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Sample records for micropatterned electrode fabrication

  1. Electrodes on a budget: Micropatterned electrode fabrication by wet chemical deposition

    PubMed Central

    Ebina, Wataru; Rowat, Amy C.; Weitz, David A.

    2009-01-01

    Precise patterning of metals is required for diverse microfluidic and microelectromechanical system (MEMS) applications ranging from the separation of proteins to the manipulation of single cells and drops of water-in-oil emulsions. Here we present a very simple, inexpensive method for fabricating micropatterned electrodes. We deposit a thin metal layer of controlled thickness using wet chemistry, thus eliminating the need for expensive equipment typically required for metal deposition. We demonstrate that the resulting deposited metal can be used to fabricate functional electrodes: The wet-deposited metal film can sustain patterning by photolithography down to micron-sized features required for MEMS and microfluidic applications, and its properties are suitable for operative electrodes used in a wide range of microfluidic applications for biological studies. PMID:20216960

  2. Two-dimensional micropatterns via crystal growth of Na2CO3 for fabrication of transparent electrodes.

    PubMed

    Lee, Dong-Eun; Go, SeungJae; Hwang, GyungSeok; Chin, Byung Doo; Lee, Dong Hyun

    2013-10-01

    The simple and versatile method to generate two-dimensional micropatterns by controlling precisely crystallization of sodium carbonate (Na2CO3) was investigated. Dense clusters of dendrites of salt crystals were homogeneously formed in a large area with an aqueous solution of Na2CO3 during evaporation of water. The dimensions and morphologies of dendritic salt crystals were tuned by changing the growth conditions such as salt concentration, relative humidity, and temperature. Then, 2D micropatterns of salt crystals were directly used as a mask for the deposition of a silver (Ag) layer to fabricate transparent electrodes. After salt crystals were completely dissolved in water, the network of an electrically conductive Ag layer, whose patterns were reversely produced from salt crystals, was generated on glass substrates. In addition, salt crystals were used as a master to prepare a replica mold of poly(dimethylsiloxane) (PDMS) for utilizing the imprinting technique. By imprinting a flexible PDMS mold with Ag inks, Ag micropatterns that were perfectly identical to dendrites of salt crystals were transferred to the other substrate. PMID:24003886

  3. Selective sintering of metal nanoparticle ink for maskless fabrication of an electrode micropattern using a spatially modulated laser beam by a digital micromirror device.

    PubMed

    An, Kunsik; Hong, Sukjoon; Han, Seungyong; Lee, Hyungman; Yeo, Junyeob; Ko, Seung Hwan

    2014-02-26

    We demonstrate selective laser sintering of silver (Ag) nanoparticle (NP) ink using a digital micromirror device (DMD) for the facile fabrication of 2D electrode pattern without any conventional lithographic means or scanning procedure. An arbitrary 2D pattern at the lateral size of 25 μm × 25 μm with 160 nm height is readily produced on a glass substrate by a short exposure of 532 nm Nd:YAG continuous wave laser. The resultant metal pattern exhibits low electrical resistivity of 10.8 uΩ · cm and also shows a fine edge sharpness by the virtue of low thermal conductivity of Ag NP ink. Furthermore, 10 × 10 star-shaped micropattern arrays are fabricated through a step-and-repeat scheme to ensure the potential of this process for the large-area metal pattern fabrication. PMID:24471931

  4. Fabrication of freestanding heteroepitaxial diamond substrate via micropatterns and microneedles

    NASA Astrophysics Data System (ADS)

    Aida, Hideo; Kim, Seong-Woo; Ikejiri, Kenjiro; Kawamata, Yuki; Koyama, Koji; Kodama, Hideyuki; Sawabe, Atsuhito

    2016-03-01

    The fabrication of a high-quality freestanding diamond substrate was successfully demonstrated via heteroepitaxy by introducing diamond micropatterns and microneedles in the early stage of growth. Micropatterns contributed to a marked reduction in the number of dislocations induced by epitaxial lateral overgrowth, and microneedles relaxed heteroepitaxial strain. Raman spectroscopy indicated the absence of nondiamond carbon inclusions in the obtained freestanding substrate. The full width at half maximum of the X-ray rocking curve for diamond (004) reflections was 0.07°, the lowest value for heteroepitaxial diamond that has been reported so far. The results provide novel insights toward realizing large-diameter single-crystalline diamond substrates.

  5. The study and fabrication of DLC micropattern on roll mold

    NASA Astrophysics Data System (ADS)

    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.

  6. Photovoltachromic device with a micropatterned bifunctional counter electrode.

    PubMed

    Cannavale, Alessandro; Manca, Michele; De Marco, Luisa; Grisorio, Roberto; Carallo, Sonia; Suranna, Gian Paolo; Gigli, Giuseppe

    2014-02-26

    A photovoltachromic window can potentially act as a smart glass skin which generates electric energy as a common dye-sensitized solar cell and, at the same time, control the incoming energy flux by reacting to even small modifications in the solar radiation intensity. We report here the successful implementation of a novel architecture of a photovoltachromic cell based on an engineered bifunctional counter electrode consisting of two physically separated platinum and tungsten oxide regions, which are arranged to form complementary comb-like patterns. Solar light is partially harvested by a dye-sensitized photoelectrode made on the front glass of the cell which fully overlaps a bifunctional counter electrode made on the back glass. When the cell is illuminated, the photovoltage drives electrons into the electrochromic stripes through the photoelectrochromic circuit and promotes the Li(+) diffusion towards the WO3 film, which thus turns into its colored state: a photocoloration efficiency of 17 cm(2) min(-1) W(-1) at a wavelength of 650 nm under 1.0 sun was reported along with fast response (coloration time <2 s and bleaching time <5 s). A fairly efficient photovoltaic functionality was also retained due to the copresence of the independently switchable micropatterned platinum electrode.

  7. A facile method for fabrication of responsive micropatterned surfaces

    NASA Astrophysics Data System (ADS)

    Demiryürek, Rıdvan; Kassim Ali, Mariamu; Ozaydin Ince, Gozde

    2014-09-01

    Responsive micropatterned surfaces are fabricated using a facile, one-step method that allows for the separate control of topography and surface chemistry. Temperature responsive poly(N-isopropylacrylamide) (pNIPAAm), and amphiphilic poly(hydroxyethyl methacrylate-co-perfluorodecylacrylate) (p(HEMA-co-PFA)) polymer thin films are deposited on prestrained polydimethylsiloxane (PDMS) substrates using the initiated chemical vapor deposition (iCVD) technique. Subsequent release of the strain results in the formation of periodic wrinkle structures on the surface of polymer thin films. The iCVD technique allows control of the chemical composition while preserving the functional groups of the polymers intact. Surface topography is controlled separately by tuning elastic modulus of the polymer coatings and substrates. Highly ordered, well-defined wrinkle structures are obtained on pNIPAAm surfaces whereas wrinkles on the amphiphilic surfaces are less ordered due to the difference in elastic moduli of the polymers. Furthermore, process temperature is observed to have detrimental effects on the ordering of the wrinkles.

  8. Development of novel designs of spark-protected micropattern gaseous detectors with resistive electrodes

    NASA Astrophysics Data System (ADS)

    Peskov, V.; Martinengo, P.; Nappi, E.; Oliveira, R.; Pietropaolo, P.; Picchi, P.

    2012-01-01

    In the last few years many efforts have been made by various groups to develop spark-protected micropattern gaseous detectors equipped with resistive electrodes instead of metallic ones. Great success has recently been achieved with resistive gas electron multipliers (GEMs), resistive micromesh gaseous structures and resistive Well/compteur a trou detectors. In this paper, we will focus on the development of a new family of spark-protected micropattern detectors: the 2D sensitive resistive microstrip counter and the resistive microhole and strip plate, which combines in one design a resistive GEM with a microstrip detector. These innovative detectors are manufactured on standard printed circuit boards by using a simple technology thus reducing the production cost. These novel detectors have several important advantages over other micropattern detectors and are unique for applications like the readout detectors for dual phase noble liquid time projection chambers and ring imaging Cherenkov detectors.

  9. Fabrication of microengineered templates and their applications into micropatterned cell culture.

    PubMed

    Choi, Jin Ho; Lee, Hyun; Jin, Hee Kyung; Bae, Jae-Sung; Kim, Gyu Man

    2013-03-01

    We present a fabrication method of PDMS microtemplates and their applications into a localized culture of primary mammalian cells. Three types of microtemplates of microwell, microstencil and microcontact printing stamp (mCP) were fabricated, and their feasibilities into cell culture were studied. All of microtemplates were fabricated by PDMS casting from SU-8 mold prepared by photolithography. The pattern used in the test was 500 microm dots. In the culture test of microstencil, a stencil was placed on a glass disk coated with Poly-D-Lysine (PDL) layer. In the other test of microcontact printing, PDL layer was patterned by microcontact printing. The mammalian cells of mouse embryonic fibroblasts (MEF) and cortical neuron were successfully cultured into micropatterns by using the microtemplates. The results showed that cells could be cultured into micropatterns with precisely controlled manner at any shapes and specific size for bioscience study and bioengineering applications. PMID:23620992

  10. Fabrication of Micropatterns using Salt Crystals from Solvent Evaporation

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Eun; Go, Seung Jae; Lee, Dong Hyun

    2013-03-01

    Herein, we investigated the crystallization behaviors of sodium carbonate (Na2CO3) from highly diluted aqueous solutions. Aqueous Na2CO3 solutions which were applied on substrate surfaces by either dropping or draining exhibited a variety of well-defined crystal structures over large areas during water evaporation. It was also found that both sizes and shapes of salt crystals could be effectively controlled by the experimental conditions such as their concentration, evaporation rate, temperature and humidity. Furthermore, it was observed that the salt crystals could be oriented to specific direction as the evaporation of water occurred on the tilted substrates. The crystals of Na2CO3\\ were then employed as the master pattern to fabricate the soft mold of poly(dimethyl siloxane) (PDMS). Then silver (Ag) inks were filled into the pores of PDMS molds and transferred to various substrates by imprinting techniques to produce electrically conductive electrodes for potential electric devices. The National Research Foundation of Korea (NRF) grant (2011-0013084) and Gyeonggi Regional Research Center (GRRC) Program (2012-111150)

  11. The development of a micropatterned electrode for studies of zinc electrodeposition

    SciTech Connect

    Sutija, D.P.; Muller, R.H.; Tobias, C.W.

    1986-12-01

    A micropatterned electrode was prepared for the study of electrocrystallization. Using microphotolithography, in conjunction with evaporation and pulse electrodeposition of thin films, a set of artificially roughened electrodes with hemispherical surface features five microns in diameter was developed. Voltammetric studies were conducted to determine the best electrode material. Gold, platinum, and various carbon surfaces were evaluated for zinc nucleation density and hydrogen overpotential. Surface homogeneity was examined by both light and scanning electron microscopy. Gold was determined to possess the best combination of material properties: chemical inertness, low melting point, and a high work function allowing underpotential deposition of zinc which reduces the rate of hydrogen evolution. Stripping coulometry was employed to determine zinc limiting currents, and evaluate effective diffusion coefficients in concentrated zinc chloride solutions. Although the method worked well for dilute zinc chloride and copper sulfate solutions, it failed at higher current densities; the emergence of surface roughness obscured actual limiting current plateaus.

  12. Fabrication of Interdigitated Micropatterns of Self-Assembled Polymer Nanofilms Containing Cell-adhesive Materials

    PubMed Central

    Mohammed, Javeed Shaikh; DeCoster, Mark A.; McShane, Michael J.

    2008-01-01

    Micropatterns of different biomaterials with micro- and nanoscale features and defined spatial arrangement on a single substrate are useful tools for studying cellular-level interactions, and recent reports have highlighted the strong influence of scaffold compliance in determining cell behavior. In this paper, a simple yet versatile and precise patterning technique for the fabrication of interdigitated micropatterns of nanocomposite multilayer coatings on a single substrate is demonstrated through a combination of lithography and layer-by-layer (LbL) assembly processes, termed as Polymer Surface Micromachining (PSM). The first nanofilm pattern is constructed using lithography, followed by LbL multilayer assembly and lift-off, and the process is repeated with optical alignment to obtain interdigitated patterns on the same substrate. Thus, the method is analogous to surface micromachining, except that the deposition materials are polymers and biological materials that are used to produce multilayer nanocomposite structures. A key feature of the multilayers is the capability to tune properties such as stiffness by appropriate selection of materials, deposition conditions, and post-deposition treatments. Two- and four-component systems on glass coverslips are presented to demonstrate the versatility of the approach to construct precisely-defined, homogeneous nanofilm patterns. In addition, an example of a complex system used as a testbed for in vitro cell adhesion and growth is provided: micropatterns of poly(sodium 4-styrenesulfonate)/poly-L-lysine hydrobromide (PSS/PLL) and secreted phospholipase A2/poly(ethyleneimine) (PEI/sPLA2) multilayers. The interdigitated square nanofilm array patterns were obtained on a single coverslip with poly(diallyldimethyl ammonium chloride) (PDDA) as a cell-repellent background. Cell culture experiments show that cortical neurons respond and bind specifically to the sPLA2 micropatterns in competition with PLL micropatterns. The

  13. Fabrication of robust micro-patterned polymeric films via static breath-figure process and vulcanization.

    PubMed

    Li, Lei; Zhong, Yawen; Gong, Jianliang; Li, Jian; Huang, Jin; Ma, Zhi

    2011-02-15

    Here, we present the preparation of thermally stable and solvent resistant micro-patterned polymeric films via static breath-figure process and sequent vulcanization, with a commercially available triblock polymer, polystyrene-b-polyisoprene-b-polystyrene (SIS). The vulcanized honeycomb structured SIS films became self-supported and resistant to a wide range of organic solvents and thermally stable up to 350°C for 2h, an increase of more than 300K as compared to the uncross-linked films. This superior robustness could be attributed to the high degree of polyisoprene cross-linking. The versatility of the methodology was demonstrated by applying to another commercially available triblock polymer, polystyrene-b-polybutadiene-b-polystyrene (SBS). Particularly, hydroxy groups were introduced into SBS by hydroboration. The functionalized two-dimensional micro-patterns feasible for site-directed grafting were created by the hydroxyl-containing polymers. In addition, the fixed microporous structures could be replicated to fabricate textured positive PDMS stamps. This simple technique offers new prospects in the field of micro-patterns, soft lithography and templates. PMID:21168143

  14. Fabrication of robust micro-patterned polymeric films via static breath-figure process and vulcanization.

    PubMed

    Li, Lei; Zhong, Yawen; Gong, Jianliang; Li, Jian; Huang, Jin; Ma, Zhi

    2011-02-15

    Here, we present the preparation of thermally stable and solvent resistant micro-patterned polymeric films via static breath-figure process and sequent vulcanization, with a commercially available triblock polymer, polystyrene-b-polyisoprene-b-polystyrene (SIS). The vulcanized honeycomb structured SIS films became self-supported and resistant to a wide range of organic solvents and thermally stable up to 350°C for 2h, an increase of more than 300K as compared to the uncross-linked films. This superior robustness could be attributed to the high degree of polyisoprene cross-linking. The versatility of the methodology was demonstrated by applying to another commercially available triblock polymer, polystyrene-b-polybutadiene-b-polystyrene (SBS). Particularly, hydroxy groups were introduced into SBS by hydroboration. The functionalized two-dimensional micro-patterns feasible for site-directed grafting were created by the hydroxyl-containing polymers. In addition, the fixed microporous structures could be replicated to fabricate textured positive PDMS stamps. This simple technique offers new prospects in the field of micro-patterns, soft lithography and templates.

  15. Method for fabrication of electrodes

    DOEpatents

    Jankowski, Alan F.; Morse, Jeffrey D.; Barksdale, Randy

    2004-06-22

    Described herein is a method to fabricate porous thin-film electrodes for fuel cells and fuel cell stacks. Furthermore, the method can be used for all fuel cell electrolyte materials which utilize a continuous electrolyte layer. An electrode layer is deposited on a porous host structure by flowing gas (for example, Argon) from the bottomside of the host structure while simultaneously depositing a conductive material onto the topside of the host structure. By controlling the gas flow rate through the pores, along with the process conditions and deposition rate of the thin-film electrode material, a film of a pre-determined thickness can be formed. Once the porous electrode is formed, a continuous electrolyte thin-film is deposited, followed by a second porous electrode to complete the fuel cell structure.

  16. Nanoscale biomimetics studies of Salvinia molesta for micropattern fabrication.

    PubMed

    Hunt, James; Bhushan, Bharat

    2011-11-01

    The emerging field of biomimetics allows one to take inspiration from nature and mimic it in order to create various products, devices and structures. There are a large number of objects, including bacteria, plants, land and aquatic animals and seashells, with properties of commercial interest. The subject of interest for this research is the water fern Salvinia molesta because of its ability to trap air. Air-retaining surfaces are of technological interest due to their ability to reduce drag when used for fluid transport, ship coatings and other submersible industrial products in which drag is a concern. The purpose of this research is to mimic the air trapping ability of S. molesta in order to prove that a structure can be created in the lab that can mimic the behavior of the fern as well as demonstrate microfabrication techniques that can be utilized in industry to produce such materials. In this work, a novel methodology for the fabrication of microstructures that mimic the water-pinning and air-trapping ability of S. molesta is introduced. Water contact angle, water roll angle and adhesive force of the new microstructure and water fern are investigated.

  17. Nanoscale biomimetics studies of Salvinia molesta for micropattern fabrication.

    PubMed

    Hunt, James; Bhushan, Bharat

    2011-11-01

    The emerging field of biomimetics allows one to take inspiration from nature and mimic it in order to create various products, devices and structures. There are a large number of objects, including bacteria, plants, land and aquatic animals and seashells, with properties of commercial interest. The subject of interest for this research is the water fern Salvinia molesta because of its ability to trap air. Air-retaining surfaces are of technological interest due to their ability to reduce drag when used for fluid transport, ship coatings and other submersible industrial products in which drag is a concern. The purpose of this research is to mimic the air trapping ability of S. molesta in order to prove that a structure can be created in the lab that can mimic the behavior of the fern as well as demonstrate microfabrication techniques that can be utilized in industry to produce such materials. In this work, a novel methodology for the fabrication of microstructures that mimic the water-pinning and air-trapping ability of S. molesta is introduced. Water contact angle, water roll angle and adhesive force of the new microstructure and water fern are investigated. PMID:21802093

  18. Micropatterning of fluoropolymers

    NASA Astrophysics Data System (ADS)

    Hale, Penny S.; Kappen, Peter; Brack, Narelle; Prissanaroon, Walaiporn; Pigram, Paul J.; Liesegang, John

    2006-01-01

    Fluoropolymer (PTFE and FEP) substrates have been patterned through micro-contact printing of an aminosilane. The silane pattern was activated with a palladium catalyst that allowed the electroless deposition of copper which was used to form micropatterned copper electrodes. Conducting polymer micropatterns were then fabricated by electrodeposition of polypyrrole (PPy) onto the copper. The resulting patterns of 80 μm and 10 μm grids and 2 μm and 5 μm checkerboards were characterized using imaging XPS, TOF-SIMS, AFM and SEM. The size and resolution of the smallest copper patterns were limited by the copper grain size created during electroless deposition. The polypyrrole patterns were also limited by the roughness of the electrolytically deposited polymer film.

  19. Polymerized micro-patterned optical birefringence film and its fabrication using multi beam mixing.

    PubMed

    Lim, Jeong-Ku; Song, Jang-Kun

    2011-12-19

    The photo-polymerized liquid crystal (LC) film aligned on a photo-alignment layer was investigated with varying polarizability of UV light exposing on the photo-alignment layer. Interestingly, the polarizability of UV light required to induce bulk LC alignment on the photo alignment layer was found to be very low down to 0.1, and UV light greater than 0.3 polarizability produced outstanding optical performance of the film. The films fabricated with low polarizability light exhibited comparable thermo-stability with one fabricated with high polarizability light. The results suggest that micro-patterned optical birefringence films (MP-OBFs) can be fabricated by using an incoherent multi beam mixing method, where the direction of polarization of UV light can be spatially modulated. A simple MP-OBF was fabricated by using a two beam mixing method, and it exhibited a quality 3D film performance. The method will be highly useful in various optical components such as the MP-OBF, optical retarders, polarization grating etc. PMID:22274279

  20. Fabrication of micropatterned mesoporous silica film on a flexible polymer substrate through pattern transfer and subsequent photocalcination

    SciTech Connect

    Hozumi, Atsushi; Kizuki, Takashi; Inagaki, Masahiko; Shirahata, Naoto

    2006-07-15

    A microfabrication method for mesoporous silica (MPS) film on a flexible polymer substrate is proposed. The method consists of three processes. First, by using a spatially defined microtemplate consisting of dual self-assembled monolayers (SAMs) with alternating trifluorocarbon (CF{sub 3}) and amino (NH{sub 2}) groups, a mesostructured silica/surfactant composite (MSSC) film was site-selectively deposited on the CF{sub 3}-terminated SAM regions through hydrophobic and van der Waals interactions between the surfactant molecules and the hydrophobic SAM surface. Next, in order to transfer these prefabricated MSSC micropatterns to a poly(ethyleneterephthalate) (PET) substrate, the sample was pressed firmly against the PET surface for 60 min at 90 deg. C under a pressure of 4 MPa. Due to the weak adhesion between the MSSC film and the CF{sub 3}-terminated SAM surface, the deposited MSSC micropatterns readily peeled off the SAM surface and were transferred to the PET substrate while preserving both the morphology and the nanostructures of the micropatterns, as evidenced by atomic force microscopy (AFM), scanning electron microscopy, energy dispersion x-ray spectroscopy, and x-ray diffractometry (XRD). Finally, to remove the surfactant molecules and obtain well-defined nanopores, a photochemical approach, known as 'photocalcination,' using UV light of 185 and 254 nm wavelengths was employed. Fourier transform infrared spectroscopy XRD, and AFM confirmed that the surfactant molecules were completely eliminated from the MSSC micropatterns without distorting either their finely patterned microstructures or their well-ordered periodic nanostructures. Through this technique, well-shaped 5 {mu}m wide MPS micropatterns were fabricated on the flexible PET substrates. These embedded MPS micropatterns adhered tightly to the PET substrates and no peeling was observed in a Scotch registered tape peeling test.

  1. Scanning electrochemical microscopy studies of micropatterned copper sulfide (CuxS) thin films fabricated by a wet chemistry method

    PubMed Central

    Chen, Miao; Zhao, Jing; Zhao, Xiaocui

    2011-01-01

    Patterned copper sulfide (CuxS) microstructures on Si (1 1 1) wafers were successfully fabricated by a relatively simple solution growth method using copper sulfate, ethylenediaminetetraacetate and sodium thiosulfate aqueous solutions as precursors. The CuxS particles were selectively deposited on a patterned self-assembled monolayer of 3-aminopropyltriethoxysilane regions created by photolithography. To obtain high quality CuxS films, preparative conditions such as concentration, proportion, pH and temperature of the precursor solutions were optimized. Various techniques such as optical microscopy, atomic force microscopy (AFM), X-ray diffraction, optical absorption and scanning electrochemical microscopy (SECM) were employed to examine the topography and properties of the micro-patterned CuxS films. Optical microscopy and AFM results indicated that the CuxS micro-pattern possessed high selectivity and clear edge resolution. From combined X-ray diffraction analysis and optical band gap calculations we conclude that Cu9S5 (digenite) was the main phase within the resultant CuxS film. Both SECM image and cyclic voltammograms confirmed that the CuxS film had good electrical conductivity. Moreover, from SECM approach curve analysis, the apparent electron-transfer rate constant (k) in the micro-pattern of CuxS dominated surface was estimated as 0.04 cm/s. The SECM current map showed high edge acuity of the micro-patterned CuxS. PMID:21785491

  2. Scanning electrochemical microscopy studies of micropatterned copper sulfide (Cu(x)S) thin films fabricated by a wet chemistry method.

    PubMed

    Chen, Miao; Zhao, Jing; Zhao, Xiaocui

    2011-05-30

    Patterned copper sulfide (Cu(x)S) microstructures on Si (1 1 1) wafers were successfully fabricated by a relatively simple solution growth method using copper sulfate, ethylenediaminetetraacetate and sodium thiosulfate aqueous solutions as precursors. The Cu(x)S particles were selectively deposited on a patterned self-assembled monolayer of 3-aminopropyltriethoxysilane regions created by photolithography. To obtain high quality Cu(x)S films, preparative conditions such as concentration, proportion, pH and temperature of the precursor solutions were optimized. Various techniques such as optical microscopy, atomic force microscopy (AFM), X-ray diffraction, optical absorption and scanning electrochemical microscopy (SECM) were employed to examine the topography and properties of the micro-patterned Cu(x)S films. Optical microscopy and AFM results indicated that the Cu(x)S micro-pattern possessed high selectivity and clear edge resolution. From combined X-ray diffraction analysis and optical band gap calculations we conclude that Cu(9)S(5) (digenite) was the main phase within the resultant Cu(x)S film. Both SECM image and cyclic voltammograms confirmed that the Cu(x)S film had good electrical conductivity. Moreover, from SECM approach curve analysis, the apparent electron-transfer rate constant (k) in the micro-pattern of Cu(x)S dominated surface was estimated as 0.04 cm/s. The SECM current map showed high edge acuity of the micro-patterned Cu(x)S.

  3. Simple Fabrication of Nickel Micropatterning under Ambient Condition: Use of Pen-Type Nanolithography and Electroless Plating

    NASA Astrophysics Data System (ADS)

    Onoue, Miki; Ushijima, Hirobumi

    2012-06-01

    Recently, the research and development of printed electronics has been expanded. Patterning of various materials is required to fabricate many electronic devices by the printing technique. Nickel patterning, for instance, is the subject matter of condensers. In this study, we demonstrated (1) catalytic Pd patterning by fountain-pen nanolithography (FPN) and (2) the preparation of Ni micropatterns by Ni electroless plating. The FPN is one of the pen-type nanolithography techniques and it can yield microsize patterns.

  4. Design and fabrication of semi-transparent screen based on micro-patterns for direct-view type head-up display in automobiles

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Yong; Kim, Hyo-Jun; Kim, Young-Joo

    2016-02-01

    A semi-transparent screen with hemisphere micro-patterns was proposed and designed to enhance the brightness uniformity of the display image toward the driver for a direct-view type head-up display. The hemisphere micro-patterns were designed to consider the inclined angle of the windshield for efficient reflection and scattering toward to the driver. The density and radius of the hemisphere micro-patterns were adjusted as a function of position on the screen based on the geometrical calculation and analyzed by the commercial optical simulation tool based on a ray-tracing method. The designed hemisphere micro-patterns was fabricated by the thermal reflow method and evaluated to confirm the uniform illumination. From the results, the semi-transparent screen with variable micro-patterns shows the 91.9 % of brightness uniformity with the enhanced luminance compare to a screen without micro-patterns. A luminance of fabricated screen also shows good agreement with the simulation result to reflect the clear and bright driving information to the driver.

  5. Fabricating solid carbon porous electrodes from powders

    DOEpatents

    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 (<50 m.sup.2 /gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. 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.

  6. Fabricating solid carbon porous electrodes from powders

    DOEpatents

    Kaschmitter, J.L.; Tran, T.D.; Feikert, J.H.; Mayer, S.T.

    1997-06-10

    Fabrication is described for conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive deionization, and waste treatment. Electrodes fabricated from low surface area (<50 m{sup 2}/gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. 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 composites 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 high surface area carbons, fuel cell electrodes can be produced. 1 fig.

  7. Parallel fabrication of nanogap electrodes.

    PubMed

    Johnston, Danvers E; Strachan, Douglas R; Johnson, A T Charlie

    2007-09-01

    We have developed a technique for simultaneously fabricating large numbers of nanogaps in a single processing step using feedback-controlled electromigration. Parallel nanogap formation is achieved by a balanced simultaneous process that uses a novel arrangement of nanoscale shorts between narrow constrictions where the nanogaps form. Because of this balancing, the fabrication of multiple nanoelectrodes is similar to that of a single nanogap junction. The technique should be useful for constructing complex circuits of molecular-scale electronic devices.

  8. Method of fabrication of electrodes and electrolytes

    DOEpatents

    Jankowski, Alan F.; Morse, Jeffrey D.

    2004-01-06

    Fuel cell stacks contain an electrolyte layer surrounded on top and bottom by an electrode layer. Porous electrodes are prepared which enable fuel and oxidant to easily flow to the respective electrode-electrolyte interface without the need for high temperatures or pressures to assist the flow. Rigid, inert microspheres in combination with thin-film metal deposition techniques are used to fabricate porous anodes, cathodes, and electrolytes. Microshperes contained in a liquid are randomly dispersed onto a host structure and dried such that the microsperes remain in position. A thin-film deposition technique is subsequently employed to deposit a metal layer onto the microsperes. After such metal layer deposition, the microspheres are removed leaving voids, i.e. pores, in the metal layer, thus forming a porous electrode. Successive repetitions of the fabrication process result in the formation of a continuous fuel cell stack. Such stacks may produce power outputs ranging from about 0.1 Watt to about 50 Watts.

  9. Fabrication of microstructured copper on an indium-tin-oxide surface using a micropatterned self-assembled monolayer as a template

    NASA Astrophysics Data System (ADS)

    Asakura, Shuuichi; Hirota, Mitsuhito; Fuwa, Akio

    2003-07-01

    The difference in chemical reactivity between indium-tin-oxide (ITO) and self-assembled monolayer (SAM) surfaces was used to fabricate copper (Cu) microstructures. ITO substrates coated with octadecyltrimethoxysilane (ODS)-SAM were photolithographically micropatterned using vacuum ultraviolet (VUV) light. Each of the micropatterned samples was subsequently immersed in an electrodeposition bath in order to deposit Cu on its surface. As confirmed by atomic force microscopy, Cu electrodeposition proceeded selectively on the VUV-irradiated areas of the ITO surface while the ODS-SAM surface served effectively as a mask to block Cu deposition. Cu microstructures with 7.5 × 7.5 μm2 features were successfully fabricated on the ITO surface.

  10. Fabrication methods for low impedance lithium polymer electrodes

    DOEpatents

    Chern, T.S.; MacFadden, K.O.; Johnson, S.L.

    1997-12-16

    A process is described for fabricating an electrolyte-electrode composite suitable for high energy alkali metal battery that includes mixing composite electrode materials with excess liquid, such as ethylene carbonate or propylene carbonate, to produce an initial formulation, and forming a shaped electrode therefrom. The excess liquid is then removed from the electrode to compact the electrode composite which can be further compacted by compression. The resulting electrode exhibits at least a 75% lower resistance.

  11. Fabrication methods for low impedance lithium polymer electrodes

    DOEpatents

    Chern, Terry Song-Hsing; MacFadden, Kenneth Orville; Johnson, Steven Lloyd

    1997-01-01

    A process for fabricating an electrolyte-electrode composite suitable for high energy alkali metal battery that includes mixing composite electrode materials with excess liquid, such as ethylene carbonate or propylene carbonate, to produce an initial formulation, and forming a shaped electrode therefrom. The excess liquid is then removed from the electrode to compact the electrode composite which can be further compacted by compression. The resulting electrode exhibits at least a 75% lower resistance.

  12. Smooth electrode and method of fabricating same

    DOEpatents

    Weaver, Stanton Earl; Kennerly, Stacey Joy; Aimi, Marco Francesco

    2012-08-14

    A smooth electrode is provided. The smooth electrode includes at least one metal layer having thickness greater than about 1 micron; wherein an average surface roughness of the smooth electrode is less than about 10 nm.

  13. Strategies for the fabrication of porous platinum electrodes.

    PubMed

    Kloke, Arne; von Stetten, Felix; Zengerle, Roland; Kerzenmacher, Sven

    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 fi rst step by chemical, photochemical or sonochemical means followed by an electrode formation step by e.g. thin fi lm 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. PMID:22180890

  14. Method of electrode fabrication and an electrode for metal chloride battery

    DOEpatents

    Bloom, I.D.; Nelson, P.A.; Vissers, D.R.

    1993-03-16

    A method of fabricating an electrode for use in a metal chloride battery and an electrode are provided. The electrode has relatively larger and more uniform pores than those found in typical electrodes. The fabrication method includes the steps of mixing sodium chloride particles selected from a predetermined size range with metal particles selected from a predetermined size range, and then rigidifying the mixture. The electrode exhibits lower resistivity values of approximately 0.5 [Omega]cm[sup 2] than those resistivity values of approximately 1.0-1.5 [Omega]cm[sup 2] exhibited by currently available electrodes.

  15. Method of electrode fabrication and an electrode for metal chloride battery

    DOEpatents

    Bloom, Ira D.; Nelson, Paul A.; Vissers, Donald R.

    1993-01-01

    A method of fabricating an electrode for use in a metal chloride battery and an electrode are provided. The electrode has relatively larger and more uniform pores than those found in typical electrodes. The fabrication method includes the steps of mixing sodium chloride particles selected from a predetermined size range with metal particles selected from a predetermined size range, and then rigidifying the mixture. The electrode exhibits lower resistivity values of approximately 0.5 .OMEGA.cm.sup.2 than those resistivity values of approximately 1.0-1.5 .OMEGA.cm.sup.2 exhibited by currently available electrodes.

  16. Fabrication of Nanoindented Electrodes for Glucose Detection

    PubMed Central

    Slaughter, Gymama

    2010-01-01

    Background The objective of this article was to design, fabricate, and evaluate a novel type of glucose biosensors based on the use of atomic force microscopy to create nanoindented electrodes (NIDEs) for the selective detection of glucose. Methods Atomic force microscopy nanoindentation techniques were extended to covalently immobilized glucose oxidase on NIDEs via composite hydrogel membranes composed of interpenetrating networks of inherently conductive poly(3,4-ethylenedioxythiophene) tetramethacrylate grown within ultraviolet cross-linked hydroxyethylmethacrylate-based hydrogels to produce an in vitro amperometric NIDE biosensor for the long-term monitoring of glucose. Results The calibration curve for glucose was linear from 0.25 to 20 mM. Results showed that the NIDE glucose biosensor has a much higher detection sensitivity of 0.32 μA/mM and rapid response times (<5 seconds). There was no interference from the competing interferent (fructose) present; the only interference was from species that react with H2O2 (ascorbic acid). The linear equation was Bresponse (μA) = 0.323 [glucose] (mM) + 0.634 (μA); n = 24, r2 = 0.994. Conclusion Results showed that the resultant NIDE glucose biosensor increases the dynamic range, device sensitivity, and response time and has excellent detecting performance for glucose. PMID:20307392

  17. Fabrication of micropatterned hydrogels for neural culture systems using dynamic mask projection photolithography.

    PubMed

    Curley, J Lowry; Jennings, Scott R; Moore, Michael J

    2011-01-01

    Increasingly, patterned cell culture environments are becoming a relevant technique to study cellular characteristics, and many researchers believe in the need for 3D environments to represent in vitro experiments which better mimic in vivo qualities. Studies in fields such as cancer research, neural engineering, cardiac physiology, and cell-matrix interaction have shown cell behavior differs substantially between traditional monolayer cultures and 3D constructs. Hydrogels are used as 3D environments because of their variety, versatility and ability to tailor molecular composition through functionalization. Numerous techniques exist for creation of constructs as cell-supportive matrices, including electrospinning, elastomer stamps, inkjet printing, additive photopatterning, static photomask projection-lithography, and dynamic mask microstereolithography. Unfortunately, these methods involve multiple production steps and/or equipment not readily adaptable to conventional cell and tissue culture methods. The technique employed in this protocol adapts the latter two methods, using a digital micromirror device (DMD) to create dynamic photomasks for crosslinking geometrically specific poly-(ethylene glycol) (PEG) hydrogels, induced through UV initiated free radical polymerization. The resulting "2.5D" structures provide a constrained 3D environment for neural growth. We employ a dual-hydrogel approach, where PEG serves as a cell-restrictive region supplying structure to an otherwise shapeless but cell-permissive self-assembling gel made from either Puramatrix or agarose. The process is a quick simple one step fabrication which is highly reproducible and easily adapted for use with conventional cell culture methods and substrates. Whole tissue explants, such as embryonic dorsal root ganglia (DRG), can be incorporated into the dual hydrogel constructs for experimental assays such as neurite outgrowth. Additionally, dissociated cells can be encapsulated in the

  18. Fabrication of high aspect ratio micro electrode by using EDM

    NASA Astrophysics Data System (ADS)

    Mejid Elsiti, Nagwa; Noordin, M. Y.; Umar Alkali, Adam

    2016-02-01

    The electrical discharge machining (EDM) process inherits characteristics that make it a promising micro-machining technique. Micro electrical discharge machining (micro- EDM) is a derived form of EDM, which is commonly used to manufacture micro and miniature parts and components by using the conventional electrical discharge machining fundamentals. Moving block electro discharge grinding (Moving BEDG) is one of the processes that can be used to fabricate micro-electrode. In this study, a conventional die sinker EDM machine was used to fabricate the micro-electrode. Modifications are made to the moving BEDG, which include changing the direction of movements and control gap in one electrode. Consequently current was controlled due to the use of roughing, semi-finishing and finishing parameters. Finally, a high aspect ratio micro-electrode with a diameter of 110.49μm and length of 6000μm was fabricated.

  19. Method of electrode fabrication for solid oxide electrochemical cells

    DOEpatents

    Jensen, Russell R.

    1990-01-01

    A process for fabricating cermet electrodes for solid oxide electrochemical cells by sintering is disclosed. First, a porous metal electrode is fabricated on a solid oxide cell, such as a fuel cell by, for example, sintering, and is then infiltrated with a high volume fraction stabilized zirconia suspension. A second sintering step is used to sinter the infiltrated zirconia to a high density in order to more securely attach the electrode to the solid oxide electrolyte of the cell. High performance fuel electrodes can be obtained with this process. Further electrode performance enhancement may be achieved if stabilized zirconia doped with cerium oxide, chromium oxide, titanium oxide, and/or praseodymium oxide for electronic conduction is used.

  20. Method of electrode fabrication for solid oxide electrochemical cells

    DOEpatents

    Jensen, R.R.

    1990-11-20

    A process for fabricating cermet electrodes for solid oxide electrochemical cells by sintering is disclosed. First, a porous metal electrode is fabricated on a solid oxide cell, such as a fuel cell by, for example, sintering, and is then infiltrated with a high volume fraction stabilized zirconia suspension. A second sintering step is used to sinter the infiltrated zirconia to a high density in order to more securely attach the electrode to the solid oxide electrolyte of the cell. High performance fuel electrodes can be obtained with this process. Further electrode performance enhancement may be achieved if stabilized zirconia doped with cerium oxide, chromium oxide, titanium oxide, and/or praseodymium oxide for electronic conduction is used. 5 figs.

  1. System of fabricating a flexible electrode array

    DOEpatents

    Krulevitch, Peter; Polla, Dennis L.; Maghribi, Mariam N.; Hamilton, Julie; Humayun, Mark S.; Weiland, James D.

    2012-01-28

    An image is captured or otherwise converted into a signal in an artificial vision system. The signal is transmitted to the retina utilizing an implant. The implant consists of a polymer substrate made of a compliant material such as poly(dimethylsiloxane) or PDMS. The polymer substrate is conformable to the shape of the retina. Electrodes and conductive leads are embedded in the polymer substrate. The conductive leads and the electrodes transmit the signal representing the image to the cells in the retina. The signal representing the image stimulates cells in the retina.

  2. System of fabricating a flexible electrode array

    DOEpatents

    Krulevitch, Peter; Polla, Dennis L.; Maghribi, Mariam N.; Hamilton, Julie; Humayun, Mark S.; Weiland, James D.

    2010-10-12

    An image is captured or otherwise converted into a signal in an artificial vision system. The signal is transmitted to the retina utilizing an implant. The implant consists of a polymer substrate made of a compliant material such as poly(dimethylsiloxane) or PDMS. The polymer substrate is conformable to the shape of the retina. Electrodes and conductive leads are embedded in the polymer substrate. The conductive leads and the electrodes transmit the signal representing the image to the cells in the retina. The signal representing the image stimulates cells in the retina.

  3. Fabrication of Dry Electrode for Recording Bio-potentials

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Guo, Kai; Pei, Wei-Hua; Gui, Qiang; Li, Xiao-Qian; Chen, Hong-Da; Yang, Jian-Hong

    2011-01-01

    Development of minimally invasive dry electrodes for recording biopotentials is presented. The detailed fabrication process is outlined. A dry electrode is formed by a number of microneedles. The lengths of the microneedles are about 150μm and the diameters are about 50μm. The tips of the microneedles are sharp enough to penetrate into the skin. The silver/silver chloride is grown on microneedle arrays and demonstrates good character. The electrocardiogram shows that the dry electrode is suitable for recording biopotentials.

  4. Controlled atmosphere for fabrication of cermet electrodes

    DOEpatents

    Ray, Siba P.; Woods, Robert W.

    1998-01-01

    A process for making an inert electrode composite wherein a metal oxide and a metal are reacted in a gaseous atmosphere at an elevated temperature of at least about 750.degree. C. The metal oxide is at least one of the nickel, iron, tin, zinc and zirconium oxides and the metal is copper, silver, a mixture of copper and silver or a copper-silver alloy. The gaseous atmosphere has an oxygen content that is controlled at about 5-3000 ppm in order to obtain a desired composition in the resulting composite.

  5. Controlled atmosphere for fabrication of cermet electrodes

    DOEpatents

    Ray, S.P.; Woods, R.W.

    1998-08-11

    A process is disclosed for making an inert electrode composite wherein a metal oxide and a metal are reacted in a gaseous atmosphere at an elevated temperature of at least about 750 C. The metal oxide is at least one of the nickel, iron, tin, zinc and zirconium oxides and the metal is copper, silver, a mixture of copper and silver or a copper-silver alloy. The gaseous atmosphere has an oxygen content that is controlled at about 5--3000 ppm in order to obtain a desired composition in the resulting composite. 2 figs.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Fabric-based active electrode design and fabrication for health monitoring clothing.

    PubMed

    Merritt, Carey R; Nagle, H Troy; Grant, Edward

    2009-03-01

    In this paper, two versions of fabric-based active electrodes are presented to provide a wearable solution for ECG monitoring clothing. The first version of active electrode involved direct attachment of surface-mountable components to a textile screen-printed circuit using polymer thick film techniques. The second version involved attaching a much smaller, thinner, and less obtrusive interposer containing the active electrode circuitry to a simplified textile circuit. These designs explored techniques for electronic textile interconnection, chip attachment to textiles, and packaging of circuits on textiles for durability. The results from ECG tests indicate that the performance of each active electrode is comparable to commercial Ag/AgCl electrodes. The interposer-based active electrodes survived a five-cycle washing test while maintaining good signal integrity.

  8. Fabric-based active electrode design and fabrication for health monitoring clothing.

    PubMed

    Merritt, Carey R; Nagle, H Troy; Grant, Edward

    2009-03-01

    In this paper, two versions of fabric-based active electrodes are presented to provide a wearable solution for ECG monitoring clothing. The first version of active electrode involved direct attachment of surface-mountable components to a textile screen-printed circuit using polymer thick film techniques. The second version involved attaching a much smaller, thinner, and less obtrusive interposer containing the active electrode circuitry to a simplified textile circuit. These designs explored techniques for electronic textile interconnection, chip attachment to textiles, and packaging of circuits on textiles for durability. The results from ECG tests indicate that the performance of each active electrode is comparable to commercial Ag/AgCl electrodes. The interposer-based active electrodes survived a five-cycle washing test while maintaining good signal integrity. PMID:19174357

  9. Fabrication of Out-of-Plane Electrodes for ACEO Pumps

    NASA Astrophysics Data System (ADS)

    Senousy, Yehya; Harnett, Cindy

    2012-02-01

    This abstract reports the fabrication process of a novel AC Electrosmosis (ACEO) pump with out of plane asymmetric interdigitated electrodes. A self-folding technique is used to fabricate the electrodes, that depends on the strain mismatch between the tensile stressed film (metal layer) and the compressive stress film (oxidized silicon layer). The electrodes roll up with a well-defined radius of curvature in the range of 100-200 microns. Two different electrical signals are connected to alternating electrodes using an insulating silicon nitride barrier that allows circuits to cross over each other without shorting. Electroosmotic micropumps are essential for low-cost, power-efficient microfluidic lab-on-chip devices used in diverse application such as analytical probes, drug delivery systems and surgical tools. ACEO pumps have been developed to address the drawbacks of the DCEO pumps such as the faradic reaction and gas bubbles. The original ACEO microfluidic pump was created with planar arrays of asymmetric interdigitated electrodes at the bottom of the channel. This rolled-up tube design improves on the planar design by including the channel walls and ceiling in the active pumping surface area of the device.

  10. Detection of Electrocardiogram by Electrodes with Fabrics Using Capacitive Coupling

    NASA Astrophysics Data System (ADS)

    Ueno, Akinori; Furusawa, Yoichi; Hoshino, Hiroshi; Ishiyama, Yoji

    This article reports on a novel technique for detecting electrocardiogram (ECG) at a condition where thin cloth is interpolated between sensing electrodes and the skin to which the electrodes are attached. The technique is based upon capacitive coupling composed of the electrode, the cloth and the skin, so that the electrode can lead alternating electrocardiographic current through capacitance of the coupling. The technique is also founded on impedance transforming circuit that has extremely high input impedance around 1000GΩ and low output impedance, so as to match high output impedance of the electrode to low input impedance required by subsequent circuitry. A pilot ECG measuring device was manufactured using the technique and experiments showed (1) ECG recordings using the device with silk of 240μm thickness or with cotton of 564μm thickness were quite similar to ECGs recorded from the skin using conventional system, (2) stable ECGs were observed with the silk below 600μm thickness or with the cotton below 1128μm thickness, (3) effects of long-term measurement and perspiration on ECG waveform were negligible. These results prove feasibility of the proposed technique for detecting ECG by electrodes with fabrics.

  11. Thermoresponsive Polymer Micropatterns Fabricated by Dip-Pen Nanolithography for a Highly Controllable Substrate with Potential Cellular Applications.

    PubMed

    Laing, Stacey; Suriano, Raffaella; Lamprou, Dimitrios A; Smith, Carol-Anne; Dalby, Matthew J; Mabbott, Samuel; Faulds, Karen; Graham, Duncan

    2016-09-21

    We report a novel approach for patterning thermoresponsive hydrogels based on N,N-diethylacrylamide (DEAAm) and bifunctional Jeffamine ED-600 by dip-pen nanolithography (DPN). The direct writing of micron-sized thermoresponsive polymer spots was achieved with efficient control over feature size. A Jeffamine-based ink prepared through the combination of organic polymers, such as DEAAm, in an inorganic silica network was used to print thermosensitive arrays on a thiol-silanized silicon oxide substrate. The use of a Jeffamine hydrogel, acting as a carrier matrix, allowed a reduction in the evaporation of ink molecules with high volatility, such as DEAAm, and facilitated the transfer of ink from tip to substrate. The thermoresponsive behavior of polymer arrays which swell/deswell in aqueous solution in response to a change in temperature was successfully characterized by atomic force microscopy (AFM) and Raman spectroscopy: a thermally induced change in height and hydration state was observed, respectively. Finally, we demonstrate that cells can adhere to and interact with these dynamic features and exhibit a change in behavior when cultured on the substrates above and below the transition temperature of the Jeffamine/DEAAm thermoresponsive hydrogels. This demonstrates the potential of these micropatterned hydrogels to act as a controllable surface for cell growth.

  12. Thermoresponsive Polymer Micropatterns Fabricated by Dip-Pen Nanolithography for a Highly Controllable Substrate with Potential Cellular Applications.

    PubMed

    Laing, Stacey; Suriano, Raffaella; Lamprou, Dimitrios A; Smith, Carol-Anne; Dalby, Matthew J; Mabbott, Samuel; Faulds, Karen; Graham, Duncan

    2016-09-21

    We report a novel approach for patterning thermoresponsive hydrogels based on N,N-diethylacrylamide (DEAAm) and bifunctional Jeffamine ED-600 by dip-pen nanolithography (DPN). The direct writing of micron-sized thermoresponsive polymer spots was achieved with efficient control over feature size. A Jeffamine-based ink prepared through the combination of organic polymers, such as DEAAm, in an inorganic silica network was used to print thermosensitive arrays on a thiol-silanized silicon oxide substrate. The use of a Jeffamine hydrogel, acting as a carrier matrix, allowed a reduction in the evaporation of ink molecules with high volatility, such as DEAAm, and facilitated the transfer of ink from tip to substrate. The thermoresponsive behavior of polymer arrays which swell/deswell in aqueous solution in response to a change in temperature was successfully characterized by atomic force microscopy (AFM) and Raman spectroscopy: a thermally induced change in height and hydration state was observed, respectively. Finally, we demonstrate that cells can adhere to and interact with these dynamic features and exhibit a change in behavior when cultured on the substrates above and below the transition temperature of the Jeffamine/DEAAm thermoresponsive hydrogels. This demonstrates the potential of these micropatterned hydrogels to act as a controllable surface for cell growth. PMID:27572916

  13. Miniaturized EAPs with compliant electrodes fabricated by ion implantation

    NASA Astrophysics Data System (ADS)

    Shea, H.

    2011-04-01

    Miniaturizing dielectric electroactive polymer (EAP) actuators will lead to highly-integrated mechanical systems on a chip, combining dozens to thousands of actuators and sensors on a few cm2. We present here µm to mm scale electroactive polymer (EAP) devices, batch fabricated on the chip or wafer scale, based on ion-implanted electrodes. Low-energy (2-10 keV) implantation of gold ions into a silicone elastomer leads to compliant stretchable electrodes consisting of a buried 20 nm thick layer of gold nanoparticles in a silicone matrix. These electrodes: 1) conduct at strains up to 175%, 2) are patternable on the µm scale, 3) have stiffness similar to silicone, 4) have good conductivity, and 5) excellent adhesion since implanted in the silicone. The EAP devices consist of 20 to 30 µm thick silicone membranes with µm to mm-scale ion-implanted electrodes on both sides, bonded to a holder. Depending on electrode shape and membrane size, several actuation modes are possible. Characterization of 3mm diameter bi-directional buckling mode actuators, mm-scale tunable lens arrays, 2-axis beam steering mirrors, as well as arrays of 72 cell-size (100x200 µm2) actuators to apply mechanical strain to single cells are reported. Speeds of up to several kHz are observed.

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

    SciTech Connect

    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.

  15. A comparative study on electrosorption behavior of carbon nanotubes electrodes fabricated via different methods

    NASA Astrophysics Data System (ADS)

    Zhu, Guang; Wang, Hongyan; Zhang, Li

    2016-04-01

    The carbon nanotubes (CNTs) electrodes were fabricated via electrophoretic deposition (EPD), press and screen printing methods, respectively. The electrochemical properties and electrosorption performance of the CNTs electrodes were tested, respectively. Inhere, screen printing, as a conventional method for fabricating supercapacitor electrodes, was used for fabricating the CDI electrodes for the first time. Such a comparison is reasonably envisaged not only to be used to further understanding the influence of fabrication method on the electrode performance, but also to form a fundamental basis for CDI applications.

