuropsychiatric disorders, for rehabilitation, and for enhancing cognitive performance. The monitoring of electrode resistance before and during tDCS is considered important for tolerability and safety, where an unusually high resistance is indicative of undesired electrode or poor skin contact conditions. Conventional resistance measurement methods do not isolate individual electrode resistance but rather measures overall voltage. Moreover, for HD-tDCS devices, cross talk across electrodes makes concurrent resistance monitoring unreliable. Objective We propose a novel method for monitoring of the individual electrode resistance during tDCS, using a super-position of direct current with a test-signal (low-intensity and low-frequency sinusoids with electrode– specific frequencies) and a single sentinel electrode (not used for DC). Methods To validate this methodology, we developed lumped-parameter models of two and multi-electrode tDCS. Approaches with and without a sentinel electrode were solved and underlying assumptions identified. Assumptions were tested and parameterized in healthy participants using forearm stimulation combining tDCS (2 mA) and sinusoidal test-signals (38 μA and 76 μA peak to peak at 1 Hz, 10 Hz, and 100 Hz) and an in vitro test (where varied electrode failure modes were created). DC and AC component voltages across the electrodes were compared and participants were asked to rate subjective pain. Results A sentinel electrode is required to isolate electrode resistance in a two-electrode tDCS system. For multi-electrode resistance tracking, cross talk was aggravated with electrode proximity and current/resistance mismatches, but could be corrected using proposed approaches. Average voltage and average pain scores were not significantly different across test current intensities and frequencies (two-way repeated measures ANOVA) indicating the

Deactivation of nickel hydroxide-gold modified electrodes

OpenAIRE

Caram, Bruno; Tucceri, Ricardo

2013-01-01

The aim of the present work was to study how the charge-transport process of a nickel hydroxide film electrochemically synthesized on a gold substrate is modified when the electrode is stored for a long time. It was found that nickel hydroxide films are deactivated under storage, that is, films became less conductive than films immediately prepared (nondeactivated). This study was carried out in the context of the rotating disc electrode voltammetry when the modified electrode contacts an ele...

Electronically conductive polymer binder for lithium-ion battery electrode

Energy Technology Data Exchange (ETDEWEB)

Liu, Gao; Xun, Shidi; Battaglia, Vincent S.; Zheng, Honghe

2017-05-16

A family of carboxylic acid group containing fluorene/fluorenon copolymers is disclosed as binders of silicon particles in the fabrication of negative electrodes for use with lithium ion batteries. These binders enable the use of silicon as an electrode material as they significantly improve the cycle-ability of silicon by preventing electrode degradation over time. In particular, these polymers, which become conductive on first charge, bind to the silicon particles of the electrode, are flexible so as to better accommodate the expansion and contraction of the electrode during charge/discharge, and being conductive promote the flow battery current.

Erosion on spark plug electrodes; Funkenerosion an Zuendkerzenelektroden

Energy Technology Data Exchange (ETDEWEB)

Rager, J.

2006-07-01

Durability of spark plugs is mainly determined by spark gap widening, caused by electrode wear. Knowledge about the erosion mechanisms of spark plug materials is of fundamental interest for the development of materials with a high resistance against electrode erosion. It is therefore crucial to identify those parameters which significantly influence the erosion behaviour of a material. In this work, a reliable and reproducible testing method is presented which produces and characterizes electrode wear under well-defined conditions and which is capable of altering parameters specifically. Endurance tests were carried out to study the dependence of the wear behaviour of pure nickel and platinum on the electrode temperature, gas, electrode gap, electrode diameter, atmospheric pressure, and partial pressure of oxygen. It was shown that erosion under nitrogen is negligible, irrespective of the material. This disproves all common mechanism discussed in the literature explaining material loss of spark plug electrodes. Based on this observation and the variation of the mentioned parameters a new erosion model was deduced. This relies on an oxidation of the electrode material and describes the erosion of nickel and platinum separately. For nickel, electrode wear is caused by the removal of an oxide layer by the spark. In the case of platinum, material loss occurs due to the plasma-assisted formation and subsequent evaporation of volatile oxides in the cathode spot. On the basis of this mechanism a new composite material was developed whose erosion resistance is superior to pure platinum. Oxidation resistant metal oxide particles were added to a platinum matrix, thus leading to a higher erosion resistance of the composite. However, this can be decreased by a side reaction, the separation of oxygen from the metal oxides, which effectively assists the oxidation of the matrix. This reaction can be suppressed by using highly stable oxides, characterized by a large negative Gibbs

HVDC Ground Electrodes - a Source of Geophysical Data

Science.gov (United States)

Freire, P. F.; Pereira, S. Y.

2015-12-01

The HVDC electrode is a component of a High Voltage Direct Current energy transmission system, and is designed to inject into the ground continuous currents up to 3500 A. The typical HVDC ground electrode is a ring of vertical conductors, 1 km wide, buried a few tens of meters.The design of a HVDC electrode is based on extensive geological, geotechnical and geophysical surveys. Geophysical data are usually electrical (VES) and electromagnetic (TEM/MT) acquisitions, for the modeling of the shallow, near-surface and deep layers of the crust. This survey aims, first, the electrode site selection, and then, at the selected site, this data is combined into a single apparent resistivity curve, which is inverted, allowing for the determination of the layered geoelectric crust model. The injection of electrical continuous current in the electrode is then simulated, with the geoelectric crust model, for the determination of the soil surface potential profile (which is usually asymmetric for different directions, due to non-1D geoelectric models).For the commissioning of a HVDC electrode, field measurements are done, such as electrode grounding resistance, soil surface potentials and metal-to-soil potentials at specific structures (buried pipelines, for instance).The geophysical data acquired during the design phase is a set of data completely independent from the electrical data acquired during the electrode commissioning phase, and both are correlated by the geoelectric model. It happens, therefore, that the geoelectric model can be calibrated based on the electrical data, with the correction of static shifts and other adjustments.This paper suggests that the commissioning of HVDC systems should be associated to a research & development program, with a university or foundation. The idea is to enjoy the opportunity of a more complete field survey, with the acquisition of a wide set of data for a better geological characterization of the area where the electrode was built.

21 CFR 876.1400 - Stomach pH electrode.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Stomach pH electrode. 876.1400 Section 876.1400...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Diagnostic Devices § 876.1400 Stomach pH electrode. (a) Identification. A stomach pH electrode is a device used to measure intragastric and intraesophageal pH (hydrogen...

Electrochemical characterization of screen-printed and conventional carbon paste electrodes

Energy Technology Data Exchange (ETDEWEB)

Fanjul-Bolado, Pablo; Hernandez-Santos, David; Lamas-Ardisana, Pedro Jose [Departamento de Quimica Fisica y Analitica, Universidad de Oviedo, 33006 Oviedo, Asturias (Spain); Martin-Pernia, Alberto [Departamento de Ingenieria Electrica, Electronica de Computadores y Sistemas, Universidad de Oviedo, 33204 Gijon, Asturias (Spain); Costa-Garcia, Agustin [Departamento de Quimica Fisica y Analitica, Universidad de Oviedo, 33006 Oviedo, Asturias (Spain)], E-mail: costa@fq.uniovi.es

2008-04-01

This work compares the electroactivity of a conventional carbon paste electrode and non-pretreated commercially available screen-printed carbon electrodes (from Alderon Biosciences, University of Florence and DropSens) towards some benchmark redox couples like hexaammineruthenium (III), ferricyanide, p-aminophenol and hydroquinone. While cyclic voltammograms of Ru{sup 3+} did not show significative electron transfer reactivity differences between the electrodes tested, the other redox systems exhibited higher reversible behaviours on DropSens electrodes. Scanning electron microscopy and roughness analysis with a profilometer were applied to detect the surface morphology of the working electrodes. The roughness evaluated of the screen-printed carbon working electrodes increased in this order Alderon < University of Florence < DropSens. Finally, the most electrochemically active and rough unpretreated electrode (DropSens commercial screen-printed electrode) was used to study the electrochemical-chemical reaction mechanism of indigo carmine oxidation in 0.1 M sulphuric acid. This study showed that the adsorption of the oxidation product of indigo carmine is stabilized when it is adsorbed on the surface of the electrode.

Nanoscale biomemory composed of recombinant azurin on a nanogap electrode

International Nuclear Information System (INIS)

Chung, Yong-Ho; Lee, Taek; Choi, Jeong-Woo; Park, Hyung Ju; Yun, Wan Soo; Min, Junhong

2013-01-01

We fabricate a nanoscale biomemory device composed of recombinant azurin on nanogap electrodes. For this, size-controllable nanogap electrodes are fabricated by photolithography, electron beam lithography, and surface catalyzed chemical deposition. Moreover, we investigate the effect of gap distance to optimize the size of electrodes for a biomemory device and explore the mechanism of electron transfer from immobilized protein to a nanogap counter-electrode. As the distance of the nanogap electrode is decreased in the nanoscale, the absolute current intensity decreases according to the distance decrement between the electrodes due to direct electron transfer, in contrast with the diffusion phenomenon of a micro-electrode. The biomemory function is achieved on the optimized nanogap electrode. These results demonstrate that the fabricated nanodevice composed of a nanogap electrode and biomaterials provides various advantages such as quantitative control of signals and exclusion of environmental effects such as noise. The proposed bioelectronics device, which could be mass-produced easily, could be applied to construct a nanoscale bioelectronics system composed of a single biomolecule. (paper)

Electrochemical characterization of screen-printed and conventional carbon paste electrodes

International Nuclear Information System (INIS)

Fanjul-Bolado, Pablo; Hernandez-Santos, David; Lamas-Ardisana, Pedro Jose; Martin-Pernia, Alberto; Costa-Garcia, Agustin

2008-01-01

This work compares the electroactivity of a conventional carbon paste electrode and non-pretreated commercially available screen-printed carbon electrodes (from Alderon Biosciences, University of Florence and DropSens) towards some benchmark redox couples like hexaammineruthenium (III), ferricyanide, p-aminophenol and hydroquinone. While cyclic voltammograms of Ru 3+ did not show significative electron transfer reactivity differences between the electrodes tested, the other redox systems exhibited higher reversible behaviours on DropSens electrodes. Scanning electron microscopy and roughness analysis with a profilometer were applied to detect the surface morphology of the working electrodes. The roughness evaluated of the screen-printed carbon working electrodes increased in this order Alderon < University of Florence < DropSens. Finally, the most electrochemically active and rough unpretreated electrode (DropSens commercial screen-printed electrode) was used to study the electrochemical-chemical reaction mechanism of indigo carmine oxidation in 0.1 M sulphuric acid. This study showed that the adsorption of the oxidation product of indigo carmine is stabilized when it is adsorbed on the surface of the electrode

Systems and methods for producing low work function electrodes

Science.gov (United States)

Kippelen, Bernard; Fuentes-Hernandez, Canek; Zhou, Yinhua; Kahn, Antoine; Meyer, Jens; Shim, Jae Won; Marder, Seth R.