  16. Process for fabricating ribbed electrode substrates and other articles

    DOEpatents

    Goller, Glen J.; Breault, Richard D.; Smith, J. Harold

    1984-01-01

    A process for fabricating a resin bonded carbon fiber article, and in particular electrochemical cell electrode substrates and the like requiring different mean pore sizes in different areas, involves simultaneously heating and compacting different mixtures of carbon fibers and resin in different areas of an article forming mold, wherein the carbon fibers in each of the different mixtures have different, known bulk densities. The different bulk densities of the carbon fibers in the mixtures are chosen to yield the desired mean pore sizes and other properties in the article after heating and compacting the mixtures. Preferably, the different bulk densities are obtained using different carbon fiber lengths in the molding mixtures. The process is well suited to forming ribbed electrode substrates with preselected optimum mean pore sizes, porosities, and densities in the ribs, the webs connecting the ribs, and in the edge seals.

  17. A comparative study on fabrication of Mn2+ selective polymeric membrane electrode and coated graphite electrode.

    PubMed

    Singh, Ashok Kumar; Bandi, Koteswara Rao; Upadhyay, Anjali; Jain, A K

    2013-03-01

    Poly(vinyl chloride)-based membranes of two ligands 2,4-bis(2-acetoxybenzylamino)-6-phenyl-1,3,5-triazine (L1) and N2,N4-di(cyanoethyl)-2,4-bis(2-acetoxybenzylamino)-6-phenyl-1,3,5-triazine (L2) were fabricated and explored as Mn(2+) ion selective electrodes. The performance of the polymeric membranes electrodes of ionophores with different plasticizers (dibutylphthalate, benzoic acid, o-nitrophenyloctyl ether, 1-chloronapthalene and tri-n-butylphosphate) and anion excluders (sodium tetraphenylborate and potassium tetrakis p-(chloro phenyl)borate) was looked in to and the better results were obtained with the membrane having composition L2: NaTPB: DBP: PVC as 6: 3: 56: 35 (w/w; mg). The coated graphite electrode (CGE) with same composition was also fabricated and investigated as Mn(2+) selective electrode. It was found that CGE showed better response characteristics than PME. The potentiometric response of CGE was independent of pH in the range 3.0-9.0 exhibiting the Nernstian slope 29.5 ± 0.3 mVdecade(-1) of activity and working concentration range 4.1 × 10(-7)-1.0 × 10(-1)mol L(-1) with a limit of detection 6.7 × 10(-8)mol L(-1). The electrode showed a fast response time of 12s with a shelf life of 105 days. The proposed CGE could be successfully used for the determination of Mn(2+) ions in different water, soil, vegetables and medicinal plants also used as an indicator electrode in potentiometric titration with EDTA.

  18. Nanofiber membrane-electrode-assembly and method of fabricating same

    DOEpatents

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

    2016-02-02

    In one aspect of the present invention, a fuel cell membrane-electrode-assembly (MEA) has an anode electrode, a cathode electrode, and a membrane disposed between the anode electrode and the cathode electrode. At least one of the anode electrode, the cathode electrode and the membrane is formed of electrospun nanofibers.

  19. Fabric-Based Wearable Dry Electrodes for Body Surface Biopotential Recording.

    PubMed

    Yokus, Murat A; Jur, Jesse S

    2016-02-01

    A flexible and conformable dry electrode design on nonwoven fabrics is examined as a sensing platform for biopotential measurements. Due to limitations of commercial wet electrodes (e.g., shelf life, skin irritation), dry electrodes are investigated as the potential candidates for long-term monitoring of ECG signals. Multilayered dry electrodes are fabricated by screen printing of Ag/AgCl conductive inks on flexible nonwoven fabrics. This study focuses on the investigation of skin-electrode interface, form factor design, electrode body placement of printed dry electrodes for a wearable sensing platform. ECG signals obtained with dry and wet electrodes are comparatively studied as a function of body posture and movement. Experimental results show that skin-electrode impedance is influenced by printed electrode area, skin-electrode interface material, and applied pressure. The printed electrode yields comparable ECG signals to wet electrodes, and the QRS peak amplitude of ECG signal is dependent on printed electrode area and electrode on body spacing. Overall, fabric-based printed dry electrodes present an inexpensive health monitoring platform solution for mobile wearable electronics applications by fulfilling user comfort and wearability.

  20. Femtosecond laser rapid fabrication of large-area rose-like micropatterns on freestanding flexible graphene films

    PubMed Central

    Shi, Xuesong; Li, Xin; Jiang, Lan; Qu, Liangti; Zhao, Yang; Ran, Peng; Wang, Qingsong; Cao, Qiang; Ma, Tianbao; Lu, Yongfeng

    2015-01-01

    We developed a simple, scalable and high-throughput method for fabrication of large-area three-dimensional rose-like microflowers with controlled size, shape and density on graphene films by femtosecond laser micromachining. The novel biomimetic microflower that composed of numerous turnup graphene nanoflakes can be fabricated by only a single femtosecond laser pulse, which is efficient enough for large-area patterning. The graphene films were composed of layer-by-layer graphene nanosheets separated by nanogaps (~10–50 nm), and graphene monolayers with an interlayer spacing of ~0.37 nm constituted each of the graphene nanosheets. This unique hierarchical layering structure of graphene films provides great possibilities for generation of tensile stress during femtosecond laser ablation to roll up the nanoflakes, which contributes to the formation of microflowers. By a simple scanning technique, patterned surfaces with controllable densities of flower patterns were obtained, which can exhibit adhesive superhydrophobicity. More importantly, this technique enables fabrication of the large-area patterned surfaces at centimeter scales in a simple and efficient way. This study not only presents new insights of ultrafast laser processing of novel graphene-based materials but also shows great promise of designing new materials combined with ultrafast laser surface patterning for future applications in functional coatings, sensors, actuators and microfluidics. PMID:26615800

  1. Femtosecond laser rapid fabrication of large-area rose-like micropatterns on freestanding flexible graphene films

    NASA Astrophysics Data System (ADS)

    Shi, Xuesong; Li, Xin; Jiang, Lan; Qu, Liangti; Zhao, Yang; Ran, Peng; Wang, Qingsong; Cao, Qiang; Ma, Tianbao; Lu, Yongfeng

    2015-11-01

    We developed a simple, scalable and high-throughput method for fabrication of large-area three-dimensional rose-like microflowers with controlled size, shape and density on graphene films by femtosecond laser micromachining. The novel biomimetic microflower that composed of numerous turnup graphene nanoflakes can be fabricated by only a single femtosecond laser pulse, which is efficient enough for large-area patterning. The graphene films were composed of layer-by-layer graphene nanosheets separated by nanogaps (~10-50 nm), and graphene monolayers with an interlayer spacing of ~0.37 nm constituted each of the graphene nanosheets. This unique hierarchical layering structure of graphene films provides great possibilities for generation of tensile stress during femtosecond laser ablation to roll up the nanoflakes, which contributes to the formation of microflowers. By a simple scanning technique, patterned surfaces with controllable densities of flower patterns were obtained, which can exhibit adhesive superhydrophobicity. More importantly, this technique enables fabrication of the large-area patterned surfaces at centimeter scales in a simple and efficient way. This study not only presents new insights of ultrafast laser processing of novel graphene-based materials but also shows great promise of designing new materials combined with ultrafast laser surface patterning for future applications in functional coatings, sensors, actuators and microfluidics.

  2. Fabrication of nanopores with embedded annular electrodes and transverse carbon nanotube electrodes.

    PubMed

    Jiang, Zhijun; Mihovilovic, Mirna; Chan, Jason; Stein, Derek

    2010-11-17

    Nanopores with one or two embedded nanoelectrodes can be fabricated by high resolution, milling-based methods. We first demonstrate how a focused ion beam, whose sputtering mechanism is well understood, can create a nanopore containing an annular electrode of an arbitrary metal, and with a regular perimeter. The inner surface of the nanopore can be insulated, and its diameter can be reduced with nanometer precision, by conformally coating a dielectric material by atomic layer deposition. We then investigate the mechanism of pore formation using a transmission electron microscope (TEM) through studies of the milling rate, and its dependence on the flux of electrons and on the atomic number of different target metals. Sputtering from the surface is identified as the dominant mechanism. Accordingly, light element conductors should be chosen to enhance the rate and resolution of TEM milling, which we demonstrate by articulating a nanopore with transverse carbon nanotube electrodes. Finally, we electrochemically verify that TEM milling preserves the quality of an annular gold electrode through cyclic voltammetry measurements performed at various stages of the fabrication.

  3. Fabrication of nanopores with embedded annular electrodes and transverse carbon nanotube electrodes

    NASA Astrophysics Data System (ADS)

    Jiang, Zhijun; Mihovilovic, Mirna; Chan, Jason; Stein, Derek

    2010-11-01

    Nanopores with one or two embedded nanoelectrodes can be fabricated by high resolution, milling-based methods. We first demonstrate how a focused ion beam, whose sputtering mechanism is well understood, can create a nanopore containing an annular electrode of an arbitrary metal, and with a regular perimeter. The inner surface of the nanopore can be insulated, and its diameter can be reduced with nanometer precision, by conformally coating a dielectric material by atomic layer deposition. We then investigate the mechanism of pore formation using a transmission electron microscope (TEM) through studies of the milling rate, and its dependence on the flux of electrons and on the atomic number of different target metals. Sputtering from the surface is identified as the dominant mechanism. Accordingly, light element conductors should be chosen to enhance the rate and resolution of TEM milling, which we demonstrate by articulating a nanopore with transverse carbon nanotube electrodes. Finally, we electrochemically verify that TEM milling preserves the quality of an annular gold electrode through cyclic voltammetry measurements performed at various stages of the fabrication.

  4. A simple approach for fabrication of dual-disk electrodes with a nanometer-radius electrode and a micrometer-radius electrode.

    PubMed

    Gao, Ning; Lin, Xiaohong; Jia, Wenzhi; Zhang, Xiaoli; Jin, Wenrui

    2007-09-30

    We developed a new simple approach to fabricate dual-disk electrodes with a nanometer-radius electrode and a micrometer-radius electrode. First, nanometer-sized electrodes and micrometer-sized electrodes were constructed using 10-mum-radius metal wires, respectively. To fabricate the nanometer-sized electrode, after the apex of the 10-mum-radius metal wire was electrochemically etched to an ultrafine point with a nanometer-radius, the metal wire was electrochemically coated with a phenol-allyphenol copolymer film. The micrometer-sized electrode was fabricated by directly electrochemical coating the metal wire with an extremely thin phenol-allyphenol copolymer film. Then, the nanometer-radius electrode (the first electrode) and the 10-mum-radius electrode (the second electrode) were inserted into two sides of a thick-septum borosilicate theta (theta) tubing, respectively. The second electrode protruded from the top of the theta tubing. The top of the theta tubing was sealed with insulating ethyl alpha-cyanoacrylate. The top of the theta tubing with both electrodes was ground flat and polished successively with fine sandpaper and aluminum oxide powder until the tip of the first electrode was exposed. Since the second electrode protruded from the top of the theta tubing, its 10-mum-radius tip was naturally formed during polishing. The dual-disk electrodes were characterized by scanning electron microscopy and cyclic voltammetry. The success rate for fabrication of the dual-disk electrodes is approximately 80% due to double insurance from two coating layers of different polymers. PMID:19073075

  5. Multiphoton photochemical crosslinking-based fabrication of protein micropatterns with controllable mechanical properties for single cell traction force measurements

    PubMed Central

    Tong, Ming Hui; Huang, Nan; Zhang, Wei; Zhou, Zhuo Long; Ngan, Alfonso Hing Wan; Du, Yanan; Chan, Barbara Pui

    2016-01-01

    Engineering 3D microstructures with predetermined properties is critical for stem cell niche studies. We have developed a multiphoton femtosecond laser-based 3D printing platform, which generates complex protein microstructures in minutes. Here, we used the platform to test a series of fabrication and reagent parameters in precisely controlling the mechanical properties of protein micropillars. Atomic force microscopy was utilized to measure the reduced elastic modulus of the micropillars, and transmission electron microscopy was used to visualize the porosity of the structures. The reduced elastic modulus of the micropillars associated positively and linearly with the scanning power. On the other hand, the porosity and pore size of the micropillars associated inversely and linearly with the scanning power and reagent concentrations. While keeping the elastic modulus constant, the stiffness of the micropillars was controlled by varying their height. Subsequently, the single cell traction forces of rabbit chondrocytes, human dermal fibroblasts, human mesenchymal stem cells, and bovine nucleus pulposus cells (bNPCs) were successfully measured by culturing the cells on micropillar arrays of different stiffness. Our results showed that the traction forces of all groups showed positive relationship with stiffness, and that the chondrocytes and bNPCs generated the highest and lowest traction forces, respectively. PMID:26817674

  6. Multiphoton photochemical crosslinking-based fabrication of protein micropatterns with controllable mechanical properties for single cell traction force measurements.

    PubMed

    Tong, Ming Hui; Huang, Nan; Zhang, Wei; Zhou, Zhuo Long; Ngan, Alfonso Hing Wan; Du, Yanan; Chan, Barbara Pui

    2016-01-01

    Engineering 3D microstructures with predetermined properties is critical for stem cell niche studies. We have developed a multiphoton femtosecond laser-based 3D printing platform, which generates complex protein microstructures in minutes. Here, we used the platform to test a series of fabrication and reagent parameters in precisely controlling the mechanical properties of protein micropillars. Atomic force microscopy was utilized to measure the reduced elastic modulus of the micropillars, and transmission electron microscopy was used to visualize the porosity of the structures. The reduced elastic modulus of the micropillars associated positively and linearly with the scanning power. On the other hand, the porosity and pore size of the micropillars associated inversely and linearly with the scanning power and reagent concentrations. While keeping the elastic modulus constant, the stiffness of the micropillars was controlled by varying their height. Subsequently, the single cell traction forces of rabbit chondrocytes, human dermal fibroblasts, human mesenchymal stem cells, and bovine nucleus pulposus cells (bNPCs) were successfully measured by culturing the cells on micropillar arrays of different stiffness. Our results showed that the traction forces of all groups showed positive relationship with stiffness, and that the chondrocytes and bNPCs generated the highest and lowest traction forces, respectively.

  7. Multiphoton photochemical crosslinking-based fabrication of protein micropatterns with controllable mechanical properties for single cell traction force measurements

    NASA Astrophysics Data System (ADS)

    Tong, Ming Hui; Huang, Nan; Zhang, Wei; Zhou, Zhuo Long; Ngan, Alfonso Hing Wan; Du, Yanan; Chan, Barbara Pui

    2016-01-01

    Engineering 3D microstructures with predetermined properties is critical for stem cell niche studies. We have developed a multiphoton femtosecond laser-based 3D printing platform, which generates complex protein microstructures in minutes. Here, we used the platform to test a series of fabrication and reagent parameters in precisely controlling the mechanical properties of protein micropillars. Atomic force microscopy was utilized to measure the reduced elastic modulus of the micropillars, and transmission electron microscopy was used to visualize the porosity of the structures. The reduced elastic modulus of the micropillars associated positively and linearly with the scanning power. On the other hand, the porosity and pore size of the micropillars associated inversely and linearly with the scanning power and reagent concentrations. While keeping the elastic modulus constant, the stiffness of the micropillars was controlled by varying their height. Subsequently, the single cell traction forces of rabbit chondrocytes, human dermal fibroblasts, human mesenchymal stem cells, and bovine nucleus pulposus cells (bNPCs) were successfully measured by culturing the cells on micropillar arrays of different stiffness. Our results showed that the traction forces of all groups showed positive relationship with stiffness, and that the chondrocytes and bNPCs generated the highest and lowest traction forces, respectively.

  8. Optimization and fabrication of porous carbon electrodes for Fe/Cr redox flow cells

    NASA Technical Reports Server (NTRS)

    Jalan, V.; Morriseau, B.; Swette, L.

    1982-01-01

    Negative electrode development for the NASA chromous/ferric Redox battery is reported. The effects of substrate material, gold/lead catalyst composition and loading, and catalyzation procedures on the performance of the chromium electrode were investigated. Three alternative catalyst systems were also examined, and 1/3 square foot size electrodes were fabricated and delivered to NASA at the conclusion of the program.

  9. Photosensitive-polyimide based method for fabricating various neural electrode architectures

    PubMed Central

    Kato, Yasuhiro X.; Furukawa, Shigeto; Samejima, Kazuyuki; Hironaka, Naoyuki; Kashino, Makio

    2012-01-01

    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 (ECoG) 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. PMID:22719725

  10. Nonwoven fabric active electrodes for biopotential measurement during normal daily activity.

    PubMed

    Kang, Tae-Ho; Merritt, Carey R; Grant, Edward; Pourdeyhimi, Behnam; Nagle, H Troy

    2008-01-01

    Body movement is responsible for most of the interference during physiological data acquisition during normal daily activities. In this paper, we introduce nonwoven fabric active electrodes that provide the comfort required for clothing while robustly recording physiological data in the presence of body movement. The nonwoven fabric active electrodes were designed and fabricated using both hand- and screen-printing thick-film techniques. Nonstretchable nonwoven (Evolon 100) was chosen as the flexible fabric substrate and a silver filled polymer ink (Creative Materials CMI 112-15) was used to form a transducer layer and conductive lines on the nonwoven fabrics. These nonwoven fabric active electrodes can be easily integrated into clothing for wearable health monitoring applications. Test results indicate that nonwoven textile-based sensors show considerable promise for physiological data acquisition in wearable healthcare monitoring applications.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Thin film lithium-based batteries and electrochromic devices fabricated with nanocomposite electrode materials

    DOEpatents

    Gillaspie, Dane T; Lee, Se-Hee; Tracy, C. Edwin; Pitts, John Roland

    2014-02-04

    Thin-film lithium-based batteries and electrochromic devices (10) are fabricated with positive electrodes (12) comprising a nanocomposite material composed of lithiated metal oxide nanoparticles (40) dispersed in a matrix composed of lithium tungsten oxide.

  13. A novel method of fabricating carbon nanotubes-polydimethylsiloxane composite electrodes for electrocardiography.

    PubMed

    Liu, Benyan; Chen, Yingmin; Luo, Zhangyuan; Zhang, Wenzan; Tu, Quan; Jin, Xun

    2015-01-01

    Polymer-based flexible electrodes are receiving much attention in medical applications due to their good wearing comfort. The current fabrication methods of such electrodes are not widely applied. In this study, polydimethylsiloxane (PDMS) and conductive additives of carbon nanotubes (CNTs) were employed to fabricate composite electrodes for electrocardiography (ECG). A three-step dispersion process consisting of ultrasonication, stirring, and in situ polymerization was developed to yield homogenous CNTs-PDMS mixtures. The CNTs-PDMS mixtures were used to fabricate CNTs-PDMS composite electrodes by replica technology. The influence of ultrasonication time and CNT concentration on polymer electrode performance was evaluated by impedance and ECG measurements. The signal amplitude of the electrodes prepared using an ultrasonication time of 12 h and CNT content of 5 wt% was comparable to that of commercial Ag/AgCl electrodes. The polymer electrodes were easily fabricated by conventional manufacturing techniques, indicating a potential advantage of reduced cost for mass production.

  14. Fabrication of an Inexpensive Ion-Selective Electrode.

    ERIC Educational Resources Information Center

    Palanivel, A.; Riyazuddin, P.

    1984-01-01

    The preparation and performance of a graphite (silver/copper sulfide) electrode is described. This rod, extracted from a used dry cell, is an acceptable substitute for ion-selective electrodes after it has been cleaned by abrasion followed by an overnight treatment with hydrochloric acid. (JN)

  15. Rapid fabrication of supercapacitor electrodes using bionanoscaffolds in capillary microfluidics

    NASA Astrophysics Data System (ADS)

    Zang, F.; Chu, S.; Gerasopoulos, K.; Culver, J. N.; Ghodssi, R.

    2015-12-01

    This paper reports the utilization of capillary microfluidics to rapidly create nanostructure-patterned electrodes for energy storage applications. Using patterned photoresist as open-channel capillary microfluidics, Tobacco mosaic virus (TMV) bio-nanoscaffolds suspended in solution are autonomously delivered onto planar gold electrodes over a 1 cm2 area. The TMVs assemble on the electrode and form a dense bio-nanoscaffold layer due to enhanced evaporation-assisted assembly in the open-channel capillary microfluidic device within an hour. The TMV structures are coated with Ni/NiO through electroless plating and thermal oxidation to form supercapacitor electrodes. The galvanostatic charge/discharge cycle showed a 3.6-fold increase in areal capacitance for the nanostructured electrode compared to planar structures.

  16. Dielectric properties of micropatterns consisting of barium titanate single-crystalline nanocubes

    NASA Astrophysics Data System (ADS)

    Mimura, Ken-ichi; Kato, Kazumi

    2015-10-01

    Micropatterns of barium titanate nanocube (BT NC) assemblies were fabricated by dip-coating self-assembly using a micropatterned mold made of Si or polyimide (PI). The microstructure of the BT NC assembly in the micropatterned mold made of PI showed the closest packing structure. This result indicated that the polymer wall in the micropatterns is swollen by the organic solvent used in the dip-coating self-assembly process. As a result, this swelling might work effectively for the self-assembly of the NCs with high ordering assisted by capillary force. Moreover, it is clarified that the line-and-space-molds with a taper angle and a large width were more useful for the self-assembly of BT NCs in microtrenches selectively. The micropatterned mold made of PI could be removed by immersing in N-methyl-2-pyrrolidone at 65 °C. The ordered structure was not destroyed during the removal process. Micropatterned BT NC capacitor structures were obtained by this method after sintering at 850 °C. The interfaces of BT NCs were conjugated face-to-face, as shown by the obtained high-resolution transmission electron microscopy (HR-TEM) cross-sectional profiles. This process has a great potential for fabricating patterned assemblies directly on substrates. The dielectric properties of BT NC micropatterned assemblies in micropatterned molds made of Si were also characterized and compared with those of BT NC assemblies on Pt/Si substrates without micropatterning.

  17. Fabrication of a flexible and conductive lyocell fabric decorated with graphene nanosheets as a stable electrode material.

    PubMed

    Mengal, Naveed; Sahito, Iftikhar Ali; Arbab, Alvira Ayoub; Sun, Kyung Chul; Qadir, Muhammad Bilal; Memon, Anam Ali; Jeong, Sung Hoon

    2016-11-01

    Textile electrodes are highly desirable for wearable electronics as they offer light-weight, flexibility, cost effectiveness and ease of fabrication. Here, we propose the use of lyocell fabric as a flexible textile electrode because of its inherently super hydrophilic characteristics and increased moisture uptake. A highly concentrated colloidal solution of graphene oxide nanosheets (GONs) was coated on to lyocell fabric and was then reduced in to graphene nanosheets (GNs) using facile chemical reduction method. The proposed textile electrode has a very high surface conductivity with a very low value of surface resistance of only 40Ωsq(-1), importantly without use of any binding or adhesive material in the processing step. Atomic force spectroscopy (AFM) and Transmission electron microscopy (TEM) were conducted to study the topographical properties and sheet exfoliation of prepared GONs. The surface morphology, structural characterization and thermal stability of the fabricated textile electrode were studied by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), X ray photon spectroscopy (XPS), Raman spectroscopy, Wide angle X ray diffraction spectroscopy (WAXD) and Thermogravimetric analysis (TGA) respectively. These results suggest that the GONs is effectively adhered on to the lyocell fabric and the conversion of GONs in to GNs by chemical reduction has no adverse effect on the crystalline structure of textile substrate. The prepared graphene coated conductive lyocell fabric was found stable in water and electrolyte solution and it maintained nearly same surface electrical conductivity at various bending angles. The electrical resistance results suggest that this lyocell based textile electrode (L-GNs) is a promising candidate for flexible and wearable electronics and energy harvesting devices. PMID:27516245

  18. Fabrication of a flexible and conductive lyocell fabric decorated with graphene nanosheets as a stable electrode material.

    PubMed

    Mengal, Naveed; Sahito, Iftikhar Ali; Arbab, Alvira Ayoub; Sun, Kyung Chul; Qadir, Muhammad Bilal; Memon, Anam Ali; Jeong, Sung Hoon

    2016-11-01

    Textile electrodes are highly desirable for wearable electronics as they offer light-weight, flexibility, cost effectiveness and ease of fabrication. Here, we propose the use of lyocell fabric as a flexible textile electrode because of its inherently super hydrophilic characteristics and increased moisture uptake. A highly concentrated colloidal solution of graphene oxide nanosheets (GONs) was coated on to lyocell fabric and was then reduced in to graphene nanosheets (GNs) using facile chemical reduction method. The proposed textile electrode has a very high surface conductivity with a very low value of surface resistance of only 40Ωsq(-1), importantly without use of any binding or adhesive material in the processing step. Atomic force spectroscopy (AFM) and Transmission electron microscopy (TEM) were conducted to study the topographical properties and sheet exfoliation of prepared GONs. The surface morphology, structural characterization and thermal stability of the fabricated textile electrode were studied by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), X ray photon spectroscopy (XPS), Raman spectroscopy, Wide angle X ray diffraction spectroscopy (WAXD) and Thermogravimetric analysis (TGA) respectively. These results suggest that the GONs is effectively adhered on to the lyocell fabric and the conversion of GONs in to GNs by chemical reduction has no adverse effect on the crystalline structure of textile substrate. The prepared graphene coated conductive lyocell fabric was found stable in water and electrolyte solution and it maintained nearly same surface electrical conductivity at various bending angles. The electrical resistance results suggest that this lyocell based textile electrode (L-GNs) is a promising candidate for flexible and wearable electronics and energy harvesting devices.

  19. Fabrication of interdigitated electrodes by inkjet printing technology for apllication in ammonia sensing

    NASA Astrophysics Data System (ADS)

    Dam Le, Duy; Nhien Nguyen, Thi Ngoc; Chanh Tin Doan, Duc; Dung Dang, Thi My; Chien Dang, Mau

    2016-06-01

    In this paper interdigitated electrodes for gas sensors were fabricated by inkjet printing technology. Silver electrodes were inkjet printed on Si/SiO2 substrates instead of traditional photolithography method. The inkjet printing parameters to obtain desired dimensions, thickness of the electrodes and distance between the interdigitated electrodes were optimized in this study. The fabricated interdigitated silver electrodes were tested for application in ammonia gas sensors. Conductive polyaniline (PANI) layer was coated on the silver interdigitated electrodes by drop-coating. Ammonia detection of the PANI-coated chips was characterized with a gas measurement system in which humidity and ammonia concentrations were well-controlled. The electrical conductivity of the PANI films coated on the electrodes was measured when the PANI films were exposed to nitrogen and ammonia. The conductivity of the PANI films decreased significantly due to the deprotonation process of PANI upon ammonia expodure. The recovery time was about 15 min by heating up the polymer chip at 60 °C. The results showed that the silver electrodes fabricated by inkjet printing technique could be used as a sensor platform for ammonia detection.

  20. Metal substrate based electrodes for flexible dye-sensitized solar cells: fabrication methods, progress and challenges.

    PubMed

    Balasingam, Suresh Kannan; Kang, Man Gu; Jun, Yongseok

    2013-12-21

    A step towards commercialization of dye-sensitized solar cells (DSSCs) requires more attention to engineering aspects, such as flexibility, the roll to roll fabrication process, the use of cost effective materials, etc. In this aspect, advantages of flexible DSSCs attracted many researchers to contemplate the transparent conducting oxide coated flexible plastic substrates and the thin metallic foils. In this feature article, the pros and cons of these two kinds of substrates are compared. The flexible dye-sensitized solar cells fabricated using metal substrates are briefly discussed. The working electrodes of DSSCs fabricated on various metal substrates, their fabrication methods, the effect of high temperature calcination and drawbacks of back illumination are reviewed in detail. A few reports on the flexible metal substrate based counter electrodes that could be combined with the plastic substrate based working electrodes are also covered at the end. PMID:24196211

  1. A flexible polypyrrole-coated fabric counter electrode for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Xu, Jie; Li, Meixia; Wu, Lei; Sun, Yongyuan; Zhu, Ligen; Gu, Shaojin; Liu, Li; Bai, Zikui; Fang, Dong; Xu, Weilin

    2014-07-01

    The current dye-sensitized solar cell (DSSC) technology is mostly based on fluorine doped tin oxide (FTO) coated glass substrate. The main problem with the FTO glass substrate is its rigidity, heavyweight and high cost. DSSCs with a fabric as substrate not only offer the advantages of flexibility, stretchability and light mass, but also provide the opportunities for easy implantation to wearable electronics. Herein, a novel fabric counter electrode (CE) for DSSCs has been reported employing a daily-used cotton fabric as substrate and polypyrrole (PPy) as catalytic material. Nickel (Ni) is deposited on the cotton fabric as metal contact by a simple electroless plating method to replace the expensive FTO. PPy is synthesized by in situ polymerization of pyrrole monomer on the Ni-coated fabric. The fabric CE shows sufficient catalytic activity towards the reduction of I3-. The DSSC fabricated using the fabric CE exhibits power conversion efficiency of ∼3.30% under AM 1.5.

  2. Photoresist-free patterning by mechanical abrasion of water-soluble lift-off resists and bare substrates: toward green fabrication of transparent electrodes.

    PubMed

    Printz, Adam D; Chan, Esther; Liong, Celine; Martinez, René S; Lipomi, Darren J

    2013-01-01

    This paper describes the fabrication of transparent electrodes based on grids of copper microwires using a non-photolithographic process. The process--"abrasion lithography"--takes two forms. In the first implementation (Method I), a water-soluble commodity polymer film is abraded with a sharp tool, coated with a conductive film, and developed by immersion in water. Water dissolves the polymer film and lifts off the conductive film in the unabraded areas. In the second implementation (Method II), the substrate is abraded directly by scratching with a sharp tool (i.e., no polymer film necessary). The abraded regions of the substrate are recessed and roughened. Following deposition of a conductive film, the lower profile and roughened topography in the abraded regions prevents mechanical exfoliation of the conductive film using adhesive tape, and thus the conductive film remains only where the substrate is scratched. As an application, conductive grids exhibit average sheet resistances of 17 Ω sq(-1) and transparencies of 86% are fabricated and used as the anode in organic photovoltaic cells in concert with the conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). Compared to devices in which PEDOT:PSS alone serves as an anode, devices comprising grids of copper/nickel microwires and PEDOT:PSS exhibit lowered series resistance, which manifests in greater fill factor and power conversion efficiency. This simple method of forming micropatterns could find use in applications where cost and environmental impact should be minimized, especially as a potential replacement for the transparent electrode indium tin oxide (ITO) in thin-film electronics over large areas (i.e., solar cells) or as a method of rapid prototyping for laboratory-scale devices.

  3. Photoresist-Free Patterning by Mechanical Abrasion of Water-Soluble Lift-Off Resists and Bare Substrates: Toward Green Fabrication of Transparent Electrodes

    PubMed Central

    Printz, Adam D.; Chan, Esther; Liong, Celine; Martinez, René S.; Lipomi, Darren J.

    2013-01-01

    This paper describes the fabrication of transparent electrodes based on grids of copper microwires using a non-photolithographic process. The process—“abrasion lithography”—takes two forms. In the first implementation (Method I), a water-soluble commodity polymer film is abraded with a sharp tool, coated with a conductive film, and developed by immersion in water. Water dissolves the polymer film and lifts off the conductive film in the unabraded areas. In the second implementation (Method II), the substrate is abraded directly by scratching with a sharp tool (i.e., no polymer film necessary). The abraded regions of the substrate are recessed and roughened. Following deposition of a conductive film, the lower profile and roughened topography in the abraded regions prevents mechanical exfoliation of the conductive film using adhesive tape, and thus the conductive film remains only where the substrate is scratched. As an application, conductive grids exhibit average sheet resistances of 17 Ω sq–1 and transparencies of 86% are fabricated and used as the anode in organic photovoltaic cells in concert with the conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). Compared to devices in which PEDOT:PSS alone serves as an anode, devices comprising grids of copper/nickel microwires and PEDOT:PSS exhibit lowered series resistance, which manifests in greater fill factor and power conversion efficiency. This simple method of forming micropatterns could find use in applications where cost and environmental impact should be minimized, especially as a potential replacement for the transparent electrode indium tin oxide (ITO) in thin-film electronics over large areas (i.e., solar cells) or as a method of rapid prototyping for laboratory-scale devices. PMID:24358321

  4. Fabric circuit board-based dry electrode and its characteristics for long-term physiological signal recording.

    PubMed

    Yoo, Jerald; Yoo, Hoi-Jun

    2011-01-01

    This paper presents a dry fabric electrode and its characteristics. For long-term physiological signal monitoring, conventional wet type electrode such as an Ag/AgCl electrode may not be sufficient, because captured signal strength degrades over time as its electrolyte dehydrates. Moreover, the electrolyte may cause skin irritation over a period of time. As a complement, a dry electrode can be used. In this work, fabric-based dry electrodes are introduced. Planar-Fabric Circuit Board (P-FCB) technology enables low cost and uniform productions of such electrodes; electrical properties of the electrodes with various materials, sizes, and time are shown. Both the strengths and drawbacks of the fabric-based electrodes are also discussed.

  5. Fabrication of catalytic electrodes for molten carbonate fuel cells

    DOEpatents

    Smith, James L.

    1988-01-01

    A porous layer of catalyst material suitable for use as an electrode in a molten carbonate fuel cell includes elongated pores substantially extending across the layer thickness. The catalyst layer is prepared by depositing particulate catalyst material into polymeric flocking on a substrate surface by a procedure such as tape casting. The loaded substrate is heated in a series of steps with rising temperatures to set the tape, thermally decompose the substrate with flocking and sinter bond the catalyst particles into a porous catalytic layer with elongated pores across its thickness. Employed as an electrode, the elongated pores provide distribution of reactant gas into contact with catalyst particles wetted by molten electrolyte.

  6. Silicon Nanowire Fabric as a Lithium Ion Battery Electrode Material

    SciTech Connect

    Chockla, Aaron M.; Harris, Justin T.; Akhavan, Vahid A.; Bogart, Timothy D.; Holmberg, Vincent C.; Steinhagen, Chet; Mullins, C. Buddie; Stevenson, Keith J.; Korgel, Brian A.

    2011-11-09

    A nonwoven fabric with paperlike qualities composed of silicon nanowires is reported. The nanowires, made by the supercritical-fluid–liquid–solid process, are crystalline, range in diameter from 10 to 50 nm with an average length of >100 μm, and are coated with a thin chemisorbed polyphenylsilane shell. About 90% of the nanowire fabric volume is void space. Thermal annealing of the nanowire fabric in a reducing environment converts the polyphenylsilane coating to a carbonaceous layer that significantly increases the electrical conductivity of the material. This makes the nanowire fabric useful as a self-supporting, mechanically flexible, high-energy-storage anode material in a lithium ion battery. Anode capacities of more than 800 mA h g{sup –1} were achieved without the addition of conductive carbon or binder.

  7. Fabrication of 3D polypyrrole microstructures and their utilization as electrodes in supercapacitors

    NASA Astrophysics Data System (ADS)

    Ho, Vinh; Zhou, Cheng; Kulinsky, Lawrence; Madou, Marc

    2013-12-01

    We present a novel fabrication method for constructing three-dimensional (3D) conducting microstructures based on the controlled-growth of electrodeposited polypyrrole (PPy) within a lithographically patterned photoresist layer. PPy thin films, post arrays, suspended planes supported by post arrays and multi-layered PPy structures were fabricated. The performance of supercapacitors based on 3D PPy electrodes doped with dodecylbenzene sulfonate (DBS-) and perchlorate (ClO4-) anions was studied using cyclic voltammetry and galvanostatic charge/discharge tests. The highest specific capacitance obtained from the multi-layered PPy(ClO4) electrodes was 401 ± 18 mF cm-2, which is roughly twice as high as the highest specific capacitance of PPy-based supercapacitor reported thus far. The increase in capacitance is the result of higher surface area per unit footprint achieved through the fabrication of multi-layered 3D electrodes.

  8. Micropatterning with a liquid crystal display (LCD) projector.

    PubMed

    Itoga, Kazuyoshi; Kobayashi, Jun; Yamato, Masayuki; Okano, Teruo

    2014-01-01

    Photolithography has been applied to biological applications such as cell and protein micropatterning and the fabrication of microfluidic channels. However, the preparation of photomasks for projecting micropattern lighting images is often time consuming and costly. Therefore, we have developed maskless photolithography devices by modifying the optics of commercially available liquid crystal display (LCD) projectors from extended to reduced projection. The developed second and third devices produce practically a centimeter-scale micropattern by dividing an original large mask pattern into several patterns, which are individually and synchronously exposed to substrates with a motorized XY-stage, applying them to cell micropatterning and polydimethylsiloxane (PDMS) microfluidic device production. The first part of this chapter describes the developments of the maskless photolithography devices. The second part describes the exposure control system with a motorized XY-stage. The third part describes the applications of devices to cell micropatterning. The last part describes the application of the devices to the fabrication of the PDMS microfluidic channel. Maskless photolithography with an LCD projector has a large advantage with no requirement for a photomask. In particular, the maskless photolithography devices show a greater power by optimizing the conditions of pattern size and shape.

  9. Micropatterning with a liquid crystal display (LCD) projector.

    PubMed

    Itoga, Kazuyoshi; Kobayashi, Jun; Yamato, Masayuki; Okano, Teruo

    2014-01-01

    Photolithography has been applied to biological applications such as cell and protein micropatterning and the fabrication of microfluidic channels. However, the preparation of photomasks for projecting micropattern lighting images is often time consuming and costly. Therefore, we have developed maskless photolithography devices by modifying the optics of commercially available liquid crystal display (LCD) projectors from extended to reduced projection. The developed second and third devices produce practically a centimeter-scale micropattern by dividing an original large mask pattern into several patterns, which are individually and synchronously exposed to substrates with a motorized XY-stage, applying them to cell micropatterning and polydimethylsiloxane (PDMS) microfluidic device production. The first part of this chapter describes the developments of the maskless photolithography devices. The second part describes the exposure control system with a motorized XY-stage. The third part describes the applications of devices to cell micropatterning. The last part describes the application of the devices to the fabrication of the PDMS microfluidic channel. Maskless photolithography with an LCD projector has a large advantage with no requirement for a photomask. In particular, the maskless photolithography devices show a greater power by optimizing the conditions of pattern size and shape. PMID:24439283

  10. Fabrication and performance evaluation of hybrid supercapacitor electrodes based on carbon nanotubes and sputtered TiO2.

    PubMed

    Aravinda, L S; Nagaraja, K K; Nagaraja, H S; Bhat, K Udaya; Bhat, B Ramachandra

    2016-08-01

    We report a simple and eco-friendly method for the fabrication of a titanium dioxide/functionalized multiwalled carbon nanotube (TiO2/FMWCNT) composite electrode for use in supercapacitors. The nanocomposite electrodes were formed by depositing titanium dioxide onto FMWCNTs using reactive magnetron sputtering, thus providing a green roue for the formation of the binder-free composite electrode. It is shown that the electrochemical performance of the fabricated electrodes can be altered by tuning the thickness of the titanium dioxide overlayer. The integrated nanocomposite electrode showed an improved specific capacitance of 90 Fg(-1) in two-electrode configuration. PMID:27334299

  11. Fabrication and performance evaluation of hybrid supercapacitor electrodes based on carbon nanotubes and sputtered TiO2

    NASA Astrophysics Data System (ADS)

    Aravinda, L. S.; Nagaraja, K. K.; Nagaraja, H. S.; Udaya Bhat, K.; Ramachandra Bhat, B.

    2016-08-01

    We report a simple and eco-friendly method for the fabrication of a titanium dioxide/functionalized multiwalled carbon nanotube (TiO2/FMWCNT) composite electrode for use in supercapacitors. The nanocomposite electrodes were formed by depositing titanium dioxide onto FMWCNTs using reactive magnetron sputtering, thus providing a green roue for the formation of the binder-free composite electrode. It is shown that the electrochemical performance of the fabricated electrodes can be altered by tuning the thickness of the titanium dioxide overlayer. The integrated nanocomposite electrode showed an improved specific capacitance of 90 Fg-1 in two-electrode configuration.

  12. Fabrication and performance evaluation of hybrid supercapacitor electrodes based on carbon nanotubes and sputtered TiO2

    NASA Astrophysics Data System (ADS)

    Aravinda, L. S.; Nagaraja, K. K.; Nagaraja, H. S.; Udaya Bhat, K.; Ramachandra Bhat, B.

    2016-08-01

    We report a simple and eco-friendly method for the fabrication of a titanium dioxide/functionalized multiwalled carbon nanotube (TiO2/FMWCNT) composite electrode for use in supercapacitors. The nanocomposite electrodes were formed by depositing titanium dioxide onto FMWCNTs using reactive magnetron sputtering, thus providing a green roue for the formation of the binder-free composite electrode. It is shown that the electrochemical performance of the fabricated electrodes can be altered by tuning the thickness of the titanium dioxide overlayer. The integrated nanocomposite electrode showed an improved specific capacitance of 90 Fg‑1 in two-electrode configuration.

  13. Fabrication of fuel cell electrodes and other catalytic structures

    DOEpatents

    Smith, J.L.

    1987-02-11

    A porous layer of catalyst material suitable for use as an electrode in a molten carbonate fuel cell includes elongated pores substantially extending across the layer thickness. The catalyst layer is prepared by depositing particulate catalyst material into polymeric flocking on a substrate surface by a procedure such as tape casting. The loaded substrate is heated in a series of steps with rising temperatures to set the tape, thermally decompose the substrate with flocking and sinter bond the catalyst particles into a porous catalytic layer with elongated pores across its thickness. Employed as an electrode, the elongated pores provide distribution of reactant gas into contact with catalyst particles wetted by molten electrolyte. 1 fig.

  14. Fabrication of highly porous platinum electrodes for micro-scale applications by pulsed electrodeposition and dealloying

    NASA Astrophysics Data System (ADS)

    Köhler, Christian; Kloke, Arne; Drzyzga, Anna; Zengerle, Roland; Kerzenmacher, Sven

    2013-11-01

    We present the implementation and optimization of a novel electrodeposition method for the fabrication of highly porous platinum electrodes. It is based on the co-deposition of platinum and copper and the selective dealloying of copper in a pulsed manner. The new process yields mechanically stable platinum electrodes with roughness factors of up to RF = 6500 ± 700, compared to the state-of-the-art cyclic electrodeposition method this corresponds to an improvement in RF by 111%. Furthermore the time demand for fabrication is reduced by 59%, whereas the platinum utilization is increased by 53%. The method is particularly advantageous for applications such as micro fuel cells since it enables the precise deposition of catalytically active electrodes on micro-structured conductive areas. In this context the novel platinum electrodes show higher current densities for the oxidation of formic acid and glucose than state-of-the-art electrodes. In terms of methanol oxidation their catalytic activity is comparable to commercial direct methanol fuel cell (DMFC) electrodes, fabricated from Pt-Ru nanoparticles dispersed on carbon black.

  15. Fabrication and Characterization of Micro-Pattern Dandelion-like and Nanobelts of β-SrV2O6 via Hydrothermal Process

    NASA Astrophysics Data System (ADS)

    Li, Zi-an; Yang, Huai-xin; Tian, Huan-fang; Zhang, Ying; Li, Jian-qi

    2007-12-01

    Dandelion-like micro-crystallites and long belt-like nanostructures of Sr-V-O materials were synthesized under mild hydrothermal reaction conditions in the presence of mineralizer adipic acid at 220°C for 60 h and 180°C for 60 h, respectively. Scanning electron microscopy measurements show that the Sr-V-O micro-crystallites in general consist of well-arranged microrods with the average length of a few hundred micrometers and diameters ranging from 1 um to 5 μm. The long belt-like nanostructures around 100 nm in width exhibit visible twist and waving in shapes, showing high flexibility in nature. Powder X-ray diffraction and electron diffraction measurements both revealed that these micro-/nanometer materials have an orthorhombic structure with the lattice parameter a=9.694 Å, b=3.687 Å, and c=12.570 Å (space group of Pnma) as reported for β-SrV2O6 phase. The electron diffraction patterns also indicate that the micro-/nanometer β-SrV2O6 crystallites preferentially grow along the lang010rang crystallographic direction. The effects of the hydrothermal treating temperature and chemical compositions ratio of Sr to V on the morphologies of the final products are extensively investigated. A possible crystallite growth mechanism for the micro-pattern formation is proposed based on the systematic analysis of the experiental results.

  16. Fabrication and electrical properties of single wall carbon nanotube channel and graphene electrode based transistors arrays

    SciTech Connect

    Seo, M.; Kim, H.; Kim, Y. H.; Yun, H.; McAllister, K.; Lee, S. W.; Na, J.; Kim, G. T.; Lee, B. J.; Kim, J. J.; Jeong, G. H.; Lee, I.; Kim, K. S.

    2015-07-20

    A transistor structure composed of an individual single-walled carbon nanotube (SWNT) channel with a graphene electrode was demonstrated. The integrated arrays of transistor devices were prepared by transferring patterned graphene electrode patterns on top of the aligned SWNT along one direction. Both single and multi layer graphene were used for the electrode materials; typical p-type transistor and Schottky diode behavior were observed, respectively. Based on our fabrication method and device performances, several issues are suggested and discussed to improve the device reliability and finally to realize all carbon based future electronic systems.

  17. Percutaneous multiple electrode connector, design parameters and fabrication (biomedical)

    NASA Technical Reports Server (NTRS)

    Myers, L. A.

    1977-01-01

    A percutaneous multielectrode connector was designed which utilizes an ultrapure carbon collar to provide an infection free biocompatible passage through the skin. The device provides reliable electrical continuity, mates and demates readily with the implant, and is fabricated with processes and materials oriented to commercial production.

  18. Design, fabrication and evaluation of a conforming circumpolar peripheral nerve cuff electrode for acute experimental use.

    PubMed

    Foldes, Emily L; Ackermann, D Michael; Bhadra, Niloy; Kilgore, Kevin L; Bhadra, Narendra

    2011-03-15

    Nerve cuff electrodes are a principle tool of basic and applied electro-neurophysiology studies and are championed for their ability to achieve good nerve recruitment with low thresholds. We describe the design and method of fabrication for a novel circumpolar peripheral nerve electrode for acute experimental use. This cylindrical cuff-style electrode provides approximately 270° of radial electrode contact with a nerve for each of an arbitrary number of contacts, has a profile that allows for simple placement and removal in an acute nerve preparation, and is designed for adjustment of the cylindrical diameter to ensure a close fit on the nerve. For each electrode, the electrical contacts were cut from 25 μm platinum foil as an array so as to maintain their positions relative to each other within the cuff. Lead wires were welded to each intended contact. The structure was then molded in silicone elastomer, after which the individual contacts were electrically isolated. The final electrode was curved into a cylindrical shape with an inner diameter corresponding to that of the intended target nerve. The positions of these contacts were well maintained during the molding and shaping process and failure rates during fabrication due to contact displacements were very low. Established electrochemical measurements were made on one electrode to confirm expected behavior for a platinum electrode and to measure the electrode impedance to applied voltages at different frequencies. These electrodes have been successfully used for nerve stimulation, recording, and conduction block in a number of different acute animal experiments by several investigators.

  19. Automated catalyst processing for cloud electrode fabrication for fuel cells

    DOEpatents

    Goller, Glen J.; Breault, Richard D.

    1980-01-01

    A process for making dry carbon/polytetrafluoroethylene floc material, particularly useful in the manufacture of fuel cell electrodes, comprises of the steps of floccing a co-suspension of carbon particles and polytetrafluoroethylene particles, filtering excess liquids from the co-suspension, molding pellet shapes from the remaining wet floc solids without using significant pressure during the molding, drying the wet floc pellet shapes within the mold at temperatures no greater than about 150.degree. F., and removing the dry pellets from the mold.

  20. Electrochemical fabrication of metallic nanostructured electrodes for electroanalytical applications.

    PubMed

    Plowman, Blake J; Bhargava, Suresh K; O'Mullane, Anthony P

    2011-12-21

    The use of electrodeposited metal-based nanostructures for electroanalytical applications has recently received widespread attention. There are several approaches to creating nanostructured materials through electrochemical routes that include facile electrodeposition at either untreated or modified electrodes, or through the use of physical or chemical templating methods. This allows the shape, size and composition of the nanomaterial to be readily tuned for the application of interest. The use of such materials is particularly suited to electroanalytical applications. In this mini-review an overview of recently developed nanostructured materials developed through electrochemical routes is presented as well as their electroanalytical applications in areas of biological and environmental importance.

  1. Micropatterning of porphyrin nanotubes thin film using focused laser writing.

    PubMed

    Gupta, Jyotsana; Lim, Xiaodai; Sow, Chorng-Haur; Vijayan, C

    2011-05-01

    We report an effective process to create micropatterns on a thin film of porphyrin nanotubes PNTs on Si substrate using focused laser beam. The optical properties of the newly synthesized porphyrin nanotubes are investigated and micropatterning is demonstrated using laser fabrication, an increasingly important tool in various fields of research. We made use of this laser cutting method to create interesting and useful two-dimensional patterned structures. The shapes and sizes of the structures created can be controlled by varying the power of the laser, angle of incident of the focused laser beam, the relative speed with which the laser beam traverse through the film and the magnification of objective lens used.

  2. Fabrication of ion-conducting carbon-polymer composite electrodes by spin-coating

    NASA Astrophysics Data System (ADS)

    Põldsalu, Inga; Mändmaa, Sven-Erik; Peikolainen, Anna-Liisa; Kesküla, Arko; Aabloo, Alvo

    2015-04-01

    We report a fabricating method for ion-conducting carbon electrodes on top of industrially produced PVDF membrane by spin-coating. Spin-coating is desirable due to its potential application in large-scale actuator manufacturing and its possibility to produce very thin electrodes. The industrial grade membrane was chosen in order to investigate more accurately the results of spin-coating without considering the deviations present in a hand-made membrane. Spin-coating and surface resistivity measurements via four-point probe were described in further detail. The production process of electrode suspension and suspension dispensing were developed and fine-tuned. The spin coater was programmed to obtain electrodes with uniform electrical properties. The arrangement of the spin coater was slightly altered to remove swelling and bubble formation effects concurrent with usage of the porous membrane. Electrodes produced with the developed method were measured and analyzed. Thickness of the film was measured with micrometer screw gauge and four-point probe was used to measure sheet resistivity, in addition film was studied under scanning electron microscope. In best cases the coefficient of variation for sheet conductivity was 6.2%. For all electrode sheet conductivities the median coefficient of variation was 7%. The thickness of the electrodes varied from 6 to 23 μm. As a proof of concept for the developed method a working actuator with spin-coated electrodes was produced.

  3. Enzyme-free glucose sensor based on Au nanobouquet fabricated indium tin oxide electrode.

    PubMed

    Lee, Jin-Ho; El-Said, Waleed Ahmed; Oh, Byung-Keun; Choi, Jeong-Woo

    2014-11-01

    In this study, we demonstrated a simple, rapid and inexpensive fabrication method to develop a novel gold nanobouquet structure fabricated indium tin oxide (GNB/ITO) electrode based on electrochemical deposition of gold ions onto ITO substrate. The morphology of the fabricated electrode surface was characterized by scanning electron microscopy (SEM) to confirm the GNB formation. Enzyme-free detection of glucose using a GNB/ITO electrode was described with high sensitivity and selectivity based on cyclic voltammetry assay. The results demonstrate a linear relation within wide concentration range (500 nM to 10 mM) of glucose, with a correlation coefficient of 0.988. The interference effect of uric acid was effectively avoided for the detection of glucose (1 μM to 10 mM). Moreover, the developed sensor was applied to determine the concentration of glucose in the presence of human serum to indicate the ability of GNB/ITO electrodes in real samples. Hence, newly developed GNB/ITO electrode has potential application in enzyme-free glucose sensor with highly sensitivity and selectivity. PMID:25958541

  4. Design and fabrication of a multi-electrode array for spinal cord epidural stimulation.

    PubMed

    Chang, Chih-Wei; Lo, Yi-Kai; Gad, Parag; Edgerton, Reggie; Liu, Wentai

    2014-01-01

    A detailed design, fabrication, characterization and test of a flexible multi-site platinum/polyimide based electrode array for electrical epidural stimulation in spinal cord prosthesis is described in this paper. Carefully designed 8.4 μm-thick structure fabrication flow achieves an electrode surface modification with 3.8 times enhanced effective surface area without extra process needed. Measured impedance and phase of two type of electrodes are 2.35±0.21 KΩ and 2.10±0.11 KΩ, -34.25±8.07° and -27.71±8.27° at 1K Hz, respectively. The fabricated arrays were then in-vitro tested by a multichannel neural stimulation system in physiological saline to validate the capability for electrical stimulation. The measured channel isolation on adjacent electrode is about -34dB. Randles cell model was used to investigate the charging waveforms, the model parameters were then extracted by various methods. The measured charge transfer resistance, double layer capacitance, and solution resistance are 1.9 KΩ, 220 nF and 15 KΩ, respectively. The results show that the fabricated array is applicable for electrical stimulation with well characterized parameters. Combined with a multichannel stimulator, this system provides a full solution for versatile neural stimulation applications. PMID:25571566

  5. Fabrication of functional micro- and nanoneedle electrodes using a carbon nanotube template and electrodeposition

    NASA Astrophysics Data System (ADS)

    An, Taechang; Choi, Wooseok; Lee, Eunjoo; Kim, In-Tae; Moon, Wonkyu; Lim, Geunbae

    2011-12-01

    Carbon nanotube (CNT) is an attractive material for needle-like conducting electrodes because it has high electrical conductivity and mechanical strength. However, CNTs cannot provide the desired properties in certain applications. To obtain micro- and nanoneedles having the desired properties, it is necessary to fabricate functional needles using various other materials. In this study, functional micro- and nanoneedle electrodes were fabricated using a tungsten tip and an atomic force microscope probe with a CNT needle template and electrodeposition. To prepare the conductive needle templates, a single-wall nanotube nanoneedle was attached onto the conductive tip using dielectrophoresis and surface tension. Through electrodeposition, Au, Ni, and polypyrrole were each coated successfully onto CNT nanoneedle electrodes to obtain the desired properties.

  6. Fabrication of functional micro- and nanoneedle electrodes using a carbon nanotube template and electrodeposition.

    PubMed

    An, Taechang; Choi, Wooseok; Lee, Eunjoo; Kim, In-Tae; Moon, Wonkyu; Lim, Geunbae

    2011-01-01

    Carbon nanotube (CNT) is an attractive material for needle-like conducting electrodes because it has high electrical conductivity and mechanical strength. However, CNTs cannot provide the desired properties in certain applications. To obtain micro- and nanoneedles having the desired properties, it is necessary to fabricate functional needles using various other materials. In this study, functional micro- and nanoneedle electrodes were fabricated using a tungsten tip and an atomic force microscope probe with a CNT needle template and electrodeposition. To prepare the conductive needle templates, a single-wall nanotube nanoneedle was attached onto the conductive tip using dielectrophoresis and surface tension. Through electrodeposition, Au, Ni, and polypyrrole were each coated successfully onto CNT nanoneedle electrodes to obtain the desired properties.

  7. The fabrication of a bifunctional oxygen electrode without carbon components for alkaline secondary batteries

    NASA Astrophysics Data System (ADS)

    Price, Stephen W. T.; Thompson, Stephen J.; Li, Xiaohong; Gorman, Scott F.; Pletcher, Derek; Russell, Andrea E.; Walsh, Frank C.; Wills, Richard G. A.

    2014-08-01

    The fabrication of a gas diffusion electrode (GDE) without carbon components is described. It is therefore suitable for use as a bifunctional oxygen electrode in alkaline secondary batteries. The electrode is fabricated in two stages (a) the formation of a PTFE-bonded nickel powder layer on a nickel foam substrate and (b) the deposition of a NiCo2O4 spinel electrocatalyst layer by dip coating in a nitrate solution and thermal decomposition. The influence of modifications to the procedure on the performance of the GDEs in 8 M NaOH at 333 K is described. The GDEs can support current densities up to 100 mA cm-2 with state-of-the-art overpotentials for both oxygen evolution and oxygen reduction. Stable performance during >50 successive, 1 h oxygen reduction/evolution cycles at a current density of 50 mA cm-2 has been achieved.

  8. Fabrication of functional micro- and nanoneedle electrodes using a carbon nanotube template and electrodeposition

    PubMed Central

    2011-01-01

    Carbon nanotube (CNT) is an attractive material for needle-like conducting electrodes because it has high electrical conductivity and mechanical strength. However, CNTs cannot provide the desired properties in certain applications. To obtain micro- and nanoneedles having the desired properties, it is necessary to fabricate functional needles using various other materials. In this study, functional micro- and nanoneedle electrodes were fabricated using a tungsten tip and an atomic force microscope probe with a CNT needle template and electrodeposition. To prepare the conductive needle templates, a single-wall nanotube nanoneedle was attached onto the conductive tip using dielectrophoresis and surface tension. Through electrodeposition, Au, Ni, and polypyrrole were each coated successfully onto CNT nanoneedle electrodes to obtain the desired properties. PMID:21711831

  9. Fabrication of efficient thermoacoustic device with an interdigitated-like electrode on indium tin oxide glass

    NASA Astrophysics Data System (ADS)

    Tsai, Ming-shan; Yang, Ko-kang; Chen, Sy-hann; Ting, Chen-ching; Jiang, I.-min

    2016-10-01

    A thermoacoustic device was fabricated on indium tin oxide (ITO) glass, exhibiting an interdigitated-like electrode pattern. Our fabrication method enhanced the sound performance by approximately 20 dB compared with that of plain ITO film. Two approaches were adopted in this study to enhance the sound pressure level (SPL). One was to decrease the heat capacity per unit area of the device by reducing the thickness of the conductor film, and the other was to increase the thermal diffusivity of the device by applying a thin Au film on the electrode. We observed that heat generated by electron accumulation on ITO protrusions resulted in a large temperature oscillation of the surroundings and induced an SPL increase. A 4 nm Au film coating on the fabricated thermoacoustic device assisted thermal energy exchange with close-proximity air, improving the efficiency by an SPL of 7 dB.

  10. Tin nanoparticle thin film electrodes fabricated by the vacuum filtration method for enhanced battery performance.

    PubMed

    Lee, Jae Hyun; Kong, Byung-Seon; Baek, Youn-Kyoung; Yang, Seung Bo; Jung, Hee-Tae

    2009-06-10

    A novel method for fabricating tin nanoparticle thin film electrodes that show good performance in lithium ion batteries during cycling is reported. The vacuum filtration method has the advantage of affording a high degree of dispersion of the electrode components, thereby providing good electrical contacts between the tin nanoparticles and the conductive carbon or current collector. The reversible capacity and initial Coulombic efficiency are 726 mA h g(-1) and 85.3%, respectively, with this thin film electrode. Cycle life performance tests under real battery conditions show that the battery capacity and reaction peaks remained stable for up to 50 cycles. SEM shows that the uniform morphology of the vacuum filtered film was maintained throughout the cycle life test. This novel vacuum filtration method for providing nanoparticle-based film electrodes has further potential applications for use in various devices such as high power, thin film batteries, supercapacitors and organic-inorganic hybrid photovoltaic cells.

  11. Simple fabrication of porous gold-film electrodes and their electroanalytical applications.

    PubMed

    Hyun, Myeounghee; Choi, Suhee; Kim, Jongwon

    2010-01-01

    A simple strategy to fabricate porous three-dimensional gold-film electrodes using gold-coated microspheres (AuMS) is presented. The AuMS deposited on gold (AuMS/Au) are electrically interconnected, and show unique electrochemical properties indicating porous surface structures. The AuMS/Au electrodes exhibit electrocatalytic activities for oxygen reduction and peroxide oxidation, which indicates that the apparent macroporous structures also retain porous regions with nanometer-scale dimensions. The porous structures on AuMS/Au electrodes also provide a selective voltammetric response for glucose against ascorbic acid due to the different electron-transfer kinetics. Since AuMS/Au electrodes are simple to prepare compared with previously suggested systems, the present system could offer potential in electroanalytical applications as new gold-based substrates for further modifications of surfaces.

  12. Fabrication of Impregnated-Electrode-Type Polyatomic Ion Source with Ionic Liquid

    SciTech Connect

    Takeuchi, Mitsuaki; Ryuto, Hiromichi; Takaoka, Gikan H.

    2011-01-07

    Three types of ionic liquid ion source characterized by needle-type, capillary-needle-type and impregnated-electrode-type emitters were fabricated and demonstrated. The ion emission of a pure ionic liquid was demonstrated for the capillary-needle- and impregnated-electrode-type emitters. The emission stability of the impregnated-electrode-type emitter is currently insufficient for the shallow implantation of carbon due to occasional discharge. However, the impregnated-electrode-type emitter showed the largest emission current of 14 {mu}A at 6 kV among these emitters. This was considered to be caused by the relatively high feedability of the ionic liquid obtained from the emitter tip made of porous copper.

  13. Fabrication and photoelectrochemical properties of interdigitated array microelectrodes consisting of optically transparent and nontransparent band electrodes

    SciTech Connect

    Horiuchi, Tsutomu; Niwa, Osamu; Morita, Masao

    1995-09-01

    Photogalvanic cells based on the photoinduced redox reactions of two redox couples can convert solar energy. However, their conversion efficiency is poor because of the recombination of photochemically produced active species before they reach the electrodes and the two-way electrode processes of those species. In an attempt to improve the conversion efficiency, the use of closely spaced electrodes structures has been proposed, such as a thin-layer photocell with a transparent electrode. A lithologic fabrication method for a new interdigitated array microelectrode (IDA) consisting of optically transparent (ITO) and nontransparent (Pt) arrays of band electrodes on a quartz substrate is presented. The new IDA is applied to the Ru(bpy){sub 3}{sup 2+}-Fe{sup 3+} photogalvanic system. The effective separation of photoinduced active species between very closely spaced electrodes is achieved by utilizing the shadow of the nontransparent electrode generated by illumination from the rear of the IDA. This back-illumination method using the new IDA is effective in increasing the conversion efficiency.

  14. Advancements in electrode design and laser techniques for fabricating micro-electrode arrays as part of a retinal prosthesis.

    PubMed

    Dodds, C W D; Schuettler, M; Guenther, T; Lovell, N H; Suaning, G J

    2011-01-01

    Retinal micro-electrode arrays (MEAs) for a visual prosthesis were fabricated by laser structuring of platinum (Pt) foil and liquid silicone rubber. A new design was created using a folding technique to create a multi-layered array from a single Pt sheet. This method allowed a reduction in both the electrode pitch, and the overall width of the array, while maintaining coplanar connection points for more stable interconnections to other components of the system. The design also included a section which could be rolled to create a cylindrical segment in order to minimise the size of the exit in the sclera after implantation. A picosecond mode-locked 532 nm laser system was investigated as a replacement for the nanosecond Q-switched 1064 nm laser currently in use. Trials showed that the ps system could produce high quality electrode tracks with a minimum pitch of 30 μm, less than 40% the pitch achievable with the ns laser. A method was investigated for the cutting of Pt foils without damaging the underlying silicone by laser machining to a depth just below the thickness of the foil. Initial samples showed promise with full penetration of the foil only occurring at cross points of the laser paths. The ps laser was also used to create roughened surfaces, in order to increase the electrochemical surface area of the electrodes. Surfaces were imaged using a scanning electron microscope, and compared to surfaces roughened with the ns laser. The ps laser was seen to offer a reduction in feature size, as well as an increase in control over the appearance of the electrode surface. PMID:22254389

  15. Fabrication and characterization of cuprous oxide solar cell with net-shaped counter electrode

    NASA Astrophysics Data System (ADS)

    Basuki, Stefanus; Uranus, Henri P.; Pangaribuan, Julinda

    2015-01-01

    In this work, simple solar cells using cuprous oxide were fabricated and characterized. The solar cells in this experiment used cuprous oxide plate as detecting electrode and copper wires which were woven into a net-shape with a gap size of 2 x 2 cm as a counter electrode. Twenty samples of solar cells were fabricated with oxide layer which were thermally grown in temperature up to 550 oC. Samples with variations in oxidation time (15 minutes, 30 minutes, 40 minutes, and 45 minutes) and distance between electrodes (2 cm, 3 cm, and 4 cm) with an electrolyte solution of NaCl with molarity of 2.188 mol/l were produced. The samples were characterized by measuring their V-I curve. For this purpose, a simple, own-made solar simulator were fabricated and characterized. Using curve fitting technique, parameters such as FF (Fill Factor), efficiency, open circuit voltage, short circuit current, internal resistance, and performance degradation as a function of time of the cells were extracted. The result shows optimum efficiency of 4.573. 10-4%, while optimum oxidation time is 40 minutes and optimum distance between electrodes is 3 cm.

  16. Fabrication of a Polyaniline Ultramicroelectrode via a Self Assembled Monolayer Modified Gold Electrode

    PubMed Central

    Bolat, Gulcin; Kuralay, Filiz; Eroglu, Gunes; Abaci, Serdar

    2013-01-01

    Herein, we report a simple and inexpensive way for the fabrication of an ultramicroelectrode and present its characterization by electrochemical techniques. The fabrication of polyaniline UME involves only two steps: modification of a gold (Au) electrode by self assembled monolayers (SAM) and then electrodeposition of polyaniline film on this thiol-coated Au electrode by using cyclic voltammetry and constant potential electrolysis methods. Two types of self-assembled monolayers (4-mercapto-1-butanol, MB, and 11-mercaptoundecanoic acid, MUA) were used, respectively, to see the effect of chain length on microelectrode formation. Microelectrode fabrication and utility of the surface was investigated by cyclic voltammetric measurements in a redox probe. The thus prepared polyaniline microelectrode was then used for DNA immobilization. Discrimination between double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA) was obtained with enhanced electrochemical signals compared to a polyaniline-coated Au electrode. Different modifications on the electrode surfaces were examined using scanning electron microscopy (SEM). PMID:23797740

  17. Facile 3D Metal Electrode Fabrication for Energy Applications via Inkjet Printing and Shape Memory Polymer

    NASA Astrophysics Data System (ADS)

    Roberts, R. C.; Wu, J.; Hau, N. Y.; Chang, Y. H.; Feng, S. P.; Li, D. C.

    2014-11-01

    This paper reports on a simple 3D metal electrode fabrication technique via inkjet printing onto a thermally contracting shape memory polymer (SMP) substrate. Inkjet printing allows for the direct patterning of structures from metal nanoparticle bearing liquid inks. After deposition, these inks require thermal curing steps to render a stable conductive film. By printing onto a SMP substrate, the metal nanoparticle ink can be cured and substrate shrunk simultaneously to create 3D metal microstructures, forming a large surface area topology well suited for energy applications. Polystyrene SMP shrinkage was characterized in a laboratory oven from 150-240°C, resulting in a size reduction of 1.97-2.58. Silver nanoparticle ink was patterned into electrodes, shrunk, and the topology characterized using scanning electron microscopy. Zinc-Silver Oxide microbatteries were fabricated to demonstrate the 3D electrodes compared to planar references. Characterization was performed using 10M potassium hydroxide electrolyte solution doped with zinc oxide (57g/L). After a 300s oxidation at 3Vdc, the 3D electrode battery demonstrated a 125% increased capacity over the reference cell. Reference cells degraded with longer oxidations, but the 3D electrodes were fully oxidized for 4 hours, and exhibited a capacity of 5.5mA-hr/cm2 with stable metal performance.

  18. Underwater microdischarge in arranged microbubbles produced by electrolysis in electrolyte solution using fabric-type electrode

    SciTech Connect

    Sakai, Osamu; Kimura, Masaru; Tachibana, Kunihide; Shirafuji, Tatsuru

    2008-12-08

    Pulsed microdischarge was generated in microbubbles produced by electrolysis in an electrolyte solution without external gas feed by using a fabric-type electrode. The electrode structure not only allowed low-voltage ignition of the atmospheric-pressure discharge in hydrogen or oxygen containing microbubbles but also worked effectively in producing and holding the bubbles on its surface. The generation of reactive species was verified by optical emissions from the produced microplasmas, and their transport into the solution was monitored by the change in hydrogen concentration.

  19. Fabrication of carbon nanotube nanogap electrodes by helium ion sputtering for molecular contacts

    SciTech Connect

    Thiele, Cornelius; Vieker, Henning; Beyer, André; Gölzhäuser, Armin; Flavel, Benjamin S.; Hennrich, Frank; Muñoz Torres, David; Eaton, Thomas R.; Mayor, Marcel; Kappes, Manfred M.; Löhneysen, Hilbert v.; and others

    2014-03-10

    Carbon nanotube nanogaps have been used to contact individual organic molecules. However, the reliable fabrication of a truly nanometer-sized gap remains a challenge. We use helium ion beam lithography to sputter nanogaps of only (2.8 ± 0.6) nm size into single metallic carbon nanotubes embedded in a device geometry. The high reproducibility of the gap size formation provides a reliable nanogap electrode testbed for contacting small organic molecules. To demonstrate the functionality of these nanogap electrodes, we integrate oligo(phenylene ethynylene) molecular rods, and measure resistance before and after gap formation and with and without contacted molecules.

  20. Fabrication and evaluation of an improved polymer-based cochlear electrode array for atraumatic insertion.

    PubMed

    Gwon, Tae Mok; Min, Kyou Sik; Kim, Jin Ho; Oh, Seung Ha; Lee, Ho Sun; Park, Min-Hyun; Kim, Sung June

    2015-04-01

    An atraumatic cochlear electrode array has become indispensable to high-performance cochlear implants such as electric acoustic stimulation (EAS), wherein the preservation of residual hearing is significant. For an atraumatic implantation, we propose and demonstrate a new improved design of a cochlear electrode array based on liquid crystal polymer (LCP), which can be fabricated by precise batch processes and a thermal lamination process, in contrast to conventional wire-based cochlear electrode arrays. Using a thin-film process of LCP-film-mounted silicon wafer and thermal press lamination, we devise a multi-layered structure with variable layers of LCP films to achieve a sufficient degree of basal rigidity and a flexible tip. A peripheral blind via and self-aligned silicone elastomer molding process can reduce the width of the array. Measuring the insertion and extraction forces in a human scala tympani model, we investigate five human temporal bone insertion trials and record electrically evoked auditory brainstem responses (EABR) acutely in a guinea pig model. The diameters of the finalized electrode arrays are 0.3 mm (tip) and 0.75 mm (base). The insertion force with a displacement of 8 mm from a round window and the maximum extraction force are 2.4 mN and 34.0 mN, respectively. The electrode arrays can be inserted from 360° to 630° without trauma at the basal turn. The EABR data confirm the efficacy of the array. A new design of LCP-based cochlear electrode array for atraumatic implantation is fabricated. Verification indicates that foretells the development of an atraumatic cochlear electrode array and clinical implant.

  1. Fabrication of nano-gap electrode arrays by the construction and selective chemical etching of nano-crosswire stacks

    NASA Technical Reports Server (NTRS)

    Son, Kyung-Ah (Inventor); Prokopuk, Nicholas (Inventor)

    2008-01-01

    Methods of fabricating nano-gap electrode structures in array configurations, and the structures so produced. The fabrication method involves depositing first and second pluralities of electrodes comprising nanowires using processes such as lithography, deposition of metals, lift-off processes, and chemical etching that can be performed using conventional processing tools applicable to electronic materials processing. The gap spacing in the nano-gap electrode array is defined by the thickness of a sacrificial spacer layer that is deposited between the first and second pluralities of electrodes. The sacrificial spacer layer is removed by etching, thereby leaving a structure in which the distance between pairs of electrodes is substantially equal to the thickness of the sacrificial spacer layer. Electrode arrays with gaps measured in units of nanometers are produced. In one embodiment, the first and second pluralities of electrodes are aligned in mutually orthogonal orientations.

  2. All-carbon based graphene field effect transistor with graphitic electrodes fabricated by e-beam direct writing on PMMA.

    PubMed

    Chen, Wei; Yu, Yayun; Zheng, Xiaoming; Qin, Shiqiao; Wang, Fei; Fang, Jingyue; Wang, Guang; Wang, Chaocheng; Wang, Li; Peng, Gang; Zhang, Xue-Ao

    2015-07-21

    A so called all-carbon based graphene field effect transistor (GFET) in which the electrodes are composed of graphite-like nano-sheets instead of metals in the traditional devices is fabricated by one-step e-beam direct writing (EBDW). It is also found that the graphite-like nano-sheets in electrodes are perpendicular to the channel graphene, which is confirmed by the transmission electron microscopy (HRTEM). The one-step fabrication of the carbonaceous electrodes is more convenient and lower-cost comparing to the preparation of traditional metal electrodes and can be applied to many other nano-electronic devices.

  3. All-carbon based graphene field effect transistor with graphitic electrodes fabricated by e-beam direct writing on PMMA

    PubMed Central

    Chen, Wei; Yu, Yayun; Zheng, Xiaoming; Qin, Shiqiao; Wang, Fei; Fang, Jingyue; Wang, Guang; Wang, Chaocheng; Wang, Li; Peng, Gang; Zhang, Xue-Ao

    2015-01-01

    A so called all-carbon based graphene field effect transistor (GFET) in which the electrodes are composed of graphite-like nano-sheets instead of metals in the traditional devices is fabricated by one-step e-beam direct writing (EBDW). It is also found that the graphite-like nano-sheets in electrodes are perpendicular to the channel graphene, which is confirmed by the transmission electron microscopy (HRTEM). The one-step fabrication of the carbonaceous electrodes is more convenient and lower-cost comparing to the preparation of traditional metal electrodes and can be applied to many other nano-electronic devices. PMID:26195033

  4. Fabrication of high aspect ratio nanogrid transparent electrodes via capillary assembly of Ag nanoparticles.

    PubMed

    Kang, Juhoon; Park, Chang-Goo; Lee, Su-Han; Cho, Changsoon; Choi, Dae-Geun; Lee, Jung-Yong

    2016-06-01

    In this report, we describe the fabrication of periodic Ag nanogrid electrodes by capillary assembly of silver nanoparticles (AgNPs) along patterned nanogrid templates. By assembling the AgNPs into these high-aspect-ratio nanogrid patterns, we can obtain high-aspect-ratio nanogratings, which can overcome the inherent trade-off between the optical transmittance and the sheet resistance of transparent electrodes. The junction resistance between the AgNPs is effectively reduced by photochemical welding and post-annealing. The fabricated high-aspect-ratio nanogrid structure with a line width of 150 nm and a height of 450 nm has a sheet resistance of 15.2 Ω sq(-1) and an optical transmittance of 85.4%. PMID:27187802

  5. Fabrication of lateral electrodes on semiconductor nanowires through structurally matched insulation for functional optoelectronics.

    PubMed

    Sheng, Yun; Sun, Huabin; Wang, Jianyu; Gao, Fan; Wang, Junzhuan; Pan, Lijia; Pu, Lin; Zheng, Youdou; Shi, Yi

    2013-01-18

    A strategy of using structurally matched alumina insulation to produce lateral electrodes on semiconductor nanowires is presented. Nanowires in the architecture are structurally matched with alumina insulation using selective anodic oxidation. Lateral electrodes are fabricated by directly evaporating metallic atoms onto the opposite sides of the nanowires. The integrated architecture with lateral electrodes propels carriers to transport them across nanowires and is crucially beneficial to the injection/extraction in optoelectronics. The matched architecture and the insulating properties of the alumina layer are investigated experimentally. ZnO nanowires are functionalized into an ultraviolet photodiode as an example. The present strategy successfully implements an advantageous architecture and is significant in developing diverse semiconductor nanowires in optoelectronic applications.

  6. Fabrication of lateral electrodes on semiconductor nanowires through structurally matched insulation for functional optoelectronics

    NASA Astrophysics Data System (ADS)

    Sheng, Yun; Sun, Huabin; Wang, Jianyu; Gao, Fan; Wang, Junzhuan; Pan, Lijia; Pu, Lin; Zheng, Youdou; Shi, Yi

    2013-01-01

    A strategy of using structurally matched alumina insulation to produce lateral electrodes on semiconductor nanowires is presented. Nanowires in the architecture are structurally matched with alumina insulation using selective anodic oxidation. Lateral electrodes are fabricated by directly evaporating metallic atoms onto the opposite sides of the nanowires. The integrated architecture with lateral electrodes propels carriers to transport them across nanowires and is crucially beneficial to the injection/extraction in optoelectronics. The matched architecture and the insulating properties of the alumina layer are investigated experimentally. ZnO nanowires are functionalized into an ultraviolet photodiode as an example. The present strategy successfully implements an advantageous architecture and is significant in developing diverse semiconductor nanowires in optoelectronic applications.

  7. Method of fabricating conductive electrodes on the front and backside of a thin film structure

    DOEpatents

    Tabada, Phillipe J.; Tabada, legal representative, Melody; Pannu, Satinderpall S.

    2011-05-22

    A method of fabricating a thin film device having conductive front and backside electrodes or contacts. Top-side cavities are first formed on a first dielectric layer, followed by the deposition of a metal layer on the first dielectric layer to fill the cavities. Defined metal structures are etched from the metal layer to include the cavity-filled metal, followed by depositing a second dielectric layer over the metal structures. Additional levels of defined metal structures may be formed in a similar manner with vias connecting metal structures between levels. After a final dielectric layer is deposited, a top surface of a metal structure of an uppermost metal layer is exposed through the final dielectric layer to form a front-side electrode, and a bottom surface of a cavity-filled portion of a metal structure of a lowermost metal layer is also exposed through the first dielectric layer to form a back-side electrode.

  8. A novel slurry concept for the fabrication of lithium-ion battery electrodes with beneficial properties

    NASA Astrophysics Data System (ADS)

    Bitsch, Boris; Dittmann, Jens; Schmitt, Marcel; Scharfer, Philip; Schabel, Wilhelm; Willenbacher, Norbert

    2014-11-01

    A novel slurry concept for the fabrication of Li-ion battery electrodes focusing on water based formulations is presented. Taking advantage of capillary forces inferred by adding a small fraction of a second fluid immiscible with the bulk continuous phase the low shear viscosity can be varied in a wide range without conventional polymeric rheology control agents disturbing the electric properties of the dry electrode. The new slurries provide superior storage stability and excellent shape accuracy of the final dry film. This reduces waste cut-off at the edges and increases the density of active ingredients, thus improving cost-efficiency. The viscosity at high shear rates remains unaffected, thus the slurries can be processed and coated using established equipment and process parameters. Adhesion to the conductor foil and electrochemical properties of the electrode layers and corresponding cells are similar to those made from conventional slurries.

  9. Fabrication of high aspect ratio nanogrid transparent electrodes via capillary assembly of Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Kang, Juhoon; Park, Chang-Goo; Lee, Su-Han; Cho, Changsoon; Choi, Dae-Geun; Lee, Jung-Yong

    2016-05-01

    In this report, we describe the fabrication of periodic Ag nanogrid electrodes by capillary assembly of silver nanoparticles (AgNPs) along patterned nanogrid templates. By assembling the AgNPs into these high-aspect-ratio nanogrid patterns, we can obtain high-aspect-ratio nanogratings, which can overcome the inherent trade-off between the optical transmittance and the sheet resistance of transparent electrodes. The junction resistance between the AgNPs is effectively reduced by photochemical welding and post-annealing. The fabricated high-aspect-ratio nanogrid structure with a line width of 150 nm and a height of 450 nm has a sheet resistance of 15.2 Ω sq-1 and an optical transmittance of 85.4%.In this report, we describe the fabrication of periodic Ag nanogrid electrodes by capillary assembly of silver nanoparticles (AgNPs) along patterned nanogrid templates. By assembling the AgNPs into these high-aspect-ratio nanogrid patterns, we can obtain high-aspect-ratio nanogratings, which can overcome the inherent trade-off between the optical transmittance and the sheet resistance of transparent electrodes. The junction resistance between the AgNPs is effectively reduced by photochemical welding and post-annealing. The fabricated high-aspect-ratio nanogrid structure with a line width of 150 nm and a height of 450 nm has a sheet resistance of 15.2 Ω sq-1 and an optical transmittance of 85.4%. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01896c

  10. Micro-patterning of ionic reservoirs within a double bilayer lipid membrane to fabricate a 2D array of ion-channel switch based electrochemical biosensors

    SciTech Connect

    Sansinena, J. M.; Yee, C. K.; Sapuri, A.; Swanson, Basil I.; Redondo, A.; Parikh, A. N.

    2004-01-01

    We present a simple approach for the design of ionic reservoir arrays within a double phospholipid bilayer to ultimately develop a 2D array of ion-channel switch based electrochemical biosensors. As a first step, a primary bilayer lipid membrane is deposited onto an array of electrodes patterned onto a substrate surface. Subsequently, an array of microvoids is created within the bilayer by a wet photolithographic patterning of phospholipid bilayers using a deep UV light source and a quartz/chrome photomask. To ensure registry, the photomask used to pattern bilayers is designed to match up the microvoids within the primary bilayer with the array of electrodes on the substrate surface. The deposition of a secondary bilayer lipid membrane onto the primary bilayer that spans across the patterned microvoids leads to the formation of the array of ionic reservoirs within the double phospholipid bilayer. This is accomplished using giant unilamellar vesicles and by exploiting membrane electrostatics. The use of ion-channels incorporated into the secondary bilayer that covers the individual ionic reservoirs allows the construction of a 2D array of ion-channel switch based electrochemical biosensors that are able to recognize different target-agents simultaneously.

  11. Design and Fabrication of Ultralight Weight, Adjustable Multi-electrode Probes for Electrophysiological Recordings in Mice

    PubMed Central

    Liang, Li; Siegle, Joshua H.; Voigts, Jakob; Wilson, Matthew; Halassa, Michael M.

    2014-01-01

    The number of physiological investigations in the mouse, mus musculus, has experienced a recent surge, paralleling the growth in methods of genetic targeting for microcircuit dissection and disease modeling. The introduction of optogenetics, for example, has allowed for bidirectional manipulation of genetically-identified neurons, at an unprecedented temporal resolution. To capitalize on these tools and gain insight into dynamic interactions among brain microcircuits, it is essential that one has the ability to record from ensembles of neurons deep within the brain of this small rodent, in both head-fixed and freely behaving preparations. To record from deep structures and distinct cell layers requires a preparation that allows precise advancement of electrodes towards desired brain regions. To record neural ensembles, it is necessary that each electrode be independently movable, allowing the experimenter to resolve individual cells while leaving neighboring electrodes undisturbed. To do both in a freely behaving mouse requires an electrode drive that is lightweight, resilient, and highly customizable for targeting specific brain structures. A technique for designing and fabricating miniature, ultralight weight, microdrive electrode arrays that are individually customizable and easily assembled from commercially available parts is presented. These devices are easily scalable and can be customized to the structure being targeted; it has been used successfully to record from thalamic and cortical regions in a freely behaving animal during natural behavior. PMID:25225749

  12. Dielectrophoresis-assisted electroconductive polymer-based fabrication of high surface area electrodes

    NASA Astrophysics Data System (ADS)

    Perez-Gonzalez, Victor H.; Ho, Vinh; Kulinsky, Lawrence; Martinez-Chapa, Sergio O.

    2014-03-01

    In this work we present a novel microfabrication process that is based on combined use of dielectrophoresis (DEP) to attract particles or cells to electrodes and to follow this step by an electrodeposition of polypyrrole (PPy) to entrap the particles or cells on electrode surface. This process can be used for mass-production of high surface area structures as well as to the creation of functionally graded materials. DEP was employed to pull the microparticles toward the surface of the electrodes and hold them in place while PPy was electrodeposited. Polystyrene microbeads with diameters ranging from 1 to 10 microns were employed in this study. Experimental results demonstrated that PPy can entrap the particles attracted to the electrode surface by the positive DEP. It was also demonstrated that hierarchical structures can be created where smaller microbeads are attached to, caught and secured on the surface of larger microbeads entrapped on the electrode surface. Furthermore, as DEP can be employed for manipulating of wide variety of polarizable materials, this process can also entrap inorganic and biological microparticles in the fabricated structure. Applications of this work include, but are not limited to, the development of biomedical, electrokinetic, and energy storage devices, electrochemical sensors, and scaffolds.

  13. Dual-electrode electrochemical detection for poly(dimethylsiloxane)-fabricated capillary electrophoresis microchips.

    PubMed

    Martin, R S; Gawron, A J; Lunte, S M

    2000-07-15

    The development of a poly(dimethylsiloxane)-based (PDMS-based) microchip electrophoresis system employing dual-electrode electrochemical detection is described. This is the first report of dual-electrode electrochemical detection in a microchip format and of electrochemical detection on chips fabricated from PDMS. The device described in this paper consists of a top layer of PDMS containing the separation and injection channels and a bottom glass layer onto which gold detection electrodes have been deposited. The two layers form a tight reversible seal, eliminating the need for high-temperature bonding, which can be detrimental to electrode stability. The channels can also be temporarily removed for cleaning, significantly extending the lifetime of the chip. The performance of the chip was evaluated using catechol as a test compound. The response was linear from 10 to 500 microM with an LOD (S/N = 3) of 4 microM and a sensitivity of 45.9 pA/microM. Collection efficiencies for catechol ranged from 28.7 to 25.9% at field strengths between 200 and 400 V/cm. Dual-electrode detection in the series configuration was shown to be useful for the selective monitoring of species undergoing chemically reversible redox reactions and for peak identification in the electropherogram of an unresolved mixture.

  14. A self-assembled monolayer-based micropatterned array for controlling cell adhesion and protein adsorption.

    PubMed

    Kim, Dong Jin; Lee, Jong Min; Park, Jin-Goo; Chung, Bong Geun

    2011-05-01

    We developed a surface micropatterning technique to control the cell adhesion and protein adsorption. This micropatterned array system was fabricated by a photolithography technique and self-assembled monolayer (SAM) deposition. It was hypothesized that the wettability and functional terminal group would regulate cell adhesion and protein adsorption. To demonstrate this hypothesis, glass-based micropatterned arrays with various functional terminal groups, such as amine (NH(2)) group (3-aminopropyl-triethoxysilane, APT), methyl (CH(3)) group (trichlorovinylsilane, TVS), and fluorocarbon (CF(3)) group (trichloro(1H, 1H, 2H, 2H-perfluorooctyl)silane, FOTS), were used. The contact angle was measured to determine the hydrophilic and hydrophobic properties of materials, demonstrating that TVS and FOTS were hydrophobic, whereas APTs were relatively hydrophilic. The cell adhesion was significantly affected by the wettability, showing that the cells were not adhered to hydrophobic surfaces, such as TVS and FOTS. Thus, the cells were selectively adhered to glass substrates within TVS- and FOTS-based micropatterned arrays. However, the cells were randomly adhered to APTs-based micropatterned arrays due to hydrophilic property of APTs. Furthermore, the protein adsorption of the SAM-based micropatterned array was analyzed, showing that the protein was more absorbed to the TVS surface. The surface functional terminal group enabled the control of protein adsorption. Therefore, this SAM-based micropatterned array system enabled the control of cell adhesion and protein adsorption and could be a potentially powerful tool for regulating the cell-cell interactions in a well-defined microenvironment.

  15. Fabrication, characterization, and functionalization of dual carbon electrodes as probes for scanning electrochemical microscopy (SECM).

    PubMed

    McKelvey, Kim; Nadappuram, Binoy Paulose; Actis, Paolo; Takahashi, Yasufumi; Korchev, Yuri E; Matsue, Tomokazu; Robinson, Colin; Unwin, Patrick R

    2013-08-01

    Dual carbon electrodes (DCEs) are quickly, easily, and cheaply fabricated by depositing pyrolytic carbon into a quartz theta nanopipet. The size of DCEs can be controlled by adjusting the pulling parameters used to make the nanopipet. When operated in generation/collection (G/C) mode, the small separation between the electrodes leads to reasonable collection efficiencies of ca. 30%. A three-dimensional finite element method (FEM) simulation is developed to predict the current response of these electrodes as a means of estimating the probe geometry. Voltammetric measurements at individual electrodes combined with generation/collection measurements provide a reasonable guide to the electrode size. DCEs are employed in a scanning electrochemical microscopy (SECM) configuration, and their use for both approach curves and imaging is considered. G/C approach curve measurements are shown to be particularly sensitive to the nature of the substrate, with insulating surfaces leading to enhanced collection efficiencies, whereas conducting surfaces lead to a decrease of collection efficiency. As a proof-of-concept, DCEs are further used to locally generate an artificial electron acceptor and to follow the flux of this species and its reduced form during photosynthesis at isolated thylakoid membranes. In addition, 2-dimensional images of a single thylakoid membrane are reported and analyzed to demonstrate the high sensitivity of G/C measurements to localized surface processes. It is finally shown that individual nanometer-size electrodes can be functionalized through the selective deposition of platinum on one of the two electrodes in a DCE while leaving the other one unmodified. This provides an indication of the future versatility of this type of probe for nanoscale measurements and imaging.

  16. Fabrication, Characterization, and Functionalization of Dual Carbon Electrodes as Probes for Scanning Electrochemical Microscopy (SECM)

    PubMed Central

    2013-01-01

    Dual carbon electrodes (DCEs) are quickly, easily, and cheaply fabricated by depositing pyrolytic carbon into a quartz theta nanopipet. The size of DCEs can be controlled by adjusting the pulling parameters used to make the nanopipet. When operated in generation/collection (G/C) mode, the small separation between the electrodes leads to reasonable collection efficiencies of ca. 30%. A three-dimensional finite element method (FEM) simulation is developed to predict the current response of these electrodes as a means of estimating the probe geometry. Voltammetric measurements at individual electrodes combined with generation/collection measurements provide a reasonable guide to the electrode size. DCEs are employed in a scanning electrochemical microscopy (SECM) configuration, and their use for both approach curves and imaging is considered. G/C approach curve measurements are shown to be particularly sensitive to the nature of the substrate, with insulating surfaces leading to enhanced collection efficiencies, whereas conducting surfaces lead to a decrease of collection efficiency. As a proof-of-concept, DCEs are further used to locally generate an artificial electron acceptor and to follow the flux of this species and its reduced form during photosynthesis at isolated thylakoid membranes. In addition, 2-dimensional images of a single thylakoid membrane are reported and analyzed to demonstrate the high sensitivity of G/C measurements to localized surface processes. It is finally shown that individual nanometer-size electrodes can be functionalized through the selective deposition of platinum on one of the two electrodes in a DCE while leaving the other one unmodified. This provides an indication of the future versatility of this type of probe for nanoscale measurements and imaging. PMID:23795948

  17. Fabrication and Characterisation of the Graphene Ring Micro Electrode (GRiME) with an Integrated, Concentric Ag/AgCl Reference Electrode

    PubMed Central

    Dickinson, James W.; Bromley, Michael; Andrieux, Fabrice P. L.; Boxall, Colin

    2013-01-01

    We report the fabrication and characterisation of the first graphene ring micro electrodes with the addition of a miniature concentric Ag/AgCl reference electrode. The graphene ring electrode is formed by dip coating fibre optics with graphene produced by a modified Hummers method. The reference electrode is formed using an established photocatalytically initiated electroless deposition (PIED) plating method. The performance of the so-formed graphene ring micro electrodes (GRiMEs) and associated reference electrode is studied using the probe redox system ferricyanide and electrode thicknesses assessed using established electrochemical methods. Using 220 μm diameter fibre optics, a ∼15 nm thick graphene ring electrode is obtained corresponding to an inner to outer radius ratio of >0.999, so allowing for use of extant analytical descriptions of very thin ring microelectrodes in data analysis. GRiMEs are highly reliable (current response invariant over >3,000 scans), with the concentric reference electrode showing comparable stability (current response invariant over >300 scans). Furthermore the micro-ring design allows for efficient use of electrochemically active graphene edge sites and the associated nA scale currents obtained neatly obviate issues relating to the high resistivity of undoped graphene. Thus, the use of graphene in ring microelectrodes improves the reliability of existing micro-electrode designs and expands the range of use of graphene-based electrochemical devices. PMID:23493126

  18. Fabrication and application of flexible graphene silk composite film electrodes decorated with spiky Pt nanospheres.

    PubMed

    Liang, Bo; Fang, Lu; Hu, Yichuan; Yang, Guang; Zhu, Qin; Ye, Xuesong

    2014-04-21

    A free-standing graphene silk composite (G/S) film was fabricated via vacuum filtration of a mixed suspension of graphene oxide and silk fibres, followed by chemical reduction. Spiky structured Pt nanospheres were grown on the film substrate by cyclic voltammetry electrodeposition. The electrical and mechanical performance of a single graphene coated silk fibre was investigated. The conductivity of a single graphene coated silk fibre is 57.9 S m(-1). During 1000 bending measurements, the conductivity was stable and showed negligible variation. The G/S film has a sheet resistivity of 90 Ω □(-1) with a porous and hierarchical structure. The spiky Pt nanosphere decorated G/S film was directly used as a H₂O₂ electrode with a sensitivity of 0.56 mA mM(-1) cm(-2), a linear range of 0-2.5 mM and an ultralow detection limit of 0.2 μM (S/N = 3). A glucose biosensor electrode was further fabricated by enzyme immobilization. The results show a sensitivity of 150.8 μA mM(-1) cm(-2) and a low detection limit of 1 μM (S/N = 3) for glucose detection. The strategy of coating graphene sheets on a silk fibre surface provides a new approach for developing electrically conductive biomaterials, tissue engineering scaffolds, bendable electrodes, and wearable biomedical devices.

  19. Design of micro, flexible light-emitting diode arrays and fabrication of flexible electrodes

    NASA Astrophysics Data System (ADS)

    Gao, Dan; Wang, Weibiao; Liang, Zhongzhu; Liang, Jingqiu; Qin, Yuxin; Lv, Jinguang

    2016-10-01

    In this study, we design micro, flexible light-emitting diode (LED) array devices. Using theoretical calculations and finite element simulations, we analyze the deformation of the conventional single electrode bar. Through structure optimization, we obtain a three-dimensional (3D), chain-shaped electrode structure, which has a greater bending degree. The optimized electrodes not only have a bigger bend but can also be made to spin. When the supporting body is made of polydimethylsiloxane (PDMS), the maximum bending degree of the micro, flexible LED arrays (4  ×  1 arrays) was approximately 230 µm this was obtained using the finite element method. The device (4  ×  1 arrays) can stretch to 15%. This paper describes the fabrication of micro, flexible LED arrays using microelectromechancial (MEMS) technology combined with electroplating technology. Specifically, the isolated grooves are made by dry etching which can isolate and protect the light-emitting units. A combination of MEMS technology and wet etching is used to fabricate the large size spacing.

  20. Initial experiments with flexible conductive electrodes for potential applications in cancer tissue screening

    NASA Astrophysics Data System (ADS)

    Chung, Daehan; Seyfollahi, Sam; Khosla, Ajit; Gray, Bonnie; Parameswaran, Ash; Ramaseshan, Ramani; Kohli, Kirpal

    2011-02-01

    We present initial results on the fabrication and testing of micropatternable conductive nanocomposite polymer (C-NCP) electrodes for tissue impedance measurements. We present these proof-of-concept results as a first step toward the realization of our goal: an improved Electrical Impedance Scanning (EIS) system, whereby tissue can be scanned for cancerous tissue and other anomalies using large arrays of highly flexible microfabricated electrodes. Previous limitations of existing EIS system are addressed by applying polymer based microelectromechanical system (MEMS) technology. In particular, we attempt to minimize mechanical skin contact issues through the use of highly compliant elastomeric polymers, and increase the spatial resolution of measurements through the development of microelectrodes that can be micropatterned into large, highly dense arrays. We accomplish these improvements through the development of C-NCP electrodes that employ silver nanoparticle fillers in an elastomer polymer base that can be easily patterned using conventional soft lithography techniques. These new electrodes are tested on conventional tissue phantoms that mimic the electrical characteristics of human tissue. We characterize the conductivity of the electrodes (average resistivity of 7x10-5 ohm-m +/- 14.3% at 60 wt-% of silver nanoparticles), and further employ the electrodes for impedance characterization via Cole-Cole plots to show that measurements employing C-NCP electrodes are comparable to those obtained with normal macroscopic metal electrodes. We also demonstrate anomaly detection using our highly flexible Ag/AgCl C-NCP electrodes on a tissue phantom.

  1. Fabrication and In vivo Evaluation of Poly(3,4-ethylenedioxythiophene) Stimulus Electrodes for Fully Implantable Retinal Prosthesis

    NASA Astrophysics Data System (ADS)

    Kigure, Chikashi; Naganuma, Hideki; Sasaki, Yuichiro; Kino, Hisashi; Tomita, Hiroshi; Tanaka, Tetsu

    2013-04-01

    The development of poly(3,4-ethylenedioxythiophene) (PEDOT) stimulus electrodes and the relationship between the electrical stimulation of a rabbit retina and electrically evoked potential (EEP) were studied in detail. We fabricated implantable flexible cables with Pt, IrOx, and PEDOT electrodes and evaluated the electrochemical impedances (EIs) and charge injection capacities (CICs) of such electrodes. From the result, we confirmed that PEDOT electrodes have both lower EIs and larger CICs than Pt and IrOx electrodes. In addition, we performed in vivo experiments with PEDOT electrodes and clarified the relationships between the electrical stimulation of the rabbit retina and EEP. It is highly probable that visual restoration will be realized safely with PEDOT electrodes.

  2. Materials and fabrication of electrode scaffolds for deposition of MnO2 and their true performance in supercapacitors

    NASA Astrophysics Data System (ADS)

    Cao, Jianyun; Li, Xiaohong; Wang, Yaming; Walsh, Frank C.; Ouyang, Jia-Hu; Jia, Dechang; Zhou, Yu

    2015-10-01

    MnO2 is a promising electrode material for high energy supercapacitors because of its large pseudo-capacitance. However, MnO2 suffers from low electronic conductivity and poor cation diffusivity, which results in poor utilization and limited rate performance of traditional MnO2 powder electrodes, obtained by pressing a mixed paste of MnO2 powder, conductive additive and polymer binder onto metallic current collectors. Developing binder-free MnO2 electrodes by loading nanoscale MnO2 deposits on pre-fabricated device-ready electrode scaffolds is an effective way to achieve both high power and energy performance. These electrode scaffolds, with interconnected skeletons and pore structures, will not only provide mechanical support and electron collection as traditional current collectors but also fast ion transfer tunnels, leading to high MnO2 utilization and rate performance. This review covers design strategies, materials and fabrication methods for the electrode scaffolds. Rational evaluation of the true performance of these electrodes is carried out, which clarifies that some of the electrodes with as-claimed exceptional performances lack potential in practical applications due to poor mass loading of MnO2 and large dead volume of inert scaffold materials/void spaces in the electrode structure. Possible ways to meet this challenge and bring MnO2 electrodes from laboratory studies to real-world applications are considered.

  3. Integration of a carbon nanotube based electrode in silicon microtechnology to fabricate electrochemical transducers

    NASA Astrophysics Data System (ADS)

    Luais, E.; Boujtita, M.; Gohier, A.; Tailleur, A.; Casimirius, S.; Djouadi, M. A.; Granier, A.; Tessier, P. Y.

    2008-10-01

    An original approach was developed and validated for the fabrication of a carbon nanotube (CNT) electrode synthesized directly onto a carbon buffer thin film deposited on a highly doped monocrystalline silicon surface. The buffer layer of amorphous carbon thin film was deposited by physical vapour deposition on the silicon substrate before CNT synthesis. For this purpose, nickel was deposited on the carbon buffer layer by an electrochemical procedure and used as a catalyst for the CNT growth. The CNT synthesis was achieved by plasma enhanced chemical vapour deposition (PECVD) in an electron cyclotron resonance (ECR) plasma chamber using a C2H2/NH3 gas mixture. In order to evaluate the electrochemical behaviour of the CNT-based electrode, the carbon layer and the silicon/carbon interface were studied. The resulting buffer layer enhanced the electronic transport from the doped silicon to the CNTs. The electrode surface was studied by XPS and characterized by both SEM and TEM. The electrochemical response exhibited by the resulting electrodes modified with CNTs was also examined by cyclic voltammetry. The whole process was found to be compatible with silicon microtechnology and could be envisaged for the direct integration of microsensors on silicon chips.