2015-07-07

According to an exemplary embodiment of the invention, systems and methods are provided for producing low work function electrodes. According to an exemplary embodiment, a method is provided for reducing a work function of an electrode. The method includes applying, to at least a portion of the electrode, a solution comprising a Lewis basic oligomer or polymer; and based at least in part on applying the solution, forming an ultra-thin layer on a surface of the electrode, wherein the ultra-thin layer reduces the work function associated with the electrode by greater than 0.5 eV. According to another exemplary embodiment of the invention, a device is provided. The device includes a semiconductor; at least one electrode disposed adjacent to the semiconductor and configured to transport electrons in or out of the semiconductor.

Fabrication of a three-electrode battery using hydrogen-storage materials

Science.gov (United States)

Roh, Chi-Woo; Seo, Jung-Yong; Moon, Hyung-Seok; Park, Hyun-Young; Nam, Na-Yun; Cho, Sung Min; Yoo, Pil J.; Chung, Chan-Hwa

2015-04-01

In this study, an energy storage device using a three-electrode battery is fabricated. The charging process takes place during electrolysis of the alkaline electrolyte where hydrogen is stored at the palladium bifunctional electrode. Upon discharging, power is generated by operating the alkaline fuel cell using hydrogen which is accumulated in the palladium hydride bifunctional electrode during the charging process. The bifunctional palladium electrode is prepared by electrodeposition using a hydrogen bubble template followed by a galvanic displacement reaction of platinum in order to functionalize the electrode to work not only as a hydrogen storage material but also as an anode in a fuel cell. This bifunctional electrode has a sufficiently high surface area and the platinum catalyst populates at the surface of electrode to operate the fuel cell. The charging and discharging performance of the three-electrode battery are characterized. In addition, the cycle stability is investigated.

Conducting polymer electrodes for gel electrophoresis.

Directory of Open Access Journals (Sweden)

Katarina Bengtsson

Full Text Available In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that π-conjugated polymers such as poly(3,4-ethylenedioxythiophene (PEDOT can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation.

Conducting polymer electrodes for gel electrophoresis.

Science.gov (United States)

Bengtsson, Katarina; Nilsson, Sara; Robinson, Nathaniel D

2014-01-01

In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that π-conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis) systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation.

DNA-FET using carbon nanotube electrodes

International Nuclear Information System (INIS)

Sasaki, T K; Ikegami, A; Aoki, N; Ochiai, Y

2006-01-01

We demonstrate DNA field effect transistor (DNA-FET) using multiwalled carbon nanotube (MWNT) as nano-structural source and drain electrodes. The MWNT electrodes have been fabricated by focused ion-beam bombardment (FIBB). A very short channel, approximately 50 nm, was easily formed between the severed MWNT. The current-voltage (I-V) characteristics of DNA molecules between the MWNT electrodes showed hopping transport property. We have also measured the gate-voltage dependence in the I-V characteristics and found that poly DNA molecules exhibits p-type conduction. The transport of DNA-FET can be explained by two hopping lengths which depend on the range of the source-drain bias voltages

Advanced screening of electrode couples

Science.gov (United States)

Giner, J. D.; Cahill, K.

1980-01-01

The chromium (Cr(3+)/Cr(2+)) redox couple (electrolyte and electrode) was investigated to determine its suitability as negative electrode for the iron (Fe(3+)/Fe(2+))-chromium (Cr(3+)/Cr(2+)) redox flow battery. Literature search and laboratory investigation established that the solubility and stability of aqueous acidic solutions of chromium(3) chloride and chromium(2) chloride are sufficient for redox battery application. Four categories of electrode materials were tested; namely, metals and metalloid materials (elements and compounds), alloys, plated materials, and Teflon-bonded materials. In all, the relative performance of 26 candidate electrode materials was evaluated on the basis of slow scan rate linear sweep voltammetry in stirred solution. No single material tested gave both acceptable anodic an acceptable cathodic performance. However, the identification of lead as a good cathodic electrocatalyst and gold as a good anodic electrocatalyst led to the invention of the lead/gold combination electrocatalyst. This type of catalyst can be fabricated in several ways and appears to offer the advantages of each metal without the disadvantages associated with their use as single materials. This lead/gold electrocatalyst was tested by NASA-Lewis Research Center in complete, flowing, redox batteries comprising a stack of several cells. A large improvement in the battery's coulombic and energy efficiency was observed.

Effect of welding process, type of electrode and electrode core diameter on the tensile property of 304L austenitic stainless steel

Directory of Open Access Journals (Sweden)

Akinlabi OYETUNJI

2014-11-01

Full Text Available The effect of welding process, type of electrode and electrode core diameter on the tensile property of AISI 304L Austenitic Stainless Steel (ASS was studied. The tensile strength property of ASS welded samples was evaluated. Prepared samples of the ASS were welded under these three various variables. Tensile test was then carried out on the welded samples. It was found that the reduction in ultimate tensile strength (UTS of the butt joint samples increases with increase in core diameter of the electrode. Also, the best electrode for welding 304L ASS is 308L stainless steel-core electrode of 3.2 mm core diameter. It is recommended that the findings of this work can be applied in the chemical, food and oil industries where 304L ASS are predominantly used.

Electrochemical characterisation of solid oxide cell electrodes for hydrogen production

DEFF Research Database (Denmark)

Bernuy-Lopez, Carlos; Knibbe, Ruth; He, Zeming

2011-01-01

Oxygen electrodes and steam electrodes are designed and tested to develop improved solid oxide electrolysis cells for H2 production with the cell support on the oxygen electrode. The electrode performance is evaluated by impedance spectroscopy testing of symmetric cells at open circuit voltage (OCV...

Electrochemical degradation of chlorobenzene on boron-doped diamond and platinum electrodes

International Nuclear Information System (INIS)

Liu Lei; Zhao Guohua; Wu Meifen; Lei Yanzhu; Geng Rong

2009-01-01

In this paper the electrochemical degradation of chlorobenzene (CB) was investigated on boron-doped diamond (BDD) and platinum (Pt) anodes, and the degradation kinetics on these two electrodes was compared. Compared with the total mineralization with a total organic carbon (TOC) removal of 85.2% in 6 h on Pt electrode, the TOC removal reached 94.3% on BDD electrode under the same operate condition. Accordingly, the mineralization current efficiency (MCE) during the mineralization on BDD electrode was higher than that on the Pt electrode. Besides TOC, the conversion of CB, the productions and decay of intermediates were also monitored. Kinetic study indicated that the decay of CB on BDD and Pt electrodes were both pseudo-first-order reactions, and the reaction rate constant (k s ) on BDD electrode was higher than that on Pt electrode. The different reaction mechanisms on the two electrodes were investigated by the variation of intermediates concentrations. Two different reaction pathways for the degradation of CB on BDD electrode and Pt electrode involving all these intermediates were proposed.

Electrochemical oxidation of nitrite on nanodiamond powder electrode

Energy Technology Data Exchange (ETDEWEB)

Chen, L.H.; Zang, J.B.; Wang, Y.H.; Bian, L.Y. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

2008-03-10

Nanodiamond (ND) powder electrodes were fabricated and the electrochemical properties were investigated in the solution containing nitrite in this article. This electrode exhibits substantial catalytic ability toward the oxidation of nitrite anions. The electrochemical oxidation mechanism of nitrite on the ND powder electrode is discussed. The oxidation of NaNO{sub 2} is a two-electron transfer process. The electrode reaction rate constant k is estimated to be 2.013 x 10{sup -4} cm/s and (1 - {alpha})n{sub {alpha}} is 0.1643. The peak current increases linearly with the rising of the concentration of NaNO{sub 2}. (author)

Single Electrode Heat Effects

DEFF Research Database (Denmark)

Jacobsen, Torben; Broers, G. H. J.

1977-01-01

The heat evolution at a single irreversibly working electrode is treated onthe basis of the Brønsted heat principle. The resulting equation is analogous to the expression for the total heat evolution in a galvanic cellwith the exception that –DeltaS is substituted by the Peltier entropy, Delta......SP, of theelectrode reaction. eta is the overvoltage at the electrode. This equation is appliedto a high temperature carbonate fuel cell. It is shown that the Peltier entropyterm by far exceeds the heat production due to the irreversible losses, and thatthe main part of heat evolved at the cathode is reabsorbed...

Composite Electrodes for Electrochemical Supercapacitors

OpenAIRE

Li, Jun; Yang, QuanMin; Zhitomirsky, Igor

2010-01-01

Abstract Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4–6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT) into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with to...

High-Efficiency Graphene Photo Sensor Using a Transparent Electrode

Institute of Scientific and Technical Information of China (English)

LIU Tao; HUANG Zheng

2011-01-01

We report the first implementation of transparent electrodes in bottom-gate graphene transistors used for photo detection.Compared to conventional nontransparent electrodes,the transparent electrodes allow photons to transmit through to the graphene beneath,providing an enlarged absorption area and thereby giving rise to an enhancement of photocurrent generation.The devices are fabricated with an asymmetric metallization scheme and the experimental results show that the maximum photocurrent density using the transparent electrodes (ITO and Pd/ITO) is over two times higher than that using the nontransparent electrodes (Ti and Pd),indicating a significant enhancement in the performance of graphene photo sensors.Graphene,a single-atomic-layer of carbon atoms with a zero-gap band structure has received great attention recently.[1-4] One promising application of graphene is in high-speed photodetection,owing to its high Fermi velocity (～1/300 of the speed of light),high electrical mobility (200000 cm2/Vs for both electrons and holes) and zero-gap induced wide absorption spectrum (in the visible-to-infrared range).[5,6]%We report the first implementation of transparent electrodes in bottom-gate graphene transistors used for photo detection. Compared to conventional nontransparent electrodes, the transparent electrodes allow photons to transmit through to the graphene beneath, providing an enlarged absorption area and thereby giving rise to an enhancement of photocurrent generation. The devices are fabricated with an asymmetric metallization scheme and the experimental results show that the maximum photocurrent density using the transparent electrodes (ITO and Pd/ITO) is over two times higher than that using the nontransparent electrodes (Ti and Pd), indicating a significant enhancement in the performance of graphene photo sensors.

Electrode for improving electrochemical measurements in high temperature water

International Nuclear Information System (INIS)

Sengarsai, T.

2005-01-01

A silver/silver-chloride (Ag/AgCl) reference electrode was specially designed and constructed in a body of oxidized titanium for potentiometric measurements under high-temperature and high-pressure conditions. To avoid the thermal decomposition of silver-chloride, the electrode is designed to maintain the reference element at low temperature while it is still connected to high-temperature process zone via a non-isothermal electrolyte bridge. This configuration leads to the development of a thermal gradient along the length of the electrode. At room temperature, the stability of the Ag/AgCl reference electrode versus a standard calomel electrode (SCE) is maintained with an accuracy of 5 mV. The electrode's performance at high temperature and pressure (up to 300 o C and 1500 psi) was examined by measuring the potential difference against platinum, which acted as a reversible hydrogen electrode (RHE). Comparison of the experimental and theoretical values verifies the reliability and reproducibility of the electrode. Deviation from the Nernst equation is considered and related to the thermal liquid junction potential (TLJP). An empirical correction factor is used to maintain the Ag/AgCl potential within an acceptable accuracy limit of ±20 mV at high temperature. (author)

Thin metal electrodes for semitransparent organic photovoltaics

KAUST Repository

Lee, Kyusung

2013-08-01

We demonstrate semitransparent organic photovoltaics (OPVs) based on thin metal electrodes and polymer photoactive layers consisting of poly(3-hexylthiophene) and [6,6]-phenyl C61 butyric acid methyl ester. The power conversion efficiency of a semitransparent OPV device comprising a 15-nm silver (Ag) rear electrode is 1.98% under AM 1.5-G illumination through the indium-tin-oxide side of the front anode at 100 mW/cm2 with 15.6% average transmittance of the entire cell in the visible wavelength range. As its thickness increases, a thin Ag electrode mainly influences the enhancement of the short circuit current density and fill factor. Its relatively low absorption intensity makes a Ag thin film a viable option for semitransparent electrodes compatible with organic layers. © 2013 ETRI.

Variations the diameter tip of electrode on the resistance spot welding using electrode Cu on worksheet Fe

Science.gov (United States)

Baskoro, A. S.; Sugeng, S.; Sifa, Agus; Badruzzaman; Endramawan, Tito

2018-04-01

Resistance Spot Weld (RSW) is a welding technology which plays an important role that is often used in industry in large manufacturing industries, especially in the automotive sector, some of the parameters are affecting the welding process that give impact in the weld quality, diameter tip important impact on the resistance spot welding, This study can be categorized as experimental study by using Electrode material such as Cu and Fe Worksheet Materials, with a material thickness of 1 mm,0,8 mm, and 0,6 mm on each worksheet, and the large diameter of tip electrode (5√t) depend on the thickness of worksheet. Testing the material in the electrode and the worksheet by testing the composition and tensile test, and the hardness of the material used are to know the material used certainly. The result of the welding process was done by using the parameters voltage of 8KV, with a duty cycle of 50% using a variation of the time 8s-10s, and variations the electrode tip diameter that are affected by the thickness of the worksheet 5\\sqrt{t}, plate thickness used 1 mm, 0,8 mm and 0,6 mm, so that the electrodes was used to a thickness of 1 mm diameter tip electrode 5 mm, thickness 0,8 mm with an electrode tip diameter 4,5 mm and a thickness 0,6 mm with an electrode diameter of 4 mm, with current welding parameter 8kVA, and variations in holding time 10s, 9s and 8s 50% duty cycle, then testing welds with the standard shear test refers ASTM A370-2012 with more results to a thickness of 0,6 has the ability to withstand greater load on the holding time 8s and 9s, 10s, to a thickness 0,8 mm and 1 mm shear test results demonstrate the ability to withstand loads on the holding time of 10s and 9s have a greater ability than 8s on worksheet that has thickness 1 mm at a holding time of 10s, and then Maximum shear test averaging of 36,41 N at a worksheet with a thickness of 0,8 mm (diameter tip 4,5 mm) at a holding time of 8s and a mean minimum shear stress of 23,73 N at worksheet that

Simple micro-patterning of high conductive polymer with UV-nano-imprinted patterned substrate and ethylene glycol-based second doping

International Nuclear Information System (INIS)

Takamatsu, Seiichi; Kurihara, Kazuma; Yamashita, Takahiro; Itoh, Toshihiro

2014-01-01

We have developed a simple micro-patterning process for high conductive polymer (i.e., poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)) with a patterned substrate by using an ultraviolet (UV) nano-imprint and an ethylene glycol-based second doping technique. In the patterning process, the PEDOT:PSS water dispersion is first coated only on the hydrophilic area, which is fabricated by UV nano-imprinting, forming patterned PEDOT:PSS on the substrate. The patterned PEDOT:PSS film is then immersed in the ethylene glycol as a second doping technique for increasing its conductivity. The proposed process provides simplicity in terms of shorter process steps of the UV nano-imprinting and PEDOT:PSS coating and higher conductivity of patterned PEDOT:PSS film than existing complicated micro-fabrication processes for organic materials. The 200 nm wide nano-imprinted pillar structures change the wettability of the substrate where the contact angle of the substrate is decreased from 66.8° to 33.3°. The patterning resolution with the nano-imprinted pattern substrate is down to 100 µm, which is useful for sensor applications. The conductivity increase delivers a low sheet resistance (120 Ω sq −1 ) of patterned PEDOT:PSS film. Then, the patterning of PEDOT:PSS sensor shapes with its 300 µm wide feature line and high conductivity are demonstrated. Therefore, our process leads to applications to a variety of PEDOT:PSS-based sensors. (paper)

Electrical resistance tomography using steel cased boreholes as electrodes

International Nuclear Information System (INIS)

Newmark, R L; Daily, W; Ramirez, A

1999-01-01

Electrical resistance tomography (ERT) using multiple electrodes installed in boreholes has been shown to be useful for both site characterization and process monitoring. In some cases, however, installing multiple downhole electrodes is too costly (e.g., deep targets) or risky (e.g., contaminated sites). For these cases we have examined the possibility of using the steel casings of existing boreholes as electrodes. The first case we investigated used an array of steel casings as electrodes. This results in very few data and thus requires additional constraints to limit the domain of possible inverse solutions. Simulations indicate that the spatial resolution and sensitivity are understandably low but it is possible to coarsely map the lateral extent of subsurface processes such as steam floods. A hybrid case uses traditional point electrode arrays combined with long-conductor electrodes (steel casings). Although this arrangement provides more data, in many cases it results in poor reconstructions of test targets. Results indicate that this method may hold promise for low resolution imaging where steel casings can be used as electrodes

Copper nanoparticle modified carbon electrode for determination of dopamine

International Nuclear Information System (INIS)

Oztekin, Yasemin; Tok, Mutahire; Bilici, Esra; Mikoliunaite, Lina; Yazicigil, Zafer; Ramanaviciene, Almira; Ramanavicius, Arunas

2012-01-01

This paper reports the synthesis and characterization of copper nanoparticles (CuNPs) and application of copper nanoparticle-modified glassy carbon electrode for the electrochemical determination of dopamine. Electrochemical measurements were performed using differently modified glassy carbon (GC) electrodes. Bare, oxidized before modification and copper nanoparticle-modified glassy carbon electrodes (bare-GC, ox-GC and CuNP/GC electrodes, respectively) were characterized by cyclic voltammetry and electrochemical impedance spectroscopy in the presence of redox probes. Atomic force microscopy was used for the visualization of electrode surfaces. The CuNP/GC electrode was found to be suitable for the selective determination of dopamine even in the presence of ascorbic acid, uric acid, and p-acetamidophenol. The observed linear range of CuNP/GC for dopamine was from 0.1 nM to 1.0 μM while the detection limit was estimated to be 50 pM. It was demonstrated that here reported glassy carbon electrode modified by copper nanoparticles is suitable for the determination of dopamine in real samples such as human blood serum.