  4. Integration of a carbon nanotube based electrode in silicon microtechnology to fabricate electrochemical transducers.

    PubMed

    Luais, E; Boujtita, M; Gohier, A; Tailleur, A; Casimirius, S; Djouadi, M A; Granier, A; Tessier, P Y

    2008-10-29

    An original approach was developed and validated for the fabrication of a carbon nanotube (CNT) electrode synthesized directly onto a carbon buffer thin film deposited on a highly doped monocrystalline silicon surface. The buffer layer of amorphous carbon thin film was deposited by physical vapour deposition on the silicon substrate before CNT synthesis. For this purpose, nickel was deposited on the carbon buffer layer by an electrochemical procedure and used as a catalyst for the CNT growth. The CNT synthesis was achieved by plasma enhanced chemical vapour deposition (PECVD) in an electron cyclotron resonance (ECR) plasma chamber using a C(2)H(2)/NH(3) gas mixture. In order to evaluate the electrochemical behaviour of the CNT-based electrode, the carbon layer and the silicon/carbon interface were studied. The resulting buffer layer enhanced the electronic transport from the doped silicon to the CNTs. The electrode surface was studied by XPS and characterized by both SEM and TEM. The electrochemical response exhibited by the resulting electrodes modified with CNTs was also examined by cyclic voltammetry. The whole process was found to be compatible with silicon microtechnology and could be envisaged for the direct integration of microsensors on silicon chips. PMID:21832696

  5. Fabrication of a Micro-Needle Array Electrode by Thermal Drawing for Bio-Signals Monitoring.

    PubMed

    Ren, Lei; Jiang, Qing; Chen, Keyun; Chen, Zhipeng; Pan, Chengfeng; Jiang, Lelun

    2016-01-01

    A novel micro-needle array electrode (MAE) fabricated by thermal drawing and coated with Ti/Au film was proposed for bio-signals monitoring. A simple and effective setup was employed to form glassy-state poly (lactic-co-glycolic acid) (PLGA) into a micro-needle array (MA) by the thermal drawing method. The MA was composed of 6 × 6 micro-needles with an average height of about 500 μm. Electrode-skin interface impedance (EII) was recorded as the insertion force was applied on the MAE. The insertion process of the MAE was also simulated by the finite element method. Results showed that MAE could insert into skin with a relatively low compression force and maintain stable contact impedance between the MAE and skin. Bio-signals, including electromyography (EMG), electrocardiography (ECG), and electroencephalograph (EEG) were also collected. Test results showed that the MAE could record EMG, ECG, and EEG signals with good fidelity in shape and amplitude in comparison with the commercial Ag/AgCl electrodes, which proves that MAE is an alternative electrode for bio-signals monitoring. PMID:27322278

  6. Fabrication of a Micro-Needle Array Electrode by Thermal Drawing for Bio-Signals Monitoring

    PubMed Central

    Ren, Lei; Jiang, Qing; Chen, Keyun; Chen, Zhipeng; Pan, Chengfeng; Jiang, Lelun

    2016-01-01

    A novel micro-needle array electrode (MAE) fabricated by thermal drawing and coated with Ti/Au film was proposed for bio-signals monitoring. A simple and effective setup was employed to form glassy-state poly (lactic-co-glycolic acid) (PLGA) into a micro-needle array (MA) by the thermal drawing method. The MA was composed of 6 × 6 micro-needles with an average height of about 500 μm. Electrode-skin interface impedance (EII) was recorded as the insertion force was applied on the MAE. The insertion process of the MAE was also simulated by the finite element method. Results showed that MAE could insert into skin with a relatively low compression force and maintain stable contact impedance between the MAE and skin. Bio-signals, including electromyography (EMG), electrocardiography (ECG), and electroencephalograph (EEG) were also collected. Test results showed that the MAE could record EMG, ECG, and EEG signals with good fidelity in shape and amplitude in comparison with the commercial Ag/AgCl electrodes, which proves that MAE is an alternative electrode for bio-signals monitoring. PMID:27322278

  7. Fabrication of Ag nanowire and Al-doped ZnO hybrid transparent electrodes

    NASA Astrophysics Data System (ADS)

    You, Sslimsearom; Park, Yong Seo; Choi, Hyung Wook; Kim, Kyung Hwan

    2016-01-01

    Among the materials used as transparent electrodes, silver nanowires (AgNWs) have attracted attention because of their high transmittance and excellent conductivity. However, AgNWs have shortcomings, including their poor adhesion, oxidation by atmospheric oxygen, and unstable characteristics at high temperature. To overcome these shortcomings, multi-layer thin films with an aluminum-doped zinc oxide (AZO)/AgNW/AZO structure were fabricated using facing targets sputtering. The samples heated to 350 °C exhibited stable electrical characteristics. In addition, the adhesion to the substrate was improved compared with AgNWs layer. The AZO/AgNW/AZO thin films with multilayer structure overcame the shortcomings of AgNWs, and we propose their use as transparent electrodes with excellent properties for optoelectronic applications.

  8. Fabrication of continuous flow microfluidics device with 3D electrode structures for high throughput DEP applications using mechanical machining.

    PubMed

    Zeinali, Soheila; Çetin, Barbaros; Oliaei, Samad Nadimi Bavil; Karpat, Yiğit

    2015-07-01

    Microfluidics is the combination of micro/nano fabrication techniques with fluid flow at microscale to pursue powerful techniques in controlling and manipulating chemical and biological processes. Sorting and separation of bio-particles are highly considered in diagnostics and biological analyses. Dielectrophoresis (DEP) has offered unique advantages for microfluidic devices. In DEP devices, asymmetric pair of planar electrodes could be employed to generate non-uniform electric fields. In DEP applications, facing 3D sidewall electrodes is considered to be one of the key solutions to increase device throughput due to the generated homogeneous electric fields along the height of microchannels. Despite the advantages, fabrication of 3D vertical electrodes requires a considerable challenge. In this study, two alternative fabrication techniques have been proposed for the fabrication of a microfluidic device with 3D sidewall electrodes. In the first method, both the mold and the electrodes are fabricated using high precision machining. In the second method, the mold with tilted sidewalls is fabricated using high precision machining and the electrodes are deposited on the sidewall using sputtering together with a shadow mask fabricated by electric discharge machining. Both fabrication processes are assessed as highly repeatable and robust. Moreover, the two methods are found to be complementary with respect to the channel height. Only the manipulation of particles with negative-DEP is demonstrated in the experiments, and the throughput values up to 105 particles / min is reached in a continuous flow. The experimental results are compared with the simulation results and the limitations on the fabrication techniques are also discussed.

  9. Improvements in purification of silver nanowires by decantation and fabrication of flexible transparent electrodes. Application to capacitive touch sensors.

    PubMed

    Mayousse, Céline; Celle, Caroline; Moreau, Eléonore; Mainguet, Jean-François; Carella, Alexandre; Simonato, Jean-Pierre

    2013-05-31

    Transparent flexible electrodes made of metallic nanowires, and in particular silver nanowires (AgNWs), appear as an extremely promising alternative to transparent conductive oxides for future optoelectronic devices. Though significant progresses have been made the last few years, there is still some room for improvement regarding the synthesis of high quality silver nanowire solutions and fabrication process of high performance electrodes. We show that the commonly used purification process can be greatly simplified through decantation. Using this process it is possible to fabricate flexible electrodes by spray coating with sheet resistance lower than 25 Ω sq⁻¹ at 90% transparency in the visible spectrum. These electrodes were used to fabricate an operative transparent flexible touch screen. To our knowledge this is the first reported AgNW based touch sensor relying on capacitive technology. PMID:23619480

  10. Novel electrochemical sensors with electrodes based on multilayers fabricated by layer-by-layer synthesis and their analytical potential

    NASA Astrophysics Data System (ADS)

    Ermakov, S. S.; Nikolaev, K. G.; Tolstoy, V. P.

    2016-08-01

    The results of studies on layer-by-layer synthesis of multilayers on the electrode surface in order to design electrochemical sensors for the determination of concentrations of inorganic, organic and bioorganic compounds are summarized and analyzed. The principle of the method is discoursed and the key advantages of the approach are highlighted, such as the possibility of single layer synthesis with specified thickness and composition under mild conditions with further fabrication of multilayers. Charge transfer conditions in the layers on the electrode surface between the analyte molecules and electrode redox centres and the operating conditions for the optimal electrode are considered. The role of electrocatalysts and intermediates of these processes is noted. Particular attention is devoted to the methods for synthesis of gold nanoparticles with different diameters. Analytical characteristics for electrochemical sensors are presented and application prospects of the layer-by-layer synthesis to electrode fabrication are discussed. The bibliography includes 241 references.

  11. Highly flexible TiO2-coated stainless steel fabric electrode prepared by liquid-phase deposition

    NASA Astrophysics Data System (ADS)

    Hwang, Hong Seo; Lee, Jeong Beom; Jung, Jiwon; Lee, Seyoung; Ryu, Ji Heon; Oh, Seung M.

    2016-10-01

    In order to construct flexible lithium-ion batteries, stainless steel (SUS) fabric is used as a current collector for the negative electrode of lithium-ion batteries. TiO2 is coated onto the SUS fabric by liquid-phase deposition to construct an electrode consisting of an SUS wire core and a TiO2 shell. A folding test is then conducted to assess the robustness of TiO2-coated SUS fabric, during which no detachment of TiO2 particles from the SUS current collector is observed; the negative electrode shows a consistent electrochemical cycle performance even under severe physical duress. The TiO2-SUS fabric integration shows excellent flexibility without loss of electrochemical efficacy under mechanical stress, which occurs owing to three main factors. First, the mechanical stress imposed by folding is effectively dissipated by the 3-dimensional structure of the SUS fabric. Secondly, the TiO2 electrode itself is free from mechanical stress owing to negligible volume change during electrochemical cycling. Thirdly, the high interfacial adhesion strength between TiO2 and SUS fabric due to covalent bond formation during liquid-phase deposition prevents the loss of active material from the negative electrode during the folding tests.

  12. Interfacial microfluidic transport on micropatterned superhydrophobic textile.

    PubMed

    Xing, Siyuan; Jiang, Jia; Pan, Tingrui

    2013-05-21

    Textile-enabled interfacial microfluidics, utilizing fibrous hydrophilic yarns (e.g., cotton) to guide biological reagent flows, has been extended to various biochemical analyses recently. The restricted capillary-driving mechanism, however, persists as a major challenge for continuous and facilitated biofluidic transport. In this paper, we have first introduced a novel interfacial microfluidic transport principle to drive three-dimensional liquid flows on a micropatterned superhydrophobic textile (MST) platform in a more autonomous and controllable manner. Specifically, the MST system utilizes the surface tension-induced Laplace pressure to facilitate the liquid motion along the hydrophilic yarn, in addition to the capillarity present in the fibrous structure. The fabrication of MST is simply accomplished by stitching hydrophilic cotton yarn into a superhydrophobic fabric substrate (contact angle 140 ± 3°), from which well-controlled wetting patterns are established for interfacial microfluidic operations. The geometric configurations of the stitched micropatterns, e.g., the lengths and diameters of the yarn and bundled arrangement, can all influence the transport process, which is investigated both experimentally and theoretically. Two operation modes, discrete and continuous transport, are also presented in detail. In addition, the gravitational effect as well as the droplet removal process have been also considered and quantitatively analysed during the transport process. As a demonstration, an MST design has been implemented on an artificial skin surface to collect and remove sweat in a highly efficient and facilitated means. The results have illustrated that the novel interfacial transport on the textile platform can be potentially extended to a variety of biofluidic collection and removal applications.

  13. Croissance et transfert de graphene pour la fabrication d'electrodes transparentes

    NASA Astrophysics Data System (ADS)

    Biron, Maxime

    This master's thesis focuses on the characterization and optimization of transparent and conductive electrodes made from graphene layers. We used a low pressure CVD method, with methane as the carbon source and copper as a catalyst and growth support, to synthesize graphene. Scanning electron microscopy and Raman spectroscopy were used to demonstrate that the graphene layers are complete and uniform. A method using a polymer (PMMA) as a mechanical support has been optimized for the transfer of graphene films onto various substrates, such as glass or silicon dioxide on silicon. Characterization of transferred samples by optical and scanning electron microscopy and Raman spectroscopy reveals that transferred films are undamaged and that the surface is free of visible residues. The intensity of the defect-related peak in Raman mapping measurements is low, indicating that the as-grown and transferred graphene layers are of high quality. This transfer process has been applied to fabricate transparent electrodes with one to four layers of graphene. The electrodes were characterized by Raman spectroscopy, optical transmission analyses and electrical resistance measurements using the van der Pauw method. Raman results indicate that the average doping level of the samples decreases with an increasing number of graphene layers. The optical measurements yield transparency values ranging from 97.5 to 90 % for wavelengths between 400 and 1000 nm, depending on the number of stacked layers. The sheet resistance of the electrodes varies between 560 and 360 O/□, which is an equivalent or superior performance to that of graphene electrodes reported in the literature. An electrochemical method was used to dope the samples in an ionic liquid to vary the Fermi level and to decrease the sheet resistance down to 260 O/□ for a monolayer graphene electrode. This doping allows to vary the work function of graphene between 3.9 and 5.6 eV. Taken together, these results demonstrate that

  14. Rapid bench-top fabrication of poly(dimethylsiloxane)/polystyrene microfluidic devices incorporating high-surface-area sensing electrodes

    PubMed Central

    Sonney, Sanjay; Shek, Norman; Moran-Mirabal, Jose M.

    2015-01-01

    The development of widely applicable point-of-care sensing and diagnostic devices can benefit from simple and inexpensive fabrication techniques that expedite the design, testing, and implementation of lab-on-a-chip devices. In particular, electrodes integrated within microfluidic devices enable the use of electrochemical techniques for the label-free detection of relevant analytes. This work presents a novel, simple, and cost-effective bench-top approach for the integration of high surface area three-dimensional structured electrodes fabricated on polystyrene (PS) within poly(dimethylsiloxane) (PDMS)-based microfluidics. Optimization of PS-PDMS bonding results in integrated devices that perform well under pressure and fluidic flow stress. Furthermore, the fabrication and bonding processes are shown to have no effect on sensing electrode performance. Finally, the on-chip sensing capabilities of a three-electrode electrochemical cell are demonstrated with a model redox compound, where the high surface area structured electrodes exhibit ultra-high sensitivity. We propose that the developed approach can significantly expedite and reduce the cost of fabrication of sensing devices where arrays of functionalized electrodes can be used for point-of-care analysis and diagnostics. PMID:25945145

  15. Fabrication of stainless steel mesh gas diffusion electrode for power generation in microbial fuel cell.

    PubMed

    You, Shi-Jie; Wang, Xiu-Heng; Zhang, Jin-Na; Wang, Jing-Yuan; Ren, Nan-Qi; Gong, Xiao-Bo

    2011-01-15

    This study reports the fabrication of a new membrane electrode assembly by using stainless steel mesh (SSM) as raw material and its effectiveness as gas diffusion electrode (GDE) for electrochemical oxygen reduction in microbial fuel cell (MFC). Based on feeding glucose (0.5 g L(-1)) substrate to a single-chambered MFC, power generation using SSM-based GDE was increased with the decrease of polytetrafluoroethylene (PTFE) content applied during fabrication, reaching the optimum power density of 951.6 mW m(-2) at 20% PTFE. Repeatable cell voltage of 0.51 V (external resistance of 400 Ω) and maximum power density of 951.6 mW m(-2) produced for the MFC with SSM-based GDE are comparable to that of 0.52 V and 972.6 mW m(-2), respectively obtained for the MFC containing typical carbon cloth (CC)-made GDE. Besides, Coulombic efficiency (CE) is found higher for GDE (SSM or CC) with membrane assembly than without, which results preliminarily from the mitigation of Coulombic loss being associated with oxygen diffusion and substrate crossover. This study demonstrates that with its good electrical conductivity and much lower cost, the SSM-made GDE suggests a promising alternative as efficient and more economically viable material to conventional typical carbon for power production from biomass in MFC.

  16. Fabrication and application of flexible graphene silk composite film electrodes decorated with spiky Pt nanospheres

    NASA Astrophysics Data System (ADS)

    Liang, Bo; Fang, Lu; Hu, Yichuan; Yang, Guang; Zhu, Qin; Ye, Xuesong

    2014-03-01

    A free-standing graphene silk composite (G/S) film was fabricated via vacuum filtration of a mixed suspension of graphene oxide and silk fibres, followed by chemical reduction. Spiky structured Pt nanospheres were grown on the film substrate by cyclic voltammetry electrodeposition. The electrical and mechanical performance of a single graphene coated silk fibre was investigated. The conductivity of a single graphene coated silk fibre is 57.9 S m-1. During 1000 bending measurements, the conductivity was stable and showed negligible variation. The G/S film has a sheet resistivity of 90 Ω □-1 with a porous and hierarchical structure. The spiky Pt nanosphere decorated G/S film was directly used as a H2O2 electrode with a sensitivity of 0.56 mA mM-1 cm-2, a linear range of 0-2.5 mM and an ultralow detection limit of 0.2 μM (S/N = 3). A glucose biosensor electrode was further fabricated by enzyme immobilization. The results show a sensitivity of 150.8 μA mM-1 cm-2 and a low detection limit of 1 μM (S/N = 3) for glucose detection. The strategy of coating graphene sheets on a silk fibre surface provides a new approach for developing electrically conductive biomaterials, tissue engineering scaffolds, bendable electrodes, and wearable biomedical devices.A free-standing graphene silk composite (G/S) film was fabricated via vacuum filtration of a mixed suspension of graphene oxide and silk fibres, followed by chemical reduction. Spiky structured Pt nanospheres were grown on the film substrate by cyclic voltammetry electrodeposition. The electrical and mechanical performance of a single graphene coated silk fibre was investigated. The conductivity of a single graphene coated silk fibre is 57.9 S m-1. During 1000 bending measurements, the conductivity was stable and showed negligible variation. The G/S film has a sheet resistivity of 90 Ω □-1 with a porous and hierarchical structure. The spiky Pt nanosphere decorated G/S film was directly used as a H2O2 electrode with a

  17. Chemical vapor-deposited carbon nanofibers on carbon fabric for supercapacitor electrode applications

    PubMed Central

    2012-01-01

    Entangled carbon nanofibers (CNFs) were synthesized on a flexible carbon fabric (CF) via water-assisted chemical vapor deposition at 800°C at atmospheric pressure utilizing iron (Fe) nanoparticles as catalysts, ethylene (C2H4) as the precursor gas, and argon (Ar) and hydrogen (H2) as the carrier gases. Scanning electron microscopy, transmission electron microscopy, and electron dispersive spectroscopy were employed to characterize the morphology and structure of the CNFs. It has been found that the catalyst (Fe) thickness affected the morphology of the CNFs on the CF, resulting in different capacitive behaviors of the CNF/CF electrodes. Two different Fe thicknesses (5 and 10 nm) were studied. The capacitance behaviors of the CNF/CF electrodes were evaluated by cyclic voltammetry measurements. The highest specific capacitance, approximately 140 F g−1, has been obtained in the electrode grown with the 5-nm thickness of Fe. Samples with both Fe thicknesses showed good cycling performance over 2,000 cycles. PMID:23181897

  18. A novel procedure for fabricating flexible screen-printed electrodes with improved electrochemical performance

    NASA Astrophysics Data System (ADS)

    Du, C. X.; Han, L.; Dong, S. L.; Li, L. H.; Wei, Y.

    2016-07-01

    Screen-printed electrodes (SPEs) with improved electrochemical performance were fabricated in this study. The SPEs on hydrophilic surface of polyethylene ethylene terephthalate (PET) film showed better electrochemical behaviour than that on hydrophobic surface. The optimal condition of pretreating fresh SPEs was that alternately dealt with chemical treatment (soaked in 3M NaOH solutions for 1h) and high temperature curing (heated at 120 °C for 15 min) for two times. After chemical treatment, the electrochemical performance of self-made SPEs was better than the commercial three electrodes system. By analyzing cyclic voltammetry (CV) curves, we found that the oxidation peak currents and peak to peak separation reached 407.65 μA and 111.16 mV, which mean the sensitivity and electron transfer rate improved 1.9 times and 3.8 times compared with fresh SPEs, and 2 times and 3 times compared with commercial DropSens (DS) electrodes. The obtained SPEs were stable, convenient and inexpensive, which could be extensively applied for developing novel electrochemical sensors.

  19. Synergistic effects of micropatterned biodegradable conduits and Schwann cells on sciatic nerve regeneration

    NASA Astrophysics Data System (ADS)

    Rutkowski, Gregory E.; Miller, Cheryl A.; Jeftinija, Srdija; Mallapragada, Surya K.

    2004-09-01

    This paper describes a novel biodegradable conduit that provides a combination of physical, chemical and biological cues at the cellular level to facilitate peripheral nerve regeneration. The conduit consists of a porous poly(D,L-lactic acid) (PDLLA) tubular support structure with a micropatterned inner lumen. Schwann cells were pre-seeded into the lumen to provide additional trophic support. Conduits with micropatterned inner lumens pre-seeded with Schwann cells (MS) were fabricated and compared with three types of conduits used as controls: M (conduits with micropatterned inner lumens without pre-seeded Schwann cells), NS (conduits without micropatterned inner lumens pre-seeded with Schwann cells) and N (conduits without micropatterned inner lumens, without pre-seeded Schwann cells). The conduits were implanted in rats with 1 cm sciatic nerve transections and the regeneration and functional recovery were compared in the four different cases. The number or size of regenerated axons did not vary significantly among the different conduits. The time of recovery, and the sciatic function index, however, were significantly enhanced using the MS conduits, based on qualitative observations as well as quantitative measurements using walking track analysis. This demonstrates that biodegradable micropatterned conduits pre-seeded with Schwann cells that provide a combination of physical, chemical and biological guidance cues for regenerating axons at the cellular level offer a better alternative for repairing sciatic nerve transactions than conventional biodegradable conduits.

  20. Study on Fabrication and UV Photoelectric Property of TiO2 Nanotube Array Electrodes.

    PubMed

    Fu, Yao; Duan, Xiao-Long; Xing, Ming-Ming; Luo, Xi-Xian; Zhang, Ying-Hui; Liu, Wang

    2016-04-01

    Highly ordered TiO2 nanotube array electrodes were successfully fabricated by a two-step anodization method on Ti sheet substrates in an electrolyte composed of ammonium fluoride, deionized water, and glycol. The tube wall was smooth, and the average internal and external diameters, wall thickness, and tube length achieved were 80 nm, 90 nm, 10 nm, and 9 µm, respectively. X-ray diffraction and field emission scanning electron microscopy results revealed that the TiO2 nanotube arrays presented an amorphous structure. When calcined at 300 °C, the arrays crystallized into the anatase phase, and the crystallization degree of the oxide layer increased as the temperature rose. Calcinating at 400 °C did not obviously disrupt the porous structure of the highly ordered arrays. However, higher temperature enlarged the diameter of the nanotube array and roughened the tube wall. When the temperature reached 600 °C, the nanotube mouth broke because of the excessive stress, causing the oxide layer's thinness and nanotube mouth clogging. The photoelectric test showed that the electrode presented obvious photoresponse under 300-400 nm UV excitation (maximized at 360 nm). The degree of crystallization and the micro-structure of the oxide layer can significantly affect the photoelectric properties of the electrode. After calcination at 400 °C, the TiO2 nanotube arrays, with highly ordered tubular structure directly connected to the Ti substrate, can ensure the rapid transportation of photo-induced electrons to the Ti substrate, while the high crystallinity of the arrays can help reduce the defect density of the nanotube and extend the lifetime of the photo-induced carriers. The electrode showed the best photoelectric property, and the photocurrent intensity was maximized (29.6 µA). However, the calcination process with over-temperature resulted in substantial loss of the TiO2 oxide layer, mouth clogging, and a severe decline in the photoelectric properties. PMID:27451743

  1. Study on Fabrication and UV Photoelectric Property of TiO2 Nanotube Array Electrodes.

    PubMed

    Fu, Yao; Duan, Xiao-Long; Xing, Ming-Ming; Luo, Xi-Xian; Zhang, Ying-Hui; Liu, Wang

    2016-04-01

    Highly ordered TiO2 nanotube array electrodes were successfully fabricated by a two-step anodization method on Ti sheet substrates in an electrolyte composed of ammonium fluoride, deionized water, and glycol. The tube wall was smooth, and the average internal and external diameters, wall thickness, and tube length achieved were 80 nm, 90 nm, 10 nm, and 9 µm, respectively. X-ray diffraction and field emission scanning electron microscopy results revealed that the TiO2 nanotube arrays presented an amorphous structure. When calcined at 300 °C, the arrays crystallized into the anatase phase, and the crystallization degree of the oxide layer increased as the temperature rose. Calcinating at 400 °C did not obviously disrupt the porous structure of the highly ordered arrays. However, higher temperature enlarged the diameter of the nanotube array and roughened the tube wall. When the temperature reached 600 °C, the nanotube mouth broke because of the excessive stress, causing the oxide layer's thinness and nanotube mouth clogging. The photoelectric test showed that the electrode presented obvious photoresponse under 300-400 nm UV excitation (maximized at 360 nm). The degree of crystallization and the micro-structure of the oxide layer can significantly affect the photoelectric properties of the electrode. After calcination at 400 °C, the TiO2 nanotube arrays, with highly ordered tubular structure directly connected to the Ti substrate, can ensure the rapid transportation of photo-induced electrons to the Ti substrate, while the high crystallinity of the arrays can help reduce the defect density of the nanotube and extend the lifetime of the photo-induced carriers. The electrode showed the best photoelectric property, and the photocurrent intensity was maximized (29.6 µA). However, the calcination process with over-temperature resulted in substantial loss of the TiO2 oxide layer, mouth clogging, and a severe decline in the photoelectric properties.

  2. Adhesion of biocompatible and biodegradable micropatterned surfaces.

    PubMed

    Kaiser, Jessica S; Kamperman, Marleen; de Souza, Emerson J; Schick, Bernhard; Arzt, Eduard

    2011-02-01

    We studied the effects of pillar dimensions and stiffness of biocompatible and biodegradable micropatterned surfaces on adhesion on different compliant substrates. The micropatterned adhesives were based on biocompatible polydimethylsiloxane (PDMS) and biodegradable poly(lactic-co-glycolic) acid (PLGA) polymer systems. Micropatterned and non-patterned compliant PDMS did not show significant differences in adhesion on compliant mice ear skin or on gelatin-glycerin model substrates. However, adhesion measurements for micropatterned stiff PLGA on compliant gelatin-glycerin model substrates showed significant enhancement in pull-off strengths compared to non-patterned controls.

  3. Development of new fabrication methods for solid oxide fuel cell electrodes

    NASA Astrophysics Data System (ADS)

    Jung, Suk-Won

    Solid oxide fuel cells (SOFC) have gained a great deal of attention in recent years since they have the potential to be high efficiency devices for the generation of electricity. The ability to use hydrocarbon fuels however requires the development of alternatives to conventional Ni/YSZ anodes that are prone to coking when exposed to hydrocarbons. The optimization of electrode microstructure and composition is also needed in order to maximize the electrode catalytic activity and thermal stability. In this thesis these issues were addressed through the development of new methods for anode fabrication that allowed for the incorporation of a wide range of materials and better control of electrode microstructure. The specific methods that were studied include (1) Impregnation with urea and (2) Electrochemical Deposition. First, how impregnation using Cu(NO3)2 and urea affect the microstructure of the Cu component in Cu/CeO2/YSZ (yittria-stabilized zirconia) composite anodes and how this influences anode performance were examined. This method produced a more homogeneous distribution of Cu throughout the anode than impregnation with only Cu(NO3)2. Second, Cu electrodeposition into 0.12 cm thick, highly porous Ni/YSZ cermets was investigated for the initial study to evaluate electrodeposition for the electrode fabrication method. An electrochemical cell in which the electrolyte solution was allowed to flow through the porous Ni/YSZ substrate was constructed in order to eliminate mass transfer limitations and determine conditions for which the potential drop in the electrolyte solution was minimized for the deposition of uniform Cu layer in the cermet. Finally it was demonstrated how the anodes for SOFCs could be prepared by electrodeposition. After the addition of CeO2, a 60 mum thin porous layer of YSZ was made conductive by the deposition of a conductive carbon layer with exposing the porous layer to C4H10 at 1123 K and either Ni or Co was then electrodeposited on the

  4. Flexible and conductive cotton fabric counter electrode coated with graphene nanosheets for high efficiency dye sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Sahito, Iftikhar Ali; Sun, Kyung Chul; Arbab, Alvira Ayoub; Qadir, Muhammad Bilal; Choi, Yun Seon; Jeong, Sung Hoon

    2016-07-01

    Textile fabric based electrodes due to their lightweight, flexibility and cost effectiveness, coupled with the ease of fabrication are recently given a huge attention as wearable energy sources. The current dye sensitized solar cells (DSSCs) are based on Platinized-Fluorinated Tin oxide (Pt-FTO) glass electrode, which is not only expensive, but also rigid and heavyweight. In this work, a highly conductive-graphene coated cotton fabric (HC-GCF) is fabricated with a surface resistance of only 7 Ω sq-1. HC-GCF is used as an efficient counter electrode (CE) in DSSC and the results are examined using photovoltaic and electrochemical analysis. HC-GCF counter electrode shows a negligible change of resistance to bending at various bending positions and is also found extremely resistant to electrolyte solution and washing with water. Cyclic voltammogram, Nyquist and the Tafel plots suggest an excellent electro catalytic activity (ECA) for the reduction of tri-iodide (I3-) ions. Symmetrical cells prepared using HC-GCF, indicate a very low charge transfer resistance (RCT) of only 1.2 Ω, which is nearly same to that of the Pt with 1.04 Ω. Furthermore, a high photovoltaic conversion efficiency (PCE) of 6.93% is achieved using HC-GCF counter electrode using polymer electrolyte.

  5. Quantum information experiments with a micro-fabricated, cryogenic, surface-electrode ion trap

    NASA Astrophysics Data System (ADS)

    Wilson, A. C.; Brown, K. R.; Ospelkaus, C.; Colombe, Y.; Leibfried, D.; Wineland, D. J.

    2011-05-01

    Although the basic components of a quantum information processor using trapped ions have been demonstrated, scaling to large numbers of qubits and operations so that algorithms and simulations of practical importance can be implemented remains a major challenge. This is technically challenging because it requires significant improvements in the precision with which quantum states of ions are prepared, manipulated and measured. Solutions are multi-disciplinary - involving micro-fabrication, cryogenics, integrated photonic devices, as wells as materials and surface science. Here we report progress from experiments that address a range of these issues. We use a micro-fabricated, cryogenic, surface-electrode ion trap, with two closely-spaced independently controlled potential wells. In the first experiment with this new apparatus, we implement a scheme for coupling two ions trapped in separate wells, and demonstrate tunable energy exchange at approximately the single quantum level. A second experiment investigates errors in single qubit gates (rotations) with the use of randomized bench-marking. Although the basic components of a quantum information processor using trapped ions have been demonstrated, scaling to large numbers of qubits and operations so that algorithms and simulations of practical importance can be implemented remains a major challenge. This is technically challenging because it requires significant improvements in the precision with which quantum states of ions are prepared, manipulated and measured. Solutions are multi-disciplinary - involving micro-fabrication, cryogenics, integrated photonic devices, as wells as materials and surface science. Here we report progress from experiments that address a range of these issues. We use a micro-fabricated, cryogenic, surface-electrode ion trap, with two closely-spaced independently controlled potential wells. In the first experiment with this new apparatus, we implement a scheme for coupling two ions trapped

  6. Fabrication and characterization of nanopore-based electrodes with radii down to 2 nm.

    PubMed

    Krapf, Diego; Wu, Meng-Yue; Smeets, Ralph M M; Zandbergen, Henny W; Dekker, Cees; Lemay, Serge G

    2006-01-01

    We report on the fabrication and characterization of gold nanoelectrodes with carefully controlled nanometer dimensions in a matrix of insulating silicon nitride. A focused electron beam was employed to drill nanopores in a thin silicon nitride membrane. The size and shape of the nanopores were studied with high-resolution transmission electron microscopy and electron-energy-loss two-dimensional maps. The pores were subsequently filled with gold, yielding conically shaped nanoelectrodes. The nanoelectrodes were examined by atomic and electrostatic force microscopy. Their applicability in electrochemistry was demonstrated by steady-state cyclic voltammetry. Pores with a radii down to 0.4 nm and electrodes with radii down to 2 nm are demonstrated.

  7. Fabrication, evaluation, and use of extracellular K+ and H+ ion-selective electrodes.

    PubMed

    Johnson, T A; Engle, C L; Kusy, R P; Knisley, S B; Graebner, C A; Gettes, L S

    1990-04-01

    Ion-selective mini-electrodes have been widely employed to measure extracellular K+ and H+ during myocardial ischemia. However, the recent availability of this technology has not been accompanied by uniform fabrication, amplification, and calibration standards. In their fabrication, the chloride tips of Teflon-coated silver wires should be covered with a cellulose acetate-titanium dioxide sponge followed by a polyvinyl chloride (PVC)-valinomycin (K+) or PVC-tridodecylamine (H+) ion-selective membrane. Critical analysis of the nonworking electrodes using scanning electron micrographs has revealed membrane holes, membrane and sponge contamination, Teflon plaque, poor membrane-sponge-Teflon adhesion, and improperly applied or torn membrane. We have also found that signal amplification must have variable-gain filtration (0-1 Hz) with 0.5-pA input offset current and 10(12)-omega input resistance. Furthermore, in vitro calibration in 3 and 10 mM KCl (K+) or pH 8 and 6 buffer (H+) should produce a Nernstian slope +/- 5 or 10%, respectively, at 26 degrees C with a response time less than or equal to 50 ms, resistance greater than or equal to 10(12) omega, and drifts less than or equal to 1 mV/h. In vivo performance and calibration criteria (delineated for K+ only) include 1) transient response to bolus injections of KCl (0.12 mM/kg body wt) yielding peak amplitude changes of 2.5-3.0 mM, response times less than or equal to 10 s, and washout time constants less than or equal to 3 min, and 2) in vivo calibration to artificial independently confirmed systemic [K+] producing a Nernstian slope +/- 15% at 38 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Focused ion beam processing to fabricate ohmic contact electrodes on a bismuth nanowire for Hall measurements

    PubMed Central

    2013-01-01

    Ohmic contact electrodes for four-wire resistance and Hall measurements were fabricated on an individual single-crystal bismuth nanowire encapsulated in a cylindrical quartz template. Focused ion beam processing was utilized to expose the side surfaces of the bismuth nanowire in the template, and carbon and tungsten electrodes were deposited on the bismuth nanowire in situ to achieve electrical contacts. The temperature dependence of the four-wire resistance was successfully measured for the bismuth nanowire, and a difference between the resistivities of the two-wire and four-wire methods was observed. It was concluded that the two-wire method was unsuitable for estimation of the resistivity due to the influence of contact resistance, even if the magnitude of the bismuth nanowire resistance was greater than the kilo-ohm order. Furthermore, Hall measurement of a 4-μm-diameter bismuth microwire was also performed as a trial, and the evaluated temperature dependence of the carrier mobility was in agreement with that for bulk bismuth, which indicates that the carrier mobility was successfully measured using this technique. PACS 81.07.Gf PMID:24070421

  9. Fabrication and Electrochemical Characterization of Polyaniline/Titanium Oxide Nanoweb Composite Electrode for Supercapacitor Application.

    PubMed

    Yu, Hyunuk; Jang, Kihun; Chung, Ildoo; Ahn, Heejoon

    2016-03-01

    In this study, polyaniline/titanium oxide (PANi-TiO2) nanoweb composite was fabricated through electrochemical deposition and electrospinning techniques, and the composite was further utilized as an electrode for a supercapacitor. The PANi-TiO2 composite film showed three-dimensional hierarchical micro/nano architecture. The film was deposited on the current collector without the use of any binders. The morphology of the PANi-TiO2 composite film was confirmed by the use of field emission scanning electron microscopy (FE-SEM) analysis that polyaniline was grown in the form of nanorods with a diameter of 100 nm-200 nm on a TiO2 nanoweb. The chemical composition and quantitative analysis were determined by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The electrochemical properties were analyzed by cyclic voltammetry (CV), chronopotentiometry, and electrochemical impedance spectroscopy (EIS). The result of electrochemical tests indicated that TiO2-PANi electrode displayed a high specific capacitance of 306.5 Fg(-1) at the scan rate of 20 mVs(-1), with the capacitance retention ratio being 103% after 500 cycles at the scan rate of 50 mVs(-1).

  10. Fabrication of a flexible Ag-grid transparent electrode using ac based electrohydrodynamic Jet printing

    NASA Astrophysics Data System (ADS)

    Park, Jaehong; Hwang, Jungho

    2014-10-01

    In the dc voltage-applied electrohydrodynamic (EHD) jet printing of metal nanoparticles, the residual charge of droplets deposited on a substrate changes the electrostatic field distribution and interrupts the subsequent printing behaviour, especially for insulating substrates that have slow charge decay rates. In this paper, a sinusoidal ac voltage was used in the EHD jet printing process to switch the charge polarity of droplets containing Ag nanoparticles, thereby neutralizing the charge on a polyethylene terephthalate (PET) substrate. Printed Ag lines with a width of 10 µm were invisible to the naked eye. After sintering lines with 500 µm of line pitch at 180 °C, a grid-type transparent electrode (TE) with a sheet resistance of ˜7 Ω sq-1 and a dc to optical conductivity ratio of ˜300 at ˜84.2% optical transmittance was obtained, values that were superior to previously reported results. In order to evaluate the durability of the TE under bending stresses, the sheet resistance was measured as the number of bending cycles was increased. The sheet resistance of the Ag grid electrode increased only slightly, by less than 20% from its original value, even after 500 cycles. To the best of our knowledge, this is the first time that Ag (invisible) grid TEs have been fabricated on PET substrates by ac voltage applied EHD jet printing.

  11. Highly Elastic Micropatterned Hydrogel for Engineering Functional Cardiac Tissue

    PubMed Central

    Annabi, Nasim; Tsang, Kelly; Mithieux, Suzanne M.; Nikkhah, Mehdi; Ameri, Afshin

    2013-01-01

    Heart failure is a major international health issue. Myocardial mass loss and lack of contractility are precursors to heart failure. Surgical demand for effective myocardial repair is tempered by a paucity of appropriate biological materials. These materials should conveniently replicate natural human tissue components, convey persistent elasticity, promote cell attachment, growth and conformability to direct cell orientation and functional performance. Here, microfabrication techniques are applied to recombinant human tropoelastin, the resilience-imparting protein found in all elastic human tissues, to generate photocrosslinked biological materials containing well-defined micropatterns. These highly elastic substrates are then used to engineer biomimetic cardiac tissue constructs. The micropatterned hydrogels, produced through photocrosslinking of methacrylated tropoelastin (MeTro), promote the attachment, spreading, alignment, function, and intercellular communication of cardiomyocytes by providing an elastic mechanical support that mimics their dynamic mechanical properties in vivo. The fabricated MeTro hydrogels also support the synchronous beating of cardiomyocytes in response to electrical field stimulation. These novel engineered micropatterned elastic gels are designed to be amenable to 3D modular assembly and establish a versatile, adaptable foundation for the modeling and regeneration of functional cardiac tissue with potential for application to other elastic tissues. PMID:24319406

  12. Maskless fabrication of a microfluidic device with interdigitated electrodes on PCB using laser ablation

    NASA Astrophysics Data System (ADS)

    Contreras-Saenz, Michael; Hassard, Christian; Vargas-Chacon, Rafael; Gordillo, Jose Luis; Camacho-Leon, Sergio

    2016-03-01

    This paper reports the maskless fabrication of a microfluidic device with interdigitated electrodes (IDE) based on the technology of MicroElectroMechanical Systems on Printed Circuit Board (PCB-MEMS) and laser ablation. The device has flame retardant (FR)-4 resin as substrate, cooper (Cu) as active material and SU-8 polymer as structural material. By adjusting the laser parameters, Cu IDEs and SU-8 microchannels were successfully patterned onto the FR-4 substrate. The respective width, gap and overlap of the IDEs were 50 μm, 25 μm and 500 μm. The respective width, depth and length of the microchannels were 210 μm, 24.6 μm and 6.3 mm. The resolution and repeatability achieved in this approach, along with the low cost of the involved materials and techniques, enable an affordable micromachining platform with rapid fabrication-test cycle to develop active multiphysic microdevices with several applications in the fields of biosensing, cell culture, drug delivery, transport and sorting of molecules, among others.

  13. Fabrication and Characterization of a Micromachined Swirl-Shaped Ionic Polymer Metal Composite Actuator with Electrodes Exhibiting Asymmetric Resistance

    PubMed Central

    Feng, Guo-Hua; Liu, Kim-Min

    2014-01-01

    This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation. PMID:24824370

  14. Fabrication and characterization of p+-i-p+ type organic thin film transistors with electrodes of highly doped polymer

    NASA Astrophysics Data System (ADS)

    Tadaki, Daisuke; Ma, Teng; Zhang, Jinyu; Iino, Shohei; Hirano-Iwata, Ayumi; Kimura, Yasuo; Rosenberg, Richard A.; Niwano, Michio

    2016-04-01

    Organic thin film transistors (OTFTs) have been explored because of their advantageous features such as light-weight, flexible, and large-area. For more practical application of organic electronic devices, it is very important to realize OTFTs that are composed only of organic materials. In this paper, we have fabricated p+-i-p+ type of OTFTs in which an intrinsic (i) regioregular poly (3-hexylthiophene) (P3HT) layer is used as the active layer and highly doped p-type (p+) P3HT is used as the source and drain electrodes. The 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) was used as the p-type dopant. A fabricating method of p+-i-p+ OTFTs has been developed by using SiO2 and aluminum films as capping layers for micro-scaled patterning of the p+-P3HT electrodes. The characteristics of the OTFTs were examined using the photoelectron spectroscopy and electrical measurements. We demonstrated that the fabricated p+-i-p+ OTFTs work with carrier injection through a built-in potential at p+/i interfaces. We found that the p+-i-p+ OTFTs exhibit better FET characteristics than the conventional P3HT-OTFT with metal (Au) electrodes, indicating that the influence of a carrier injection barrier at the interface between the electrode and the active layer was suppressed by replacing the metal electrodes with p+-P3HT layers.

  15. Fabrication and In Situ Testing of Scalable Nitrate-Selective Electrodes for Distributed Observations

    NASA Astrophysics Data System (ADS)

    Harmon, T. C.; Rat'ko, A.; Dietrich, H.; Park, Y.; Wijsboom, Y. H.; Bendikov, M.

    2008-12-01

    Inorganic nitrogen (nitrate (NO3-) and ammonium (NH+)) from chemical fertilizer and livestock waste is a major source of pollution in groundwater, surface water and the air. While some sources of these chemicals, such as waste lagoons, are well-defined, their application as fertilizer has the potential to create distributed or non-point source pollution problems. Scalable nitrate sensors (small and inexpensive) would enable us to better assess non-point source pollution processes in agronomic soils, groundwater and rivers subject to non-point source inputs. This work describes the fabrication and testing of inexpensive PVC-membrane- based ion selective electrodes (ISEs) for monitoring nitrate levels in soil water environments. ISE-based sensors have the advantages of being easy to fabricate and use, but suffer several shortcomings, including limited sensitivity, poor precision, and calibration drift. However, modern materials have begun to yield more robust ISE types in laboratory settings. This work emphasizes the in situ behavior of commercial and fabricated sensors in soils subject to irrigation with dairy manure water. Results are presented in the context of deployment techniques (in situ versus soil lysimeters), temperature compensation, and uncertainty analysis. Observed temporal responses of the nitrate sensors exhibited diurnal cycling with elevated nitrate levels at night and depressed levels during the day. Conventional samples collected via lysimeters validated this response. It is concluded that while modern ISEs are not yet ready for long-term, unattended deployment, short-term installations (on the order of 2 to 4 days) are viable and may provide valuable insights into nitrogen dynamics in complex soil systems.

  16. Fabrication of a microfluidic Ag/AgCl reference electrode and its application for portable and disposable electrochemical microchips.

    PubMed

    Zhou, Jianhua; Ren, Kangning; Zheng, Yizhe; Su, Jing; Zhao, Yihua; Ryan, Declan; Wu, Hongkai

    2010-09-01

    This report describes a convenient method for the fabrication of a miniaturized, reliable Ag/AgCl reference electrode with nanofluidic channels acting as a salt bridge that can be easily integrated into microfluidic chips. The Ag/AgCl reference electrode shows high stability with millivolt variations. We demonstrated the application of this reference electrode in a portable microfluidic chip that is connected to a USB-port microelectrochemical station and to a computer for data collection and analysis. The low fabrication cost of the chip with the potential for mass production makes it disposable and an excellent candidate for real-world analysis and measurement. We used the chip to quantitatively analyze the concentrations of heavy metal ions (Cd(2+) and Pb(2+)) in sea water. We believe that the Ag/AgCl reference microelectrode and the portable electrochemical system will be of interest to people in microfluidics, environmental science, clinical diagnostics, and food research.

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

    PubMed

    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.

  18. Continuous Droplet Removal upon Dropwise Condensation of Humid Air on a Hydrophobic Micropatterned Surface

    PubMed Central

    2015-01-01

    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. PMID:25073014

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

    PubMed

    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.

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

    PubMed

    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. PMID:27571339

  1. Fabrication of Micro-Needle Electrodes for Bio-Signal Recording by a Magnetization-Induced Self-Assembly Method

    PubMed Central

    Chen, Keyun; Ren, Lei; Chen, Zhipeng; Pan, Chengfeng; Zhou, Wei; Jiang, Lelun

    2016-01-01

    Micro-needle electrodes (MEs) have attracted more and more attention for monitoring physiological electrical signals, including electrode-skin interface impedance (EII), electromyography (EMG) and electrocardiography (ECG) recording. A magnetization-induced self-assembling method (MSM) was developed to fabricate a microneedle array (MA). A MA coated with Ti/Au film was assembled as a ME. The fracture and insertion properties of ME were tested by experiments. The bio-signal recording performance of the ME was measured and compared with a typical commercial wet electrode (Ag/AgCl electrode). The results show that the MA self-assembled from the magnetic droplet array under the sum of gravitational surface tension and magnetic potential energies. The ME had good toughness and could easily pierce rabbit skin without being broken or buckling. When the compression force applied on the ME was larger than 2 N, ME could stably record EII, which was a lower value than that measured by Ag/AgCl electrodes. EMG signals collected by ME varied along with the contraction of biceps brachii muscle. ME could record static ECG signals with a larger amplitude and dynamic ECG signals with more distinguishable features in comparison with a Ag/AgCl electrode, therefore, ME is an alternative electrode for bio-signal monitoring in some specific situations. PMID:27657072

  2. Fabrication of interdigitated high-performance zinc oxide nanowire modified electrodes for glucose sensing.

    PubMed

    Haarindraprasad, R; Hashim, Uda; Gopinath, Subash C B; Perumal, Veeradasan; Liu, Wei-Wen; Balakrishnan, S R

    2016-06-21

    Diabetes is a metabolic disease with a prolonged elevated level of glucose in the blood leads to long-term complications and increases the chances for cardiovascular diseases. The present study describes the fabrication of a ZnO nanowire (NW)-modified interdigitated electrode (IDE) to monitor the level of blood glucose. A silver IDE was generated by wet etching-assisted conventional lithography, with a gap between adjacent electrodes of 98.80 μm. The ZnO-based thin films and NWs were amended by sol-gel and hydrothermal routes. High-quality crystalline and c-axis orientated ZnO thin films were observed by XRD analyses. The ZnO thin film was annealed for 1, 3 and 5 h, yielding a good-quality crystallite with sizes of 50, 100 and 110 nm, and the band gaps were measured as 3.26, 3.20 and 3.17 eV, respectively. Furthermore, a flower-modeled NW was obtained with the lowest diameter of 21 nm. Our designed ZnO NW-modified IDE was shown to have a detection limit as low as 0.03 mg/dL (correlation coefficient = 0.98952) of glucose with a low response time of 3 s, perform better than commercial glucose meter, suitable to instantly monitor the glucose level of diabetes patients. This study demonstrated the high performance of NW-mediated IDEs for glucose sensing as alternative to current glucose sensors. PMID:27188319

  3. Direct micropatterning of polymer materials by ice mold

    NASA Astrophysics Data System (ADS)

    Yu, Xinhong; Xing, Rubo; Luan, Shifang; Wang, Zhe; Han, Yanchun

    2006-10-01

    Micropatterning of functional polymer materials by micromolding in capillaries (MIMIC) with ice mold is reported in this paper. Ice mold was selected due to its thaw or sublimation. Thus, the mold can be easily removed. Furthermore, the polymer solution did not react with, swell, or adhere to the ice mold, so the method is suitable for many kinds of materials (such as P3HT, PMMA Alq 3/PVK, PEDOT: PSS, PS, P2VP, etc.). Freestanding polymer microstructures, binary polymer pattern, and microchannels have been fabricated by the use of ice mold freely.

  4. Aging of porous silicon in physiological conditions: cell adhesion modes on scaled 1D micropatterns.

    PubMed

    Noval, Alvaro Muñoz; Vaquero, Vanessa Sánchez; Quijorna, Esther Punzón; Costa, Vicente Torres; Pérez, Darío Gallach; Méndez, Laura González; Montero, Isabel; Palma, Raul J Martín; Font, Aurelio Climent; Ruiz, Josefa P García; Silván, Miguel Manso

    2012-06-01

    The surface properties of porous silicon (PSi) evolve rapidly in phosphate-buffered saline. X-ray photoelectron spectra indicate the formation of a Si-OH and C-O enriched surface, which becomes increasingly hydrophilic with aging time. Multiscale stripe micropatterns of Si and PSi have been fabricated by means of a high-energy ion-beam irradiation process. These micropatterns have been aged in physiological conditions and used to analyze human mesenchymal stem cell (hMSC) adhesion. The actin cytoskeleton of hMSCs orients following the uniaxial micropatterns. In the wider Si stripes, hMSCs are dominantly located on Si areas. However, for reduced Si widths, adhesion is avoided on PSi by a split assembly of the actin cytoskeleton on two parallel Si areas. These results confirm that nanostructured Si-OH/C-O-rich surfaces with hydrophilic character are specially adapted for the creation of cell adhesion surface contrasts.

  5. Facile fabrication of sub-100 nm mesoscale inverse opal films and their application in dye-sensitized solar cell electrodes

    NASA Astrophysics Data System (ADS)

    Lee, Jung Woo; Lee, Jaemin; Kim, Cheolho; Cho, Chang-Yeol; Moon, Jun Hyuk

    2014-10-01

    Inverse opal (IO) films with mesoporous structures hold promise as high-performance electrodes for various photoelectrochemical devices because of their high specific area as well as their fully connected pore structure. A great challenge to their use is obtaining an intact film of mesoscale colloidal crystals as a template. Here, using the plate-sliding coating method coupled with hot air flow, we successfully deposited mesoscale colloidal crystals onto the substrate. A TiO2 mesoscale IO (meso-IO) with 70 nm pores was then successfully fabricated via atomic layer deposition of TiO2 and subsequent removal of the template. As a photoelectrochemical electrode, the meso-IO structure exhibits enhanced charge transport properties as well as a high specific area. Moreover, dye-sensitized solar cells fabricated using the meso-IO electrode exhibit a higher photocurrent and cell efficiency than a cell constructed using a conventional TiO2 nanoparticle electrode. This meso-IO film provides a new platform for developing electrodes for use in various energy storage and conversion devices.

  6. Multiwalled carbon nanotube coated polyester fabric as textile based flexible counter electrode for dye sensitized solar cell.

    PubMed

    Arbab, Alvira Ayoub; Sun, Kyung Chul; Sahito, Iftikhar Ali; Qadir, Muhammad Bilal; Jeong, Sung Hoon

    2015-05-21

    Textile wearable electronics offers the combined advantages of both electronics and textile characteristics. The essential properties of these flexible electronics such as lightweight, stretchable, and wearable power sources are in strong demand. Here, we have developed a facile route to fabricate multi walled carbon nanotube (MWCNT) coated polyester fabric as a flexible counter electrode (CE) for dye sensitized solar cells (DSSCs). A variety of MWCNT and enzymes with different structures were used to generate individual enzyme-dispersed MWCNT (E-MWCNT) suspensions by non-covalent functionalization. A highly concentrated colloidal suspension of E-MWCNT was deposited on polyester fabric via a simple tape casting method using an air drying technique. In view of the E-MWCNT coating, the surface structure is represented by topologically randomly assembled tubular graphene units. This surface morphology has a high density of colloidal edge states and oxygen-containing surface groups which execute multiple catalytic sites for iodide reduction. A highly conductive E-MWCNT coated fabric electrode with a surface resistance of 15 Ω sq(-1) demonstrated 5.69% power conversion efficiency (PCE) when used as a flexible CE for DSSCs. High photo voltaic performance of our suggested system of E-MWCNT fabric-based DSSCs is associated with high sheet conductivity, low charge transfer resistance (RCT), and excellent electro catalytic activity (ECA). Such a conductive fabric demonstrated stable conductivity against bending cycles and strong mechanical adhesion of E-MWCNT on polyester fabric. Moreover, the polyester fabric is hydrophobic and, therefore, has good sealing capacity and retains the polymer gel electrolyte without seepage. This facile E-MWCNT fabric CE configuration provides a concrete fundamental background towards the development of textile-integrated solar cells.

  7. Multiwalled carbon nanotube coated polyester fabric as textile based flexible counter electrode for dye sensitized solar cell.

    PubMed

    Arbab, Alvira Ayoub; Sun, Kyung Chul; Sahito, Iftikhar Ali; Qadir, Muhammad Bilal; Jeong, Sung Hoon

    2015-05-21

    Textile wearable electronics offers the combined advantages of both electronics and textile characteristics. The essential properties of these flexible electronics such as lightweight, stretchable, and wearable power sources are in strong demand. Here, we have developed a facile route to fabricate multi walled carbon nanotube (MWCNT) coated polyester fabric as a flexible counter electrode (CE) for dye sensitized solar cells (DSSCs). A variety of MWCNT and enzymes with different structures were used to generate individual enzyme-dispersed MWCNT (E-MWCNT) suspensions by non-covalent functionalization. A highly concentrated colloidal suspension of E-MWCNT was deposited on polyester fabric via a simple tape casting method using an air drying technique. In view of the E-MWCNT coating, the surface structure is represented by topologically randomly assembled tubular graphene units. This surface morphology has a high density of colloidal edge states and oxygen-containing surface groups which execute multiple catalytic sites for iodide reduction. A highly conductive E-MWCNT coated fabric electrode with a surface resistance of 15 Ω sq(-1) demonstrated 5.69% power conversion efficiency (PCE) when used as a flexible CE for DSSCs. High photo voltaic performance of our suggested system of E-MWCNT fabric-based DSSCs is associated with high sheet conductivity, low charge transfer resistance (RCT), and excellent electro catalytic activity (ECA). Such a conductive fabric demonstrated stable conductivity against bending cycles and strong mechanical adhesion of E-MWCNT on polyester fabric. Moreover, the polyester fabric is hydrophobic and, therefore, has good sealing capacity and retains the polymer gel electrolyte without seepage. This facile E-MWCNT fabric CE configuration provides a concrete fundamental background towards the development of textile-integrated solar cells. PMID:25912056

  8. Field Emission of Wet Transferred Suspended Graphene Fabricated on Interdigitated Electrodes.

    PubMed

    Xu, Ji; Wang, Qilong; Tao, Zhi; Qi, Zhiyang; Zhai, Yusheng; Wu, Shengqi; Zhang, Xiaobing; Lei, Wei

    2016-02-10

    Suspended graphene (SG) membranes could enable strain-engineering of ballistic Dirac fermion transport and eliminate the extrinsic bulk disorder by annealing. When freely suspended without contact to any substrates, graphene could be considered as the ultimate two-dimensional (2D) morphology, leading to special field characteristics with the 2D geometrical effect and effectively utilized as an outstanding structure to explore the fundamental electronic or optoelectronic mechanism. In this paper, we report field emission characterization on an individual suspended few-layer graphene. A controllable wet transfer method is used to obtain the continuous and suspended graphene membrane on interdigitated gold electrodes. This suspended structure displays an overall field emission from the entirely surface, except for the variation in the emitting positions, acquiring a better enhancement than the exfoliated graphene on the conventional flat substrate. We also observe the transition process from space charge flow at low bias to the Fowler-Nordheim theory at high current emission regime. It could enable theoretical and experimental investigation of the typical electron emission properties of the 2D regime. Numerical simulations are also carried out to study the electrical properties of the suspended structure. Further improvement on the fabrication would realize low disorder, high quality, and large-scale suspended graphene devices. PMID:26795930

  9. Field Emission of Wet Transferred Suspended Graphene Fabricated on Interdigitated Electrodes.

    PubMed

    Xu, Ji; Wang, Qilong; Tao, Zhi; Qi, Zhiyang; Zhai, Yusheng; Wu, Shengqi; Zhang, Xiaobing; Lei, Wei

    2016-02-10

    Suspended graphene (SG) membranes could enable strain-engineering of ballistic Dirac fermion transport and eliminate the extrinsic bulk disorder by annealing. When freely suspended without contact to any substrates, graphene could be considered as the ultimate two-dimensional (2D) morphology, leading to special field characteristics with the 2D geometrical effect and effectively utilized as an outstanding structure to explore the fundamental electronic or optoelectronic mechanism. In this paper, we report field emission characterization on an individual suspended few-layer graphene. A controllable wet transfer method is used to obtain the continuous and suspended graphene membrane on interdigitated gold electrodes. This suspended structure displays an overall field emission from the entirely surface, except for the variation in the emitting positions, acquiring a better enhancement than the exfoliated graphene on the conventional flat substrate. We also observe the transition process from space charge flow at low bias to the Fowler-Nordheim theory at high current emission regime. It could enable theoretical and experimental investigation of the typical electron emission properties of the 2D regime. Numerical simulations are also carried out to study the electrical properties of the suspended structure. Further improvement on the fabrication would realize low disorder, high quality, and large-scale suspended graphene devices.

  10. Design and fabrication of nanowire electrodes on a flexible substrate for detection of myocardial ischemia

    NASA Astrophysics Data System (ADS)

    Ramachandran, Vasuda; Yoon, Hargsoon; Varadan, Vijay K.

    2009-03-01

    According to a report by the American Heart Association, there are approximately 3-4 million Americans that may experience silent Myocardial Ischemia (MI). Silent MI is a serious heart condition that can progress to a severe heart attack without any warning and the consequences of such an event can turn fatal quickly. Therefore, there is a strong need for a sensor that can continuously monitor the onset of the condition to prevent high risk individuals from deadly heart attacks. An increase in extracellular potassium levels is the first sign of MI and timely sensing with an implantable potassium sensing biosensor could play a critical role in detecting and expediting care. There are challenges in the development of an implantable potassium sensing electrode one of which includes signal drift. The incorporation of novel nanostructures and smarter materials hold the potential to combat these problems. This paper presents a unique design for an all-solid-state potassium sensing device which offers miniaturization along with enhanced signal transduction. These characteristics are important when it comes to implantable devices and signal drift. Sensor design details along with fabrication processes and sensing results are discussed.

  11. Fabrication of Gate-Electrode Integrated Carbon-Nanotube Bundle Field Emitters

    NASA Technical Reports Server (NTRS)

    Toda, Risaku; Bronikowski, Michael; Luong, Edward; Manohara, Harish

    2008-01-01

    A continuing effort to develop carbon-nanotube-based field emitters (cold cathodes) as high-current-density electron sources has yielded an optimized device design and a fabrication scheme to implement the design. One major element of the device design is to use a planar array of bundles of carbon nanotubes as the field-emission tips and to optimize the critical dimensions of the array (principally, heights of bundles and distances between them) to obtain high area-averaged current density and high reliability over a long operational lifetime a concept that was discussed in more detail in Arrays of Bundles of Carbon Nanotubes as Field Emitters (NPO-40817), NASA Tech Briefs, Vol. 31, No. 2 (February 2007), page 58. Another major element of the design is to configure the gate electrodes (anodes used to extract, accelerate, and/or focus electrons) as a ring that overhangs a recess wherein the bundles of nanotubes are located, such that by virtue of the proximity between the ring and the bundles, a relatively low applied potential suffices to generate the large electric field needed for emission of electrons.

  12. Complex micropatterning of proteins within microfluidic channels.

    PubMed

    Kim, Miju; Doh, Junsang

    2014-01-01

    Microfluidic channels containing protein micropatterned surfaces are useful in many bioanalytical and biological applications. In this study, we developed a new method to integrate microfluidics and protein micropatterning by attaching poly(dimethylsiloxane) (PDMS) microfluidic channels to bio-friendly photoresist films via poly(dopamine) (PDA) adhesive. A bio-friendly photoresist poly(2,2-dimethoxy nitrobenzyl methacrylate-r-methyl methacrylate-r-poly(ethylene glycol) methacrylate) (PDMP) was synthesized and used. By performing microscope projection photolithography (MPP) to the PDMP thin films within PDMS microchannels, complex micropatterns of proteins were successfully generated within microfluidic channels. PMID:25570075

  13. Fabrication of nano-porous hydroxyapatite modified electrode and its application for determination of p-chlorophenol.

    PubMed

    Chu, Lin; Zhang, Xiaoli

    2012-01-01

    Nano-porous hydroxyapatite (HAp) modified electrode was fabricated by simply electrodepositing HAp onto the glassy carbon electrode (GCE) from the electrolytes solution containing Ca(NO3)2 4H2O and NH4H2PO4, the resulting electrode (nano-HAp/GCE) was characterized with scanning electron microscopy (SEM). The electrochemical behavior of p-chlorophenol (p-CP) at nano-HAp/GCE was studied by cyclic voltammetry. The electrode displayed selective and enhanced electroanalytical response towards p-CP, obviously because p-CP is accumulated at the electrode. For the greater sensitivity, a semi-derivative technique was adopted to obtain the current signal. The results indicated that the nano-HAp/GCE exhibits substantial enhancement in electrochemical sensitivity for p-CP due to its large surface area and particular adsorbability. After accumulation of 4 min for p-CP on nano-HAp/GCE, the peak height was linearly related to the concentration of p-CP in the range of 1.0 x 10(-8) to 1.0 x 10(-7) mol L(-1). The detection limit was 4.0 x 10(-9) mol L-(1) at 3sigma level. Based on this, the modified electrode was successfully applied in water samples with low cost and high sensitivity.

  14. Fabrication and functional demonstration of a smart electrode with a built-in CMOS microchip for neural stimulation of a retinal prosthesis.

    PubMed

    Noda, Toshihiko; Fujisawa, Takumi; Kawasaki, Ryohei; Tashiro, Hiroyuki; Takehara, Hiroaki; Sasagawa, Kiyotaka; Tokuda, Takashi; Ohta, Jun

    2015-01-01

    In this study, we propose an advanced architecture of a smart electrode for neural stimulation of a retinal prosthesis. A feature of the proposed architecture is embedding CMOS microchips into the core of the stimulus electrodes. Microchip integration without dead space on the array is possible. Additionally, higher durability can be expected because the microchips are protected by the stimulus electrodes like a metal casing. Dedicated circular-shaped CMOS microchips were designed and fabricated. The microchip measured 400 μm in diameter. Stimulus electrodes that had a microcavity for embedding the microchip were also fabricated. In the assembly process, the CMOS microchip was mounted on a flexible substrate, and then the stimulus electrode was mounted to cover the microchip. The microchip was completely built into the inside of the electrode. By performing an ex-vivo experiment using the extracted eyeball of a pig, stimulus function of the electrode was demonstrated successfully. PMID:26737011

  15. Neural Pathfinding on Uni- and Multidirectional Photopolymerized Micropatterns

    PubMed Central

    2015-01-01

    Overcoming signal resolution barriers of neural prostheses, such as the commercially available cochlear impant (CI) or the developing retinal implant, will likely require spatial control of regenerative neural elements. To rationally design materials that direct nerve growth, it is first necessary to determine pathfinding behavior of de novo neurite growth from prosthesis-relevant cells such as spiral ganglion neurons (SGNs) in the inner ear. Accordingly, in this work, repeating 90° turns were fabricated as multidirectional micropatterns to determine SGN neurite turning capability and pathfinding. Unidirectional micropatterns and unpatterned substrates are used as comparisons. Spiral ganglion Schwann cell alignment (SGSC) is also examined on each surface type. Micropatterns are fabricated using the spatial reaction control inherent to photopolymerization with photomasks that have either parallel line spacing gratings for unidirectional patterns or repeating 90° angle steps for multidirectional patterns. Feature depth is controlled by modulating UV exposure time by shuttering the light source at given time increments. Substrate topography is characterized by white light interferometry and scanning electron microscopy (SEM). Both pattern types exhibit features that are 25 μm in width and 7.4 ± 0.7 μm in depth. SGN neurites orient randomly on unpatterned photopolymer controls, align and consistently track unidirectional patterns, and are substantially influenced by, but do not consistently track, multidirectional turning cues. Neurite lengths are 20% shorter on multidirectional substrates compared to unidirectional patterns while neurite branching and microfeature crossing events are significantly higher. For both pattern types, the majority of the neurite length is located in depressed surface features. Developing methods to understand neural pathfinding and to guide de novo neurite growth to specific stimulatory elements will enable design of innovative

  16. Anisotropic micro-cloths fabricated from DNA-stabilized carbon nanotubes: one-stop manufacturing with electrode needles

    NASA Astrophysics Data System (ADS)

    Frusawa, Hiroshi; Yoshii, Gen

    2015-03-01

    Among a variety of solution-based approaches to fabricate anisotropic films of aligned carbon nanotubes (CNTs), we focus on the dielectrophoretic assembly method using AC electric fields in DNA-stabilized CNT suspensions. We demonstrate that a one-stop manufacturing system using electrode needles can draw anisotropic DNA-CNT hybrid films of 10 to 100 µm in size (i.e., free-standing DNA-CNT micro-cloths) from the remaining suspension into the atmosphere while maintaining structural order. It has been found that a maximal degree of polarization (ca. 40%) can be achieved by micro-cloths fabricated from a variety of DNA-CNT mixtures. Our results suggest that the one-stop method can impart biocompatibility to the downsized CNT films and that the DNA-stabilized CNT micro-cloths directly connected to an electrode could be useful for biofuel cells in terms of electron transfer and/or enzymatic activity.

  17. Fabrication of nano-electrode arrays of free-standing carbon nanotubes on nano-patterned substrate by imprint method

    NASA Astrophysics Data System (ADS)

    Chang, W. S.; Kim, J. W.; Choi, D. G.; Han, C. S.

    2011-01-01

    The synthesis of isolated carbon nanotubes with uniform outer diameters and ordered spacing over wafer-scale areas was investigated for fabrication of nano-electrode arrays on silicon wafers for field emission and sensor devices. Multi-walled carbon nanotubes (MWCNTs) were grown on TiN electrode layer with iron catalyst patterned by nano-imprint lithography (NIL), which allows the precise placement of individual CNTs on a substrate. The proposed techniques, including plasma-enhanced chemical vapor deposition (PECVD) and NIL, are simple, inexpensive, and reproducible methods for fabrication of nano-scale devices in large areas. The catalyst patterns were defined by an array of circles with 200 nm in diameter, and variable lengths of pitch. The nano-patterned master and Fe catalyst were observed with good pattern fidelity over a large area by atomic force microscope (AFM) and scanning electron microscopy (SEM). Nano-electrodes of MWCNTs had diameters ranging from 50 nm to 100 nm and lengths of about 300 nm. Field emission tests showed the reducing ignition voltage as the geometry of nanotube arrays was controlled by catalyst patterning. These results showed a wafer-scale approach to the control of the size, pitch, and position of nano-electrodes of nanotubes for various applications including electron field-emission sources, electrochemical probes, functionalized sensor elements, and so on.

  18. Fabrication of gallium hexacyanoferrate modified carbon ionic liquid paste electrode for sensitive determination of hydrogen peroxide and glucose.

    PubMed

    Haghighi, Behzad; Khosravi, Mehdi; Barati, Ali

    2014-07-01

    Gallium hexacyanoferrate (GaHCFe) and graphite powder were homogeneously dispersed into n-dodecylpyridinium hexafluorophosphate and paraffin to fabricate GaHCFe modified carbon ionic liquid paste electrode (CILPE). Mixture experimental design was employed to optimize the fabrication of GaHCFe modified CILPE (GaHCFe-CILPE). A pair of well-defined redox peaks due to the redox reaction of GaHCFe through one-electron process was observed for the fabricated electrode. The fabricated GaHCFe-CILPE exhibited good electrocatalytic activity towards reduction and oxidation of H2O2. The observed sensitivities for the electrocatalytic oxidation and reduction of H2O2 at the operating potentials of +0.8 and -0.2V were about 13.8 and 18.3 mA M(-1), respectively. The detection limit (S/N=3) for H2O2 was about 1 μM. Additionally, glucose oxidase (GOx) was immobilized on GaHCFe-CILPE using two methodology, entrapment into Nafion matrix and cross-linking with glutaraldehyde and bovine serum albumin, in order to fabricate glucose biosensor. Linear dynamic rage, sensitivity and detection limit for glucose obtained by the biosensor fabricated using cross-linking methodology were 0.1-6mM, 0.87 mA M(-1) and 30 μM, respectively and better than those obtained (0.2-6mM, 0.12 mA M(-1) and 50 μM) for the biosensor fabricated using entrapment methodology.

  19. Micropatterning of a Bipolar Plate Using Direct Laser Melting Process

    SciTech Connect

    Jang, Jeong-hwan; Joo, Byeong-don; Mun, Sung-min; Moona, Young-hoon

    2010-06-15

    Direct laser melting (DLM) technology has been used to fabricate the micro-pattern of the bipolar plate in a direct methanol fuel cell (DMFC). A suitable approach to enhance the performance of the bipolar plate has been performed to optimize the DLM process. To fabricate the micro pattern, a DLM process with 316L stainless steel powder has been used. For the melted height of 1 mm, the DLM process conditions were optimized such as; laser power of 200 W, scan rate of 36.62 mm/s and the 8-layer structures. To characterize the effect of material type, the bipolar plates of various types were analyzed. In case of the 316L stainless steel DLM patterning, a current density of 297 mA/cm{sup 2} was achieved but the case of the 316L stainless steel plate, 248 mA/cm{sup 2} current density that is lower than that of other materials was achieved. The overall cell performance of 316L stainless steel DLM patterning bipolar plate was better than that of the 316L stainless steel plate. This has significant advantages for the micropatterning using DLM process. The use of 316L stainless steel powder material as micro pattern material will reduce the machining cost as well as volume of the fuel cell stack.

  20. Bipolarly stacked electrolyser for energy and space efficient fabrication of supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Liu, Xiaojuan; Wu, Tao; Dai, Zengxin; Tao, Keran; Shi, Yong; Peng, Chuang; Zhou, Xiaohang; Chen, George Z.

    2016-03-01

    Stacked electrolysers with titanium bipolar plates are constructed for electrodeposition of polypyrrole electrodes for supercapacitors. The cathode side of the bipolar Ti plates are pre-coated with activated carbon. In this new design, half electrolysis occurs which significantly lowers the deposition voltage. The deposited electrodes are tested in a symmetrical unit cell supercapacitor and an asymmetrical supercapacitor stack. Both devices show excellent energy storage performances and the capacitance values are very close to the design value, suggesting a very high current efficiency during the electrodeposition. The electrolyser stack offers multi-fold benefits for preparation of conducting polymer electrodes, i.e. low energy consumption, facile control of the electrode capacitance and simultaneous preparation of a number of identical electrodes. Therefore, the stacked bipolar electrolyser is a technology advance that offers an engineering solution for mass production of electrodeposited conducting polymer electrodes for supercapacitors.

  1. Rationally designed hierarchical MnO2-shell/ZnO-nanowire/carbon-fabric for high-performance supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Yang, Q.; Zhang, X. T.; Zhang, M. Y.; Gao, Y.; Gao, H.; Liu, X. C.; Liu, H.; Wong, K. W.; Lau, W. M.

    2014-12-01

    High-performance supercapacitor electrodes with a novel hierarchical structure of MnO2/ZnO/carbon-fabric were rationally designed, and prepared by a simple three-step-solution method. The design comprises ZnO nanowires radially grown on each micron-size fiber of a carbon-fabric electrode, with a thin MnO2 shell on each ZnO nano-core. This multi-scale hierarchical structure yields: (a) high specific area of pseudo-capacitive MnO2 to maximize specific capacitance; (b) effective MnO2-electrolyte interface to facilitate fast charging/discharging; and (c) conductive MnO2-ZnO-electrode path to reduce energy loss. In addition, the overall capacitor performance is optimized by choosing proper thickness of MnO2 shell and aspect ratio of ZnO nano-core. The design was realized and validated with the development of a simple three-step-solution method: (a) radial deposition of nano-ZnO on carbon fabric; (b) coating ZnO by a thin layer of carbon; and (c) reduction of MnO4- and replacement of this carbon overlayer by MnO2. With this design and method, high specific capacitance of 886 F g-1 was found from electrodes with 5 nm MnO2 on ZnO having an average diameter of 50 nm and aspect ratio of 30. These samples showed specific energy of 16 Wh kg-1 and specific power of 27 kW kg-1 at current density of 20 mA cm-2, and good long-term cycling stability.

  2. Fabrication of a planar-form screen-printed solid electrolyte modified Ag/AgCl reference electrode for application in a potentiometric biosensor.

    PubMed

    Liao, Wei-Yin; Chou, Tse-Chuan

    2006-06-15

    This study features the fabrication of a planar-form, solid electrolyte modified, (PSEM) Ag/AgCl reference electrode using a screen-printing method. The PSEM Ag/AgCl reference electrode uses agar gel as the inner electrolyte and chloroprene rubber for the liquid junction and insulator. These common low-cost materials and the simple fabrication processes involved render the proposed reference electrode an ideal candidate for cost-efficient mass production. It is shown that the developed reference electrode is insensitive to most of the physiologically important ionic species, including Na+, K+, Li+, Ca2+, NH4+, and Cl-, under continuous measurement conditions. Moreover, as with conventional commercial reference electrodes, the proposed reference electrode exhibits a reversible response, which is maintained until the agar gel dries out. The PSEM Ag/AgCl reference electrode is integrated with an iridium oxide modified Pt-based pH indicator electrode to form a chip-type pH biosensor. The performance of this biosensor is consistent with that obtained from a pH meter based on a macroscopic commercial Ag/AgCl reference electrode. The experimental results confirm that the proposed biosensor is capable of providing precise pH measurements of various real samples. Accordingly, the PSEM Ag/AgCl reference electrode presented in this study provides a viable alternative to the macroscopic Ag/AgCl reference electrode used in many conventional chip-based pH sensors.

  3. Fabrication of coated graphite electrode for the selective determination of europium (III) ions.

    PubMed

    Upadhyay, Anjali; Singh, Ashok Kumar; Bandi, Koteswara Rao; Jain, A K

    2013-10-15

    Preliminary complexation study showed that two ligands (ionophores) (2-((2-phenyl-2-(pyridin-2-yl)hydazono)methyl)pyridine) [L1], (2-((2-phenyl-2-(pyridin-2-yl)hydazono) methyl)phenol) [L2] can act as europium selective electrode. Europium selective coated graphite electrodes (CGE) were prepared by using ligands [L1] and [L2] and their potentiometric characteristics were determined. Membranes having different compositions of poly(vinylchloride) (PVC), the different plasticizers, anionic additives and ionophores were coated onto the graphite surface. The potential response measurements showed that the best performance was exhibited by the proposed CGE. This electrode had the widest working concentration range, Nernstian slope and fast response times of 10s. The selectivity studies showed that this electrode have higher selectivity towards Eu(3+) over a large number of cations. Furthermore, the electrode generated constant potentials in the pH range 2.7-9.0. This electrode can be used to quantify europium in soil, binary mixtures and also used as an indicator electrode in the potentiometric titration of Eu(3+) with EDTA. The proposed electrode was also successfully applied to the determination of fluoride ions in real samples.

  4. All-Organic Actuator Fabricated with Single Wall Carbon Nanotube Electrodes

    NASA Technical Reports Server (NTRS)

    Lowther, Sharon E.; Harrison, Joycelyn S.; Kang, Jinho; Park, Cheol; Park, Chan Eon

    2008-01-01

    Compliant electrodes to replace conventional metal electrodes have been required for many actuators to relieve the constraint on the electroactive layer. Many conducting polymers have been proposed for the alternative electrodes, but they still have a problem of poor thermal stability. This article reports a novel all-organic actuator with single wall carbon nanotube (SWCNT) films as the alternative electrode. The SWCNT film was obtained by filtering a SWCNT solution through an anodized alumina membrane. The conductivity of the SWCNT film was about 280 S/cm. The performance of the SWCNT film electrode was characterized by measuring the dielectric properties of NASA Langley Research Center - Electroactive Polymer (LaRC-EAP) sandwiched by the SWCNT electrodes over a broad range of temperature (from 25 C to 280 C) and frequency (from 1 KHz to 1 MHz). The all-organic actuator with the SWCNT electrodes showed a larger electric field-induced strain than that with metal electrodes, under identical measurement conditions.

  5. Electrochemically switchable platform for the micro-patterning and release of heterotypic cell sheets.

    PubMed

    Guillaume-Gentil, Orane; Gabi, Michael; Zenobi-Wong, Marcy; Vörös, Janos

    2011-02-01

    This article describes a dynamic platform in which the biointerfacial properties of micro-patterned domains can be switched electrochemically through the spatio-temporally controlled dissolution and adsorption of polyelectrolyte coatings. Insulating SU-8 micro-patterns created on a transparent indium tin oxide electrode by photolithography allowed for the local control over the electrochemical dissolution of polyelectrolyte mono- and multilayers, with polyelectrolytes shielded from the electrochemical treatment by the underlying photoresist stencil. The platform allowed for the creation of micro-patterned cell co-cultures through the electrochemical removal of a non-fouling polyelectrolyte coating and the localized adsorption of a cell adhesive one after attachment of the first cell population. In addition, the use of weak adhesive polyelectrolyte coatings on the photoresist domains allowed for the detachment of a contiguous heterotypic cell sheet upon electrochemical trigger. Cells grown on the ITO domains peeled off upon electrochemical dissolution of the sacrificial polyelectrolyte substrate, whereas adjacent cell areas on the insulated weakly adhesive substrate easily detached through the contractile force generated by neighboring cells. This electrochemical strategy for the micro-patterning and detachment of heterotypic cell sheets combines simplicity, precision and versatility, and presents great prospects for the creation of cellular constructs which mimic the cellular complexity of native tissues. PMID:21057978

  6. Continuous flow ink etching for direct micropattern of silicon dioxide

    NASA Astrophysics Data System (ADS)

    Xing, Jiyao; Rong, Weibin; Wang, Lefeng; Sun, Lining

    2016-07-01

    A continuous flow ink etching (CFIE) method is presented to directly create micropatterns on a 60 nm thick silicon dioxide (SiO2) layer. This technique employs a micropipette filled with potassium bifluoride (KHF2) aqueous solution to localize SiO2 dissolution in the vicinity of the micropipette tip. Both dot and line features with well-defined edges were fabricated and used as hardmasks for silicon etching. The linear density of etchant ink deposited on the SiO2 can be used to regulate the depth, width and 2D morphology of the line pattern. The characterization of CFIE including the resolution (about 4 μm), reproducibility and capability to form complex structures are reported. This technique provides a simple and flexible alternative to generate the SiO2 hardmask for silicon microstructure fabrication.

  7. Fabrication of NiO thin film electrode for supercapacitor applications

    SciTech Connect

    Mali, V. V.; Navale, S. T.; Chougule, M. A.; Khuspe, G. D.; Godse, P. R.; Patil, V. B.; Pawar, S. A.

    2014-04-24

    Nanocrystalline NiO electrode is successfully electrosynthesized for supercapacitor application. The nanocrystalline NiO electrode is characterized using scanning electron microscope (SEM). Nickel oxide is a highly porous and the film surface looked smooth and composed of fine elongated particles. The supercapacitive performance of NiO electrode is tested using cyclic voltammetry (C-V) technique in 0.5M Na{sub 2}S{sub 2}O{sub 3} electrolyte within potential range of −1.2 to +1.2 V. The effect of scan rate on the capacitance of NiO electrode is studied. The highest specific capacitance of 439 Fg{sup −1} at the voltage scan rate of 50mVs{sup −1} is achieved. Additionally stability and charging–discharging of NiO electrode are studied.

  8. Design, Fabrication, and Testing of Silicon-integrated Li-ion Secondary Micro Batteries with Interdigital Electrodes

    NASA Astrophysics Data System (ADS)

    Hoeppner, K.; Ferch, M.; Froebe, A.; Gernhardt, R.; Hahn, R.; Mackowiak, P.; Mukhopadhyay, B.; Roder, S.; Saalhofen, I.; Lang, K.-D.

    2015-12-01

    This paper reports the design, fabrication, and testing of silicon-integrated lithium ion secondary micro batteries with a side-by-side electrode setup. Cavities separated by narrow silicon spacers served as containments for two interdigitally arranged electrodes and were etched into <110>-Si by wet chemical etching. The etched silicon battery containments were passivated by a layer of SiOx/SixNy. Al current collectors were applied by sputtering and back etching. A volumetric micro dispenser served to fill the cavities with slurries of the active materials - lithium cobalt manganese oxide (Liy(Ni1/2Co1/5Mn3/10)O2) as the cathode and lithium titanate (Li4Ti5O12) as the anode material. Filling with electrolyte, encapsulation, and electrochemical characterization of the finished cells took place in an Ar-filled glove box. The fabricated batteries with IDE show considerably lower impedances than cells with single side by side electrodes and are capable of constant current loads up to 10 C. A linear capacity loss rate of <0.1% per cycle was observed over 30 full cycles at 0.2C.

  9. Lift-Off Free Fabrication Approach for Periodic Structures with Tunable Nano Gaps for Interdigitated Electrode Arrays.

    PubMed

    Partel, Stefan; Dincer, Can; Kasemann, Stephan; Kieninger, Jochen; Edlinger, Johannes; Urban, Gerald

    2016-01-26

    We report a simple, low-cost and lift-off free fabrication approach for periodic structures with adjustable nanometer gaps for interdigitated electrode arrays (IDAs). It combines an initial structure and two deposition process steps; first a dielectric layer is deposited, followed by a metal evaporation. The initial structure can be realized by lithography or any other structuring technique (e.g., nano imprint, hot embossing or injection molding). This method allows the fabrication of nanometer sized gaps and completely eliminates the need for a lift-off process. Different substrate materials like silicon, Pyrex or polymers can be used. The electrode gap is controlled primarily by sputter deposition of the initial structure, and thus, adjustable gaps in the nanometer range can be realized independently of the mask or stamp pattern. Electrochemical characterizations using redox cycling in ferrocenemethanol (FcMeOH) demonstrate signal amplification factors of more than 110 together with collection factors higher than 99%. Furthermore, the correlation between the gap width and the amplification factor was studied to obtain an electrochemical performance assessment of the nano gap electrodes. The results demonstrate an exponential relationship between amplification factor and gap width. PMID:26625012

  10. Positive Electrode Fabrication for Bi-polar Ni-h2 Cells

    NASA Technical Reports Server (NTRS)

    Edgar, T. A.

    1984-01-01

    Bi-Polar nickel hydrogen design studies indicated a potential improvement in energy density and specific energy if positive electrodes could be manufactured in configurations of twice or more of the present normal thickness. Such electrodes would have to achieve similar active material loading, utilization, and cycle life to conventional 0.8mm I.P.U. nickel hydrogen electrodes. A capability for producing 1.0mm dry sinter and 1.5mm slurry sinter structures on production processes and equipment was demonstrated. The EPI/USAF electrochemical impregnation process proved capable of loading thick electrodes to 1.60 g/cubic centimeters void or higher. Sample electrodes incurred 2000 high rate stress cycles without significant structural or performance degradation. Formation regimes developed for thin plaque are not optimal for thick plaque and further investigation into electrode capacity build-up would seem warranted. Thick electrode technology development is continuing under other programs and shows promise of fulfilling the projected energy density and specific energy improvements.

  11. A three-dimensional flexible supercapacitor with enhanced performance based on lightweight, conductive graphene-cotton fabric electrode

    NASA Astrophysics Data System (ADS)

    Zhou, Qianlong; Ye, Xingke; Wan, Zhongquan; Jia, Chunyang

    2015-11-01

    Recently, the topic of developing lightweight, flexible and implantable energy storage systems to address the energy-supply problem of wearable electronics has aroused increasing interests. In this paper, by introducing reduced graphene oxide (rGO), we successfully converted the commercial cotton fabric into free-standing, electrically conductive and electrochemically active fabric. Flexible supercapacitor based on the obtained conductive reduced graphene oxide-carbonized cotton fabric (rGO/CCF) exhibits high capacitance (87.53 mF cm-2 at 2 mV s-1), well cycling stability (89.82% capacitance retention after 1000 charge-discharge cycles) and excellent electrochemical stability (90.5% capacitance retention after 100 bending cycles). Moreover, a macroscopic three-dimensional sandwich-interdigital device structure was designed to enhance the supercapacitor performance. The unique rGO/CCF based sandwich-interdigital structure (SIS) supercapacitor shows a volumetric capacitance of 5.53 F cm-3 at current density of 0.0625 A cm-3 in aqueous electrolyte, which is 1.67 and 4.28 orders higher than the traditional sandwich structure (SS) and interdigital structure (IS) supercapacitor based on the same electrode material and electrolyte. Furthermore, energy density enhancement of the supercapacitor has also been achieved by adopting the well-designed device structure. The original SIS supercapacitor based on the elaborate device structure and high-performance electrode material may provide new design opportunities for flexible energy storage devices.

  12. Capacitive behavior of amorphous and crystalline RuO 2 composite electrode fabricated by spark plasma sintering technique

    NASA Astrophysics Data System (ADS)

    Bharali, P.; Kuratani, K.; Takeuchi, T.; Kiyobayashi, T.; Kuriyama, N.

    This study is intended to determine if the capacitive properties are improved when a specific amount of crystalline ruthenium oxide (c-RuO 2) is added to an amorphous hydrous ruthenium oxide (a-RuO 2) electrode fabricated by the spark plasma sintering technique. For at the cyclic voltammetry scan rates higher than 10 mV s -1, the capacitance of a highly pseudo-capacitive, but less electron-conductive a-RuO 2 electrode is augmented by adding 5-20 wt.% of c-RuO 2 which is less capacitive, but more electron-conductive than a-RuO 2. The capacitance fades when more than 20 wt.% of c-RuO 2 is added because the less capacitive nature of c-RuO 2 prevails. The proximate cause of this phenomenon is the electronic conductivity, σ, of the composite electrode as we observe a maximum in σ at around a 5-20 wt.% c-RuO 2 content. The fact that c-RuO 2 is composed of smaller particles than a-RuO 2 seems to be related to the maximum σ value for a certain c-RuO 2 content of the composite electrode.

  13. Fabrication of Functionalized Carbon Nanotube Buckypaper Electrodes for Application in Glucose Biosensors

    PubMed Central

    Papa, Henry; Gaillard, Melissa; Gonzalez, Leon; Chatterjee, Jhunu

    2014-01-01

    A highly sensitive glucose detection method was developed using functionalized carbon nanotube buckypaper as a free standing electrode in an electrochemical biosensor. Glucose oxidase was immobilized onto various buckypaper samples in order to oxidize glucose resulting in a measureable current/voltage signal output of the biosensor. Cyclic voltammetry (CV) and amperometry were utilized to determine the sensitivity of these buckypaper electrodes. Sensors of three different types of buckypaper were prepared and compared. These modified buckypaper electrode-based sensors showed much higher sensitivity to glucose compared to other electrochemical glucose sensors. PMID:25587433

  14. Fabrication of nanocrystalline CdS electrode via chemical bath deposition technique for application to cholesterol sensor

    NASA Astrophysics Data System (ADS)

    Dhyani, Hemant; Srivastava, Saurabh; Azahar Ali, Md; Malhotra, B. D.; Sen, Prasenjit

    2012-04-01

    A nanocystalline CdS electrode has been fabricated by chemical bath deposition (CBD) technique onto hydrolyzed indium tin oxide (ITO) coated glass substrate at 78°C for the immobilization of cholesterol oxidase (ChOx). The prepared Nano-CdS based electrode has been characterized using UV-visible, X-ray diffraction (XRD), Fourier transform-infrared (FTIR) and scanning electron microscopy (SEM). The ChOx/Nano-CdS/ITO bioelectrode shows the detection range of cholesterol from 50 to 400 mg/dl with improved sensitivity of 1.35 μA/mgdl-1/cm2, low detection limit (6.1 mg/dl) and low Km (0.45mM) value indicating strong enzyme (cholesterol oxidase)-matrix (CdS) affinity.

  15. Micropatterning of neural stem cells and Purkinje neurons using a polydimethylsiloxane (PDMS) stencil.

    PubMed

    Choi, Jin Ho; Lee, Hyun; Jin, Hee Kyung; Bae, Jae-sung; Kim, Gyu Man

    2012-12-01

    A new fabrication method of a polydimethylsiloxane (PDMS) stencil embedded microwell plate is proposed and applied to a localized culture of Purkinje neurons (PNs) and neural stem cells (NSCs). A microwell plate combines a PDMS stencil and well plate. The PDMS stencil was fabricated by spin casting from an SU-8 master mold. Gas blowing using nitrogen was adopted to perforate the stencil membrane. An acrylic well plate compartment mold was fabricated using computer numerical control (CNC) machining. By PDMS casting using a stencil placed on an acrylic mold, microwell plates were fabricated without punching or the use of a plasma bonding process. By using the stencil as a physical mask for the cell culture, PNs and NSCs were successfully cultured into micropatterns. The microwell plate could be applied to the localizing and culturing of a cell. The micropatterned NSCs were differentiated into neurons, astrocytes, and oligodendrocytes. The results showed that cells could be cultured and differentiated into micropatterns in a precisely controlled manner in any shape and in specific sizes for bioscience study and bioengineering applications. PMID:23042549

  16. Micropatterning of neural stem cells and Purkinje neurons using a polydimethylsiloxane (PDMS) stencil.

    PubMed

    Choi, Jin Ho; Lee, Hyun; Jin, Hee Kyung; Bae, Jae-sung; Kim, Gyu Man

    2012-12-01

    A new fabrication method of a polydimethylsiloxane (PDMS) stencil embedded microwell plate is proposed and applied to a localized culture of Purkinje neurons (PNs) and neural stem cells (NSCs). A microwell plate combines a PDMS stencil and well plate. The PDMS stencil was fabricated by spin casting from an SU-8 master mold. Gas blowing using nitrogen was adopted to perforate the stencil membrane. An acrylic well plate compartment mold was fabricated using computer numerical control (CNC) machining. By PDMS casting using a stencil placed on an acrylic mold, microwell plates were fabricated without punching or the use of a plasma bonding process. By using the stencil as a physical mask for the cell culture, PNs and NSCs were successfully cultured into micropatterns. The microwell plate could be applied to the localizing and culturing of a cell. The micropatterned NSCs were differentiated into neurons, astrocytes, and oligodendrocytes. The results showed that cells could be cultured and differentiated into micropatterns in a precisely controlled manner in any shape and in specific sizes for bioscience study and bioengineering applications.

  17. Pt metallization of laser transformed medical grade silicone rubber: Last step toward a miniaturized nerve electrode fabrication process

    NASA Astrophysics Data System (ADS)

    Dupas-Bruzek, C.; Dréan, P.; Derozier, D.

    2009-10-01

    Chronic nerve recording and stimulation became possible through the use of implanted electrodes cuffs. In particular, self-sizing spiral electrode cuffs limit mechanical damage to the tissue: these have been shown to be suitable for long term implantation in animal and in man. However, up to now, such electrode cuffs were handmade and were hardly reproducible. They possessed a small number of electrodes (dot contacts), each being linked to its own wire. In order to improve the selectivity of nerve recording and/or stimulation (functional electrical stimulation), the numbers of electrodes and tracks have to be increased within the same electrode cuff surface. To fulfill this requirement, we have developed a fabrication process that uses an UV laser to induce surface modification, which activates the silicone rubber and is used with a mask to give high definition tracks and electrodes. After this primary step, silicone rubber is immersed in a Pt autocatalytic bath leading to a selective Pt metallization of the laser activated tracks and electrodes. We report our process as well as the results on the Pt metallization, including its morphology, how the DC resistance of Pt tracks depends on the laser used and the irradiation conditions, and also the electrical resistance of Pt tracks submitted to Scotch tape tests or to imposed strains. We show that (i) the type of laser and the irradiation conditions have a strong influence on the nucleation and growth rate of platinum and thus on the DC resistance of the tracks, (ii) the tracks of width 400 μm and thickness 10 μm have a sheet resistivity of 0.2 Ω/sq, (iii) DC resistance does not change much during a 6 month soak in saline, (iv) strains above 2% breaks the track continuity, and (v) when strains below 53% are relaxed, the DC resistance returns to a low value. This recovery from large tensile strains means that nerve cuffs with such metallization could be handled by the surgeon without great care before and during

  18. In vitro neurite guidance effects induced by polylysine pinstripe micropatterns with polylysine background.

    PubMed

    Joo, Sunghoon; Kang, Kyungtae; Nam, Yoonkey

    2015-08-01

    Engineered culture substrates with chemical neurite guidance cues have been used for studying the mechanism of axon pathfinding at cellular level. In this study, we designed a novel poly-l-lysine (PLL) micropattern ("pinstripe micropattern") to investigate how the same biomolecules with slightly different surface concentration can affect in vitro neuronal growth. The pinstripe micropattern was fabricated by stamping PLL on a PLL-coated glass coverslip, which resulted in denser PLL lines and a less-dense PLL background. There were two effects of the substrate on cultured primary hippocampal neuron: neurite initiation and growth cone turning. Although the whole surface was permissive for neurite outgrowth, we observed that the growth direction of neurites had a strong tendency to follow the stamped PLL line patterns with PLL background. However, the micropattern did not affect the spreading of cell body on the substrate. According to these investigations, we concluded that the PLL pinstripe pattern with PLL background, which had the step difference of polylysine concentrations, would be very useful for designing novel cell assays for the investigation of neurite guidance mechanisms, and suggested it as a new design method for controlling the direction of neurite growth on in vitro neural network.

  19. Direct immobilization of biotin on the micro-patterned PEN foil treated by excimer laser.

    PubMed

    Štofik, Marcel; Semerádtová, Alena; Malý, Jan; Kolská, Zdeňka; Neděla, Oldřich; Wrobel, Dominika; Slepička, Petr

    2015-04-01

    Polymers with functionalized surfaces have attracted a lot of attention in the last few years. Due to the progress in the techniques of polymer micro-patterning, miniaturized bioanalytical assays and biocompatible devices can be developed. In the presented work, we performed surface modification of polyethylene naphthalate (PEN) foil by an excimer laser beam through a photolithographic contact mask. The aim was to fabricate micro-patterned areas with surface functional groups available for localized covalent immobilization of biotin. It was found out that depending on the properties of the laser scans, a polymer surface exhibits different degrees of modification and as a consequence, different degrees of surface biotinylation can be achieved. Several affinity tests with optical detection of fluorescently labeled streptavidin were successfully performed on biotinylated micro-patterns of a PEN foil. The polymer surface properties were also evaluated by electrokinetic analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results have shown that PEN foils can be considered suitable substrates for construction of micro-patterned bioanalytical affinity assays.

  20. Modeling cell shape and dynamics on micropatterns

    PubMed Central

    Albert, Philipp J.; Schwarz, Ulrich S.

    2016-01-01

    ABSTRACT Adhesive micropatterns have become a standard tool to study cells under defined conditions. Applications range from controlling the differentiation and fate of single cells to guiding the collective migration of cell sheets. In long-term experiments, single cell normalization is challenged by cell division. For all of these setups, mathematical models predicting cell shape and dynamics can guide pattern design. Here we review recent advances in predicting and explaining cell shape, traction forces and dynamics on micropatterns. Starting with contour models as the simplest approach to explain concave cell shapes, we move on to network and continuum descriptions as examples for static models. To describe dynamic processes, cellular Potts, vertex and phase field models can be used. Different types of model are appropriate to address different biological questions and together, they provide a versatile tool box to predict cell behavior on micropatterns. PMID:26838278

  1. Fabrication of ordered NiO coated Si nanowire array films as electrodes for a high performance lithium ion battery.

    PubMed

    Qiu, M C; Yang, L W; Qi, X; Li, Jun; Zhong, J X

    2010-12-01

    Highly ordered NiO coated Si nanowire array films are fabricated as electrodes for a high performance lithium ion battery via depositing Ni on electroless-etched Si nanowires and subsequently annealing. The structures and morphologies of as-prepared films are characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. When the potential window versus lithium was controlled, the coated NiO can be selected to be electrochemically active to store and release Li+ ions, while highly conductive crystalline Si cores function as nothing more than a stable mechanical support and an efficient electrical conducting pathway. The hybrid nanowire array films exhibit superior cyclic stability and reversible capacity compared to that of NiO nanostructured films. Owing to the ease of large-scale fabrication and superior electrochemical performance, these hybrid nanowire array films will be promising anode materials for high performance lithium-ion batteries.

  2. On-chip metal/polypyrrole quasi-reference electrodes for robust ISFET operation.

    PubMed

    Duarte-Guevara, Carlos; Swaminathan, Vikhram V; Burgess, Mark; Reddy, Bobby; Salm, Eric; Liu, Yi-Shao; Rodriguez-Lopez, Joaquin; Bashir, Rashid

    2015-05-21

    To operate an ion-sensitive field-effect transistor (ISFETs) it is necessary to set the electrolyte potential using a reference electrode. Conventional reference electrodes are bulky, fragile, and too big for applications where the electrolyte volume is small. Several researchers have proposed tackling this issue using a solid-state planar micro-reference electrode or a reference field-effect transistor. However, these approaches are limited by poor robustness, high cost, or complex integration with other microfabrication processes. Here we report a simple method to create robust on-chip quasi-reference electrodes by electrodepositing polypyrrole on micro-patterned metal leads. The electrodes were fabricated through the polymerization of pyrrole on patterned metals with a cyclic voltammetry process. Open circuit potential measurements were performed to characterize the polypyrrole electrode performance, demonstrating good stability (±1 mV), low drift (∼1 mV h(-1)), and reduced pH response (5 mV per pH). In addition, the polypyrrole deposition was repeated in microelectrodes made of different metals to test compatibility with standard complementary metal-oxide-semiconductor (CMOS) processes. Our results suggest that nickel, a metal commonly used in semiconductor foundries for silicide formation, is a good candidate to form the polypyrrole quasi-reference electrodes. Finally, the polypyrrole microelectrodes were used to operate foundry fabricated ISFETs. These experiments demonstrated that transistors biased with polypyrrole electrodes have pH sensitivity and resolution comparable to ones that are biased with standard reference electrodes. Therefore, the simple fabrication, high compatibility, and robust electrical performance make polypyrrole an ideal choice for the fabrication of outstanding microreference electrodes that enable robust and sensitive operation of multiple ISFET sensors on a chip. PMID:25869990

  3. Ultrathin MXene-Micropattern-Based Field-Effect Transistor for Probing Neural Activity.

    PubMed

    Xu, Bingzhe; Zhu, Minshen; Zhang, Wencong; Zhen, Xu; Pei, Zengxia; Xue, Qi; Zhi, Chunyi; Shi, Peng

    2016-05-01

    A field-effect transistor (FET) based on ultrathin Ti3 C2 -MXene micropatterns is developed and utilized as a highly sensitive biosensor. The device is produced with the microcontact printing technique, making use of its unique advantages for easy fabrication. Using the MXene-FET device, label-free probing of small molecules in typical biological environments and fast detection of action potentials in primary neurons is demonstrated. PMID:26924616

  4. Fabrication of CuO nanosheets modified Cu electrode and its excellent electrocatalytic performance towards glucose

    NASA Astrophysics Data System (ADS)

    Tian, Liangliang; Liu, Bitao

    2013-10-01

    Glucose (Glu) detection is of great importance in the fields of biological, environmental, and clinical analyses. In this study, CuO nanosheets (NSs) electrode prepared by a one-step synthesis route was applied to construct nonenzymatic glucose biosensor. The as-prepared CuO NSs were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Electrocatalytic oxidation of the CuO NSs electrode towards glucose was studied by cyclic voltammetry (CV) and chronoamperometry. For the amperometric glucose detection, the low detection limit of 0.8 μM (S/N = 3) with linear range from 0.8 μM to 2200 μM can be obtained using the CuO NSs electrode. Under the applied potential of 0.5 V vs. Ag/AgCl, the CuO NSs electrode exhibits a high sensitivity of 2792.64 μA mM-1 cm-2. It is believed that CuO NSs electrode is a promising material for the development of nonenzymatic electrochemical glucose sensors.

  5. Transparent aluminium nanowire electrodes with optical and electrical anisotropic response fabricated by defocused ion beam sputtering

    NASA Astrophysics Data System (ADS)

    Repetto, Diego; Giordano, Maria Caterina; Martella, Christian; Buatier de Mongeot, Francesco

    2015-02-01

    Self-organized Al nanowire (NW) electrodes have been obtained by defocused Ion Beam Sputtering (IBS) of polycrystalline Al films grown by sputter deposition. The electrical sheet resistance of the electrode has been acquired in situ during ion bombardment of the samples, evidencing an increase of the electronic transport anisotropy as a function of ion fluence between the two directions parallel and orthogonal to the NWs axis. Optical spectra in transmission also show a large dichroism between the two directions, suggesting the role of localized plasmons in the UV spectral range. The results show that Al NW electrodes, prepared under experimental conditions which are compatible with those of conventional industrial coaters and implanters, could represent a low cost alternative to the transparent conductive oxides employed in optoelectronic devices.

  6. Carbon Fiber/Epoxy Composite Ring-disk Electrode: Fabrication, Characterization and Application to Electrochemical Detection in Capillary High Performance Liquid Chromatography.

    PubMed

    Xu, Xiaomi; Weber, Stephen G

    2009-05-15

    Carbon fiber/epoxy composite materials, which are manufactured using the pultrusion process, are commercially available in various shapes and sizes at very low cost. Here we demonstrate the application of such a material as an electrochemical detector in a flow system. Cyclic voltammetry shows that the material's electrochemical behavior resembles that of glassy carbon. Using tube and rod composites, we successfully fabricated a ring-disk electrode with a 20 μm gap between the ring and the disk. The narrow gap is favorable for mass transfer in the generator-collector experiment. This composite ring-disk electrode is assembled in a thin-layer radial-flow cell and used as an electrochemical detector. The disk electrode, placed directly opposite to the flow inlet, is operated as a generator electrode with the ring electrode being a collector. The high collection efficiency on the ring electrode (0.8 for a chemically reversible species) enhances the detection selectivity.