Solvent-Free Manufacturing of Electrodes for Lithium-ion Batteries

Science.gov (United States)

Ludwig, Brandon; Zheng, Zhangfeng; Shou, Wan; Wang, Yan; Pan, Heng

2016-03-01

Lithium ion battery electrodes were manufactured using a new, completely dry powder painting process. The solvents used for conventional slurry-cast electrodes have been completely removed. Thermal activation time has been greatly reduced due to the time and resource demanding solvent evaporation process needed with slurry-cast electrode manufacturing being replaced by a hot rolling process. It has been found that thermal activation time to induce mechanical bonding of the thermoplastic polymer to the remaining active electrode particles is only a few seconds. Removing the solvent and drying process allows large-scale Li-ion battery production to be more economically viable in markets such as automotive energy storage systems. By understanding the surface energies of various powders which govern the powder mixing and binder distribution, bonding tests of the dry-deposited particles onto the current collector show that the bonding strength is greater than slurry-cast electrodes, 148.8 kPa as compared to 84.3 kPa. Electrochemical tests show that the new electrodes outperform conventional slurry processed electrodes, which is due to different binder distribution.

Film stresses and electrode buckling in organic solar cells

KAUST Repository

Brand, Vitali

2012-08-01

We investigate the film stresses that develop in the polymer films and metal electrodes of poly(3-hexyl thiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) bulk heterojunction (BHJ) organic solar cells. A compressive biaxial stress of ∼-36 MPa was measured in PEDOT:PSS while a tensile stress of ∼6 MPa was measured in the BHJ layer. We then analyze the effect of electrode deposition rate on the film stresses in the Al electrode. Compressive stresses of ∼-100 to -145 MPa in the Al electrode lead to a buckling instability resulting in undulating electrode surface topography. The BHJ layer was found to have the lowest cohesion (∼1.5-1.8 J/m 2) among the layers of the solar cell and dependent on the Al electrode deposition rate. The cohesive failure path in the BHJ layer exhibited the same periodicity and orientation of the Al electrode buckling topography. We discuss the implications of the film stresses on damage processes during device fabrication and operation. © 2012 Elsevier B.V. All rights reserved.

Methods and systems for in-situ electroplating of electrodes

Science.gov (United States)

Zappi, Guillermo Daniel; Zarnoch, Kenneth Paul; Huntley, Christian Andrew; Swalla, Dana Ray

2015-06-02

The present techniques provide electrochemical devices having enhanced electrodes with surfaces that facilitate operation, such as by formation of a porous nickel layer on an operative surface, particularly of the cathode. The porous metal layer increases the surface area of the electrode, which may result in increasing the efficiency of the electrochemical devices. The formation of the porous metal layer is performed in situ, that is, after the assembly of the electrodes into an electrochemical device. The in situ process offers a number of advantages, including the ability to protect the porous metal layer on the electrode surface from damage during assembly of the electrochemical device. The enhanced electrode and the method for its processing may be used in any number of electrochemical devices, and is particularly well suited for electrodes in an electrolyzer useful for splitting water into hydrogen and oxygen.

Determination of the Resistance of Cone-Shaped Solid Electrodes

DEFF Research Database (Denmark)

Frandsen, Henrik Lund; Hendriksen, Peter Vang; Koch, Søren

2017-01-01

during processing can be avoided. Newman's formula for current constriction in the electrolyte is then used to deduce the active contact area based on the ohmic resistance of the cell, and from this the surface specific electro-catalytic activity. However, for electrode materials with low electrical......A cone-shaped electrode pressed into an electrolyte can with advantage be utilized to characterize the electro-catalytic properties of the electrode, because it is less dependent on the electrode microstructure than e.g. thin porous composite electrodes, and reactions with the electrolyte occurring...... conductivity (like Ce1-xPrxO2-δ), the resistance of the cell is significantly influenced by the ohmic resistance of the cone electrode, wherefore it must be included. In this work the ohmic resistance of a cone is modelled analytically based on simplified geometries. The two analytical models only differ...

Linear particle accelerator with seal structure between electrodes and insulators

Science.gov (United States)

Broadhurst, John H.

1989-01-01

An electrostatic linear accelerator includes an electrode stack comprised of primary electrodes formed or Kovar and supported by annular glass insulators having the same thermal expansion rate as the electrodes. Each glass insulator is provided with a pair of fused-in Kovar ring inserts which are bonded to the electrodes. Each electrode is designed to define a concavo-convex particle trap so that secondary charged particles generated within the accelerated beam area cannot reach the inner surface of an insulator. Each insulator has a generated inner surface profile which is so configured that the electrical field at this surface contains no significant tangential component. A spark gap trigger assembly is provided, which energizes spark gaps protecting the electrodes affected by over voltage to prevent excessive energy dissipation in the electrode stack.

Liquid and gel electrodes for transverse free flow electrophoresis

Science.gov (United States)

Jung, Byoungsok; Rose, Klint A; Shusteff, Maxim; Persat, Alexandre; Santiago, Juan

2015-04-07

The present invention provides a mechanism for separating or isolating charged particles under the influence of an electric field without metal electrodes being in direct contact with the sample solution. The metal electrodes normally in contact with the sample are replaced with high conductivity fluid electrodes situated parallel and adjacent to the sample. When the fluid electrodes transmit the electric field across the sample, particles within the sample migrate according to their electrophoretic mobility.

Analytical Applications of Solid and Paste Amalgam Electrodes

Czech Academy of Sciences Publication Activity Database

Josypčuk, Bohdan; Barek, J.

2009-01-01

Roč. 39, č. 3 (2009), s. 189-203 ISSN 1040-8347 R&D Projects: GA ČR GA203/07/1195; GA AV ČR IAA400400806; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40400503 Keywords : solid amalgam electrodes * voltammetry * paste amalgam electrodes * reference amalgam electrodes Subject RIV: CG - Electrochemistry Impact factor: 2.621, year: 2009

Supercapacitors based on modified graphene electrodes with poly(ionic liquid)

Science.gov (United States)

Trigueiro, João Paulo C.; Lavall, Rodrigo L.; Silva, Glaura G.

2014-06-01

The improved accessibility of the electrolyte to the surface of carbon nanomaterials is a challenge to be overcome in supercapacitors based on ionic liquid electrolytes. In this study, we report the preparation of supercapacitors based on reduced graphene oxide (RGO) electrodes and ionic liquid as the electrolyte (specifically, 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide or [MPPy][TFSI]). Two types of electrodes were compared: the RGO-based electrode and a poly(ionic liquid)-modified RGO electrode (PIL:RGO). The supercapacitor produced with the PIL:RGO electrode and [MPPy][TFSI] showed an electrochemical stability of 3 V and provided a capacitance of 71.5 F g-1 at room temperature; this capacitance is 130% higher with respect to the RGO-based supercapacitor. The decrease of the specific capacitance after 2000 cycles is only 10% for the PIL:RGO-based device. The results revealed the potential of the PIL:RGO material as an electrode for supercapacitors. This composite electrode increases the compatibility with the ionic liquid electrolyte compared to an RGO electrode, promoting an increase in the effective surface area of the electrode accessible to the electrolyte ions.

Photosensitive-polyimide based method for fabricating various neural electrode architectures

Directory of Open Access Journals (Sweden)

Yasuhiro X Kato

2012-06-01

Full Text Available An extensive photosensitive polyimide (PSPI-based method for designing and fabricating various neural electrode architectures was developed. The method aims to broaden the design flexibility and expand the fabrication capability for neural electrodes to improve the quality of recorded signals and integrate other functions. After characterizing PSPI’s properties for micromachining processes, we successfully designed and fabricated various neural electrodes even on a non-flat substrate using only one PSPI as an insulation material and without the time-consuming dry etching processes. The fabricated neural electrodes were an electrocorticogram electrode, a mesh intracortical electrode with a unique lattice-like mesh structure to fixate neural tissue, and a guide cannula electrode with recording microelectrodes placed on the curved surface of a guide cannula as a microdialysis probe. In vivo neural recordings using anesthetized rats demonstrated that these electrodes can be used to record neural activities repeatedly without any breakage and mechanical failures, which potentially promises stable recordings for long periods of time. These successes make us believe that this PSPI-based fabrication is a powerful method, permitting flexible design and easy optimization of electrode architectures for a variety of electrophysiological experimental research with improved neural recording performance.

Micropatterned coculture of vascular endothelial and smooth muscle cells on layered electrospun fibrous mats toward blood vessel engineering.

Science.gov (United States)

Li, Huinan; Liu, Yaowen; Lu, Jinfu; Wei, Jiaojun; Li, Xiaohong

2015-06-01

A major challenge in vascular engineering is the establishment of proper microenvironment to guide the spatial organization, growth, and extracellular matrix (ECM) productions of cells found in blood vessels. In the current study, micropatterned fibrous mats with distinct ridges and grooves of different width were created to load smooth muscle cells (SMCs), which were assembled by stacking on vascular endothelial cell (EC)-loaded flat fibrous mats to mimic the in vivo-like organized structure of blood vessels. SMCs were mainly distributed in the ridges, and aligned fibers in the patterned regions led to the formation of elongated cell bodies, intense actin filaments, and expressions of collagen I and α-smooth muscle actin in a parallel direction with fibers. ECs spread over the flat fibrous mats and expressed collagen IV and laminin with a cobblestone-like feature. A z-stack scanning of fluorescently stained fibrous mats indicated that SMCs effectively infiltrated into fibrous scaffolds at the depth of around 200 μm. Compared with SMCs cultured alone, the coculture with ECs enhanced the proliferation, infiltration, and cytoskeleton elongation of SMCs on patterned fibrous mats. Although the coculture of SMCs made no significant difference in the EC growth, the coculture system on patterned fibrous scaffolds promoted ECM productions of both ECs and SMCs. Thus, this patterned fibrous configuration not only offers a promising technology in the design of tissue engineering scaffolds to construct blood vessels with durable mechanical properties, but also provides a platform for patterned coculture to investigate cell-matrix and cell-cell interactions in highly organized tissues. © 2014 Wiley Periodicals, Inc.

Reliable reference electrodes for lithium-ion batteries

KAUST Repository

La Mantia, F.; Wessells, C.D.; Deshazer, H.D.; Cui, Yi

2013-01-01

Despite the high attention drawn to the lithium-ion batteries by the scientific and industrial community, most of the electrochemical characterization is carried out using poor reference electrodes or even no reference electrode. In this case

APPLICATIONS OF A SINGLE CARBON ELECTRODE

African Journals Online (AJOL)

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Page 1 ... ABSTRACT: A single carbon electrode used with a common arc welder has been successfully used on steel to weld, to surface harden, to spot weld sheet, to pierce holes and to do simple brazing. ... applications: welding, spot welding, hole piercing, etc. The metal tube holding the carbon electrodes is banded with ...

Added clinical value of the inferior temporal EEG electrode chain.

Science.gov (United States)

Bach Justesen, Anders; Eskelund Johansen, Ann Berit; Martinussen, Noomi Ida; Wasserman, Danielle; Terney, Daniella; Meritam, Pirgit; Gardella, Elena; Beniczky, Sándor

2018-01-01

To investigate the diagnostic added value of supplementing the 10-20 EEG array with six electrodes in the inferior temporal chain. EEGs were recorded with 25 electrodes: 19 positions of the 10-20 system, and six additional electrodes in the inferior temporal chain (F9/10, T9/10, P9/10). Five-hundred consecutive standard and sleep EEG recordings were reviewed using the 10-20 array and the extended array. We identified the recordings with EEG abnormalities that had peak negativities at the inferior temporal electrodes, and those that only were visible at the inferior temporal electrodes. From the 286 abnormal recordings, the peak negativity was at the inferior temporal electrodes in 81 cases (28.3%) and only visible at the inferior temporal electrodes in eight cases (2.8%). In the sub-group of patients with temporal abnormalities (n = 134), these represented 59% (peak in the inferior chain) and 6% (only seen at the inferior chain). Adding six electrodes in the inferior temporal electrode chain to the 10-20 array improves the localization and identification of EEG abnormalities, especially those located in the temporal region. Our results suggest that inferior temporal electrodes should be added to the EEG array, to increase the diagnostic yield of the recordings. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Electrochemical behaviour of rhenium-graphite electrode

International Nuclear Information System (INIS)

Varypaev, V.N.; Krasikov, V.L.

1980-01-01

Electrochemical behaviour of combination electrode from graphite with electrodeposited thin coating of electrolytic rhenium is studied. Solution of 0.5 m NaCl+0.04 m AlCl 3 served as an electrolite. Polarization galvanostatic curves of hydrogen evolution upon electrodes with conditional rhenium thickness of 3.5 and 0.35 μm, 35 and 3.5 nm are obtained. Possibility of preparation of rhenium-graphite cathode with extremely low rhenium consume, electro-chemical properties of which are simu-lar to purely rhenium cathode is shown. Such electrode is characterized with stable in time low cathode potential of hydrogen evolution in chloride electrolyte and during cathode polarization it is not affected by corrosion

Production of Manual Metal Arc Welding Electrodes with Local Raw ...

African Journals Online (AJOL)

Manual arc welding using flux coated electrodes is carried out by producing an electric arc between the base metal and a flux covered metal electrode with electric current that depends on the type of electrode, material, welding position and the desired strength. The composition of flux coated electrodes is complex and a ...

Dependence of hydrogen arcjet operation on electrode geometry

Science.gov (United States)

Pencil, Eric J.; Sankovic, John M.; Sarmiento, Charles J.; Hamley, John A.

1992-01-01

The dependence of 2 kW hydrogen arcjet performance on cathode to anode electrode spacing was evaluated at specific impulses of 900 and 1000 s. Less than 2 absolute percent change in efficiency was measured for the spacings tested which did not repeat the 14 absolute percent variation reported in earlier work with similar electrode designs. A different nozzle configuration was used to quantify the variation in hydrogen arcjet performance over an extended range of electrode spacing. Electrode gap variation resulted in less than 3 absolute percent change in efficiency. These null results suggested that electrode spacing is decoupled from hydrogen arcjet performance considerations over the ranges tested. Initial studies were conducted on hydrogen arcjet ignition. The dependence of breakdown voltage on mass flow rate and hydrogen arcjet ignition on rates of pulse repetition and pulse voltage rise were also included for comparison with previous results obtained using simulated hydrazine.

A model for electrode effects using percolation theory

International Nuclear Information System (INIS)

Wuethrich, R.; Bleuler, H.

2004-01-01

Electrode effects are known for more than 150 years. These effects, with undesirable consequences in industrial aluminium electrolysis, can be used to micro-machine glass with Spark Assisted Chemical Engraving (SACE). In this paper, a novel approach for theoretical analysis of the phenomenon is proposed by considering the bubble growth and bubble departure from electrodes as a stochastic process. The critical conditions (critical voltage and current density) are predicted in function of electrode geometry and electrolyte concentration as well as the static mean current-voltage characteristics prior to the onset of the effects. The different regions of the current-voltage characteristics, as identified by previous authors, are described and explained. It is shown that all relevant processes for the onset of the electrodes effects happen in the adherence region of the bubble layer. The model is applied for vertical cylindrical electrodes and compared with experimental data

Composite Electrodes for Electrochemical Supercapacitors

Science.gov (United States)

Li, Jun; Yang, Quan Min; Zhitomirsky, Igor

2010-03-01

Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4-6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT) into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with total mass loading of 7-15 mg cm-2, showed a capacitive behavior in 0.5-M Na2SO4 solutions. The decrease in stirring time during precipitation of the nanofibers resulted in reduced agglomeration and higher specific capacitance (SC). The highest SC of 185 F g-1 was obtained at a scan rate of 2 mV s-1 for mass loading of 7 mg cm-2. The SC decreased with increasing scan rate and increasing electrode mass.

Phenomenological theory of current-producing processes at the solid oxide electrolyte/gas electrode interface: steady-state polarization of fuel-cell electrodes

International Nuclear Information System (INIS)

Murygin, I.V.; Chebotin, V.N.

1979-01-01

The polarization of fuel-cell electrodes (mixtures CO + CO 2 and H 2 + H 2 O) in systems with solid oxide electrolytes is discussed. The theory is based upon a process model where the electrode reaction zone can spread along the line of three-phase contact by diffusion of reaction partners and products across the electrolyte/electrode and electrolyte/gas interface

The role of the micro-pattern and nano-topography of hydroxyapatite bioceramics on stimulating osteogenic differentiation of mesenchymal stem cells.

Science.gov (United States)

Zhao, Cancan; Wang, Xiaoya; Gao, Long; Jing, Linguo; Zhou, Quan; Chang, Jiang

2018-06-01

The micro/nano hybrid structure is considered to be a biomaterial characteristic to stimulate osteogenesis by mimicking the three-dimensional structure of the bone matrix. However, the mechanism of the hybrid structure induced osteogenic differentiation of stem cells is still unknown. For elucidating the mechanisms, one of the challenge is to directly fabricate micro/nano hybrid structure on bioceramics because of its brittleness. In this study, hydroxyapatite (HA) bioceramics with the micro/nano hybrid structure were firstly fabricated via a hydrothermal treatment and template method, and the effect of the different surface structures on the expression of integrins, BMP2 signaling pathways and cell-cell communication was investigated. Interestingly, the results suggested that the osteogenic differentiation induced by micro/nano structures was modulated first through activating integrins and then further activating BMP2 signaling pathway and cell-cell communication, while activated BMP2 could in turn activate integrins and Cx43-related cell-cell communication. Furthermore, differences in activation of integrins, BMP2 signaling pathway, and gap junction-mediated cell-cell communication were observed, in which nanorod and micropattern structures activated different integrin subunits, BMP downstream receptors and Cx43. This finding may explain the synergistic effect of the micro/nano hybrid structure on the activation of osteogenic differentiation of BMSCs. Based on our study, we concluded that the different activation mechanisms of micro- and nano-structures led to the synergistic stimulatory effect on integrin activation and osteogenesis, in which not only the direct contact of cells on micro/nano structure played an important role, but also other surface characteristics such as protein adsorption might contribute to the bioactive effect. The micro/nano hybrid structure has been found to have synergistic bioactivity on osteogenesis. However, it is still a challenge

Electrode design for soil decontamination with Radio-Frequency heating

Energy Technology Data Exchange (ETDEWEB)

Roland, U.; Holzer, F.; Kraus, M.; Trommler, U.; Kopinke, F.D. [Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Engineering, Leipzig (Germany)

2011-10-15

Radio-frequency heating to enhance soil decontamination requires adjusted solutions for the electrode design depending on scale and remediation technique. Parallel plate electrodes provide widely homogeneous field and temperature distributions and are, therefore, most suitable for supporting biodegradation processes. For thermally enhanced soil vapor extraction, certain temperature gradients can be accepted and, therefore, the less-demanding geometry of rod-shaped electrodes is usually applied. For electrode lengths of some meters, a design with an air gap has to be used in order to focus heating to the desired depth. Perforated rod electrodes may be simultaneously employed as extraction wells. Placing an oxidation catalyst in situ within the electrodes is an option for handling of highly loaded air flows. Coaxial antenna may be utilized to selectively heat soil compartments far from the surface of the soil. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Applications of Graphene-Modified Electrodes in Microbial Fuel Cells

Directory of Open Access Journals (Sweden)

Fei Yu

2016-09-01

Full Text Available Graphene-modified materials have captured increasing attention for energy applications due to their superior physical and chemical properties, which can significantly enhance the electricity generation performance of microbial fuel cells (MFC. In this review, several typical synthesis methods of graphene-modified electrodes, such as graphite oxide reduction methods, self-assembly methods, and chemical vapor deposition, are summarized. According to the different functions of the graphene-modified materials in the MFC anode and cathode chambers, a series of design concepts for MFC electrodes are assembled, e.g., enhancing the biocompatibility and improving the extracellular electron transfer efficiency for anode electrodes and increasing the active sites and strengthening the reduction pathway for cathode electrodes. In spite of the challenges of MFC electrodes, graphene-modified electrodes are promising for MFC development to address the reduction in efficiency brought about by organic waste by converting it into electrical energy.