  7. Carbon Fiber/Epoxy Composite Ring-disk Electrode: Fabrication, Characterization and Application to Electrochemical Detection in Capillary High Performance Liquid Chromatography

    PubMed Central

    Xu, Xiaomi

    2009-01-01

    Carbon fiber/epoxy composite materials, which are manufactured using the pultrusion process, are commercially available in various shapes and sizes at very low cost. Here we demonstrate the application of such a material as an electrochemical detector in a flow system. Cyclic voltammetry shows that the material's electrochemical behavior resembles that of glassy carbon. Using tube and rod composites, we successfully fabricated a ring-disk electrode with a 20 μm gap between the ring and the disk. The narrow gap is favorable for mass transfer in the generator-collector experiment. This composite ring-disk electrode is assembled in a thin-layer radial-flow cell and used as an electrochemical detector. The disk electrode, placed directly opposite to the flow inlet, is operated as a generator electrode with the ring electrode being a collector. The high collection efficiency on the ring electrode (0.8 for a chemically reversible species) enhances the detection selectivity. PMID:20160941

  8. Nano-fabricated perpendicular magnetic anisotropy electrodes for lateral spin valves and observation of Nernst-Ettingshausen related signals

    SciTech Connect

    Chejanovsky, N.; Sharoni, A.

    2014-08-21

    Lateral spin valves (LSVs) are efficient structures for characterizing spin currents in spintronics devices. Most LSVs are based on ferromagnetic (FM) electrodes for spin-injection and detection. While there are advantages for using perpendicular magnetic anisotropy (PMA) FM, e.g., stability to nano-scaling, these have almost not been studied. This is mainly due to difficulties in fabricating PMA FMs in a lateral geometry. We present here an efficient method, based on ion-milling through an AlN mask, for fabrication of LSVs with multi-layered PMA FMs such as Co/Pd and Co/Ni. We demonstrate, using standard permalloy FMs, that the method enables efficient spin injection. We show the multi-layer electrodes retain their PMA properties as well as spin injection and detection in PMA LSVs. In addition, we find a large asymmetric voltage signal which increases with current. We attribute this to a Nernst-Ettingshausen effect caused by local Joule heating and the perpendicular magnetic easy axis.

  9. Removal characteristics of plasma chemical vaporization machining with a pipe electrode for optical fabrication

    SciTech Connect

    Takino, Hideo; Yamamura, Kazuya; Sano, Yasuhisa; Mori, Yuzo

    2010-08-10

    Plasma chemical vaporization machining (CVM) is a high-precision chemical shaping method using rf plasma generated in the proximity of an electrode in an atmospheric environment. The purpose of the present study is to clarify the removal characteristics of plasma CVM using a pipe electrode. Polished fused silica plates were processed by plasma CVM, polishing, and precision grinding under various conditions. The removal rate of plasma CVM was about 4 to 1100 times faster than that of polishing, and the maximum removal rate was almost equal to that of precision grinding. The roughness of the resultant surfaces was almost the same as that of the polished surfaces.

  10. Graphitized-Carbon-Nanofiber Paper-Enzyme Electrode Fabrication Through Non-Covalent Modification for Enzyme Biofuel Cell Application.

    PubMed

    Fapyane, Deby; Lee, Soo-Jin; Kang, Seung-Hwan; Ahn, Jou-Hyeon; Chang, In Seop

    2015-01-01

    Carbon nanofibers are an emerging smart material that are promising for use as a biosensor and a biofuel cell transducer material due to their morphological and electrochemical characteristics. In particular, graphitized carbon nanofibers possess unique structures of graphite-like edges within their high surface area that provide a large active site for enzyme attachment. For a specific application such as a biofuel cell, which requires highly stable electrical communication and electricity generation, non-covalent enzyme immobilization using bifunctional molecule is suggested as an appropriate approach because it does not change the carbon hybridization from sp2 to sp3 as covalent immobilization by acid treatment does. Graphitized carbon-nanofiber paper (GCNFp) electrode were fabricated through dispersion-filtration method in which glucose oxidase as model enzyme were immobilized by a bifunctional molecule that forms π-π stacking of the pyrene moiety with the nanofiber wall coupled by a reactive end-amine reaction. This system provides a practical enzyme-electrode hybrid that facilitates comparatively faster enzyme-electrode electrical communication than other system using similar material, as calculated from the heterogeneous electron-transfer rate constant (K(s)) which was 5.45 s(-1). PMID:26301307

  11. A top-down approach for fabricating free-standing bio-carbon supercapacitor electrodes with a hierarchical structure.

    PubMed

    Li, Yingzhi; Zhang, Qinghua; Zhang, Junxian; Jin, Lei; Zhao, Xin; Xu, Ting

    2015-01-01

    Biomass has delicate hierarchical structures, which inspired us to develop a cost-effective route to prepare electrode materials with rational nanostructures for use in high-performance storage devices. Here, we demonstrate a novel top-down approach for fabricating bio-carbon materials with stable structures and excellent diffusion pathways; this approach is based on carbonization with controlled chemical activation. The developed free-standing bio-carbon electrode exhibits a high specific capacitance of 204 F g(-1) at 1 A g(-1); good rate capability, as indicated by the residual initial capacitance of 85.5% at 10 A g(-1); and a long cycle life. These performance characteristics are attributed to the outstanding hierarchical structures of the electrode material. Appropriate carbonization conditions enable the bio-carbon materials to inherit the inherent hierarchical texture of the original biomass, thereby facilitating effective channels for fast ion transfer. The macropores and mesopores that result from chemical activation significantly increase the specific surface area and also play the role of temporary ion-buffering reservoirs, further shortening the ionic diffusion distance. PMID:26394834

  12. Graphene-epoxy composite electrode fabricated by in situ polycondensation for enhanced amperometric detection in capillary electrophoresis.

    PubMed

    Tang, Dengfeng; Ma, Guo; Zhang, Luyan; Chen, Gang

    2013-11-01

    This report describes the development and application of a novel graphene-epoxy composite electrode as a sensitive amperometric detector of capillary electrophoresis. The composite electrode was fabricated on the basis of the in situ polycondensation of a mixture of graphene and 1,2-ethanediamine-containing bisphenol A epoxy resin in the inner bore of a piece of fused silica capillary under heat. The structure of the material was investigated by scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and Fourier transform infrared spectroscopy. The results indicated that graphene sheets were well dispersed and interconnected throughout the composite to form an electrically conductive network. The performance of this unique electrode was demonstrated by separating and detecting two naturally occurring phenolic compounds in rosemary in combination with capillary electrophoresis. The graphene-based detector offered significantly lower operating potentials, higher sensitivity, satisfactory resistance to surface fouling, and lower expense of operation, indicating great promise for a wide range of applications. PMID:24119752

  13. A top-down approach for fabricating free-standing bio-carbon supercapacitor electrodes with a hierarchical structure

    PubMed Central

    Li, Yingzhi; Zhang, Qinghua; Zhang, Junxian; Jin, Lei; Zhao, Xin; Xu, Ting

    2015-01-01

    Biomass has delicate hierarchical structures, which inspired us to develop a cost-effective route to prepare electrode materials with rational nanostructures for use in high-performance storage devices. Here, we demonstrate a novel top-down approach for fabricating bio-carbon materials with stable structures and excellent diffusion pathways; this approach is based on carbonization with controlled chemical activation. The developed free-standing bio-carbon electrode exhibits a high specific capacitance of 204 F g−1 at 1 A g−1; good rate capability, as indicated by the residual initial capacitance of 85.5% at 10 A g−1; and a long cycle life. These performance characteristics are attributed to the outstanding hierarchical structures of the electrode material. Appropriate carbonization conditions enable the bio-carbon materials to inherit the inherent hierarchical texture of the original biomass, thereby facilitating effective channels for fast ion transfer. The macropores and mesopores that result from chemical activation significantly increase the specific surface area and also play the role of temporary ion-buffering reservoirs, further shortening the ionic diffusion distance. PMID:26394834

  14. Fabrication of graphene/gold-modified screen-printed electrode for detection of carcinoembryonic antigen.

    PubMed

    Chan, K F; Lim, H N; Shams, N; Jayabal, S; Pandikumar, A; Huang, N M

    2016-01-01

    Immunosensors based on gold nanoparticles and reduced graphene oxide (AuNPs/rGO)-modified screen-printed electrodes (SPEs) were successfully synthesized using an electrochemical deposition method. The modified SPEs were characterized using a field emission scanning electron microscope (FESEM) and Raman spectroscopy to analyze the morphology and composition of AuNPs and rGO. Both the FESEM and Raman spectroscopy revealed that the AuNPs were successfully anchored on the thin film of rGO deposited on the surface of the SPEs. Characterization with a ferri-ferrocyanide couple [Fe(CN)6(3-/4-)] showed that the electron transfer kinetic between the analyte and electrode was enhanced after the modification with the AuNPs/rGO composite on the electrode surface, in addition to increasing the effective surface area of the electrode. The modified SPE was immobilized with a sandwich type immunosensor to mimic the ELISA (enzyme-linked immunosorbent assay) immunoassay. The modified SPE that was fortified with the sandwich type immunosensor exhibited double electrochemical responses in the detection of carcinoembryonic antigen (CEA), with linear ranges of 0.5-50 ng/mL and 250-2000 ng/mL and limits of detection of 0.28 ng/mL and 181.5 ng/mL, respectively. PMID:26478358

  15. Surface oxygen micropatterns on glow discharge polymer targets by photo irradiation

    NASA Astrophysics Data System (ADS)

    Reynolds, Hannah; Baxamusa, Salmaan; Haan, Steven W.; Fitzsimmons, Paul; Carlson, Lane; Farrell, Mike; Nikroo, Abbas; Watson, Brian J.

    2016-02-01

    Recent simulations predict surface oxygen may be a significant source of disruptive perturbations in the implosion process of glow-discharge polymers (GDP) ablators at the National Ignition Facility. GDP material held in ambient atmospheric conditions showed an increase in mass when stored in light transparent containers, which suggests that photo exposure is a driving force for oxygen absorption. To investigate if surface oxygen is a contributing factor of disruptive perturbations during implosion, a method to imprint a periodic micropattern of oxygen on the surface of GDP was developed and used to fabricate a flat sample for empirical testing. Photo exposure using collimated blue light was used to generate micropatterns of surface oxygen on the GDP material. The periodic oxygen micropattern was confirmed by secondary ion mass spectrometry (SIMS) and energy dispersive spectroscopy. A SIMS depth profile showed the atomic percent of oxygen ranged from 8 at. % near the surface to 1 at. % at a depth of 2 μm in a sample exposed for 4 min. The molecular interactions formed between the GDP and oxygen molecules were characterized using Fourier transform infrared resonance (FTIR), which showed the formation of hydroxyl (O-H) and carbonyl (C=O) bonds. The FTIR enabled the oxygen mass uptake as a function of photo exposure time to be quantified (resolved to typically 0.05 at. % oxygen). This experimental protocol was then applied to produce a GDP flat part with a periodic 75 μm wavelength micropattern of photo exposed (oxygen rich) and masked (oxygen deficient) regions. The micropatterned GDP ablators developed in this work are being used to assess the effect of surface oxygen on disruptive perturbations during the inertial confinement fusion implosion process.

  16. Nano-level monitoring of Mn(2+) ion by fabrication of coated pyrolytic graphite electrode based on isonicotinohydrazide derivatives.

    PubMed

    Sahani, Manoj Kumar; Singh, A K; Jain, A K

    2015-05-01

    The two ionophores N'(N',N‴E,N',N‴E)-N',N‴-((((oxybis(ethane-2,1-diyl))bis(oxy)) bis(2,1-phenylene))bis(methanylylidene))di(isonicotinohydrazide) (I1) and (N',N‴E,N',N‴E)-N',N‴-(((propane-1,3-diylbis(oxy))bis(2,1-phenylene))bis(methanylylidene))di(isonicotinohydrazide) (I2) were synthesised and investigated as neutral carrier in the fabrication of Mn(2+) ion selective sensor. Several membranes were prepared by incorporating different plasticizers and anionic excluders and their effect on potentiometric response was studied. The best analytical performance was obtained with the electrode having a membrane of composition of I2: PVC: o-NPOE: NaTPB in the ratio of 6:34:58:2 (w/w, mg). Comparative studies of coated graphite electrode (CGE) and coated pyrolytic graphite electrode (CPGE) based on I2 reveal the superiority of CPGE. The CPGE exhibits wide working concentration range of 1.23×10(-8)-1.0×10(-1) mol L(-1) and a detection limit down to 4.78×10(-9) mol L(-1) with a Nernstian slope of 29.5±0.4 mV decade(-1) of activity. The sensor performs satisfactorily over a wide pH range (3.5-9.0) and exhibited a quick response time (9s). The sensor can work satisfactorily in water-acetonitrile and water-methanol mixtures. It can tolerate 30% acetonitrile and 20% methanol content in the mixtures. The sensor could be used for a period of four months without any significant divergence in performance. The sensor reflects its utility in the quantification of Mn(2+) ion in real samples and has been successfully employed as an indicator electrode in the potentiometric titration of Mn(2+) ion with ethylenediaminetetraacetic acid (EDTA).

  17. Nano-level monitoring of Mn(2+) ion by fabrication of coated pyrolytic graphite electrode based on isonicotinohydrazide derivatives.

    PubMed

    Sahani, Manoj Kumar; Singh, A K; Jain, A K

    2015-05-01

    The two ionophores N'(N',N‴E,N',N‴E)-N',N‴-((((oxybis(ethane-2,1-diyl))bis(oxy)) bis(2,1-phenylene))bis(methanylylidene))di(isonicotinohydrazide) (I1) and (N',N‴E,N',N‴E)-N',N‴-(((propane-1,3-diylbis(oxy))bis(2,1-phenylene))bis(methanylylidene))di(isonicotinohydrazide) (I2) were synthesised and investigated as neutral carrier in the fabrication of Mn(2+) ion selective sensor. Several membranes were prepared by incorporating different plasticizers and anionic excluders and their effect on potentiometric response was studied. The best analytical performance was obtained with the electrode having a membrane of composition of I2: PVC: o-NPOE: NaTPB in the ratio of 6:34:58:2 (w/w, mg). Comparative studies of coated graphite electrode (CGE) and coated pyrolytic graphite electrode (CPGE) based on I2 reveal the superiority of CPGE. The CPGE exhibits wide working concentration range of 1.23×10(-8)-1.0×10(-1) mol L(-1) and a detection limit down to 4.78×10(-9) mol L(-1) with a Nernstian slope of 29.5±0.4 mV decade(-1) of activity. The sensor performs satisfactorily over a wide pH range (3.5-9.0) and exhibited a quick response time (9s). The sensor can work satisfactorily in water-acetonitrile and water-methanol mixtures. It can tolerate 30% acetonitrile and 20% methanol content in the mixtures. The sensor could be used for a period of four months without any significant divergence in performance. The sensor reflects its utility in the quantification of Mn(2+) ion in real samples and has been successfully employed as an indicator electrode in the potentiometric titration of Mn(2+) ion with ethylenediaminetetraacetic acid (EDTA). PMID:25746253

  18. Micropatterned Surfaces with Controlled Ligand Tethering

    PubMed Central

    Petrie, Timothy A.; Stanley, Brandon T.; García, Andrés J.

    2008-01-01

    Microcontact printing (μ-CP) is a facile, cost-effective, and versatile soft-lithography technique to create 2-dimensional patterns of domains with distinct functionalities that provides a robust platform to generate micropatterned biotechnological arrays and cell culture substrates. Current μ-CP approaches rely on non-specific immobilization of biological ligands, either by direct printing or adsorption from solution, onto micropatterned domains surrounded by a non-fouling background. This technique is limited by insufficient control over ligand density. We present a modified μ-CP protocol involving stamping mixed ratios of carboxyl- and tri(ethylene glycol)-terminated alkanethiols that provides for precise covalent tethering of single or multiple ligands to prescribed micropatterns via standard peptide chemistry. Processing parameters were optimized to identify conditions that control relevant endpoint pattern characteristics. This technique provides a facile method to generate micropatterned arrays with tailorable and controlled presentation of biological ligands for biotechnological applications and analyses of cell-material interactions. PMID:18570314

  19. Fabrication and characterization of protonic-ceramic fuel cells and electrolysis cells utilizing infiltrated lanthanum nickelate electrodes

    NASA Astrophysics Data System (ADS)

    Babiniec, Sean M.

    High-temperature protonic ceramics (HTPCs) have gained interest as fuel cell and electrolysis cell electrolytes, as well as hydrogen separation membranes. The transport of hydrogen as opposed to oxygen results in several benefits and applications, including higher fuel efficiency, dehydrogenation of fuel streams, and hydrogen-based chemical synthesis. However, limited work has been done in the development of air/steam electrodes for these devices. This work presents the characterization of lanthanum nickelate, La 2NiO4+delta (LN), as a potential air/steam electrode material for use with BaCe0.2Zr0.7Y0.1O3-delta (BCZY27) HTPC electrolytes fabricated by the solid-state reactive sintering technique. Two types of devices were made; a symmetric cell used for electrode characterization, and a full fuel cell/electrolysis cell used for device performance characterization. The symmetric cell consists of a 1 mm thick BCZY27 substrate with identical air/steam electrodes on both sides. Air/steam electrodes were made by infiltrating ˜ 50 nm lanthanum nickelate nanoparticles into a BCZY27 porous backbone. The fuel cell/electrolysis cell consists of a 1mm thick Ni/BCZY27 anode support, a 25 mum thick BCZY27 electrolyte, and a 50 mum thick porous BCZY27 backbone infiltrated with lanthanum nickelate. Through symmetric cell testing, it was found that the electrode polarization resistance decreases with increasing oxygen content, indicating good oxygen reduction reaction characteristics. A minimum polarization resistance was found as 2.58 Ohm-cm2 in 3% humidied oxygen at 700 °C. Full cell testing revealed a peak power density of 27 mW-cm-2 at 700 °C. Hydrogen flux measurements were also taken in the both galvanic/post-galvanic and electrolytic operation. Galvanic/post-galvanic fluxes exhibit a very high faradaic efficiency. However, electrolytic hydrogen fluxes were much lower than the calculated hydrogen faradaic flux, indicating a different charge carrier other than protons is

  20. Direct top-down fabrication of nanoscale electrodes for organic semiconductors using fluoropolymer resists

    NASA Astrophysics Data System (ADS)

    Park, Jungho; Ho, Jonathan; Yun, Hoyeol; Park, Myeongjin; Lee, Jung Hyun; Seo, Miri; Campbell, Eleanor E. B.; Lee, Changhee; Pyo, Seungmoon; Lee, Sang Wook

    2013-06-01

    We report the use of a fluoropolymer resist for the damage-free e-beam lithographic patterning of organic semiconductors. The same material is also shown to be suitable as an orthogonal electron beam resist for the patterning of top-contact electrodes on organic thin films. We demonstrate this by characterizing pentacene field-effect transistors with feature sizes as small as 100 nm and compare the performance of bottom- and top-contacted devices.

  1. Surface micropattern limits bacterial contamination

    PubMed Central

    2014-01-01

    Background Bacterial surface contamination contributes to transmission of nosocomial infections. Chemical cleansers used to control surface contamination are often toxic and incorrectly implemented. Additional non-toxic strategies should be combined with regular cleanings to mitigate risks of human error and further decrease rates of nosocomial infections. The Sharklet micropattern (MP), inspired by shark skin, is an effective tool for reducing bacterial load on surfaces without toxic additives. The studies presented here were carried out to investigate the MP surfaces capability to reduce colonization of methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) compared to smooth control surfaces. Methods The MP and smooth surfaces produced in acrylic film were compared for remaining bacterial contamination and colonization following inoculation. Direct sampling of surfaces was carried out after inoculation by immersion, spray, and/or touch methods. Ultimately, a combination assay was developed to assess bacterial contamination after touch transfer inoculation combined with drying (persistence) to mimic common environmental contamination scenarios in the clinic or hospital environment. The combination transfer and persistence assay was then used to test antimicrobial copper beside the MP for the ability to reduce MSSA and MRSA challenge. Results The MP reduced bacterial contamination with log reductions ranging from 87-99% (LR = 0.90-2.18; p < 0.05) compared to smooth control surfaces. The MP was more effective than the 99.9% pure copper alloy C11000 at reducing surface contamination of S. aureus (MSSA and MRSA) through transfer and persistence of bacteria. The MP reduced MSSA by as much as 97% (LR = 1.54; p < 0.01) and MRSA by as much as 94% (LR = 1.26; p < 0.005) compared to smooth controls. Antimicrobial copper had no significant effect on MSSA contamination, but reduced MRSA contamination by 80% (LR

  2. FABRICATION OF LATERAL ORGANIC SPIN VALVES BASED ON La0.7Sr0.3MnO3 ELECTRODES

    NASA Astrophysics Data System (ADS)

    Jiang, S. W.; Wang, P.; Jiang, S. C.; Chen, B. B.; Wang, M.; Jiang, Z. S.; Wu, D.

    2014-06-01

    We report the successful fabrication of lateral organic spin valves (OSVs) using polycrystalline pentacene as spacer and half-metallic La0.7Sr0.3MnO3 (LSMO) as two electrodes. The distance between two electrodes ranges from 30 nm to 100 nm. The current-voltage characteristics follow the power law relation, which are attributed to the space charge limited current behavior. The devices with a spacing of 30 nm exhibits clear spin-valve characteristics with a magnetoresistance (MR) ratio of 2% at 9 K. The MR effects disappear for electrode spacing about 100 nm, suggesting that the spin diffusion length is less than 100 nm.

  3. PDMS bonding to a bio-friendly photoresist via self-polymerized poly(dopamine) adhesive for complex protein micropatterning inside microfluidic channels.

    PubMed

    Kim, Miju; Song, Kwang Hoon; Doh, Junsang

    2013-12-01

    Protein micropatterned surfaces integrated with microfluidics are useful in numerous bioanalytical and biological applications. In this study, we demonstrated the fabrication of complex protein micropatterned surfaces within poly(dimethylsiloxane) (PDMS) microfluidic channels by attaching the PDMS channels to bio-friendly photoresist films and subsequently performing microscope projection photolithography (MPP). A muscle-inspired poly(dopamine) (PDA) coating was employed to mediate the bonding between the PDMS and the bio-friendly photoresist poly(2,2-dimethoxy nitrobenzyl methacrylate-r-methyl methacrylate-r-poly(ethylene glycol) methacrylate) (PDMP). By adjusting the dip-coating time for the PDA coating, we could successfully introduce sufficient amounts of functional groups on the PDMP surfaces to mediate strong bonding between the PDMS channels and the PDA-coated PDMP thin films with minimal alteration of the surface properties of the PDMP thin films that are critical for protein micropatterning. Using this novel bonding strategy, we successfully fabricated multiple protein micropatterns and gradient micropatterns of proteins within microfluidic channels. The technique developed in this study will be useful for the fabrication of complex biochips for multiplex bioassays and fundamental cell biological studies.

  4. Interdigitated 50 nm Ti electrode arrays fabricated using XeF2 enhanced focused ion beam etching

    NASA Astrophysics Data System (ADS)

    Santschi, Ch; Jenke, M.; Hoffmann, P.; Brugger, J.

    2006-06-01

    The fabrication of interdigitated titanium nanoelectrode arrays of 50 nm in width and spacing is described in this work. The nanoarrays have been realized using a Ga+ focused ion beam (FIB). FIB milling is typically accompanied by redeposition of removed material, which represents an important hindrance for milling closely spaced nanostructures. Redeposition effects have been reduced by means of XeF2 gas assistance, which increases the etch yield by a factor of seven compared with pure ion milling. Furthermore, we used a simple adsorption model, which led to the conclusion that dwell time and refresh time should be <500 ns and >30 ms, respectively, for optimized XeF2 assisted Ti milling. The measured resistance R of the electrodes is higher than 1 GΩ.

  5. A facile electrochemical fabrication of hierarchically structured nickel-copper composite electrodes on nickel foam for hydrogen evolution reaction

    NASA Astrophysics Data System (ADS)

    Yin, Zuwei; Chen, Fuyi

    2014-11-01

    A NiCu composite electrode with hierarchical structure has been successfully fabricated by an electrochemical method, which consisted of galvanic replacement reaction (GRR), activation process and cyclic voltammetry (CV) treatment. The three-dimensional (3D) Ni-Cu precursors were prepared firstly by dipping Ni foam into three kinds of different copper ion solutions and identified that CuCl2 is a favorite electrolyte. This may be attributed to the adsorption of chloride ion on copper surface to form the CuCln1-n complex and the hydrolysis of CuCln1-n. After an activation process to reduce the hydrolytic product Cu2O into Cu, a CV treatment was performed to form a hierarchical structure to improve the surface area and to heighten the hydrogen evolution reaction (HER) activity. The optimal number of CV cycles is 3.

  6. Flexible, Transparent and Conductive Carbon Nanotube Aerogels /PEDOT:PSS Electrodes created by Top-bottom Fabrication

    NASA Astrophysics Data System (ADS)

    Martinez, Patricia M.; Cerdan Pasaran, Andrea; Zakhidov, Anvar; University of Guanajuato, Mexico Collaboration

    The sheets of Carbon Nanotubes (CNT) have proven to be a good substitute for ITO. To improve their conductivity and increase optical transparency we have created composites which incorporate silver nanowires or other evaporated metals. Coating CNT/metals with PEDOT:PSS is important for creating hole transport/electron barrier layer functionality, but it is not easy to achieve using PEDOT:PSS solutions due to the hydrophobicity of CNT. We report a new top-to-bottom approach for the fabrication of highly flexible, transparent and conductive carbon nanotube-based electrodes using PDMS as a substrate. A uniform and smooth layer of approximately 50 nm of PEDOT:PSS was spin coated on top of a PDMS stamp followed by the deposition of vapor densified freestanding Multiwall Carbon Nanotube (MWNT) aerogels. An incorporation of silver nanowires, silver or Aluminum thin layer can be sprayed or evaporated on top of the freestanding MWNT aerogels in order to lower the sheet resistance even further. The PDMS substrate is drop cast on top of the configuration then the PDMS stamp is lifted-up. The PEDOT:PSS layer is selectively deposited on top of the MWNT only. The composite electrodes can be laminated on photovoltaic devices and on LEDs.

  7. Fabrication of Oxidation-Resistant Metal Wire Network-Based Transparent Electrodes by a Spray-Roll Coating Process.

    PubMed

    Kiruthika, S; Gupta, Ritu; Anand, Aman; Kumar, Ankush; Kulkarni, G U

    2015-12-16

    Roll and spray coating methods have been employed for the fabrication of highly oxidation resistant transparent and conducting electrodes (TCEs) by a simple solution process using crackle lithography technique. We have spray-coated a crackle paint-based precursor to produce highly interconnected crackle network on PET roll mounted on a roll coater with web speed of 0.6 m/min. Ag TCE with a transmittance of 78% and sheet resistance of ∼20 Ω/□ was derived by spraying Ag precursor ink over the crackle template followed by lift-off and annealing under ambient conditions. The Ag wire mesh was stable toward bending and sonication tests but prone to oxidation in air. When electrolessly coated with Pd, its robustness toward harsh oxidation conditions was enhanced. A low-cost transparent electrode has also been realized by using only small amounts of Ag as seed layer and growing Cu wire mesh by electroless method. Thus, made Ag/Cu meshes are found to be highly stable for more than a year even under ambient atmosphere. PMID:26580415

  8. A highly oriented hybrid microarray modified electrode fabricated by a template-free method for ultrasensitive electrochemical DNA recognition.

    PubMed

    Shi, Lei; Chu, Zhenyu; Dong, Xueliang; Jin, Wanqin; Dempsey, Eithne

    2013-11-01

    Highly oriented growth of a hybrid microarray was realized by a facile template-free method on gold substrates for the first time. The proposed formation mechanism involves an interfacial structure-directing force arising from self-assembled monolayers (SAMs) between gold substrates and hybrid crystals. Different SAMs and variable surface coverage of the assembled molecules play a critical role in the interfacial directing forces and influence the morphologies of hybrid films. A highly oriented hybrid microarray was formed on the highly aligned and vertical SAMs of 1,4-benzenedithiol molecules with rigid backbones, which afforded an intense structure-directing power for the oriented growth of hybrid crystals. Additionally, the density of the microarray could be adjusted by controlling the surface coverage of assembled molecules. Based on the hybrid microarray modified electrode with a large specific area (ca. 10 times its geometrical area), a label-free electrochemical DNA biosensor was constructed for the detection of an oligonucleotide fragment of the avian flu virus H5N1. The DNA biosensor displayed a significantly low detection limit of 5 pM (S/N = 3), a wide linear response from 10 pM to 10 nM, as well as excellent selectivity, good regeneration and high stability. We expect that the proposed template-free method can provide a new reference for the fabrication of a highly oriented hybrid array and the as-prepared microarray modified electrode will be a promising paradigm in constructing highly sensitive and selective biosensors.

  9. Graphene/polyaniline woven fabric composite films as flexible supercapacitor electrodes.

    PubMed

    Zang, Xiaobei; Li, Xiao; Zhu, Miao; Li, Xinming; Zhen, Zhen; He, Yijia; Wang, Kunlin; Wei, Jinquan; Kang, Feiyu; Zhu, Hongwei

    2015-04-28

    We report the design and preparation of graphene and polyaniline (PANI) woven-fabric composite films by in situ electropolymerization. The introduction of PANI greatly improves the electrochemical properties of solid-state supercapacitors which possess capacitances as high as 23 mF cm(-2), and exhibit excellent cycling stability with ∼ 100% capacitance retention after 2000 cycles. The devices have displayed superior flexibility with improved areal specific capacitances to 118% during deformation.

  10. A sensitive DNA biosensor fabricated from gold nanoparticles and graphene oxide on a glassy carbon electrode.

    PubMed

    Hajihosseini, Saeedeh; Nasirizadeh, Navid; Hejazi, Mohammad Saeid; Yaghmaei, Parichereh

    2016-04-01

    A sensitive electrochemical DNA biosensor was developed for Helicobacter pylori (H. pylori) detection using differential pulse voltammetry. Single-stranded DNA probe was immobilized on a graphene oxide/gold nanoparticles modified glassy carbon electrode (GO/AuNPs/GCE). A hybridization reaction was conducted with the target DNA and the immobilized DNA on the electrode surface. Oracet blue (OB) was selected for the first time as a redox indicator for amplifying the electrochemical signal of DNA. Enhanced sensitivity was achieved through combining the excellent electric conductivity of GO/AuNPs and the electroactivity of the OB. The DNA biosensor displayed excellent performance to demonstrate the differences between the voltammetric signals of the OB obtained from different hybridization samples (non-complementary, mismatch and complementary DNAs). The proposed biosensor has a linear range of 60.0-600.0 pM and a detection limit of 27.0 pM for detection of H. pylori. In addition, the biosensor have responded very well in the simulated real sample evaluations, signifying its potential to be used in future clinical detection of the H. pylori bacteria.

  11. Three-Dimensional Photolithographic Micropatterning: A Novel Tool to Probe the Complexities of Cell Migration

    PubMed Central

    West, Jennifer L.

    2013-01-01

    In order to independently study the numerous variables that influence cell movement, it will be necessary to employ novel tools and materials that allow for exquisite control of the cellular microenvirenment. In this work, we have applied advanced 3D micropatterning technology, known as two-photon laser scanning lithography (TP-LSL), to poly(ethylene glycol) (PEG) hydrogels modified with bioactive peptides in order to fabricate precisely designed microenvirenments to guide and quantitatively investigate cell migration. Specifically, TP-LSL was used to fabricate cell adhesive PEG-RGDS micropatterns on the surface of non-degradable PEG-based hydrogels (2D) and in the interior of proteolytically degradable PEG-based hydrogels (3D). HT1080 cell migration was guided down these adhesive micropatterns in both 2D and 3D, as observed via time-lapse microscopy. Differences in cell speed, cell persistence, and cell shape were observed based on variation of adhesive ligand, hydrogel composition, and patterned area for both 2D and 3D migration. Results indicated that HT1080s migrate faster and with lower persistence on 2D surfaces, while HT1080s migrating in 3D were smaller and more elongated. Further, cell migration was shown to have a biphasic dependence on PEG-RGDS concentration and cells moving within PEG-RGDS micropatterns were seen to move faster and with more persistence over time. Importantly, the work presented here begins to elucidate the multiple complex factors involved in cell migration, with typical confounding factors being independently controlled. The development of this unique platform will allow researchers to probe how cells behave within increasingly complex 3D microenvironments that begin to mimic specifically chosen aspects of the in vivo landscape. PMID:23460015

  12. Fabrication process for CMUT arrays with polysilicon electrodes, nanometre precision cavity gaps and through-silicon vias

    NASA Astrophysics Data System (ADS)

    Due-Hansen, J.; Midtbø, K.; Poppe, E.; Summanwar, A.; Jensen, G. U.; Breivik, L.; Wang, D. T.; Schjølberg-Henriksen, K.

    2012-07-01

    Capacitive micromachined ultrasound transducers (CMUTs) can be used to realize miniature ultrasound probes. Through-silicon vias (TSVs) allow for close integration of the CMUT and read-out electronics. A fabrication process enabling the realization of a CMUT array with TSVs is being developed. The integrated process requires the formation of highly doped polysilicon electrodes with low surface roughness. A process for polysilicon film deposition, doping, CMP, RIE and thermal annealing that resulted in a film with sheet resistance of 4.0 Ω/□ and a surface roughness of 1 nm rms has been developed. The surface roughness of the polysilicon film was found to increase with higher phosphorus concentrations. The surface roughness also increased when oxygen was present in the thermal annealing ambient. The RIE process for etching CMUT cavities in the doped polysilicon gave a mean etch depth of 59.2 ± 3.9 nm and a uniformity across the wafer ranging from 1.0 to 4.7%. The two presented processes are key processes that enable the fabrication of CMUT arrays suitable for applications in for instance intravascular cardiology and gastrointestinal imaging.

  13. Fabrication of folic acid sensor based on the Cu doped SnO2 nanoparticles modified glassy carbon electrode

    NASA Astrophysics Data System (ADS)

    Lavanya, N.; Radhakrishnan, S.; Sudhan, N.; Sekar, C.; Leonardi, S. G.; Cannilla, C.; Neri, G.

    2014-07-01

    A novel folic acid biosensor has been fabricated using Cu doped SnO2 nanoparticles (NPs) synthesized by a simple microwave irradiation method. Powder XRD and TEM studies confirmed that both the pure and Cu doped SnO2 (Cu: 0, 10, 20wt%) crystallized in tetragonal rutile-type structure with spherical morphology. The average crystallite size of pure SnO2 was estimated to be around 16 nm. Upon doping, the crystallite sizes decreased to 9 nm and 5 nm for 10 and 20wt% Cu doped SnO2 respectively. XPS studies confirmed the electronic state of Sn and Cu to be 4+ and 2+ respectively. Cu (20wt%) doped SnO2 NPs are proved to be a good sensing element for the determination of folic acid (FA). Cu-SnO2 NPs (20wt%) modified glassy carbon electrode (GCE) exhibited the lowest detection limit of 0.024 nM over a wide folic acid concentration range of 1.0 × 10-10 to 6.7 × 10-5 M at physiological pH of 7.0. The fabricated sensor is highly selective towards the determination of FA even in the presence of a 100 fold excess of common interferent ascorbic acid. The sensor proved to be useful for the estimation of FA content in pharmaceutical sample with satisfactory recovery.

  14. Fast fabrication of copper nanowire transparent electrodes by a high intensity pulsed light sintering technique in air.

    PubMed

    Ding, Su; Jiu, Jinting; Tian, Yanhong; Sugahara, Tohru; Nagao, Shijo; Suganuma, Katsuaki

    2015-12-14

    Copper nanowire transparent electrodes have received increasing interest due to the low price and nearly equal electrical conductivity compared with other TEs based on silver nanowires and indium tin oxide (ITO). However, a post-treatment at high temperature in an inert atmosphere or a vacuum environment was necessary to improve the conductivity of Cu NW TEs due to the easy oxidation of copper in air atmosphere, which greatly cancelled out the low price advantage of Cu NWs. Here, a high intensity pulsed light technique was introduced to sinter and simultaneously deoxygenate these Cu NWs into a highly conductive network at room temperature in air. The strong light absorption capacity of Cu NWs enabled the welding of the nanowires at contact spots, as well as the removal of the thin layer of residual organic compounds, oxides and hydroxide of copper even in air. The Cu NW TE with a sheet resistance of 22.9 Ohm sq(-1) and a transparency of 81.8% at 550 nm has been successfully fabricated within only 6 milliseconds exposure treatment, which is superior to other films treated at high temperature in a hydrogen atmosphere. The HIPL process was simple, convenient and fast to fabricate easily oxidized Cu NW TEs in large scale in an air atmosphere, which will largely extend the application of cheap Cu NW TEs.

  15. Fast fabrication of copper nanowire transparent electrodes by a high intensity pulsed light sintering technique in air.

    PubMed

    Ding, Su; Jiu, Jinting; Tian, Yanhong; Sugahara, Tohru; Nagao, Shijo; Suganuma, Katsuaki

    2015-12-14

    Copper nanowire transparent electrodes have received increasing interest due to the low price and nearly equal electrical conductivity compared with other TEs based on silver nanowires and indium tin oxide (ITO). However, a post-treatment at high temperature in an inert atmosphere or a vacuum environment was necessary to improve the conductivity of Cu NW TEs due to the easy oxidation of copper in air atmosphere, which greatly cancelled out the low price advantage of Cu NWs. Here, a high intensity pulsed light technique was introduced to sinter and simultaneously deoxygenate these Cu NWs into a highly conductive network at room temperature in air. The strong light absorption capacity of Cu NWs enabled the welding of the nanowires at contact spots, as well as the removal of the thin layer of residual organic compounds, oxides and hydroxide of copper even in air. The Cu NW TE with a sheet resistance of 22.9 Ohm sq(-1) and a transparency of 81.8% at 550 nm has been successfully fabricated within only 6 milliseconds exposure treatment, which is superior to other films treated at high temperature in a hydrogen atmosphere. The HIPL process was simple, convenient and fast to fabricate easily oxidized Cu NW TEs in large scale in an air atmosphere, which will largely extend the application of cheap Cu NW TEs. PMID:26536570

  16. Photopatternable transparent conducting oxide nanoparticles for transparent electrodes

    NASA Astrophysics Data System (ADS)

    Kim, Won Jin; Kim, Sung Jin; Cartwright, Alexander N.; Prasad, Paras N.

    2013-02-01

    We report a method to fabricate tailored transparent electrodes using photopatternable transparent conducting oxide nanoparticles (TCO NPs). We demonstrate solution-processed micropatterns by a conventional photolithography technique. We have synthesized indium tin oxide (ITO) NPs and functionalized them with a photolabile group, such as t-butoxycarbonyl (t-BOC), which can be deprotected by a chemical amplification reaction in the solid state film. The chemical amplification reaction leads to a shortening of the ligand that changes the solubility of the resulting ITO films. This ligand shortening process also contributes to a reduction of the sheet resistance in the resulting photopatterned ITO films. Furthermore, we have demonstrated the general viability and strength of this approach by also photopatterning zinc oxide (ZnO) NPs.

  17. Endothelial cell micropatterning: Methods, effects, and applications

    PubMed Central

    Anderson, Deirdre E.J.; Hinds, Monica T.

    2012-01-01

    The effects of flow on endothelial cells have been widely examined for the ability of fluid shear stress to alter cell morphology and function; however, the effects of endothelial cell morphology without flow have only recently been observed. An increase in lithographic techniques in cell culture spurred a corresponding increase in research aiming to confine cell morphology. These studies lead to a better understanding of how morphology and cytoskeletal configuration affect the structure and function of the cells. This review examines endothelial cell micropatterning research by exploring both the many alternative methods used to alter endothelial cell morphology and the resulting changes in cellular shape and phenotype. Micropatterning induced changes in endothelial cell proliferation, apoptosis, cytoskeletal organization, mechanical properties, and cell functionality. Finally, the ways these cellular manipulation techniques have been applied to biomedical engineering research, including angiogenesis, cell migration, and tissue engineering, is discussed. PMID:21761242

  18. Direct electrochemistry of Shewanella loihica PV-4 on gold nanoparticles-modified boron-doped diamond electrodes fabricated by layer-by-layer technique.

    PubMed

    Wu, Wenguo; Xie, Ronggang; Bai, Linling; Tang, Zuming; Gu, Zhongze

    2012-05-01

    Microbial Fuel Cells (MFCs) are robust devices capable of taping biological energy, converting pollutants into electricity through renewable biomass. The fabrication of nanostructured electrodes with good bio- and electrochemical activity, play a profound role in promoting power generation of MFCs. Au nanoparticles (AuNPs)-modified Boron-Doped Diamond (BDD) electrodes are fabricated by layer-by-layer (LBL) self-assembly technique and used for the direct electrochemistry of Shewanella loihica PV-4 in an electrochemical cell. Experimental results show that the peak current densities generated on the Au/PAH multilayer-modified BDD electrodes increased from 1.25 to 2.93 microA/cm(-2) as the layer increased from 0 to 6. Different cell morphologies of S. loihica PV-4 were also observed on the electrodes and the highest density of cells was attached on the (Au/PAH)6/BDD electrode with well-formed three-dimensional nanostructure. The electrochemistry of S. loihica PV-4 was enhanced on the (Au/PAH)4/BDD electrode due to the appropriate amount of AuNPsand thickness of PAH layer.

  19. Graphene/polyaniline woven fabric composite films as flexible supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Zang, Xiaobei; Li, Xiao; Zhu, Miao; Li, Xinming; Zhen, Zhen; He, Yijia; Wang, Kunlin; Wei, Jinquan; Kang, Feiyu; Zhu, Hongwei

    2015-04-01

    We report the design and preparation of graphene and polyaniline (PANI) woven-fabric composite films by in situ electropolymerization. The introduction of PANI greatly improves the electrochemical properties of solid-state supercapacitors which possess capacitances as high as 23 mF cm-2, and exhibit excellent cycling stability with ~100% capacitance retention after 2000 cycles. The devices have displayed superior flexibility with improved areal specific capacitances to 118% during deformation.We report the design and preparation of graphene and polyaniline (PANI) woven-fabric composite films by in situ electropolymerization. The introduction of PANI greatly improves the electrochemical properties of solid-state supercapacitors which possess capacitances as high as 23 mF cm-2, and exhibit excellent cycling stability with ~100% capacitance retention after 2000 cycles. The devices have displayed superior flexibility with improved areal specific capacitances to 118% during deformation. Electronic supplementary information (ESI) available: SEM image, Raman spectrum and electrochemical characterizations. See DOI: 10.1039/c5nr00584a

  20. Large scale micropatterning of multi-walled carbon nanotube/polydimethylsiloxane nanocomposite polymer on highly flexible 12×24 inch substrates

    NASA Astrophysics Data System (ADS)

    Khosla, A.; Hilbich, D.; Drewbrook, C.; Chung, D.; Gray, B. L.

    2011-03-01

    We present the large scale micro-pattering of an electrically conducting multiwalled carbon nanotube (MWCNT) polydimethylsiloxane (PDMS) nanocomposite polymer prepared by high frequency (42 kHz) ultrasonic agitation of MWCNTs in the PDMS polymer matrix. Large scale micropatterning of the MWCNT-PDMS nanocomposite is achieved via soft lithography employing a 12" × 24" poly-methyl methacrylate (PMMA, commercially known as Plexiglass) micromold. The process has a 20µm minimum feature size. The PMMA micromold is fabricated by laser ablating 5-mm thick, 12" × 24" sheets using the Universal Laser System's VersaLASERlaser cutter system which employs a CO2 laser. We have characterized and compared the resistivity of 1cm × 0.5cm × 0.5cm MWCNT-PDMS structures with varying weight percentage (wt-%) of MWCNT (1-10% wt%) in the PDMS matrix with a result that the percolation threshold is achieved at 2 wt-%. Furthermore, we have demonstrated the ability to fabricate large numbers of microelectrodes with a length of 3.0 cm, width of 500µm, and height of 400µm. The resistivity of these electrodes was found to be equal to 9.93Ωm with a deviation of approximately 10%, indicating uniformity across large areas of the substrate. We have also demonstrated a large scale 12" × 24 hybrid microfabrication process for combining micromolded MWCNT-PDMS nanocomposite microstructures with nonconductive PDMS polymer.

  1. Fabrication of graphene-based electrode in less than a minute through hybrid microwave annealing.

    PubMed

    Youn, Duck Hyun; Jang, Ji-Wook; Kim, Jae Young; Jang, Jum Suk; Choi, Sun Hee; Lee, Jae Sung

    2014-06-30

    Highly efficient and stable MoS2 nanocrystals on graphene sheets (MoS2/GR) are synthesized via a hybrid microwave annealing process. Through only 45 second-irradiation using a household microwave oven equipped with a graphite susceptor, crystallization of MoS2 and thermal reduction of graphene oxide into graphene are achieved, indicating that our synthetic method is ultrafast and energy-economic. Graphene plays a crucial role as an excellent microwave absorber as well as an ideal support material that mediates the growth of MoS2 nanocrystals. The formed MoS2/GR electrocatalyst exhibits high activity of hydrogen evolution reaction with small onset overpotential of 0.1 V and Tafel slope of 50 mV per decade together with an excellent stability in acid media. Thus our hybrid microwave annealing could be an efficient generic method to fabricate various graphene-based hybrid electric materials for broad applications.

  2. Fabrication of graphene-based electrode in less than a minute through hybrid microwave annealing

    NASA Astrophysics Data System (ADS)

    Youn, Duck Hyun; Jang, Ji-Wook; Kim, Jae Young; Jang, Jum Suk; Choi, Sun Hee; Lee, Jae Sung

    2014-06-01

    Highly efficient and stable MoS2 nanocrystals on graphene sheets (MoS2/GR) are synthesized via a hybrid microwave annealing process. Through only 45 second-irradiation using a household microwave oven equipped with a graphite susceptor, crystallization of MoS2 and thermal reduction of graphene oxide into graphene are achieved, indicating that our synthetic method is ultrafast and energy-economic. Graphene plays a crucial role as an excellent microwave absorber as well as an ideal support material that mediates the growth of MoS2 nanocrystals. The formed MoS2/GR electrocatalyst exhibits high activity of hydrogen evolution reaction with small onset overpotential of 0.1 V and Tafel slope of 50 mV per decade together with an excellent stability in acid media. Thus our hybrid microwave annealing could be an efficient generic method to fabricate various graphene-based hybrid electric materials for broad applications.

  3. Fabrication and photoelectrocatalytic properties of nanocrystalline monoclinic BiVO4 thin-film electrode.

    PubMed

    Zhou, Bin; Qu, Jiuhui; Zhao, Xu; Liu, Huijuan

    2011-01-01

    Monoclinic bismuth vanadate (BiVO4) thin film was fabricated on indium-tin oxide glass from an amorphous heteronuclear complex via dip-coating. After annealation at 400, 500, and 600 degrees C, the thin films were characterized by X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis spectrophotometry. The BiVO4 particles on the ITO glass surface had a monoclinic structure. The UV-Visible diffuse reflection spectra showed the BiVO4 thin film had photoabsorption properties, with a band gap around 2.5 eV. In addition, the thin film showed high visible photocatalytic activities towards 2,4-dichlorophenol and Bisphenol A degradation under visible light irradiation (lambda > 420 nm). Over 90% of the two organic pollutants were removed in 5 hr. A possible degradation mechanism of 2,4-dichlorophenol were also studied. PMID:21476355

  4. Fabrication and characteristics of an implantable, polymer-based, intrafascicular electrode.

    PubMed

    Lawrence, Stephen M; Dhillon, Gurpreet S; Horch, Kenneth W

    2003-12-30

    We describe new manufacturing techniques and physical properties of an improved polymer-based longitudinal intrafascicular electrode (polyLIFE). Modifications were made to correct: (1) poor metal film adhesion and fatigue resistance, (2) inconsistent insulation adhesion and control over recording/stimulation zone length, and (3) insufficient tensile strength for clinical use. Metal adhesion was significantly improved by both plasma treatment and fiber rotation (about the long axis) during metal deposition. Fatigue resistance was improved by reduction in sputtering energy (time x power) combined with long axis rotation, resulting in thin metal films that were 250 times more resistant to cyclic bending fatigue. Insulation adhesion was enhanced with the application of an adhesion-promoting silicone (MED2-4013, Nusil), while the recording/stimulation zone length was controlled to 1 +/- 0.2mm (mean +/- S.D.). The polyLIFE was made more robust by the inclusion of three individually metallized fibers, improving its tensile strength by a factor of 4 while producing minimal changes to its overall stiffness. However, the metallized fiber redundancy did not significantly affect fatigue resistance. The manufacturing changes described in this study enable the construction of more mechanically robust polyLIFEs, which should provide greater success when chronically implanted in peripheral nerves.

  5. DNA-modified Electrodes Fabricated using Copper-Free Click Chemistry for Enhanced Protein Detection

    PubMed Central

    Furst, Ariel L.; Hill, Michael G.; Barton, Jacqueline K.

    2014-01-01

    A method of DNA monolayer formation has been developed using copper-free click chemistry that yields enhanced surface homogeneity and enables variation in the amount of DNA assembled; extremely low-density DNA monolayers, with as little as 5% of the monolayer being DNA, have been formed. These DNA-modified electrodes (DMEs) were characterized visually, with AFM, and electrochemically, and were found to facilitate DNA-mediated reduction of a distally bound redox probe. These low-density monolayers were found to be more homogeneous than traditional thiol-modified DNA monolayers, with greater helix accessibility through an increased surface area-to-volume ratio. Protein binding efficiency of the transcriptional activator TATA-binding protein (TBP) was also investigated on these surfaces and compared to that on DNA monolayers formed with standard thiol-modified DNA. Our low-density monolayers were found to be extremely sensitive to TBP binding, with a signal decrease in excess of 75% for 150 nM protein. This protein was detectable at 4 nM, on the order of its dissociation constant, with our low-density monolayers. The improved DNA helix accessibility and sensitivity of our low-density DNA monolayers to TBP binding reflects the general utility of this method of DNA monolayer formation for DNA-based electrochemical sensor development. PMID:24328347

  6. Laser-induced forward transfer of carbon nanowalls for soft electrodes fabrication

    NASA Astrophysics Data System (ADS)

    Constantinescu, Catalin; Vizireanu, Sorin; Ion, Valentin; Aldica, Gheorghe; Stoica, Silviu Daniel; Lazea-Stoyanova, Andrada; Alloncle, Anne-Patricia; Delaporte, Philippe; Dinescu, Gheorghe

    2016-06-01

    Carbon nanowalls (CNW) are two-dimensional interconnected graphitic nanostructures that have a few μm in length and height, reaching typical thicknesses of a few tens of nm. We present results on such layers synthesized in a low pressure argon plasma jet, injected with acetylene and hydrogen, on transparent substrates (quartz) heated at 600 °C, without catalyst. Thermogravimetric analysis reveals that the CNW are stable up to 420 °C in air, and Raman spectroscopy investigations highlight their graphene-like structure. Finally, using a pulsed Nd:YAG laser device (355 nm, 50 ps), we show that 2D-arrays of CNW (pixels and lines) can be printed by laser-induced forward transfer (LIFT), preserving their architecture and structure. Electrical measurements on 1 μm thick CNW demonstrate typical values in the range of 357.5-358.4 Ω for the samples grown on Au/Cr electrodes, and in the range of 450.1-474.7 Ω for the LIFT printed lines (under positive, negative, and neutral polarization; 1 kHz-5 MHz frequency range; 500 mV and 1 V, respectively). Their morphology is highlighted by means of optical and electronic microscopy. Such structures have potential applications as soft conductive lines, in sensor development and/or embedding purposes.