Dual-electrode biasing experiments in KT-5C device

International Nuclear Information System (INIS)

Yu Yi; Lu Ronghua; Wang Chen; Pan Geshen; Wen Yizhi; Yu Changxuan; Ma Jinxiu; Wan Shude; Liu Wandong

2005-01-01

Based on the single biasing electrode experiments to optimize the confinement of plasma in the device of KT-5C tokamak, dual-biasing electrodes were inserted into the KT5C plasma for the first time to explore the enhancement of the effects of biasing and the mechanisms of the biasing. By means of applying different combinations of biasing voltages to the dual electrodes, the changes in E r , which is the key factor for boosting up the Er x B flow shear, were observed. The time evolution showed the inner electrode played a major role in dual-biasing, for it always drew a larger current than the outer one. The outer electrode made little influence. It turned out that the dual-biasing electrodes were as effective as a single one, in improving plasma confinement, for the mechanism of biasing was essentially an edge effect. (author)

Crystallic silver amalgam--a novel electrode material.

Science.gov (United States)

Danhel, Ales; Mansfeldova, Vera; Janda, Pavel; Vyskocil, Vlastimil; Barek, Jiri

2011-09-21

A crystallic silver amalgam was found to be a suitable working electrode material for voltammetric determination of electrochemically reducible organic nitro-compounds. Optimum conditions for crystal growth were found, the crystal surface was investigated by atomic force microscopy in tapping mode and single crystals were used for the preparation of quasi-cylindrical single crystal silver amalgam electrode (CAgAE). An electrochemical behavior of this alternative electrode material was investigated in aqueous media by direct current voltammetry, cyclic voltammetry (CV), differential pulse voltammetry (DPV) and adsorptive stripping voltammetry (AdSV) using 4-nitrophenol as a model compound. Applicable potential windows of the CAgAE were found comparable with those obtained at a hanging mercury drop electrode, providing high hydrogen overpotential, and polished silver solid amalgam electrode. Thanks to the smooth single crystal electrode surface, the effect of the passivation is not too pronounced, direct DPV determination of 100 μmol l(-1) of 4-nitrophenol at CAgAEs in 0.2 mol l(-1) acetate buffer pH 4.8 provides a RSD around 1.5% (n = 15). DPV calibration curves of 4-nitrophenol are linear in the whole concentration range 1-100 μmol l(-1) with a limit of quantification of 1.5 μmol l(-1). The attempt to increase sensitivity by application of AdSV was not successful. The mechanism of 4-nitrophenol reduction at CAgAE was investigated by CV.

Microfabricated Reference Electrodes and their Biosensing Applications

Directory of Open Access Journals (Sweden)

M. Jamal Deen

2010-03-01

Full Text Available Over the past two decades, there has been an increasing trend towards miniaturization of both biological and chemical sensors and their integration with miniaturized sample pre-processing and analysis systems. These miniaturized lab-on-chip devices have several functional advantages including low cost, their ability to analyze smaller samples, faster analysis time, suitability for automation, and increased reliability and repeatability. Electrical based sensing methods that transduce biological or chemical signals into the electrical domain are a dominant part of the lab-on-chip devices. A vital part of any electrochemical sensing system is the reference electrode, which is a probe that is capable of measuring the potential on the solution side of an electrochemical interface. Research on miniaturization of this crucial component and analysis of the parameters that affect its performance, stability and lifetime, is sparse. In this paper, we present the basic electrochemistry and thermodynamics of these reference electrodes and illustrate the uses of reference electrodes in electrochemical and biological measurements. Different electrochemical systems that are used as reference electrodes will be presented, and an overview of some contemporary advances in electrode miniaturization and their performance will be provided.

Site Selection for Hvdc Ground Electrodes

Science.gov (United States)

Freire, P. F.; Pereira, S. Y.

2014-12-01

High-Voltage Direct Current (HVDC) transmission systems are composed of a bipole transmission line with a converter substation at each end. Each substation may be equipped with a HVDC ground electrode, which is a wide area (up to 1 km Ø) and deep (from 3 to 100m) electrical grounding. When in normal operation, the ground electrode will dissipate in the soil the unbalance of the bipole (~1.5% of the rated current). When in monopolar operation with ground return, the HVDC electrode will inject in the soil the nominal pole continuous current, of about 2000 to 3000 Amperes, continuously for a period up to a few hours. HVDC ground electrodes site selection is a work based on extensive geophysical and geological surveys, in order to attend the desired design requirements established for the electrodes, considering both its operational conditions (maximum soil temperature, working life, local soil voltage gradients etc.) and the interference effects on the installations located up to 50 km away. This poster presents the geophysical investigations conducted primarily for the electrodes site selection, and subsequently for the development of the crust resistivity model, which will be used for the interference studies. A preliminary site selection is conducted, based on general geographical and geological criteria. Subsequently, the geology of each chosen area is surveyed in detail, by means of electromagnetic/electrical geophysical techniques, such as magnetotelluric (deep), TDEM (near-surface) and electroresistivity (shallow). Other complementary geologic and geotechnical surveys are conducted, such as wells drilling (for geotechnical characterization, measurement of the water table depth and water flow, and electromagnetic profiling), and soil and water sampling (for measurement of thermal parameters and evaluation of electrosmosis risk). The site evaluation is a dynamic process along the surveys, and some sites will be discarded. For the two or three final sites, the

Self-positioned thin Pb-alloy base electrode Josephson junction

International Nuclear Information System (INIS)

Kuroda, K.; Sato, K.

1986-01-01

A self-positioned thin (SPOT) Pb-alloy base electrode Josephson junction is developed. In this junction, a 50-nm thick Pb-alloy base electrode is restricted within the junction region on an Nb underlayer using a self-alignment technique. The grain size reduction and the base electrode area restriction greatly improve thermal cycling stability, where the thermal cycling tests of 4000 proposed junctions (5 x 5 μm 2 ) showed no failures after 4000 cycles. In addition, the elimination of insulator layer stress on the Pb-alloy base electrode rectifies the problem of size effect on current density. The Nb underlayers also serve to isolate the Pb-alloy base electrodes from the resistors

Electronically conductive polymer binder for lithium-ion battery electrode

Energy Technology Data Exchange (ETDEWEB)

Liu, Gao; Xun, Shidi; Battaglia, Vincent S.; Zheng, Honghe; Wu, Mingyan

2017-08-01

A family of carboxylic acid groups containing fluorene/fluorenon copolymers is disclosed as binders of silicon particles in the fabrication of negative electrodes for use with lithium ion batteries. Triethyleneoxide side chains provide improved adhesion to materials such as, graphite, silicon, silicon alloy, tin, tin alloy. These binders enable the use of silicon as an electrode material as they significantly improve the cycle-ability of silicon by preventing electrode degradation over time. In particular, these polymers, which become conductive on first charge, bind to the silicon particles of the electrode, are flexible so as to better accommodate the expansion and contraction of the electrode during charge/discharge, and being conductive promote the flow battery current.

Electronically conductive polymer binder for lithium-ion battery electrode

Science.gov (United States)

Liu, Gao; Xun, Shidi; Battaglia, Vincent S.; Zheng, Honghe; Wu, Mingyan

2015-07-07

A family of carboxylic acid groups containing fluorene/fluorenon copolymers is disclosed as binders of silicon particles in the fabrication of negative electrodes for use with lithium ion batteries. Triethyleneoxide side chains provide improved adhesion to materials such as, graphite, silicon, silicon alloy, tin, tin alloy. These binders enable the use of silicon as an electrode material as they significantly improve the cycle-ability of silicon by preventing electrode degradation over time. In particular, these polymers, which become conductive on first charge, bind to the silicon particles of the electrode, are flexible so as to better accommodate the expansion and contraction of the electrode during charge/discharge, and being conductive promote the flow battery current.

Characteristics of electrode impedance and stimulation efficacy of a chronic cortical implant using novel annulus electrodes in rat motor cortex

Science.gov (United States)

Wang, Chun; Brunton, Emma; Haghgooie, Saman; Cassells, Kahli; Lowery, Arthur; Rajan, Ramesh

2013-08-01

Objective. Cortical neural prostheses with implanted electrode arrays have been used to restore compromised brain functions but concerns remain regarding their long-term stability and functional performance. Approach. Here we report changes in electrode impedance and stimulation thresholds for a custom-designed electrode array implanted in rat motor cortex for up to three months. Main Results. The array comprises four 2000 µm long electrodes with a large annular stimulating surface (7860-15700 µm2) displaced from the penetrating insulated tip. Compared to pre-implantation in vitro values there were three phases of impedance change: (1) an immediate large increase of impedance by an average of two-fold on implantation; (2) a period of continued impedance increase, albeit with considerable variability, which reached a peak at approximately four weeks post-implantation and remained high over the next two weeks; (3) finally, a period of 5-6 weeks when impedance stabilized at levels close to those seen immediately post-implantation. Impedance could often be temporarily decreased by applying brief trains of current stimulation, used to evoke motor output. The stimulation threshold to induce observable motor behaviour was generally between 75-100 µA, with charge density varying from 48-128 µC cm-2, consistent with the lower current density generated by electrodes with larger stimulating surface area. No systematic change in thresholds occurred over time, suggesting that device functionality was not compromised by the factors that caused changes in electrode impedance. Significance. The present results provide support for the use of annulus electrodes in future applications in cortical neural prostheses.