  7. A highly oriented hybrid microarray modified electrode fabricated by a template-free method for ultrasensitive electrochemical DNA recognition

    NASA Astrophysics Data System (ADS)

    Shi, Lei; Chu, Zhenyu; Dong, Xueliang; Jin, Wanqin; Dempsey, Eithne

    2013-10-01

    Highly oriented growth of a hybrid microarray was realized by a facile template-free method on gold substrates for the first time. The proposed formation mechanism involves an interfacial structure-directing force arising from self-assembled monolayers (SAMs) between gold substrates and hybrid crystals. Different SAMs and variable surface coverage of the assembled molecules play a critical role in the interfacial directing forces and influence the morphologies of hybrid films. A highly oriented hybrid microarray was formed on the highly aligned and vertical SAMs of 1,4-benzenedithiol molecules with rigid backbones, which afforded an intense structure-directing power for the oriented growth of hybrid crystals. Additionally, the density of the microarray could be adjusted by controlling the surface coverage of assembled molecules. Based on the hybrid microarray modified electrode with a large specific area (ca. 10 times its geometrical area), a label-free electrochemical DNA biosensor was constructed for the detection of an oligonucleotide fragment of the avian flu virus H5N1. The DNA biosensor displayed a significantly low detection limit of 5 pM (S/N = 3), a wide linear response from 10 pM to 10 nM, as well as excellent selectivity, good regeneration and high stability. We expect that the proposed template-free method can provide a new reference for the fabrication of a highly oriented hybrid array and the as-prepared microarray modified electrode will be a promising paradigm in constructing highly sensitive and selective biosensors.Highly oriented growth of a hybrid microarray was realized by a facile template-free method on gold substrates for the first time. The proposed formation mechanism involves an interfacial structure-directing force arising from self-assembled monolayers (SAMs) between gold substrates and hybrid crystals. Different SAMs and variable surface coverage of the assembled molecules play a critical role in the interfacial directing forces and

  8. Micropatterning of perfluoroalkyl self-assembled monolayers for arraying proteins and cells on chips

    NASA Astrophysics Data System (ADS)

    Kira, Atsushi; Okano, Kazunori; Hosokawa, Yoichiroh; Naito, Akira; Fuwa, Koh; Yuyama, Jyunpei; Masuhara, Hiroshi

    2009-06-01

    Organosilane self-assembled monolayers (SAMs) with perfluoroalkyl groups ( Rf) on glass surfaces were used for arraying proteins and cells on chips. Quartz crystal microbalance measurements confirmed the inhibition of protein adsorption on Rf-SAM-modified surfaces and showed efficient adsorption on hydroxyl-, carboxyl-, and amino group-modified surfaces. The characteristics of Rf-modified surfaces were evaluated using solvent contact angle measurement and Fourier transform infrared (FTIR) spectroscopy. The Rf surface was highly water- and oil-resistant, as inferred from the contact angles of water, oleic acid, and hexadecane. Specific peaks of IR spectra were detected in the region from 1160 to 1360 cm -1. Etching with dry plasma completely exfoliated the Rf-SAM, exposing the underlying intact glass surface. Modification conditions were optimized using contact angle and FTIR measurements. After dry plasma processing, the contact angles of all solvents became undetectable, and the IR peaks disappeared. Micrometer scale protein and cell patterns can be fabricated using the proposed method. Protein adsorption on micropatterned Rf-SAM-modified chips was evaluated using fluorescence analysis; protein adsorption was easily controlled by patterning Rf-SAM. PC12 and HeLa cells grew well on micropatterned Rf-SAM-modified chips. Micropatterning of Rf-SAM by dry plasma treatment with photolithography is useful for the spatial arrangement of proteins and cells.

  9. Template-stripped, ultraflat gold surfaces with coplanar, embedded titanium micropatterns.

    PubMed

    Venkataraman, Nagaiyanallur V; Pei, Jia; Cremmel, Clément V M; Rossi, Antonella; Spencer, Nicholas D

    2013-08-01

    Ultraflat gold surfaces with coplanar, embedded titanium micropatterns, exhibiting extremely low roughness over the entire surface, have been obtained by a modified template-stripping procedure. Titanium is deposited onto photolithographically predefined regions of a silicon template. Following photoresist lift-off, the entire surface is backfilled with gold, template stripping is conducted, and an ultraflat micropatterned surface is revealed. Atomic force microscopy confirms a roughness of <0.5 nm RMS on both Ti and Au regions, with a topographically indistinguishable gold-titanium interface. Detailed surface-chemical maps of the patterned surfaces have been obtained by means of imaging X-ray photoelectron spectroscopy (i-XPS) as well as time-of-flight secondary-ion mass spectrometry (ToF-SIMS). They confirm the presence of well-separated Ti and Au regions, with a chemical contrast that is sharp (as determined by ToF-SIMS) and complete (as determined by i-XPS) across the Ti-Au interface. Thus, a surface has been fabricated that is physically homogeneous down to the nanoscale incorporating chemically distinct micropatterns consisting of two different metals, with totally contrasting surface chemistries.

  10. Fabrication of graphene-based electrode in less than a minute through hybrid microwave annealing

    PubMed Central

    Youn, Duck Hyun; Jang, Ji-Wook; Kim, Jae Young; Jang, Jum Suk; Choi, Sun Hee; Lee, Jae Sung

    2014-01-01

    Highly efficient and stable MoS2 nanocrystals on graphene sheets (MoS2/GR) are synthesized via a hybrid microwave annealing process. Through only 45 second-irradiation using a household microwave oven equipped with a graphite susceptor, crystallization of MoS2 and thermal reduction of graphene oxide into graphene are achieved, indicating that our synthetic method is ultrafast and energy-economic. Graphene plays a crucial role as an excellent microwave absorber as well as an ideal support material that mediates the growth of MoS2 nanocrystals. The formed MoS2/GR electrocatalyst exhibits high activity of hydrogen evolution reaction with small onset overpotential of 0.1 V and Tafel slope of 50 mV per decade together with an excellent stability in acid media. Thus our hybrid microwave annealing could be an efficient generic method to fabricate various graphene-based hybrid electric materials for broad applications. PMID:24974846

  11. Simultaneous fabrication of nanogap electrodes using field-emission-induced electromigration

    SciTech Connect

    Ito, Mitsuki; Yagi, Mamiko; Morihara, Kohei; Shirakashi, Jun-ichi

    2015-07-07

    We present a simple technique for simultaneous control of the electrical properties of multiple Ni nanogaps. This technique is based on electromigration induced by a field emission current and is called “activation.” Simultaneous tuning of the tunnel resistance of multiple nanogaps was achieved by passing a Fowler–Nordheim (F-N) field emission current through an initial group of three Ni nanogaps connected in series. The Ni nanogaps, which had asymmetrical shapes with initial gap separations in the 80–110-nm range, were fabricated by electron-beam lithography and a lift-off process. By performing the activation procedure, the current–voltage properties of the series-connected nanogaps were varied simultaneously from “insulating” to “metallic” via “tunneling” properties by increasing the preset current of the activation procedure. We can also simultaneously control the tunnel resistances of the series-connected nanogaps, which range from a resistance of the order of 100 TΩ–100 kΩ, by increasing the preset current from 1 nA to 30 μA. This tendency is quite similar to that of individually activated nanogaps, and the tunnel resistance values of the simultaneously activated nanogaps were almost the same at each preset current. These results clearly imply that the electrical properties of the series-connected nanogaps can be controlled simultaneously via the activation procedure.

  12. Nanometer sized electrodes fabricated by electromigration of Au and Pd nanowires

    NASA Astrophysics Data System (ADS)

    Vlad, Alexandru; Faniel, Sébastien; Hackens, Benoît; Bayot, Vincent; Melinte, Sorin

    2008-03-01

    Electromigration-driven metallic nanowire failure is presented. Here, Au and Pd nanowires patterned by electron-beam lithography were electrically stressed up to their breaking point. Feedback control and simple voltage sweep techniques have been successfully used to form nanometer-sized gaps. We observe a material- and geometry-dependent behavior. The Au nanowires showed a Joule-induced reversible resistance increase with the applied voltage up to the breaking point. In contrast, Pd nanowires presented an anomalous resistance decrease close to their failure point. This was associated to the melting and agglomeration of metallic grains within the electrically stressed nanowires. The SEM images acquired at intermediate stages of electromigration agree with the electrical data findings. The influence of the nanowire geometry upon the morphology of fabricated nanoelectrodes is considered. Beside the morphological characterization of our break junctions, we also measured their current-voltage characteristics. We observed single electron tunneling effects, probably due to the presence of metallic clusters formed close to the nanoelectrodes during the electromigration. Our results are consistent with recent findings on Coulomb blockade phenomena in electromigrated gold break junctions.

  13. Design, fabrication, and performance of brazed, graphite electrode, multistage depressed collectors with 500-W, continuous wave, 4.8- to 9.6-GHz traveling-wave tubes

    NASA Technical Reports Server (NTRS)

    Ramins, Peter; Ebihara, Ben

    1989-01-01

    A small, isotropic graphite electrode, multistage depressed collector (MDC) was designed, fabricated, and evaluated in conjunction with a 500-W, continuous wave (CW), 4.8- to 9.6-GHz traveling-wave tube (TWT). The carbon electrode surfaces were used to improve the TWT overall efficiency by minimizing the secondary electron emission losses in the MDC. The design and fabrication of the brazed graphite MDC assembly are described. The brazing technique, which used copper braze filler metal, is compatible with both vacuum and the more commonly available hydrogen atmosphere brazing furnaces. The TWT and graphite electrode MCC bakeout, processing, and outgassing characteristics were evaluated and found to be comparable to TWT's equipped with copper electrode MDC's. The TWT and MDC performance was optimized for broadband CW operation at saturation. The average radiofrequency (RF), overall, and MDC efficiencies were 14.9, 46.4, and 83.6 percent, respectively, across the octave operating band. A 1500-hr CW test, conducted without the use of an appendage ion pump, showed no gas buildup and excellent stability of the electrode surfaces.

  14. Facile fabrication of sub-100 nm mesoscale inverse opal films and their application in dye-sensitized solar cell electrodes.

    PubMed

    Lee, Jung Woo; Lee, Jaemin; Kim, Cheolho; Cho, Chang-Yeol; Moon, Jun Hyuk

    2014-10-28

    Inverse opal (IO) films with mesoporous structures hold promise as high-performance electrodes for various photoelectrochemical devices because of their high specific area as well as their fully connected pore structure. A great challenge to their use is obtaining an intact film of mesoscale colloidal crystals as a template. Here, using the plate-sliding coating method coupled with hot air flow, we successfully deposited mesoscale colloidal crystals onto the substrate. A TiO2 mesoscale IO (meso-IO) with 70 nm pores was then successfully fabricated via atomic layer deposition of TiO2 and subsequent removal of the template. As a photoelectrochemical electrode, the meso-IO structure exhibits enhanced charge transport properties as well as a high specific area. Moreover, dye-sensitized solar cells fabricated using the meso-IO electrode exhibit a higher photocurrent and cell efficiency than a cell constructed using a conventional TiO2 nanoparticle electrode. This meso-IO film provides a new platform for developing electrodes for use in various energy storage and conversion devices.

  15. Facile fabrication of sub-100 nm mesoscale inverse opal films and their application in dye-sensitized solar cell electrodes.

    PubMed

    Lee, Jung Woo; Lee, Jaemin; Kim, Cheolho; Cho, Chang-Yeol; Moon, Jun Hyuk

    2014-01-01

    Inverse opal (IO) films with mesoporous structures hold promise as high-performance electrodes for various photoelectrochemical devices because of their high specific area as well as their fully connected pore structure. A great challenge to their use is obtaining an intact film of mesoscale colloidal crystals as a template. Here, using the plate-sliding coating method coupled with hot air flow, we successfully deposited mesoscale colloidal crystals onto the substrate. A TiO2 mesoscale IO (meso-IO) with 70 nm pores was then successfully fabricated via atomic layer deposition of TiO2 and subsequent removal of the template. As a photoelectrochemical electrode, the meso-IO structure exhibits enhanced charge transport properties as well as a high specific area. Moreover, dye-sensitized solar cells fabricated using the meso-IO electrode exhibit a higher photocurrent and cell efficiency than a cell constructed using a conventional TiO2 nanoparticle electrode. This meso-IO film provides a new platform for developing electrodes for use in various energy storage and conversion devices. PMID:25348114

  16. Facile fabrication of sub-100 nm mesoscale inverse opal films and their application in dye-sensitized solar cell electrodes

    PubMed Central

    Lee, Jung Woo; Lee, Jaemin; Kim, Cheolho; Cho, Chang-Yeol; Moon, Jun Hyuk

    2014-01-01

    Inverse opal (IO) films with mesoporous structures hold promise as high-performance electrodes for various photoelectrochemical devices because of their high specific area as well as their fully connected pore structure. A great challenge to their use is obtaining an intact film of mesoscale colloidal crystals as a template. Here, using the plate-sliding coating method coupled with hot air flow, we successfully deposited mesoscale colloidal crystals onto the substrate. A TiO2 mesoscale IO (meso-IO) with 70 nm pores was then successfully fabricated via atomic layer deposition of TiO2 and subsequent removal of the template. As a photoelectrochemical electrode, the meso-IO structure exhibits enhanced charge transport properties as well as a high specific area. Moreover, dye-sensitized solar cells fabricated using the meso-IO electrode exhibit a higher photocurrent and cell efficiency than a cell constructed using a conventional TiO2 nanoparticle electrode. This meso-IO film provides a new platform for developing electrodes for use in various energy storage and conversion devices. PMID:25348114

  17. Simple micropatterning method for enhancing fusion efficiency and responsiveness to electrical stimulation of C2C12 myotubes.

    PubMed

    Takayama, Yuzo; Wagatsuma, Akira; Hoshino, Takayuki; Mabuchi, Kunihiko

    2015-01-01

    Cultured myotubes induced in vitro from myoblast cell lines have been widely used to investigate muscle functional properties and disease-related biological phenotypes. Until now, several cell patterning techniques have been applied to regulate in vitro myotube structures. However, these previous studies required specific geometry patterns or soft materials for inducing efficient myotube formation. Thus, more simple and easy handling method will be promising. In this study, we aimed to provide a method to form C2C12 myotubes with regulated sizes and orientations in simple line patterns. We used a poly(dimethylsiloxane) (PDMS) stamp and a 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer solution to fabricate line patterns for myotube formation onto a culture dish. We confirmed that C2C12 myotubes of well-defined size and orientation were reproducibly formed. In particular, myotubes formed in the micropatterned lines showed the increased fusion efficiency. Then, functional dynamics in the micropatterned myotubes were detected and analyzed using a calcium imaging method. We confirmed micropatterning in line patterns enhanced the responsiveness of myotubes to external electrical stimulations. These results indicate that micropatterning myoblasts with the MPC polymer is a simple and effective method to form functional myotube networks. PMID:25311428

  18. Nanoparticle-Mediated Physical Exfoliation of Aqueous-Phase Graphene for Fabrication of Three-Dimensionally Structured Hybrid Electrodes

    PubMed Central

    Lee, Younghee; Choi, Hojin; Kim, Min-Sik; Noh, Seonmyeong; Ahn, Ki-Jin; Im, Kyungun; Kwon, Oh Seok; Yoon, Hyeonseok

    2016-01-01

    Monodispersed polypyrrole (PPy) nanospheres were physically incorporated as guest species into stacked graphene layers without significant property degradation, thereby facilitating the formation of unique three-dimensional hybrid nanoarchitecture. The electrochemical properties of the graphene/particulate PPy (GPPy) nanohybrids were dependent on the sizes and contents of the PPy nanospheres. The nanohybrids exhibited optimum electrochemical performance in terms of redox activity, charge-transfer resistance, and specific capacitance at an 8:1 PPy/graphite (graphene precursor) weight ratio. The packing density of the alternately stacked nanohybrid structure varied with the nanosphere content, indicating the potential for high volumetric capacitance. The nanohybrids also exhibited good long-term cycling stability because of a structural synergy effect. Finally, fabricated nanohybrid-based flexible all–solid state capacitor cells exhibited good electrochemical performance in an acidic electrolyte with a maximum energy density of 8.4 Wh kg−1 or 1.9 Wh L−1 at a maximum power density of 3.2 kW kg−1 or 0.7 kW L−1; these performances were based on the mass or packing density of the electrode materials. PMID:26813878

  19. Nanoparticle-Mediated Physical Exfoliation of Aqueous-Phase Graphene for Fabrication of Three-Dimensionally Structured Hybrid Electrodes

    NASA Astrophysics Data System (ADS)

    Lee, Younghee; Choi, Hojin; Kim, Min-Sik; Noh, Seonmyeong; Ahn, Ki-Jin; Im, Kyungun; Kwon, Oh Seok; Yoon, Hyeonseok

    2016-01-01

    Monodispersed polypyrrole (PPy) nanospheres were physically incorporated as guest species into stacked graphene layers without significant property degradation, thereby facilitating the formation of unique three-dimensional hybrid nanoarchitecture. The electrochemical properties of the graphene/particulate PPy (GPPy) nanohybrids were dependent on the sizes and contents of the PPy nanospheres. The nanohybrids exhibited optimum electrochemical performance in terms of redox activity, charge-transfer resistance, and specific capacitance at an 8:1 PPy/graphite (graphene precursor) weight ratio. The packing density of the alternately stacked nanohybrid structure varied with the nanosphere content, indicating the potential for high volumetric capacitance. The nanohybrids also exhibited good long-term cycling stability because of a structural synergy effect. Finally, fabricated nanohybrid-based flexible all-solid state capacitor cells exhibited good electrochemical performance in an acidic electrolyte with a maximum energy density of 8.4 Wh kg-1 or 1.9 Wh L-1 at a maximum power density of 3.2 kW kg-1 or 0.7 kW L-1 these performances were based on the mass or packing density of the electrode materials.

  20. Nanoparticle-Mediated Physical Exfoliation of Aqueous-Phase Graphene for Fabrication of Three-Dimensionally Structured Hybrid Electrodes

    NASA Astrophysics Data System (ADS)

    Lee, Younghee; Choi, Hojin; Kim, Min-Sik; Noh, Seonmyeong; Ahn, Ki-Jin; Im, Kyungun; Kwon, Oh Seok; Yoon, Hyeonseok

    2016-01-01

    Monodispersed polypyrrole (PPy) nanospheres were physically incorporated as guest species into stacked graphene layers without significant property degradation, thereby facilitating the formation of unique three-dimensional hybrid nanoarchitecture. The electrochemical properties of the graphene/particulate PPy (GPPy) nanohybrids were dependent on the sizes and contents of the PPy nanospheres. The nanohybrids exhibited optimum electrochemical performance in terms of redox activity, charge-transfer resistance, and specific capacitance at an 8:1 PPy/graphite (graphene precursor) weight ratio. The packing density of the alternately stacked nanohybrid structure varied with the nanosphere content, indicating the potential for high volumetric capacitance. The nanohybrids also exhibited good long-term cycling stability because of a structural synergy effect. Finally, fabricated nanohybrid-based flexible all–solid state capacitor cells exhibited good electrochemical performance in an acidic electrolyte with a maximum energy density of 8.4 Wh kg‑1 or 1.9 Wh L‑1 at a maximum power density of 3.2 kW kg‑1 or 0.7 kW L‑1 these performances were based on the mass or packing density of the electrode materials.

  1. Thermoresponsive Micropatterned Substrates for Single Cell Studies

    PubMed Central

    Mandal, Kalpana; Balland, Martial; Bureau, Lionel

    2012-01-01

    We describe the design of micropatterned surfaces for single cell studies, based on thermoresponsive polymer brushes. We show that brushes made of poly(N-isopropylacrylamide) grafted at high surface density display excellent protein and cell anti-adhesive properties. Such brushes are readily patterned at the micron scale via deep UV photolithography. A proper choice of the adhesive pattern shapes, combined with the temperature-dependent swelling properties of PNIPAM, allow us to use the polymer brush as a microactuator which induces cell detachment when the temperature is reduced below C. PMID:22701519

  2. Surface oxygen micropatterns on glow discharge polymer targets by photo irradiation

    DOE PAGESBeta

    Reynolds, Hannah; Baxamusa, Salmaan; Haan, Steven W.; Fitzsimmons, Paul; Carlson, Lane; Farrell, Mike; Nikroo, Abbas; Watson, Brian J.

    2016-02-24

    Recent simulations predict surface oxygen may be a significant source of disruptive perturbations in the implosion process of glow-discharge polymers (GDP) ablators at the National Ignition Facility. GDP material held in ambient atmospheric conditions showed an increase in mass when stored in light transparent containers, which suggests that photo exposure is a driving force for oxygen absorption. To investigate if surface oxygen is a contributing factor of disruptive perturbations during implosion, we developed a method to imprint a periodic micropattern of oxygen on the surface of GDP and used it to fabricate a flat sample for empirical testing.

  3. Photochemical Production of Oligothiophene and Polythiophene Micropatterns from 2,5-diiodothiophene on Au in UHV

    SciTech Connect

    Liu,G.; Natarajan, S.; Kim, S.

    2005-01-01

    Fabrication of oligothiophene and polythiophene micropatterns is demonstrated by photochemical reactions of 2, 5-diiodothiophene adsorbed on an Au coated Si wafer under UHV conditions. For patterning, a TEM grid is utilized as a model stencil mask. Fluorescence microscopic analysis shows that polymer microstructures with good pattern fidelity are attained over a large area. RAIRS and NEXAFS analyses indicate that the electronic and molecular structures of the produced polymer are similar to those of chemically synthesized polythiophene. The structural defects of the photochemically produced polymer are negligible. The present procedure provides a very efficient strategy for growth and patterning of conjugated polymer microstructures with high quality in one step.

  4. Fabrication

    NASA Astrophysics Data System (ADS)

    Angel, Roger; Helms, Richard; Bilbro, Jim; Brown, Norman; Eng, Sverre; Hinman, Steve; Hull-Allen, Greg; Jacobs, Stephen; Keim, Robert; Ulmer, Melville

    1992-08-01

    What aspects of optical fabrication technology need to be developed so as to facilitate existing planned missions, or enable new ones? Throughout the submillimeter to UV wavelengths, the common goal is to push technology to the limits to make the largest possible apertures that are diffraction limited. At any one wavelength, the accuracy of the surface must be better than lambda/30 (rms error). The wavelength range is huge, covering four orders of magnitude from 1 mm to 100 nm. At the longer wavelengths, diffraction limited surfaces can be shaped with relatively crude techniques. The challenge in their fabrication is to make as large as possible a reflector, given the weight and volume constraints of the launch vehicle. The limited cargo diameter of the shuttle has led in the past to emphasis on deployable or erectable concepts such as the Large Deployable Reflector (LDR), which was studied by NASA for a submillimeter astrophysics mission. Replication techniques that can be used to produce light, low-cost reflecting panels are of great interest for this class of mission. At shorter wavelengths, in the optical and ultraviolet, optical fabrication will tax to the limit the most refined polishing methods. Methods of mechanical and thermal stabilization of the substrate will be severely stressed. In the thermal infrared, the need for large aperture is tempered by the even stronger need to control the telescope's thermal emission by cooled or cryogenic operation. Thus, the SIRTF mirror at 1 meter is not large and does not require unusually high accuracy, but the fabrication process must produce a mirror that is the right shape at a temperature of 4 K. Future large cooled mirrors will present more severe problems, especially if they must also be accurate enough to work at optical wavelengths. At the very shortest wavelengths accessible to reflecting optics, in the x-ray domain, the very low count fluxes of high energy photons place a premium on the collecting area. It is

  5. Fabrication

    NASA Technical Reports Server (NTRS)

    Angel, Roger; Helms, Richard; Bilbro, Jim; Brown, Norman; Eng, Sverre; Hinman, Steve; Hull-Allen, Greg; Jacobs, Stephen; Keim, Robert; Ulmer, Melville

    1992-01-01

    What aspects of optical fabrication technology need to be developed so as to facilitate existing planned missions, or enable new ones? Throughout the submillimeter to UV wavelengths, the common goal is to push technology to the limits to make the largest possible apertures that are diffraction limited. At any one wavelength, the accuracy of the surface must be better than lambda/30 (rms error). The wavelength range is huge, covering four orders of magnitude from 1 mm to 100 nm. At the longer wavelengths, diffraction limited surfaces can be shaped with relatively crude techniques. The challenge in their fabrication is to make as large as possible a reflector, given the weight and volume constraints of the launch vehicle. The limited cargo diameter of the shuttle has led in the past to emphasis on deployable or erectable concepts such as the Large Deployable Reflector (LDR), which was studied by NASA for a submillimeter astrophysics mission. Replication techniques that can be used to produce light, low-cost reflecting panels are of great interest for this class of mission. At shorter wavelengths, in the optical and ultraviolet, optical fabrication will tax to the limit the most refined polishing methods. Methods of mechanical and thermal stabilization of the substrate will be severely stressed. In the thermal infrared, the need for large aperture is tempered by the even stronger need to control the telescope's thermal emission by cooled or cryogenic operation. Thus, the SIRTF mirror at 1 meter is not large and does not require unusually high accuracy, but the fabrication process must produce a mirror that is the right shape at a temperature of 4 K. Future large cooled mirrors will present more severe problems, especially if they must also be accurate enough to work at optical wavelengths. At the very shortest wavelengths accessible to reflecting optics, in the x-ray domain, the very low count fluxes of high energy photons place a premium on the collecting area. It is

  6. Preparation and characterization of MWCNT-graft-PCA-Pt electrode fabricated by electrospray deposition method for proton exchange membrane fuel cell.

    PubMed

    Sarlak, Nahid; Karimi, Mostafa; Dourani, Akram

    2014-09-01

    In this paper, the development and application of a novel carbon nanotube/Polycitric acid (MWCNT-graft-PCA-Pt) nanocomposite as an efficient nanocatalyst for PEM fuel cell is reported. Covalent attachment to PCA agents is the main method for the modification of CNTs with polymers. By this method electrocatalysts with a narrow particle-size distribution and good dispersion have been produced. Carbon nanotube (CNT) film electrodes have been fabricated by a novel process involving the electrostatic spray deposition (ESD) of a CNT solution. The CNT film electrodes have shown well-entangled and interconnected porous structures with good adherence to the substrate. Cyclic voltammograms (CV) of catalysts using the spongy thin layer electrode technique were obtained for the catalysts surface at evaluation and for Methanol Oxidation reaction (MOR). CV results have demonstrated that the current density and MOR activity of the MWCNT-graft-PCA-Pt is respectively higher than of the MWCNT-Pt nanocatalyst.

  7. Using tobacco mosaic virus template for the fabrication of three-dimensional hierarchical microbattery electrodes with high energy and high power density

    NASA Astrophysics Data System (ADS)

    Pomerantseva, Ekaterina; Gerasopoulos, Konstantinos; Gnerlich, Markus; Odenwald, Philipp; Culver, James; Ghodssi, Reza

    2013-09-01

    We present a novel approach for the fabrication of lithium-ion microbattery electrodes which deliver high energy and high power density. The key enabling technology is the use of self-assembled Tobacco mosaic virus (TMV) nanoforests as a template for active battery materials. The self-assembling TMV is a genetically modified biological nanorod with increased metal binding properties for enhanced manufacturability. High energy density is achieved due to the active surface area increase within a given footprint by combining TMV with three-dimensional (3D) microfabricated structures. The TMV nanostructure enables high power density through larger electrode/electrolyte contact area and faster charge transport. The electrodes consist of an array of electroplated gold micropillars. The pillars are coated with the self-assembled nanoscale TMV template and subsequently metalized in-place. Active battery material (V2O5) is conformally deposited using atomic layer deposition (ALD) on the hierarchical micro/nano network. Electrochemical testing of these electrodes indicates a 3-5 fold increase in energy density, compared to the TMV-templated electrodes without micropillars, without increasing footprint area or reducing rate performance. Further increase in energy density can be achieved by increasing surface area of 3D microelements as demonstrated by fabrication and electrochemical testing of the electrodes with hollow gold micropillars. Scaling up energy density by increasing active material thickness beyond 100 nm revealed some loss in surface area which highlighted the importance of nanoscale engineering for achieving maximum energy and power density in energy storage systems.

  8. Fabrication and characterization of implantable and flexible nerve cuff electrodes with Pt, Ir and IrOx films deposited by RF sputtering

    NASA Astrophysics Data System (ADS)

    Lee, Soo Hyun; Jung, Jung Hwan; Chae, Youn Mee; Suh, Jun-Kyo Francis; Kang, Ji Yoon

    2010-03-01

    This paper presents the fabrication and characterization of implantable and flexible nerve cuff electrodes for neural interfaces using the conventional BioMEMS technique. In order to fabricate a flexible nerve electrode, polyimide (PI) was chosen as the substrate material. Then, nerve electrodes were thermally re-formed in a cuff shape so as to increase the area in which the charges were transferred to the nerve. Platinum (Pt), iridium (Ir) and iridium oxide (IrOx) films, which were to serve as conducting materials for the nerve electrodes, were deposited at different working pressures by RF magnetron sputtering. The electrochemical properties of the deposited films were characterized by electrochemical impedance spectroscopy (EIS). The charge delivery capacities of the films were recorded and calculated by cyclic voltammetry (CV). The deposited films of Pt, Ir and IrOx have strong differences in electrochemical properties, which depend on the working pressure of sputter. Each film deposited at 30 mTorr of working pressure shows the highest value of charge delivery capacity (CDC). For the IrOx films, the electrochemical properties were strongly affected by the working pressure as well as the Ar:O2 gas ratio. The IrOx film deposited with an Ar:O2 gas ratio of 8:1 showed the highest CDC of 59.5 mC cm-2, which was about five times higher than that of films deposited with a 1:1 gas ratio.

  9. Cell micropatterning on superhydrophobic diamond nanowires.

    PubMed

    Marcon, Lionel; Addad, Ahmed; Coffinier, Yannick; Boukherroub, Rabah

    2013-01-01

    Cell micropatterning was achieved in a spatially controlled manner based on heterogeneously wetted superhydrophilic/superhydrophobic diamond nanowire (NW) surfaces. Diamond NWs were synthesized on boron-doped diamond substrates using reactive ion etching and functionalized with octadecyltrichlorosilane to achieve superhydrophobicity. Superhydrophilic motifs of 400×400 μm(2) and 10×10 μm(2) single cell-sized motifs, surrounded by superhydrophobic regions, were then generated by selectively exposing the substrates to UV light. This design allowed successful patterning of single HeLa and MCF-10A cells within the superhydrophilic regions without additional surface modification. To add a further level of complexity, micropatterned co-cultures were obtained using bovine serum albumin to promote cell adhesion. This method is simple and does not require any complicated processing steps such as mask deposition or template removal. Potential applications are in the development of cell-based biological assays in well-controlled and biologically relevant environments. PMID:22922066

  10. Injection molded polymeric micropatterns for bone regeneration study.

    PubMed

    Zanchetta, Erika; Guidi, Enrica; Della Giustina, Gioia; Sorgato, Marco; Krampera, Mauro; Bassi, Giulio; Di Liddo, Rosa; Lucchetta, Giovanni; Conconi, Maria Teresa; Brusatin, Giovanna

    2015-04-01

    An industrially feasible process for the fast mass-production of molded polymeric micro-patterned substrates is here presented. Microstructured polystyrene (PS) surfaces were obtained through micro injection molding (μIM) technique on directly patterned stamps realized with a new zirconia-based hybrid spin-on system able to withstand 300 cycles at 90 °C. The use of directly patterned stamps entails a great advantage on the overall manufacturing process as it allows a fast, flexible, and simple one-step process with respect to the use of milling, laser machining, electroforming techniques, or conventional lithographic processes for stamp fabrication. Among the different obtainable geometries, we focused our attention on PS replicas reporting 2, 3, and 4 μm diameter pillars with 8, 9, 10 μm center-to-center distance, respectively. This enabled us to study the effect of the substrate topography on human mesenchymal stem cells behavior without any osteogenic growth factors. Our data show that microtopography affected cell behavior. In particular, calcium deposition and osteocalcin expression enhanced as diameter and interpillar distance size increases, and the 4-10 surface was the most effective to induce osteogenic differentiation. PMID:25756304

  11. From coin cells to 400 mAh pouch cells: Enhancing performance of high-capacity lithium-ion cells via modifications in electrode constitution and fabrication

    NASA Astrophysics Data System (ADS)

    Trask, Stephen E.; Li, Yan; Kubal, Joseph J.; Bettge, Martin; Polzin, Bryant J.; Zhu, Ye; Jansen, Andrew N.; Abraham, Daniel P.

    2014-08-01

    In this article we describe efforts to improve performance and cycle life of cells containing Li1.2Ni0.15Mn0.55Co0.1O2-based positive and graphite-based negative electrodes. Initial work to identify high-performing materials, compositions, fabrication variables, and cycling conditions is conducted in coin cells. The resulting information is then used for the preparation of double-sided electrodes, assembly of pouch cells, and electrochemical testing. We report the cycling performance of cells with electrodes prepared under various conditions. Our data indicate that cells with positive electrodes containing 92 wt.% Li1.2Ni0.15Mn0.55Co0.1O2, 4 wt.% carbons (no graphite), and 4 wt.% PVdF (92-4-4) show ∼20% capacity fade after 1000 cycles in the 2.5-4.4 V range, significantly better than our baseline cells that show the same fade after only 450 cycles. Our analyses indicate that the major contributors to cell energy fade are capacity loss and impedance rise. Therefore incorporating approaches that minimize capacity fade and impedance rise, such as electrode coatings and electrolyte additives, can significantly enhance calendar and cycle life of this promising cell chemistry.

  12. Design, fabrication and performance of small, graphite electrode, multistage depressed collectors with 200-W, CW, 8- to 18-GHz traveling-wave tubes

    NASA Technical Reports Server (NTRS)

    Ebihara, Ben T.; Ramins, Peter

    1987-01-01

    Small multistage depressed collectors (MDC's) which used pyrolytic graphite, ion-beam-textured pyrolytic graphite, and isotropic graphite electrodes were designed, fabricated, and evaluated in conjuntion with 200-W, continuous wave (CW), 8- to 18-GHz traveling-wave tubes (TWT's). The design, construction, and performance of the MDC's are described. The bakeout performance of the collectors, in terms of gas evolution, was indistinguishable from that of typical production tubes with copper collectors. However, preliminary results indicate that some additional radiofrequency (RF) and dc beam processing time (and/or longer or higher temperature bakeouts) may be needed beyond that of typical copper electrode collectors. This is particularly true for pyrolytic graphite electrodes and for TWT's without appendage ion pumps. Extended testing indicated good long-term stability of the textured pyrolytic graphite and isotropic graphite electrode surfaces. The isotropic graphite in particular showed considerable promise as an MDC electrode material because of its high purity, low cost, simple construction, potential for very compact overall size, and relatively low secondary electron emission yield characteristics in the as-machined state. However, considerably more testing experience is required before definitive conclusions on its suitability for electronic countermeasure systems and space TWT's can be made.

  13. Micro-patterns fabrication using focused proton beam lithography

    NASA Astrophysics Data System (ADS)

    Cutroneo, M.; Havranek, V.; Mackova, A.; Semian, V.; Torrisi, L.; Calcagno, L.

    2016-03-01

    Proton beam writing technique was recently introduced at 3MV Tandetron accelerator at Nuclear Physics Institute in Rez (Czech Republic). It has been used, to produce three-dimensional (3D) micro-structures in poly(methylmethacrylate) by 2.0 MeV and 2.6 MeV protons micro-beam. Micro-channels (52 μm × 52 μm) have been realized. After chemical etching, the quality of the bottom and side walls of the produced structures in PMMA were analyzed using Scanning Transmission Ion Microscopy (STIM).

  14. Simple fabrication of flexible electrodes with high metal-oxide content: electrospun reduced tungsten oxide/carbon nanofibers for lithium ion battery applications

    NASA Astrophysics Data System (ADS)

    Lee, Jaehyuk; Jo, Changshin; Park, Bangrock; Hwang, Woonbong; Lee, Hyung Ik; Yoon, Songhun; Lee, Jinwoo

    2014-08-01

    A one-step and mass-production synthetic route for a flexible reduced tungsten oxide-carbon composite nanofiber (WOx-C-NF) film is demonstrated via an electrospinning technique. The WOx-C-NF film exhibits unprecedented high content of metal-oxides (~80 wt%) and good flexibility (the tensile strength of the specimen was 6.13 MPa) without the use of flexible support materials like CNTs or graphene. The WOx-C-NF film is directly used as an anode in a lithium ion battery (LIB). Compared with previously reported tungsten oxide electrodes, the WOx-C-NF film exhibits high reversible capacity (481 mA h g-1total electrode), stable cycle, and improved rate performance, without the use of additive carbon, a polymeric binder and a current collector. Moreover, control electrodes fabricated by conventional processes support the positive effects of both the freestanding electrode and metal-oxide embedded carbon 1-D nanofiber structure.A one-step and mass-production synthetic route for a flexible reduced tungsten oxide-carbon composite nanofiber (WOx-C-NF) film is demonstrated via an electrospinning technique. The WOx-C-NF film exhibits unprecedented high content of metal-oxides (~80 wt%) and good flexibility (the tensile strength of the specimen was 6.13 MPa) without the use of flexible support materials like CNTs or graphene. The WOx-C-NF film is directly used as an anode in a lithium ion battery (LIB). Compared with previously reported tungsten oxide electrodes, the WOx-C-NF film exhibits high reversible capacity (481 mA h g-1total electrode), stable cycle, and improved rate performance, without the use of additive carbon, a polymeric binder and a current collector. Moreover, control electrodes fabricated by conventional processes support the positive effects of both the freestanding electrode and metal-oxide embedded carbon 1-D nanofiber structure. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01033g

  15. Micropatterned Culture and Differentiation of Human Bone Marrow Mesenchymal Stem Cells Using a Polydimethylsiloxane Microstencil.

    PubMed

    Choi, Jin Ho; Bae, Jae-Sung; Lee, Hyun; Jin, Hee Kyung; Kim, Gyu Man

    2016-02-01

    A method for fabrication of polydimethylsiloxane (PDMS) microstencils was developed and its application to localized culture of human bone marrow mesenchymal stem cells (hMSCs) was tested. Unlike conventional culture methods, which culture cells on an entire surface, microscale cell culture provides precise control of the size and shape of stem cell patterns, and minimizes consumption of cells and culture media. A PDMS microstencil was fabricated by PDMS casting using an SU-8 mold prepared by photolithography. A pattern of 500-µm dots was tested. For the test, a PDMS microstencil was placed on a glass disk and cells were seeded on the stencil at a density of 5 x 10⁴ cells/cm². The hMSCs were cultured for 2 days at 37 °C in a humidified 5% CO2 atmosphere. The PDMS microstencil was removed after 2 days and the hMSC patterns were inspected under a microscope. The results confirmed that stem cells can be cultured using a PDMS microstencil. The micropatterned hMSCs retained their ability to differentiate into osteogenic and adipogenic cells. Thus, using a PDMS microstencil, stem cells can be cultured and differentiated in micropatterns in a precisely controlled manner, in any shape and size, for research and bioengineering applications. PMID:27305770

  16. Fabrication of fast, highly sensitive all-printed capacitive humidity sensors with carbon nanotube/polyimide hybrid electrodes

    NASA Astrophysics Data System (ADS)

    Itoh, Eiji; Takada, Akinori

    2016-02-01

    We have developed capacitive humidity sensors with highly gas permeable carbon nanotube top electrodes using solution techniques. The hydrophobic, porous carbon nanotube (CNT) network with polyimide as a binder was suitable for gas permeation, and the response of the capacitive humidity sensors was faster than that of the device with a 20-nm-thick Au top electrode. The capacitance change of the polymide capacitive humidity sensor with the printed CNT top electrode was almost proportional to the relative humidity and the capacitance was almost independent of the environmental temperature. The CNT electrodes strongly adhered to the partially fluorinated polyimide when CNT/polyimide nanocomposites were used as top electrodes. The response time was almost proportional to the square of the thickness of the polyimide dielectric layer, d, and the sensitivity was inversely proportional to d. The response time and sensitivity respectively decreased to less than 1 s and 1 pF/%RH in the device with d less than 1 µm.

  17. Using Silver Nano-Particle Ink in Electrode Fabrication of High Frequency Copolymer Ultrasonic Transducers: Modeling and Experimental Investigation

    PubMed Central

    Decharat, Adit; Wagle, Sanat; Jacobsen, Svein; Melandsø, Frank

    2015-01-01

    High frequency polymer-based ultrasonic transducers are produced with electrodes thicknesses typical for printed electrodes obtained from silver (Ag) nano-particle inks. An analytical three-port network is used to study the acoustic effects imposed by a thick electrode in a typical layered transducer configuration. Results from the network model are compared to experimental findings for the implemented transducer configuration, to obtain a better understanding of acoustical effects caused by the additional printed mass loading. The proposed investigation might be supportive of identification of suitable electrode-depositing methods. It is also believed to be useful as a feasibility study for printed Ag-based electrodes in high frequency transducers, which may reduce both the cost and production complexity of these devices. PMID:25903552

  18. Influence of substrate micropatterning on biofilm growth

    NASA Astrophysics Data System (ADS)

    Koehler, Stephan; Li, Yiwei; Liu, Bi-Feng Liu; Weitz, David

    2015-11-01

    We culture triple reporter Bacillus Subtilis biofilm on micropatterned agar substrates. We track the biofilm development in terms of size, thickness, shape, and phenotype expression. For a tiling composed of elevated rectangles, we observe the biofilm develops an oval shape or triangular shape depending on the rectangle's aspect ratio and orientation. The motile cells are primarily located in the valleys between the rectangles and the matrix producing cells are mostly located on the rectangles. Wrinkles form at the edges of the elevated surfaces, and upon merging form channels centered on the elevated surface. After a few days, the spore-forming cells appear at the periphery. Since biofilms in nature grow on irregular surfaces, our work may provide insight into the complex patterns observed.

  19. Fabrication of an ultrasensitive ibuprofen nanoaptasensor based on covalent attachment of aptamer to electrochemically deposited gold-nanoparticles on glassy carbon electrode.

    PubMed

    Roushani, Mahmoud; Shahdost-Fard, Faezeh

    2015-11-01

    The paper reports the development of an ultrasensitive nanoaptasensor based on the covalent attachment of an aptamer (Apt) to gold-nanoparticles (AuNPs) deposited on the surface of a glassy carbon electrode (GCE) as the unique platform. The developed nanoaptasensor was utilized to assay the anti-inflammatory drug, ibuprofen (IBP). The sensing platform was fabricated using a single-stage electrodeposite approach. It is worth noting that the proposed nanoaptasensor combines the advantages of the deposition of neatly arranged AuNPs (enlarged active surface area and strengthened electrochemical signal) and the elimination of enzymes or antibodies for the amplified detection of IBP, with the covalent attachment of the Apt to the surface of the modified electrode. Moreover, the newly developed nanoaptasensor embraces a number of attractive features such as ease of fabrication, low detection limit, excellent selectivity, good stability and a wide linear range with respect to IBP. Meanwhile, interference of common interfering analgesic drugs was effectively avoided. In optimized empirical conditions, the response current of the nanoaptasensor is linear to IBP concentrations from 0.005 nmol(-1) to 7 nmol(-1) with the detection limit (LOD) as accurate as 0.5 pmol(-1). This LOD value proves more sensitive in comparison with previously reported methods. Thus, the fabricated nanoaptasensor can serve as a powerful sensor for rapid diagnosis of IBP in human blood samples and shows great potential for practical bioapplication.

  20. Silver Nanowires Binding with Sputtered ZnO to Fabricate Highly Conductive and Thermally Stable Transparent Electrode for Solar Cell Applications.

    PubMed

    Singh, Manjeet; Rana, Tanka R; Kim, SeongYeon; Kim, Kihwan; Yun, Jae Ho; Kim, JunHo

    2016-05-25

    Silver nanowire (AgNW) film has been demonstrated as excellent and low cost transparent electrode in organic solar cells as an alternative to replace scarce and expensive indium tin oxide (ITO). However, the low contact area and weak adhesion with low-lying surface as well as junction resistance between nanowires have limited the applications of AgNW film to thin film solar cells. To resolve this problem, we fabricated AgNW film as transparent conductive electrode (TCE) by binding with a thin layer of sputtered ZnO (40 nm) which not only increased contact area with low-lying surface in thin film solar cell but also improved conductivity by connecting AgNWs at the junction. The TCE thus fabricated exhibited transparency and sheet resistance of 92% and 20Ω/□, respectively. Conductive atomic force microscopy (C-AFM) study revealed the enhancement of current collection vertically and laterally through AgNWs after coating with ZnO thin film. The CuInGaSe2 solar cell with TCE of our AgNW(ZnO) demonstrated the maximum power conversion efficiency of 13.5% with improved parameters in comparison to solar cell fabricated with conventional ITO as TCE. PMID:27149372

  1. Silver Nanowires Binding with Sputtered ZnO to Fabricate Highly Conductive and Thermally Stable Transparent Electrode for Solar Cell Applications.

    PubMed

    Singh, Manjeet; Rana, Tanka R; Kim, SeongYeon; Kim, Kihwan; Yun, Jae Ho; Kim, JunHo

    2016-05-25

    Silver nanowire (AgNW) film has been demonstrated as excellent and low cost transparent electrode in organic solar cells as an alternative to replace scarce and expensive indium tin oxide (ITO). However, the low contact area and weak adhesion with low-lying surface as well as junction resistance between nanowires have limited the applications of AgNW film to thin film solar cells. To resolve this problem, we fabricated AgNW film as transparent conductive electrode (TCE) by binding with a thin layer of sputtered ZnO (40 nm) which not only increased contact area with low-lying surface in thin film solar cell but also improved conductivity by connecting AgNWs at the junction. The TCE thus fabricated exhibited transparency and sheet resistance of 92% and 20Ω/□, respectively. Conductive atomic force microscopy (C-AFM) study revealed the enhancement of current collection vertically and laterally through AgNWs after coating with ZnO thin film. The CuInGaSe2 solar cell with TCE of our AgNW(ZnO) demonstrated the maximum power conversion efficiency of 13.5% with improved parameters in comparison to solar cell fabricated with conventional ITO as TCE.

  2. Supercapacitor electrode based on mixtures of graphene/graphite and carbon nanotubes fabricated using a new dynamic air-brush deposition technique

    NASA Astrophysics Data System (ADS)

    Bondavalli, P.; Delfaure, C.; Pribat, D.; Legagneux, P.

    2013-09-01

    This contribution deals with the fabrication of electrode and supercapacitor cell using a new dynamic air-brush deposition technique. This method allows to achieve extremely (ou highly) uniform mats with finely tuned thickness and weight in a completely reproducible way. Using this deposition technique, we have analyzed the effect of mixture of CNTs and graphene/graphite on the electrode and cell properties (energy, power and capacitance). using a mixture of 75% of graphene/graphite and 25% of CNTs we increased the power by a factor 2.5 compared to bare CNTs based electrodes. We also analyzed the effect of the weight firstly on the capacitance and specific energy and then on the specific power. We were able to reach a specific power of 200kW/Kg and a specific energy of 9.1Wh/Kg with an electrode having a surface of 2cm2 and a weight of 0.25mg composed by 50% of CNTs and graphene/graphite (using a common aqueous electrolyte). using our deposition technique we are able to achieve supercapacitors with ad-hoc characteristics simply modulating the weight and the concentration of the mixture in a completely reproducible way.

  3. Molecular imprinting method for fabricating novel glucose sensor: polyvinyl acetate electrode reinforced by MnO2/CuO loaded on graphene oxide nanoparticles.

    PubMed

    Farid, Mohammad Masoudi; Goudini, Leila; Piri, Farideh; Zamani, Abbasali; Saadati, Fariba

    2016-03-01

    An enzyme free glucose sensor was prepared by a molecular imprinting method (MIP). The procedure was developed by in situ preparation of a new polyvinyl acetate (PVA) electrode reinforced by MnO2/CuO loaded on graphene oxide (GO) nanoparticles (PVA/MnO2@GO/CuO). The nanocomposite was modified in the presence of glucose and then imprinted. A carbone paste method with voltammetry was used in the fabrication of the sensor from prepared MIP nanocomposite. PVA/MnO2@GO/CuO electrode was characterized by X-ray diffraction, FT-IR spectroscopy and scanning electron microscopy. Electrocatalytic activity of the electrode toward glucose oxidation was then investigated by cyclic voltammetry in alkaline medium. The results show that the response of PVA/MnO2@GO/CuO MIP is much higher than PVA/MnO2@GO/CuO non-imprinted electrode toward glucose oxidation. The detection limit was 53μM, and the sensor responses are linear for concentrations from 0.5 to 4.4mM. Relative standard deviations for intra- and inter-day determination were less than 6.0%. The relative recoveries for different samples were 96%.

  4. Molecular imprinting method for fabricating novel glucose sensor: polyvinyl acetate electrode reinforced by MnO2/CuO loaded on graphene oxide nanoparticles.