Methods for calculating the electrode position Jacobian for impedance imaging.

Science.gov (United States)

Boyle, A; Crabb, M G; Jehl, M; Lionheart, W R B; Adler, A

2017-03-01

Electrical impedance tomography (EIT) or electrical resistivity tomography (ERT) current and measure voltages at the boundary of a domain through electrodes. The movement or incorrect placement of electrodes may lead to modelling errors that result in significant reconstructed image artifacts. These errors may be accounted for by allowing for electrode position estimates in the model. Movement may be reconstructed through a first-order approximation, the electrode position Jacobian. A reconstruction that incorporates electrode position estimates and conductivity can significantly reduce image artifacts. Conversely, if electrode position is ignored it can be difficult to distinguish true conductivity changes from reconstruction artifacts which may increase the risk of a flawed interpretation. In this work, we aim to determine the fastest, most accurate approach for estimating the electrode position Jacobian. Four methods of calculating the electrode position Jacobian were evaluated on a homogeneous halfspace. Results show that Fréchet derivative and rank-one update methods are competitive in computational efficiency but achieve different solutions for certain values of contact impedance and mesh density.

Electrostatic Spectrograph with a Wide Range of Simultaneously Recorded Energies Composed of Two Coaxial Electrodes with Closed End Faces and a Discrete Combined External Electrode

Science.gov (United States)

Fishkova, T. Ya.

2018-01-01

An optimal set of geometric and electrical parameters of a high-aperture electrostatic charged-particle spectrograph with a range of simultaneously recorded energies of E/ E min = 1-50 has been found by computer simulation, which is especially important for the energy analysis of charged particles during fast processes in various materials. The spectrograph consists of two coaxial electrodes with end faces closed by flat electrodes. The external electrode with a conical-cylindrical form is cut into parts with potentials that increase linearly, except for the last cylindrical part, which is electrically connected to the rear end electrode. The internal cylindrical electrode and the front end electrode are grounded. In the entire energy range, the system is sharply focused on the internal cylindrical electrode, which provides an energy resolution of no worse than 3 × 10-3.

Flexible and stretchable electrodes for dielectric elastomer actuators

Science.gov (United States)

Rosset, Samuel; Shea, Herbert R.

2013-02-01

Dielectric elastomer actuators (DEAs) are flexible lightweight actuators that can generate strains of over 100 %. They are used in applications ranging from haptic feedback (mm-sized devices), to cm-scale soft robots, to meter-long blimps. DEAs consist of an electrode-elastomer-electrode stack, placed on a frame. Applying a voltage between the electrodes electrostatically compresses the elastomer, which deforms in-plane or out-of plane depending on design. Since the electrodes are bonded to the elastomer, they must reliably sustain repeated very large deformations while remaining conductive, and without significantly adding to the stiffness of the soft elastomer. The electrodes are required for electrostatic actuation, but also enable resistive and capacitive sensing of the strain, leading to self-sensing actuators. This review compares the different technologies used to make compliant electrodes for DEAs in terms of: impact on DEA device performance (speed, efficiency, maximum strain), manufacturability, miniaturization, the integration of self-sensing and self-switching, and compatibility with low-voltage operation. While graphite and carbon black have been the most widely used technique in research environments, alternative methods are emerging which combine compliance, conduction at over 100 % strain with better conductivity and/or ease of patternability, including microfabrication-based approaches for compliant metal thin-films, metal-polymer nano-composites, nanoparticle implantation, and reel-to-reel production of μm-scale patterned thin films on elastomers. Such electrodes are key to miniaturization, low-voltage operation, and widespread commercialization of DEAs.

Experimental characterization of PZT fibers using IDE electrodes

Science.gov (United States)

Wyckoff, Nicholas; Ben Atitallah, Hassene; Ounaies, Zoubeida

2016-04-01

Lead zirconate titanate (PZT) fibers are mainly used in active fiber composites (AFC) where they are embedded in a polymer matrix. Interdigitated electrodes (IDE) along the direction of the fibers are used to achieve planar actuation, hereby exploiting the d33 coefficient of PZT. When embedded in the AFC, the PZT fibers are subjected to mechanical loading as well as non-uniform electric field as a result of the IDEs. Therefore, it is important to characterize the electrical and electromechanical behavior of these fibers ex-situ using the IDE electrodes to assess the impact of nonuniform electric field on the properties of the fibers. For that reason, this work aims at quantifying the impact of IDE electrodes on the electrical and electromechanical behavior of PZT fibers, which is necessary for their successful implementation in devices like AFC. The tested fibers were purchased from Advanced Cerametrics and they have an average diameter of 250 micrometers. The IDE electrodes were screen printed on an acrylic substrate. The PZT fibers were subjected to frequency sweeps at low voltages to determine permittivity for parallel and interdigitated electrodes. The piezoelectric e33 constant is determined from electromechanical testing of PZT fibers in parallel electrodes to compare the electromechanical behavior for PZT in bulk and fiber form. The dielectric constant and e33 were found to be lower for the IDE and parallel electrodes compared to bulk but comparable to results published in literature.

Textile Electrodes for EEG Recording — A Pilot Study

Directory of Open Access Journals (Sweden)

Johan Löfhede

2012-12-01

Full Text Available The overall aim of our research is to develop a monitoring system for neonatal intensive care units. Long-term EEG monitoring in newborns require that the electrodes don’t harm the sensitive skin of the baby, an especially relevant feature for premature babies. Our approach to EEG monitoring is based on several electrodes distributed over the head of the baby, and since the weight of the head always will be on some of them, any type of hard electrode will inevitably cause a pressure-point that can irritate the skin. Therefore, we propose the use of soft conductive textiles as EEG electrodes, primarily for neonates, but also for other kinds of unobtrusive long-term monitoring. In this paper we have tested two types of textile electrodes on five healthy adults and compared them to standard high quality electrodes. The acquired signals were compared with respect to morphology, frequency distribution, spectral coherence, correlation and power line interference sensitivity, and the signals were found to be similar in most respects. The good measurement performance exhibited by the textile electrodes indicates that they are feasible candidates for EEG recording, opening the door for long-term EEG monitoring applications.

Doped polymer electrodes for high performance ferroelectric capacitors on plastic substrates

KAUST Repository

Khan, M. A.

2012-10-03

Flexible ferroelectric capacitors with doped polymer electrodes have been fabricated on plastic substrates with performance as good as metal electrodes. The effect of doping on the morphology of polymer electrodes and its impact on device performance have been studied. Improved fatigue characteristics using doped and undoped poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) electrodes versus metal electrodes are observed. It is shown that the polymer electrodes follow classical ferroelectric and dielectric responses, including series resistance effects. The improved device characteristics obtained using highly conducting doped PEDOT:PSS suggest that it may be used both as an electrode and as global interconnect for all-polymer transparent circuits on flexible substrates.

Evaluation of the hybrid-L24 electrode using microcomputed tomography.

Science.gov (United States)

Driscoll, Colin L W; Carlson, Matthew L; Fama, Anthony F; Lane, John I

2011-07-01

To compare electrode array position, and depth of insertion of the Cochlear Hybrid-L24 electrode array following traditional cochleostomy and round window (RW) insertion. Prospective cadaveric temporal bone study. Ten cadaveric temporal bones were implanted with the Hybrid-L24 electrode array; half were introduced through a RW approach, whereas the other half were inserted through a traditional scala tympani cochleostomy. A micro-CT scanner was then used to evaluate electrode position, intracochlear trauma, and depth of insertion. All electrodes were inserted into the scala tympani without significant resistance. No electrodes demonstrated tip fold-over or through-fracturing of the osseous spiral lamina, basilar membrane, or spiral ligament. The average angular depth of insertion for all 10 electrodes was 252.4°. Compared to cochleostomy insertions, electrodes inserted through the RW more commonly acquired a proximal perimodiolar orientation, followed a more predictable course, and less commonly contacted critical soft tissue structures. The results of this study demonstrate that the Hybrid-L24 electrode can be successfully inserted using a RW or traditional cochleostomy technique with minimal intracochlear trauma. Our data also suggests that with this model, RW insertions may provide particular advantages with respect to hearing preservation over the traditional cochleostomy approach. Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.

Microneedle array electrode for human EEG recording.

NARCIS (Netherlands)

Lüttge, Regina; van Nieuwkasteele-Bystrova, Svetlana Nikolajevna; van Putten, Michel Johannes Antonius Maria; Vander Sloten, Jos; Verdonck, Pascal; Nyssen, Marc; Haueisen, Jens

2009-01-01

Microneedle array electrodes for EEG significantly reduce the mounting time, particularly by circumvention of the need for skin preparation by scrubbing. We designed a new replication process for numerous types of microneedle arrays. Here, polymer microneedle array electrodes with 64 microneedles,

A configurable electrical capacitance tomography system using a combining electrode strategy

International Nuclear Information System (INIS)

Yang, Yunjie; Peng, Lihui

2013-01-01

Systematic investigation of a combining electrode strategy for electrical capacitance tomography (ECT) is carried out. A configurable digital and analogue mixed ECT system using a combining electrode strategy is presented. Compared to the traditional ECT system, the presented system can be configured flexibly as the traditional ECT sensor mode and the combining electrode mode by connecting a number of electrodes as a combined electrode. In particular, the combining electrode mode is increasing the number of capacitance measurement data and the amelioration of sensitivity distribution. An image reconstruction framework is proposed by configuring the presented ECT system as the corresponding sensor mode adaptive to the permittivity distribution to be reconstructed, which includes the traditional ECT sensor mode, the symmetric combining electrode mode, the asymmetric combining electrode mode and the mixed combining electrode mode. Both simulation and experimental results show that image reconstructions with better quality and robustness to measurement noise can be obtained under the proposed adaptive image reconstruction framework by using the presented configurable ECT system. (paper)

A novel high-performance counter electrode for dye-sensitized solar cells

International Nuclear Information System (INIS)

Wang Guiqiang; Lin Ruifeng; Lin Yuan; Li Xueping; Zhou Xiaowen; Xiao Xurui

2005-01-01

A novel Pt counter electrode for dye-sensitized solar cells (DSC) was prepared by thermal decomposition of H 2 PtCl 6 on NiP-plated glass substrate. The charge-transfer kinetic properties of the platinized NiP-plated glass electrode (Pt/NiP electrode) for triiodide reduction were studied by electrochemical impedance spectroscopy. Pt/NiP electrode has the advantage over the platinized FTO conducting glass electrode (Pt/FTO electrode) in increasing the light reflectance and reducing the sheet resistance leading to improve the light harvest efficiency and the fill factor of the dye-sensitized solar cells effectively. The photon-to-current efficiency and the overall conversion efficiency of DSC using Pt/NiP counter electrode is increased by 20% and 33%, respectively, compared to that of using Pt/FTO counter electrode. Examination of the anodic dissolution and the long-term test on the variation of charge-transfer resistance indicates the good stability of the Pt/NiP electrode in the electrolyte containing iodide/triiodide

Wearable carbon nanotube based dry-electrodes for electrophysiological sensors

Science.gov (United States)

Kang, Byeong-Cheol; Ha, Tae-Jun

2018-05-01

In this paper, we demonstrate all-solution-processed carbon nanotube (CNT) dry-electrodes for the detection of electrophysiological signals such as electrocardiograms (ECG) and electromyograms (EMG). The key parameters of P, Q, R, S, and T peaks are successfully extracted by such CNT based dry-electrodes, which is comparable with conventional silver/chloride (Ag/AgCl) wet-electrodes with a conducting gel film for the ECG recording. Furthermore, the sensing performance of CNT based dry-electrodes is secured during the bending test of 200 cycles, which is essential for wearable electrophysiological sensors in a non-invasive method on human skin. We also investigate the application of wearable CNT based dry-electrodes directly attached to the human skins such as forearm for sensing the electrophysiological signals. The accurate and rapid sensing response can be achieved by CNT based dry-electrodes to supervise the health condition affected by excessive physical movements during the real-time measurements.

Evaluation of high-perimeter electrode designs for deep brain stimulation

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Howell, Bryan; Grill, Warren M.

2014-08-01

Objective. Deep brain stimulation (DBS) is an effective treatment for movement disorders and a promising therapy for treating epilepsy and psychiatric disorders. Despite its clinical success, complications including infections and mis-programing following surgical replacement of the battery-powered implantable pulse generator adversely impact the safety profile of this therapy. We sought to decrease power consumption and extend battery life by modifying the electrode geometry to increase stimulation efficiency. The specific goal of this study was to determine whether electrode contact perimeter or area had a greater effect on increasing stimulation efficiency. Approach. Finite-element method (FEM) models of eight prototype electrode designs were used to calculate the electrode access resistance, and the FEM models were coupled with cable models of passing axons to quantify stimulation efficiency. We also measured in vitro the electrical properties of the prototype electrode designs and measured in vivo the stimulation efficiency following acute implantation in anesthetized cats. Main results. Area had a greater effect than perimeter on altering the electrode access resistance; electrode (access or dynamic) resistance alone did not predict stimulation efficiency because efficiency was dependent on the shape of the potential distribution in the tissue; and, quantitative assessment of stimulation efficiency required consideration of the effects of the electrode-tissue interface impedance. Significance. These results advance understanding of the features of electrode geometry that are important for designing the next generation of efficient DBS electrodes.

Redox electrodes comprised of polymer-modified carbon nanomaterials

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Roberts, Mark; Emmett, Robert; Karakaya, Mehmet; Podila, Ramakrishna; Rao, Apparao; Clemson Physics Team; Clemson Chemical Engineering Team

2013-03-01

A shift in how we generate and use electricity requires new energy storage materials and systems compatible with hybrid electric transportation and the integration of renewable energy sources. Supercapacitors provide a solution to these needs by combining the high power, rapid switching, and exceptional cycle life of a capacitor with the high energy density of a battery. Our research brings together nanotechnology and materials chemistry to address the limitations of electrode materials. Paper electrodes fabricated with various forms of carbon nanomaterials, such as nanotubes, are modified with redox-polymers to increase the electrode's energy density while maintaining rapid discharge rates. In these systems, the carbon nanomaterials provide the high surface area, electrical conductivity, nanoscale and porosity, while the redox polymers provide a mechanism for charge storage through Faradaic charge transfer. The design of redox polymers and their incorporation into nanomaterial electrodes will be discussed with a focus on enabling high power and high energy density electrodes.

Electrochemical Oxidation of Cyanide Using Platinized Ti Electrodes

Directory of Open Access Journals (Sweden)

Aušra VALIŪNIENĖ

2013-12-01

Full Text Available The cyanide-containing effluents are dangerous ecological hazards and must be treated before discharging into the environment. Anodic oxidation is one of the best ways to degrade cyanides. Pt anodes as the most efficient material for the cyanide electrochemical degradation are widely used. However, these electrodes are too expensive for industrial purposes. In this work Ti electrodes covered with nano-sized Pt particle layer were prepared and used for the anodic oxidation of cyanide ions. Surface images of Ti electrodes and Ti electrodes covered with different thickness layer of Pt were compared and characterized by the atomic force microscopy (AFM. The products formed in the solution during the CN- ions electrooxidation were examined by the Raman spectroscopy. An electrochemical Fast Fourier transformation (FFT impedance spectroscopy was used to estimate the parameters that reflect real surface roughness of Pt-modified Ti electrodes.DOI: http://dx.doi.org/10.5755/j01.ms.19.4.2514

Manganese oxide-based materials as electrochemical supercapacitor electrodes.

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Wei, Weifeng; Cui, Xinwei; Chen, Weixing; Ivey, Douglas G

2011-03-01

Electrochemical supercapacitors (ECs), characteristic of high power and reasonably high energy densities, have become a versatile solution to various emerging energy applications. This critical review describes some materials science aspects on manganese oxide-based materials for these applications, primarily including the strategic design and fabrication of these electrode materials. Nanostructurization, chemical modification and incorporation with high surface area, conductive nanoarchitectures are the three major strategies in the development of high-performance manganese oxide-based electrodes for EC applications. Numerous works reviewed herein have shown enhanced electrochemical performance in the manganese oxide-based electrode materials. However, many fundamental questions remain unanswered, particularly with respect to characterization and understanding of electron transfer and atomic transport of the electrochemical interface processes within the manganese oxide-based electrodes. In order to fully exploit the potential of manganese oxide-based electrode materials, an unambiguous appreciation of these basic questions and optimization of synthesis parameters and material properties are critical for the further development of EC devices (233 references).

Embedded Metal Electrode for Organic-Inorganic Hybrid Nanowire Solar Cells.

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Um, Han-Don; Choi, Deokjae; Choi, Ahreum; Seo, Ji Hoon; Seo, Kwanyong

2017-06-27

We demonstrate here an embedded metal electrode for highly efficient organic-inorganic hybrid nanowire solar cells. The electrode proposed here is an effective alternative to the conventional bus and finger electrode which leads to a localized short circuit at a direct Si/metal contact and has a poor collection efficiency due to a nonoptimized electrode design. In our design, a Ag/SiO 2 electrode is embedded into a Si substrate while being positioned between Si nanowire arrays underneath poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), facilitating suppressed recombination at the Si/Ag interface and notable improvements in the fabrication reproducibility. With an optimized microgrid electrode, our 1 cm 2 hybrid solar cells exhibit a power conversion efficiency of up to 16.1% with an open-circuit voltage of 607 mV and a short circuit current density of 34.0 mA/cm 2 . This power conversion efficiency is more than twice as high as that of solar cells using a conventional electrode (8.0%). The microgrid electrode significantly minimizes the optical and electrical losses. This reproducibly yields a superior quantum efficiency of 99% at the main solar spectrum wavelength of 600 nm. In particular, our solar cells exhibit a significant increase in the fill factor of 78.3% compared to that of a conventional electrode (61.4%); this is because of the drastic reduction in the metal/contact resistance of the 1 μm-thick Ag electrode. Hence, the use of our embedded microgrid electrode in the construction of an ideal carrier collection path presents an opportunity in the development of highly efficient organic-inorganic hybrid solar cells.

Ultrasmall and customizable multichannel electrodes for extracellular recordings.

Science.gov (United States)

Piironen, Arto; Weckström, Matti; Vähäsöyrinki, Mikko

2011-03-01

Increasing demand exists for smaller multichannel electrodes that enable simultaneous recordings of many neurons in a noninvasive manner. We report a novel method for manufacturing ultrasmall carbon fiber electrodes with up to seven closely spaced recording sites. The electrodes were designed to minimize damage to neuronal circuitry and to be fully customizable in three dimensions so that their dimensions can be optimally matched to those of the targeted neuron population.

High Energy Conversion Efficiency with 3-D Micro-Patterned Photoanode for Enhancement Diffusivity and Modification of Photon Distribution in Dye-Sensitized Solar Cells.