    PubMed

    Farid, Mohammad Masoudi; Goudini, Leila; Piri, Farideh; Zamani, Abbasali; Saadati, Fariba

    2016-03-01

    An enzyme free glucose sensor was prepared by a molecular imprinting method (MIP). The procedure was developed by in situ preparation of a new polyvinyl acetate (PVA) electrode reinforced by MnO2/CuO loaded on graphene oxide (GO) nanoparticles (PVA/MnO2@GO/CuO). The nanocomposite was modified in the presence of glucose and then imprinted. A carbone paste method with voltammetry was used in the fabrication of the sensor from prepared MIP nanocomposite. PVA/MnO2@GO/CuO electrode was characterized by X-ray diffraction, FT-IR spectroscopy and scanning electron microscopy. Electrocatalytic activity of the electrode toward glucose oxidation was then investigated by cyclic voltammetry in alkaline medium. The results show that the response of PVA/MnO2@GO/CuO MIP is much higher than PVA/MnO2@GO/CuO non-imprinted electrode toward glucose oxidation. The detection limit was 53μM, and the sensor responses are linear for concentrations from 0.5 to 4.4mM. Relative standard deviations for intra- and inter-day determination were less than 6.0%. The relative recoveries for different samples were 96%. PMID:26471527

  5. A low-temperature fabricated gate-stack structure for Ge-based MOSFET with ferromagnetic epitaxial Heusler-alloy/Ge electrodes

    NASA Astrophysics Data System (ADS)

    Fujita, Yuichi; Yamada, Michihiro; Nagatomi, Yuta; Yamamoto, Keisuke; Yamada, Shinya; Sawano, Kentarou; Kanashima, Takeshi; Nakashima, Hiroshi; Hamaya, Kohei

    2016-06-01

    A possible low-temperature fabrication process of a gate-stack for Ge-based spin metal-oxide-semiconductor field-effect transistor (MOSFET) is investigated. First, since we use epitaxial ferromagnetic Heusler alloys on top of the phosphorous doped Ge epilayer as spin injector and detector, we need a dry etching process to form Heusler-alloy/n+-Ge Schottky-tunnel contacts. Next, to remove the Ge epilayers damaged by the dry etching process, the fabricated structures are dipped in a 0.03% diluted H2O2 solution. Finally, Al/SiO2/GeO2/Ge gate-stack structures are fabricated at 300 °C as a top gate-stack structure. As a result, the currents in the Ge-MOSFET fabricated here can be modulated by applying gate voltages even by using the low-temperature formed gate-stack structures. This low-temperature fabrication process can be utilized for operating Ge spin MOSFETs with a top gate electrode.

  6. A low-temperature fabricated gate-stack structure for Ge-based MOSFET with ferromagnetic epitaxial Heusler-alloy/Ge electrodes

    NASA Astrophysics Data System (ADS)

    Fujita, Yuichi; Yamada, Michihiro; Nagatomi, Yuta; Yamamoto, Keisuke; Yamada, Shinya; Sawano, Kentarou; Kanashima, Takeshi; Nakashima, Hiroshi; Hamaya, Kohei

    2016-06-01

    A possible low-temperature fabrication process of a gate-stack for Ge-based spin metal–oxide–semiconductor field-effect transistor (MOSFET) is investigated. First, since we use epitaxial ferromagnetic Heusler alloys on top of the phosphorous doped Ge epilayer as spin injector and detector, we need a dry etching process to form Heusler-alloy/n+-Ge Schottky-tunnel contacts. Next, to remove the Ge epilayers damaged by the dry etching process, the fabricated structures are dipped in a 0.03% diluted H2O2 solution. Finally, Al/SiO2/GeO2/Ge gate-stack structures are fabricated at 300 °C as a top gate-stack structure. As a result, the currents in the Ge-MOSFET fabricated here can be modulated by applying gate voltages even by using the low-temperature formed gate-stack structures. This low-temperature fabrication process can be utilized for operating Ge spin MOSFETs with a top gate electrode.

  7. The Use of Glass Substrates with Bi-Functional Silanes for Designing Micropatterned Cell-Secreted Cytokine Immunoassays

    PubMed Central

    Seo, Jeong Hyun; Chen, Li-Jung; Verkhoturov, Stanislav V.; Schweikert, Emile A.; Revzin, Alexander

    2011-01-01

    It is often desirable to sequester cells in specific locations on the surface and to integrate sensing elements next to the cells. In the present study, surfaces were fabricated so as to position cytokine sensing domains inside non-fouling poly(ethylene glycol) (PEG) hydrogel microwells. Our aim was to increase sensitivity of micropatterned cytokine immunoassays through covalent attachment of biorecognition molecules. To achieve this, glass substrates were functionalized with a binary mixture of acrylate- and thiol-terminated methoxysilanes. During subsequent hydrogel photopatterning step acrylate moieties served to anchor hydrogel microwells to glass substrates. Importantly, glass attachment sites within the microwells contained thiol groups that could be activated with a hetero-bifunctional cross-linker for covalent immobilization of proteins. After incubation with fluorescently-labeled avidin, microwells fabricated on a mixed acryl/thiol silane layer emitted ~6 times more fluorescence compared to microwells fabricated on an acryl silane alone. This result highlighted the advantages of covalent attachment of avidin inside the microwells. To create cytokine immunoassays, micropatterned surfaces were incubated with biotinylated IFN-γ or TNF-α antibodies (Abs). Micropatterned immunoassays prepared in this manner were sensitive down to 1 ng/ml or 60 pM IFN-γ. To further prove utility of this bionterface design, macrophages were seeded into 30 µm diameter microwells fabricated on either bi-functional (acryl/thiol) or monofunctional silane layers. Both types of microwells were coated with avidin and biotin-anti-TNF-α prior to cell seeding. Short mitogenic activation followed by immunostaining for TNF-α revealed that microwells created on bi-functional silane layer had 3 times higher signal due to macrophage-secreted TNF-α compared to microwells fabricated on mono-functional silane. The rational design of cytokine-sensing surfaces described here will be leveraged

  8. UV/Vis Spectroelectrochemistry as a Tool for Monitoring the Fabrication of Sensors Based on Silver Nanoparticle Modified Electrodes

    PubMed Central

    Fernández-Blanco, Cristina; Colina, Álvaro; Heras, Aránzazu

    2013-01-01

    A new controlled current multipulse methodology has been developed to modify the screen-printed electrode surface with silver nanoparticles (AgNPs). Spectroelectrochemistry has provided not only information about the type of nanoparticles (NPs) deposited on the electrode surface, but also about the electrosynthesis process. Small NPs without plasmon band are initially generated. Next, these nuclei grow to form bigger NPs in the reduction pulses with a characteristic plasmon band centered at 400 nm. Most of the NPs are generated during the first reduction pulses and a linear growth of the absorbance at a lower reaction rate was obtained in the subsequent pulses. Oxidation pulses do not redissolve completely silver NPs but only partially, meaning that very stable NPs are generated. AgNPs-modified electrodes have been successfully used to determine hydrogen peroxide. Spectroelectrochemistry has also yielded very useful information to understand the voltammetric signal obtained during the reduction of H2O2 on silver modified electrodes. PMID:23645107

  9. A low-cost rapid prototyping method for metal electrode fabrication using a CO2 laser cutter

    NASA Astrophysics Data System (ADS)

    Toossi, A.; Daneshmand, M.; Sameoto, D.

    2013-04-01

    In this note, a novel approach on the use of a low-power CO2 laser cutter is proposed to pattern thin metal electrode prototypes. Although low-power CO2 laser cutters have been used to etch and cut a wide range of materials, based on our knowledge, metal electrode patterning has not been previously explored. Using the proposed approach, metal electrodes can be patterned on the substrates that are good absorbers of CO2 wavelength. Here, polymethylmethacrylate substrates are selected and metal electrode patterning using the commercial CO2 laser cutter of VLS 3.50 Versa Laser is investigated. This approach has a wide range of applications, and two of those examples for microwave heating and antenna applications are presented.

  10. Versatile Micropatterning of Plasmonic Nanostructures by Visible Light Induced Electroless Silver Plating on Gold Nanoseeds.

    PubMed

    Yoshikawa, Hiroyuki; Hironou, Asami; Shen, ZhengJun; Tamiya, Eiichi

    2016-09-14

    A versatile fabrication technique for plasmonic silver (Ag) nanostructures that uses visible light exposure for micropatterning and plasmon resonance tuning is presented. The surface of a glass substrate modified with gold (Au) nanoseeds by a thermal dewetting process was used as a Ag plating platform. When a solution containing silver nitrate and sodium citrate was dropped on the Au nanoseeds under visible light exposure, the plasmon-mediated reduction of Ag ions was induced on the Au nanoseeds to form Ag nanostructures. The plasmon resonance spectra of Ag nanostructures were examined by an absorption spectral measurement and a finite-difference time-domain (FDTD) simulation. Some examples of Ag nanostructure patterning were demonstrated by means of light exposure through a photomask, direct writing with a focused laser beam, and the interference between two laser beams. Surface enhanced Raman spectroscopy (SERS) of 4-aminothiophenol (4-ATP) was conducted with fabricated Ag nanostructures.

  11. Versatile Micropatterning of Plasmonic Nanostructures by Visible Light Induced Electroless Silver Plating on Gold Nanoseeds.

    PubMed

    Yoshikawa, Hiroyuki; Hironou, Asami; Shen, ZhengJun; Tamiya, Eiichi

    2016-09-14

    A versatile fabrication technique for plasmonic silver (Ag) nanostructures that uses visible light exposure for micropatterning and plasmon resonance tuning is presented. The surface of a glass substrate modified with gold (Au) nanoseeds by a thermal dewetting process was used as a Ag plating platform. When a solution containing silver nitrate and sodium citrate was dropped on the Au nanoseeds under visible light exposure, the plasmon-mediated reduction of Ag ions was induced on the Au nanoseeds to form Ag nanostructures. The plasmon resonance spectra of Ag nanostructures were examined by an absorption spectral measurement and a finite-difference time-domain (FDTD) simulation. Some examples of Ag nanostructure patterning were demonstrated by means of light exposure through a photomask, direct writing with a focused laser beam, and the interference between two laser beams. Surface enhanced Raman spectroscopy (SERS) of 4-aminothiophenol (4-ATP) was conducted with fabricated Ag nanostructures. PMID:27564976

  12. Micropatternable elastic electrets based on a PDMS/carbon nanotube composite

    NASA Astrophysics Data System (ADS)

    Xu, W. J.; Kranz, M.; Kim, S. H.; Allen, M. G.

    2010-10-01

    This paper reports the fabrication and performance of an elastic electret based on polydimethylsiloxane (PDMS)/carbon-nanotube (CNT) nanocomposites. The composite formulation concentrates CNTs near the surface of the PDMS and thereby combines the excellent electrical properties and room temperature micropatternability of the CNT with the elasticity of PDMS. The fabrication approach preserves the good rheological properties of unfilled PDMS and also efficiently utilizes the CNTs. The material was corona charged and the charge storage behavior was characterized using surface potential measurements. Substantial improvements in charge storage capacity and stability were observed compared to either pure PDMS or CNTs on the surface of PDMS at room temperature over a 280 h measurement period. The power generation of the corona-charged elastic composite was initially demonstrated through a ball drop experiment.

  13. Controlled skeletal progenitor cell migration on nanostructured porous silicon/silicon micropatterns

    NASA Astrophysics Data System (ADS)

    Torres-Costa, V.; Sánchez-Vaquero, V.; Muñoz-Noval, Á.; González-Méndez, L.; Punzón-Quijorna, E.; Gallach-Pérez, D.; Manso-Silván, M.; Martínez-Muñoz, G.; Climent-Font, A.; García-Ruiz, J. P.; Martín-Palma, R. J.

    2011-10-01

    In this work nanostructured porous silicon (nanoPS) was used for the fabrication of surface micropatterns aiming at controlling cell adhesion and migration. In particular, surface patterns of nanoPS and Si were engineered by high-energy ion-beam irradiation and subsequent anodization. It was found that human skeletal progenitor cells are sensitive to oneand two-dimensional patterns and that focal adhesion is inhibited on nanoPS areas. In spite of this anti-fouling characteristics, studies on patterns with reduced Si areas show that cells conform to nanoPS pathways favoring migration through cell protrusion, body translocation and tail retraction from two parallel Si traction rails. Moreover, migration can be blocked and cells tend to arrange when grid patterns with the appropriate dimensions are fabricated. The experimental results confirm that progenitor cells are able to exploit nanoPS anti-fouling designs by adapting to it for migration purposes.

  14. Facile fabrication of an efficient BiVO4 thin film electrode for water splitting under visible light irradiation

    PubMed Central

    Jia, Qingxin; Iwashina, Katsuya; Kudo, Akihiko

    2012-01-01

    An efficient BiVO4 thin film electrode for overall water splitting was prepared by dipping an F-doped SnO2 (FTO) substrate electrode in an aqueous nitric acid solution of Bi(NO3)3 and NH4VO3, and subsequently calcining it. X-ray diffraction of the BiVO4 thin film revealed that a photocatalytically active phase of scheelite-monoclinic BiVO4 was obtained. Scanning electron microscopy images showed that the surface of an FTO substrate was uniformly coated with the BiVO4 film with 300–400 nm of the thickness. The BiVO4 thin film electrode gave an excellent anodic photocurrent with 73% of an IPCE at 420 nm at 1.0 V vs. Ag/AgCl. Modification with CoO on the BiVO4 electrode improved the photoelectrochemical property. A photoelectrochemical cell consisting of the BiVO4 thin film electrode with and without CoO, and a Pt counter electrode was constructed for water splitting under visible light irradiation and simulated sunlight irradiation. Photocurrent due to water splitting to form H2 and O2 was confirmed with applying an external bias smaller than 1.23 V that is a theoretical voltage for electrolysis of water. Water splitting without applying external bias under visible light irradiation was demonstrated using a SrTiO3∶Rh photocathode and the BiVO4 photoanode. PMID:22699499

  15. Fabrication and Optimization of ChE/ChO/HRP-AuNPs/c-MWCNTs Based Silver Electrode for Determining Total Cholesterol in Serum.

    PubMed

    Lata, Kusum; Dhull, Vikas; Hooda, Vikas

    2016-01-01

    The developed method used three enzymes comprised of cholesterol esterase, cholesterol oxidase, and peroxidase for fabrication of amperometric biosensor in order to determine total cholesterol in serum samples. Gold nanoparticles (AuNPs) and carboxylated multiwall carbon nanotubes (cMWCNTs) were used to design core of working electrode, having covalently immobilized ChO, ChE, and HRP. Polyacrylamide layer was finally coated on working electrode in order to prevent enzyme leaching. Chemically synthesised Au nanoparticles were subjected to transmission electron microscopy (TEM) for analysing the shape and size of the particles. Working electrode was subjected to FTIR and XRD. The combined action of AuNP and c-MWCNT showed enhancement in electrocatalytic activity at a very low potential of 0.27 V. The pH 7, temperature 40°C, and response time of 20 seconds, respectively, were observed. The biosensor shows a broad linear range from 0.5 mg/dL to 250 mg/dL (0.01 mM-5.83 mM) with minimum detection limit being 0.5 mg/dL (0.01 mM). The biosensor showed reusability of more than 45 times and was stable for 60 days. The biosensor was successfully tested for determining total cholesterol in serum samples amperometrically with no significant interference by serum components. PMID:26885393

  16. High-Resolution, Large-Area Fabrication of Compliant Electrodes via Laser Ablation for Robust, Stretchable Dielectric Elastomer Actuators and Sensors.

    PubMed

    Araromi, Oluwaseun A; Rosset, Samuel; Shea, Herbert R

    2015-08-19

    A key element in stretchable actuators, sensors, and systems based on elastomer materials are compliant electrodes. While there exist many methodologies for fabricating electrodes on dielectric elastomers, very few succeed in achieving high-resolution patterning over large areas. We present a novel approach for the production of mechanically robust, high-resolution compliant electrodes for stretchable silicone elastomer actuators and sensors. Cast, 2-50 μm thick poly(dimethylsiloxane) (PDMS)-carbon composite layers are patterned by laser ablation and subsequently bonded to a PDMS membrane by oxygen plasma activation. The technique affords great design flexibility and high resolution and readily scales to large-area arrays of devices. We validate our methodology by producing arrays of actuators and sensors on up to A4-size substrates, reporting on microscale dielectric elastomer actuators (DEA) generating area strains of over 25%, and interdigitated capacitive touch sensors with high sensitivity yet insensitivity to substrate stretching. We demonstrate the ability to cofabricate highly integrated multifunctional transducers using the same process flow, showing the methodology's promise in realizing sophisticated and reliable complex stretchable devices with fine features over large areas.

  17. Fabrication and Optimization of ChE/ChO/HRP-AuNPs/c-MWCNTs Based Silver Electrode for Determining Total Cholesterol in Serum

    PubMed Central

    Lata, Kusum; Dhull, Vikas

    2016-01-01

    The developed method used three enzymes comprised of cholesterol esterase, cholesterol oxidase, and peroxidase for fabrication of amperometric biosensor in order to determine total cholesterol in serum samples. Gold nanoparticles (AuNPs) and carboxylated multiwall carbon nanotubes (cMWCNTs) were used to design core of working electrode, having covalently immobilized ChO, ChE, and HRP. Polyacrylamide layer was finally coated on working electrode in order to prevent enzyme leaching. Chemically synthesised Au nanoparticles were subjected to transmission electron microscopy (TEM) for analysing the shape and size of the particles. Working electrode was subjected to FTIR and XRD. The combined action of AuNP and c-MWCNT showed enhancement in electrocatalytic activity at a very low potential of 0.27 V. The pH 7, temperature 40°C, and response time of 20 seconds, respectively, were observed. The biosensor shows a broad linear range from 0.5 mg/dL to 250 mg/dL (0.01 mM–5.83 mM) with minimum detection limit being 0.5 mg/dL (0.01 mM). The biosensor showed reusability of more than 45 times and was stable for 60 days. The biosensor was successfully tested for determining total cholesterol in serum samples amperometrically with no significant interference by serum components. PMID:26885393

  18. Parallelized cytoindentation using convex micropatterned surfaces.

    PubMed

    Jia, Bojing; Wee, Tse-Luen; Boudreau, Colton G; Berard, Daniel J; Mallik, Adiel; Juncker, David; Brown, Claire M; Leslie, Sabrina R

    2016-01-01

    Here we present a high-throughput, parallelized cytoindentor for local compression of live cells. The cytoindentor uses convex lens-induced confinement (CLiC) to indent micrometer-sized areas in single cells and/or populations of cells with submicron precision. This is accomplished using micropatterned poly(dimethylsiloxane) (PDMS) films that are adhered to a convex lens to create arrays of extrusions referred to here as "posts." These posts caused local deformation of subcellular regions without any evidence of cell lysis upon CLiC indentation. Our micropost arrays were also functionalized with glycoproteins, such as fibronectin, to both pull and compress cells under customized confinement geometries. Measurements of Chinese hamster ovary (CHO-K1) cell migration trajectories and oxidative stress showed that the CLiC device did not damage or significantly stress the cells. Our novel tool opens a new area of investigation for visualizing mechanobiology and mechanochemistry within living cells, and the high-throughput nature of the technique will streamline investigations as current tools for mechanically probing material properties and molecular dynamics within cells, such as traditional cytoindentors and atomic force microscopy (AFM), are typically restricted to single-cell manipulation. PMID:27528072

  19. Leidenfrost point reduction on micropatterned metallic surfaces.

    PubMed

    del Cerro, Daniel Arnaldo; Marín, Alvaro G; Römer, Gertwillem R B E; Pathiraj, B; Lohse, Detlef; Huis in 't Veld, Albertus J

    2012-10-23

    Droplets are able to levitate when deposited over a hot surface exceeding a critical temperature. This is known as the Leidenfrost effect. This phenomenon occurs when the surface is heated above the so-called Leidenfrost point (LFP), above which the vapor film between the droplet and hot surface is able to levitate the droplet. Such a critical temperature depends on several factors. One of the most studied parameters has been the surface roughness. Almost all of the experimental studies in the literature have concluded that the LFP increases with the roughness. According to these results, it seems that the roughness is detrimental for the stability of the vapor film. In contrast with these results, we present here a micropatterned surface that significantly reduces the LFP. The temperature increase, relative to the boiling point, required to reach the LFP is 70% lower than that on the flat surface. The reasons for such an effect are qualitatively and quantitatively discussed with a simple semiempirical model. This result can be relevant to save energy in applications that take advantage of the Leidenfrost effect for drop control or drag reduction.

  20. Fabrication, characterization of two nano-composite CuO-ZnO working electrodes for dye-sensitized solar cell.

    PubMed

    Habibi, Mohammad Hossein; Karimi, Bahareh; Zendehdel, Mahmoud; Habibi, Mehdi

    2013-12-01

    Two kind of CuO-ZnO nanocomposite working electrodes were synthesized by sol-gel technology and applied in dye-sensitized solar cells (DSSCs). Their characteristics were studied by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and UV-Vis diffuse reflectance spectrum (DRS). CuO-ZnO nanocomposite thin films were prepared doctor blade technique on the fluorine-doped tin oxide (FTO) and used as working electrodes in dye sensitized solar cells (DSSC). Their photovoltaic behavior were compared with standard using D35 dye and an electrolyte containing [Co(bpy)3](PF6)2, [Co(pby)3](PF6)3, LiClO4, and 4-tert-butylpyridine (TBP). The ranges of short-circuit current (JSC) from 0.18 to 0.21 (mA/cm(2)), open-circuit voltage (VOC) from 0.24 to 0.55V, and fill factor from 0.34 to 0.39 were obtained for the DSSCs made using the working electrodes. The efficiency of the working electrodes after the addition of TBL was more than doubled. The light scattering and carrier transport properties of these composites promote the performance of dye-sensitized solar cells (DSSCs). PMID:23973582

  1. Fabrication of silver nanowires and metal oxide composite transparent electrodes and their application in UV light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Yan, Xingzhen; Ma, Jiangang; Xu, Haiyang; Wang, Chunliang; Liu, Yichun

    2016-08-01

    In this paper, we prepared the silver nanowires (AgNWs)/aluminum-doped zinc oxide (AZO) composite transparent conducting electrodes for n-ZnO/p-GaN heterojunction light emitting-diodes (LEDs) by drop casting AgNW networks and subsequent atomic layer deposition (ALD) of AZO at 150 °C. The contact resistances between AgNWs were dramatically reduced by pre-annealing in the vacuum chamber before the ALD of AZO. In this case, AZO works not only as the conformal passivation layer that protects AgNWs from oxidation, but also as the binding material that improves AgNWs adhesion to substrates. Due to the localized surface plasmons (LSPs) of the AgNWs resonant coupling with the ultraviolet (UV) light emission from the LEDs, a higher UV light extracting efficiency is achieved from LEDs with the AgNWs/AZO composite electrodes in comparison with the conventional AZO electrodes. Additionally, the antireflective nature of random AgNW networks in the composite electrodes caused a broad output light angular distribution, which could be of benefit to certain optoelectronic devices like LEDs and solar cells.

  2. Field-Effect Transistors: Ultrathin MXene-Micropattern-Based Field-Effect Transistor for Probing Neural Activity (Adv. Mater. 17/2016).

    PubMed

    Xu, Bingzhe; Zhu, Minshen; Zhang, Wencong; Zhen, Xu; Pei, Zengxia; Xue, Qi; Zhi, Chunyi; Shi, Peng

    2016-05-01

    A field-effect transistor (FET) based on ultrathin Ti3 C2 -MXene micropatterns is developed by C. Zhi, P. Shi, and co-workers, as described on page 3333. The FET can be utilized for label-free probing of small molecules in typical biological environments, e.g., for fast detection of action potentials in primary neurons. This device is produced with a microcontact printing technique, harnessing the unique advantages for easy fabrication. PMID:27122113

  3. Study on the fabrication of transparent electrodes by using a thermal-roll imprinted Ag mesh and anATO thin film

    NASA Astrophysics Data System (ADS)

    Kim, Sung Jin; Choi, Kyoon; Choi, Se Young

    2016-03-01

    Transparent conductive films have been widely studied because of their potential applications in optoelectronic devices such as paper displays, dye-sensitized solar cells (DSSCs), organic lighting-emitting diodes (OLEDs), organic solar cells and so on. In this paper, we report on a low-resistance, a high-transparents conductive film that can be applied as It a flexible device substrate. In order to the fabricate transparent conductive film, we used a high-resolution roll imprinting method. The following steps were performed: The design and manufacture of an electroforming stamp mold, the fabrication of high resolution roll imprinted on flexible film, and the manufacture of an Ag grid that was filled by using a doctor blade process with a nano-sized Ag paste. Then on patterned Its films, antimony tin oxide was coated with ATO sol solution by using bar the coating method. The fabricated ATO/Ag mesh electrode showed good flexibility, and It exhibited a high optical transmittance of 85.3% in the visible wavelength and a sheet resistance of 41 Ω/sq. Furthermore, the bending test for mechanical properties showed that the ATO/Ag thin film had good flexibility.

  4. Capability of Sputtered Micro-patterned NiTi Thick Films

    NASA Astrophysics Data System (ADS)

    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.

  5. Fabrication of polycrystalline CdTe thin-film solar cells using carbon electrodes with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Okamoto, Tamotsu; Hayashi, Ryoji; Ogawa, Yohei; Hosono, Aikyo; Doi, Makoto

    2015-04-01

    The effects of adding carbon nanotubes (CNTs) to carbon back electrodes in polycrystalline CdTe thin-film solar cells were investigated. The CNTs were prepared by arc discharge under atmospheric pressure. The conductivity of the obtained CNT film with a density of 1.65 g/cm3 was approximately 2.6 × 103 S/cm. In the CdTe solar cells using carbon back electrodes with CNTs, the fill factor (FF) was improved as a result of adding CNTs with a concentration of 1 to 5 wt %. The improvement of FF was mainly due to the decrease in the series resistance of the CdTe solar cell. Furthermore, the open-circuit voltage (VOC) was improved by the CNT addition. The improvement of VOC was probably due to the reduction of the back barrier at the back contact.

  6. Fabrication of Carbon-Platinum Interdigitated Array Electrodes and Their Application for Investigating Homogeneous Hydrogen Evolution Catalysis

    SciTech Connect

    Liu, Fei; Divan, Ralu; Parkinson, Bruce A.

    2015-06-29

    Carbon interdigitated array (IDA) electrodes have been applied to study the homogeneous hydrogen evolution electrocatalyst [Ni(PPh2NBn2)2]2+ (where PPh2NBn2 is 1,5-dibenzyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane). The existence of reaction intermediates in the catalytic cycle is inferred from the electrochemical behavior of a glassy carbon disk electrodes and carbon IDA electrodes. The currents on IDA electrodes for an EC’ (electron transfer reaction followed by a catalytic reaction) mechanism are derived from the number of redox cycles and the contribution of non-catalytic currents. The catalytic reaction rate constant was then extracted from the IDA current equations. Applying the IDA current and kinetic equations to the electrochemical response of the [Ni(PPh2NBn2)2]2+ catalyst yielded a rate constant of 0.10 s-1 for the hydrogen evolution reaction that agrees with the literature value. The quantitative analysis of IDA cyclic voltammetry can be used as a simple and straightforward method for determining rate constants in other catalytic systems. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for DOE. Use of the Center for Nanoscale Materials was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

  7. Method of fabricating electrode catalyst layers with directionally oriented carbon support for proton exchange membrane fuel cell

    DOEpatents

    Liu, Di-Jia; Yang, Junbing

    2012-03-20

    A membrane electrode assembly (MEA) of the invention comprises an anode and a cathode and a proton conductive membrane therebetween, the anode and the cathode each comprising a patterned sheet of longitudinally aligned transition metal-containing carbon nanotubes, wherein the carbon nanotubes are in contact with and are aligned generally perpendicular to the membrane, wherein a catalytically active transition metal is incorporated throughout the nanotubes.

  8. Solid-state supercapacitors with rationally designed heterogeneous electrodes fabricated by large area spray processing for wearable energy storage applications

    PubMed Central

    Huang, Chun; Zhang, Jin; Young, Neil P.; Snaith, Henry J.; Grant, Patrick S.

    2016-01-01

    Supercapacitors are in demand for short-term electrical charge and discharge applications. Unlike conventional supercapacitors, solid-state versions have no liquid electrolyte and do not require robust, rigid packaging for containment. Consequently they can be thinner, lighter and more flexible. However, solid-state supercapacitors suffer from lower power density and where new materials have been developed to improve performance, there remains a gap between promising laboratory results that usually require nano-structured materials and fine-scale processing approaches, and current manufacturing technology that operates at large scale. We demonstrate a new, scalable capability to produce discrete, multi-layered electrodes with a different material and/or morphology in each layer, and where each layer plays a different, critical role in enhancing the dynamics of charge/discharge. This layered structure allows efficient utilisation of each material and enables conservative use of hard-to-obtain materials. The layered electrode shows amongst the highest combinations of energy and power densities for solid-state supercapacitors. Our functional design and spray manufacturing approach to heterogeneous electrodes provide a new way forward for improved energy storage devices. PMID:27161379

  9. Solid-state supercapacitors with rationally designed heterogeneous electrodes fabricated by large area spray processing for wearable energy storage applications

    NASA Astrophysics Data System (ADS)

    Huang, Chun; Zhang, Jin; Young, Neil P.; Snaith, Henry J.; Grant, Patrick S.

    2016-05-01

    Supercapacitors are in demand for short-term electrical charge and discharge applications. Unlike conventional supercapacitors, solid-state versions have no liquid electrolyte and do not require robust, rigid packaging for containment. Consequently they can be thinner, lighter and more flexible. However, solid-state supercapacitors suffer from lower power density and where new materials have been developed to improve performance, there remains a gap between promising laboratory results that usually require nano-structured materials and fine-scale processing approaches, and current manufacturing technology that operates at large scale. We demonstrate a new, scalable capability to produce discrete, multi-layered electrodes with a different material and/or morphology in each layer, and where each layer plays a different, critical role in enhancing the dynamics of charge/discharge. This layered structure allows efficient utilisation of each material and enables conservative use of hard-to-obtain materials. The layered electrode shows amongst the highest combinations of energy and power densities for solid-state supercapacitors. Our functional design and spray manufacturing approach to heterogeneous electrodes provide a new way forward for improved energy storage devices.

  10. Fabrication of a nano-structured PbO2 electrode by using printing technology: Surface characterization and application

    NASA Astrophysics Data System (ADS)

    Kannan, K.; Muthuraman, G.; Cho, G.; Moon, I. S.

    2014-08-01

    This investigation aimed to introduce printing technology for the first time to prepare a nanostrucutured PbO2 electrode and its application to a cerium redox transfer process. The new method of nano-size PbO2 preparation demonstrated that nano-PbO2 could be obtained in less time and at less cost at room temperature. The prepared nano-PbO2 screen printed on a Ti electrode by three different compositions under similar conditions showed through surface and electrochemical analyses no adherence on Ti and no contact with other nano-PbO2 particles. Gravure printing of nano-PbO2 on a PET (poly ethylene thin) film at high pressure was done with two different compositions for the first time. The selective composition of 57.14 % nano-PbO2 powder with 4.28 % carbon black and 38.58 % ECA (ethyl carbitol acetate) produced a film with a nanoporous structure with an electron transfer ability. Finally, the optimized gravure-printed nano-PbO2 electrode was applied to the oxidation of Ce(III) to Ce(IV) by using cyclic voltammetry. The gravure-printed nano-PbO2 should pave the way to promising applications in electrochemical and sensor fields.

  11. Solid-state supercapacitors with rationally designed heterogeneous electrodes fabricated by large area spray processing for wearable energy storage applications.

    PubMed

    Huang, Chun; Zhang, Jin; Young, Neil P; Snaith, Henry J; Grant, Patrick S

    2016-01-01

    Supercapacitors are in demand for short-term electrical charge and discharge applications. Unlike conventional supercapacitors, solid-state versions have no liquid electrolyte and do not require robust, rigid packaging for containment. Consequently they can be thinner, lighter and more flexible. However, solid-state supercapacitors suffer from lower power density and where new materials have been developed to improve performance, there remains a gap between promising laboratory results that usually require nano-structured materials and fine-scale processing approaches, and current manufacturing technology that operates at large scale. We demonstrate a new, scalable capability to produce discrete, multi-layered electrodes with a different material and/or morphology in each layer, and where each layer plays a different, critical role in enhancing the dynamics of charge/discharge. This layered structure allows efficient utilisation of each material and enables conservative use of hard-to-obtain materials. The layered electrode shows amongst the highest combinations of energy and power densities for solid-state supercapacitors. Our functional design and spray manufacturing approach to heterogeneous electrodes provide a new way forward for improved energy storage devices. PMID:27161379

  12. A Fully Integrated and Miniaturized Heavy-metal-detection Sensor Based on Micro-patterned Reduced Graphene Oxide

    NASA Astrophysics Data System (ADS)

    Xuan, Xing; Hossain, Md. Faruk; Park, Jae Yeong

    2016-09-01

    For this paper, a fully integrated and highly miniaturized electrochemical sensor was designed and fabricated on a silicon substrate. A solvothermal-assisted reduced graphene oxide named “TRGO” was then successfully micro-patterned using a lithography technique, followed by the electrodeposition of bismuth (Bi) on the surface of the micro-patterned TRGO for the electrochemical detection of heavy metal ions. The fully integrated electrochemical micro-sensor was then measured and evaluated for the detection of cadmium and lead-heavy metal ions in an acetic-acid buffered solution using the square wave anodic stripping voltammetry (SWASV) technique. The fabricated micro-sensor exhibited a linear detection range of 1.0 μg L‑1 to 120.0 μg L‑1 for both of the metal ions, and detection limits of 0.4 μg L‑1 and 1.0 μg L‑1 were recorded for the lead and cadmium (S/N = 3), respectively. Drinking-water samples were used for the practical assessment of the fabricated micro-sensor, and it showed an acceptable detection performance regarding the metal ions.

  13. A Fully Integrated and Miniaturized Heavy-metal-detection Sensor Based on Micro-patterned Reduced Graphene Oxide.

    PubMed

    Xuan, Xing; Hossain, Md Faruk; Park, Jae Yeong

    2016-09-12

    For this paper, a fully integrated and highly miniaturized electrochemical sensor was designed and fabricated on a silicon substrate. A solvothermal-assisted reduced graphene oxide named "TRGO" was then successfully micro-patterned using a lithography technique, followed by the electrodeposition of bismuth (Bi) on the surface of the micro-patterned TRGO for the electrochemical detection of heavy metal ions. The fully integrated electrochemical micro-sensor was then measured and evaluated for the detection of cadmium and lead-heavy metal ions in an acetic-acid buffered solution using the square wave anodic stripping voltammetry (SWASV) technique. The fabricated micro-sensor exhibited a linear detection range of 1.0 μg L(-1) to 120.0 μg L(-1) for both of the metal ions, and detection limits of 0.4 μg L(-1) and 1.0 μg L(-1) were recorded for the lead and cadmium (S/N = 3), respectively. Drinking-water samples were used for the practical assessment of the fabricated micro-sensor, and it showed an acceptable detection performance regarding the metal ions.

  14. A Fully Integrated and Miniaturized Heavy-metal-detection Sensor Based on Micro-patterned Reduced Graphene Oxide

    PubMed Central

    Xuan, Xing; Hossain, Md. Faruk; Park, Jae Yeong

    2016-01-01

    For this paper, a fully integrated and highly miniaturized electrochemical sensor was designed and fabricated on a silicon substrate. A solvothermal-assisted reduced graphene oxide named “TRGO” was then successfully micro-patterned using a lithography technique, followed by the electrodeposition of bismuth (Bi) on the surface of the micro-patterned TRGO for the electrochemical detection of heavy metal ions. The fully integrated electrochemical micro-sensor was then measured and evaluated for the detection of cadmium and lead-heavy metal ions in an acetic-acid buffered solution using the square wave anodic stripping voltammetry (SWASV) technique. The fabricated micro-sensor exhibited a linear detection range of 1.0 μg L−1 to 120.0 μg L−1 for both of the metal ions, and detection limits of 0.4 μg L−1 and 1.0 μg L−1 were recorded for the lead and cadmium (S/N = 3), respectively. Drinking-water samples were used for the practical assessment of the fabricated micro-sensor, and it showed an acceptable detection performance regarding the metal ions. PMID:27616629

  15. A Fully Integrated and Miniaturized Heavy-metal-detection Sensor Based on Micro-patterned Reduced Graphene Oxide.

    PubMed

    Xuan, Xing; Hossain, Md Faruk; Park, Jae Yeong

    2016-01-01

    For this paper, a fully integrated and highly miniaturized electrochemical sensor was designed and fabricated on a silicon substrate. A solvothermal-assisted reduced graphene oxide named "TRGO" was then successfully micro-patterned using a lithography technique, followed by the electrodeposition of bismuth (Bi) on the surface of the micro-patterned TRGO for the electrochemical detection of heavy metal ions. The fully integrated electrochemical micro-sensor was then measured and evaluated for the detection of cadmium and lead-heavy metal ions in an acetic-acid buffered solution using the square wave anodic stripping voltammetry (SWASV) technique. The fabricated micro-sensor exhibited a linear detection range of 1.0 μg L(-1) to 120.0 μg L(-1) for both of the metal ions, and detection limits of 0.4 μg L(-1) and 1.0 μg L(-1) were recorded for the lead and cadmium (S/N = 3), respectively. Drinking-water samples were used for the practical assessment of the fabricated micro-sensor, and it showed an acceptable detection performance regarding the metal ions. PMID:27616629

  16. Fabrication of microtemplates for the control of bacterial immobilization

    SciTech Connect

    Miyahara, Yasuhiro; Mitamura, Koji; Saito, Nagahiro; Takai, Osamu

    2009-09-15

    The authors described a region-selective immobilization methods of bacteria by using superhydrophobic/superhydrophilic and superhydrophobic/poly(ethylene glycol) (PEG) micropatterns for culture scaffold templates. In the case of superhydrophobic/superhydrophilic micropatterns, the superhydrophobic surface was prepared first by microwave-plasma enhanced chemical vapor deposition (MPECVD) from trimethylmethoxysilane. Then the superhydrophilic regions were fabricated by irradiating the superhydrophobic surface with vuv light through a stencil mask. In the case of the superhydrophobic/PEG micropatterned surfaces, PEG surfaces were fabricated first by chemical reaction of ester groups of p-nitrophenyl PEG with NH{sub 2} group of NH{sub 2}-terminated self assembled monolayer from n-6-hexyl-3-aminopropyltrimethoxysilane. The superhydrophobic regions were fabricated by MPECVD thorough a stencil mask. In this study four bacteria were selected from viewpoint of peptidoglycan cell wall (E. coli versus B. subtilis), extracellular polysaccharide (E.coli versus P. stutzeri, P. aeruginosa), and growth rate (P. stutzeri versus P. aeruginosa). The former micropattern brought discrete adhesions of E. coli and B. subtilis specifically on the hydrophobic regions, Furthermore, using the superhydrophobic/PEG micropattern, adhesion of bacteria expanded for E. coli, B. subtilis, P. stutzeri, and P. aeruginosa. They observed a high bacterial adhesion onto superhydrophobic surfaces and the inhibitive effect of bacterial adhesion on PEG surfaces.

  17. 3D Micropatterned Surface Inspired by Salvinia molesta via Direct Laser Lithography.

    PubMed

    Tricinci, Omar; Terencio, Tercio; Mazzolai, Barbara; Pugno, Nicola M; Greco, Francesco; Mattoli, Virgilio

    2015-11-25

    Biomimetic functional surfaces are attracting increasing attention for their relevant technological applications. Despite these efforts, inherent limitations of microfabrication techniques prevent the replication of complex hierarchical microstructures. Using a 3D laser lithography technique, we fabricated a 3D patterned surface bioinspired to Salvinia molesta leaves. The artificial hairs, with crownlike heads, were reproduced by scaling down (ca. 100 times smaller) the dimensions of natural features, so that microscale hairs with submicrometric resolution were attained. The micropatterned surface, in analogy with the natural model, shows interesting properties in terms of hydrophobicity and air retention when submerged by water, even if realized with a hydrophilic material. Furthermore, we successfully demonstrated the capability to promote localized condensation of water droplets from moisture in the atmosphere. PMID:26558410

  18. Three-Dimensional Soft Material Micropatterning via Direct Laser Lithography of Flexible Molds.

    PubMed

    Bernardeschi, Irene; Tricinci, Omar; Mattoli, Virgilio; Filippeschi, Carlo; Mazzolai, Barbara; Beccai, Lucia

    2016-09-28

    Three-dimensionally micropatterned surfaces are attracting increasing interest in soft robotics owing to the potential of mimicking natural morphologies at the micro/nanoscale. We employ direct laser lithography to fabricate molds with complex three-dimensional (3D) micrometric features, in a positive photoresist on flexible substrates, to pattern curved macroscopic soft surfaces with shapes not achievable with standard methods (e.g., reentrant angles). We present several 3D intricate microstructures in poly(dimethylsiloxane) (PDMS) and show a soft cylinder patterned with 3D microstructures with one molding process. Finally, we deform PDMS-based 3D architectures and show soft microgripping capability, indicating the potentiality of this approach for future application in soft robotics. PMID:27606899

  19. 3D Micropatterned Surface Inspired by Salvinia molesta via Direct Laser Lithography

    PubMed Central

    2015-01-01

    Biomimetic functional surfaces are attracting increasing attention for their relevant technological applications. Despite these efforts, inherent limitations of microfabrication techniques prevent the replication of complex hierarchical microstructures. Using a 3D laser lithography technique, we fabricated a 3D patterned surface bioinspired to Salvinia molesta leaves. The artificial hairs, with crownlike heads, were reproduced by scaling down (ca. 100 times smaller) the dimensions of natural features, so that microscale hairs with submicrometric resolution were attained. The micropatterned surface, in analogy with the natural model, shows interesting properties in terms of hydrophobicity and air retention when submerged by water, even if realized with a hydrophilic material. Furthermore, we successfully demonstrated the capability to promote localized condensation of water droplets from moisture in the atmosphere. PMID:26558410

  20. Layer by layer assembly of ultrathin V₂O₅ anchored MWCNTs and graphene on textile fabrics for fabrication of high energy density flexible supercapacitor electrodes.

    PubMed

    Shakir, Imran; Ali, Zahid; Bae, Jihyun; Park, Jongjin; Kang, Dae Joon

    2014-04-21

    Among transition metal oxides, vanadium oxides have received relatively modest attention for supercapacitor applications. Yet, this material is abundant, relatively inexpensive and offer several oxidation states which can provide a broad range of redox reactions suitable for supercapacitor operation. Electrochemical supercapacitors based on nanostructured vanadium oxide (V₂O₅) suffer from relatively low energy densities as they have low surface area and poor electrical conductivities. To overcome these problems, we developed a layer by layer assembly (LBL) technique in which a graphene layer was alternatively inserted between MWCNT films coated with ultrathin (3 nm) V₂O₅. The insertion of a conductive spacer of graphene between the MWCNT films coated with V₂O₅ not only prevents agglomeration between the MWCNT films but also substantially enhances the specific capacitance by 67%, to as high as ∼2590 F g(-1). Furthermore, the LBL assembled multilayer supercapacitor electrodes exhibited an excellent cycling performance of >97%, capacitance retention over 5000 cycles and a high energy density of 96 W h kg(-1) at a power density of 800 W kg(-1). Our approach clearly offers an exciting opportunity for enhancing the device performance of metal oxide-based electrochemical supercapacitors suitable for next-generation flexible energy storage devices by employing a facile LBL assembly technique.

  1. Micropatterning topology on soft substrates affects myoblast proliferation and differentiation.

    PubMed

    Zatti, Susi; Zoso, Alice; Serena, Elena; Luni, Camilla; Cimetta, Elisa; Elvassore, Nicola

    2012-02-01

    Micropatterning techniques and substrate engineering are becoming useful tools to investigate several aspects of cell-cell interaction biology. In this work, we rationally study how different micropatterning geometries can affect myoblast behavior in the early stage of in vitro myogenesis. Soft hydrogels with physiological elastic modulus (E = 15 kPa) were micropatterned in parallel lanes (100, 300, and 500 μm width) resulting in different local and global myoblast densities. Proliferation and differentiation into multinucleated myotubes were evaluated for murine and human myoblasts. Wider lanes showed a decrease in murine myoblast proliferation: (69 ± 8)% in 100 μm wide lanes compared to (39 ± 7)% in 500 μm lanes. Conversely, fusion index increased in wider lanes: from (46 ± 7)% to (66 ± 7)% for murine myoblasts, and from (15 ± 3)% to (36 ± 2)% for human primary myoblasts, using a patterning width of 100 and 500 μm, respectively. These results are consistent with both computational modeling data and conditioned medium experiments, which demonstrated that wider lanes favor the accumulation of endogenous secreted factors. Interestingly, human primary myoblast proliferation is not affected by patterning width, which may be because the high serum content of their culture medium overrides the effect of secreted factors. These data highlight the role of micropatterning in shaping the cellular niche through secreted factor accumulation, and are of paramount importance in rationally understanding myogenesis in vitro for the correct design of in vitro skeletal muscle models.

  2. Directed endothelial cell morphogenesis in micropatterned gelatin methacrylate hydrogels.

    PubMed

    Nikkhah, Mehdi; Eshak, Nouran; Zorlutuna, Pinar; Annabi, Nasim; Castello, Marco; Kim, Keekyoung; Dolatshahi-Pirouz, Alireza; Edalat, Faramarz; Bae, Hojae; Yang, Yunzhi; Khademhosseini, Ali

    2012-12-01

    Engineering of organized vasculature is a crucial step in the development of functional and clinically relevant tissue constructs. A number of previous techniques have been proposed to spatially regulate the distribution of angiogenic biomolecules and vascular cells within biomaterial matrices to promote vascularization. Most of these approaches have been limited to two-dimensional (2D) micropatterned features or have resulted in formation of random vasculature within three-dimensional (3D) microenvironments. In this study, we investigate 3D endothelial cord formation within micropatterned gelatin methacrylate (GelMA) hydrogels with varying geometrical features (50-150 μm height). We demonstrated the significant dependence of endothelial cells proliferation, alignment and cord formation on geometrical dimensions of the patterned features. The cells were able to align and organize within the micropatterned constructs and assemble to form cord structures with organized actin fibers and circular/elliptical cross-sections. The inner layer of the cord structure was filled with gel showing that the micropatterned hydrogel constructs guided the assembly of endothelial cells into cord structures. Notably, the endothelial cords were retained within the hydrogel microconstructs for all geometries after two weeks of culture; however, only the 100 μm-high constructs provided the optimal microenvironment for the formation of circular and stable cord structures. Our findings suggest that endothelial cord formation is a preceding step to tubulogenesis and the proposed system can be used to develop organized vasculature for engineered tissue constructs.

  3. Directed Endothelial Cell Morphogenesis in Micropatterned Gelatin Methacrylate Hydrogels

    PubMed Central

    Nikkhah, Mehdi; Eshak, Nouran; Zorlutuna, Pinar; Annabi, Nasim; Castello, Marco; Kim, Keekyoung; Dolatshahi-Pirouz, Alireza; Edalat, Faramarz; Bae, Hojae; Yang, Yunzhi; Khademhosseini, Ali

    2013-01-01

    Engineering of organized vasculature is a crucial step in the development of functional and clinically relevant tissue constructs. A number of previous techniques have been proposed to spatially regulate the distribution of angiogenic biomolecules and vascular cells within biomaterial matrices to promote vascularization. Most of these approaches have been limited to two-dimensional (2D) micropatterned features or have resulted in formation of random vasculature within three-dimensional (3D) microenvironments. In this study, we investigate 3D endothelial cord formation within micropatterned gelatin methacrylate (GelMA) hydrogels with varying geometrical features (50–150 µm height). We demonstrated the significance dependence of endothelial cells proliferation, alignment and cord formation on geometrical dimensions of the patterned features. The cells were able to align and organize within the micropatterned constructs and assemble to form cord structures with organized actin fibers and circular/elliptical cross-sections. The inner layer of the cord structure was filled with gel showing that the micropatterned hydrogel constructs guided the assembly of endothelial cells into cord structures. Notably, the endothelial cords were retained within the hydrogel microconstructs for all geometries after two weeks of culture; however, only the 100 µm-high constructs provided the optimal microenvironment for the formation of circular and stable cord structures. Our findings suggest that endothelial cord formation is a preceding step to tubulogenesis and the proposed system can be used to develop organized vasculature for engineered tissue constructs. PMID:23018132

  4. One-step fabrication of copper sulfide nanoparticles decorated on graphene sheets as highly stable and efficient counter electrode for CdS-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Hessein, Amr; Wang, Feiju; Masai, Hirokazu; Matsuda, Kazunari; Abd El-Moneim, Ahmed

    2016-11-01

    Quantum-dot-sensitized solar cells (QDSSCs) are thin-film photovoltaics and highly promising as next-generation solar cells owing to their high theoretical efficiency, easy fabrication process, and low production cost. However, the practical photoconversion efficiencies (PCEs) of QDSSCs are still far below the theoretically estimated value owing to the lack of an applicable design of the materials and electrodes. In this work, we developed a highly stable and efficient counter electrode (CE) from copper sulfide nanocrystals and reduced graphene oxide (Cu x S@RGO) for QDSSC applications. The Cu x S@RGO electrocatalyst was successfully prepared by a facile one-pot hydrothermal method, then directly applied to a fluorine-doped tin oxide (FTO)-coated glass substrate by the simple drop-casting technique. Owing to the synergistic effect between Cu x S nanocrystals and conductive RGO sheets, the Cu x S@RGO CE showed high electrocatalytic activity for polysulfide electrolyte reduction. A CdS QDSSC based on the Cu x S@RGO CE yielded a high and reproducible PCE of 2.36%, exceeding those of 1.57 and 1.33% obtained with the commonly used Cu2S/brass and Pt CEs, respectively. Moreover, the QDSSC with the Cu x S@RGO CE showed excellent photostability in a light-soaking test without any obvious decay in the photocurrent, whereas the cell based on the Cu2S/brass CE was severely degraded.

  5. High-performance flexible Ag nanowire electrode with low-temperature atomic-layer-deposition fabrication of conductive-bridging ZnO film.

    PubMed

    Duan, Ya-Hui; Duan, Yu; Chen, Ping; Tao, Ye; Yang, Yong-Qiang; Zhao, Yi

    2015-01-01

    As material for flexible transparent electrodes for organic photoelectric devices, the silver nanowires (AgNWs) have been widely studied. In this work, we propose a hybrid flexible anode with photopolymer substrate, which is composed of spin-coating-processed AgNW meshes and of zinc oxide (ZnO) prepared by low-temperature (60°C) atomic layer deposition. ZnO effectively fills in the voids of the AgNW mesh electrode, which is thus able to contact to the device all over the active area, to allow for efficient charge extraction/injection. Furthermore, ZnO grown by low temperature mainly relies on hole conduction to make the anode play a better role. Hole-only devices are fabricated to certify the functionality of the low-temperature ZnO film. Finally, we confirm that the ZnO film grown at a low temperature bring a significant contribution to the performance of the modified AgNW anode.

  6. Enhanced power production of a membrane electrode assembly microbial fuel cell (MFC) using a cost effective poly [2,5-benzimidazole] (ABPBI) impregnated non-woven fabric filter.

    PubMed

    Choi, Soojung; Kim, Jung Rae; Cha, Jaehwan; Kim, Yejin; Premier, Giuliano C; Kim, Changwon

    2013-01-01

    A membrane electrode assembly (MEA) microbial fuel cell (MFC) with a non-woven paper fabric filter (NWF) was investigated as an alternative to a proton exchange membrane (PEM) separator. The MFC with a NWF generated a cell voltage of 545 mV and a maximum power density of 1027 mW/m(3), which was comparable to that obtained from MFCs with a PEM (551 mV, 609 mW/m(3)). The MFC with a NWF showed stable cell performance (550 mV) over 300 days, whereas, the MFC with PEM performance decreased significantly from 551 mV to 415 mV due to biofilm formation and chemical precipitation on the membrane surface. Poly [2,5-benzimidazole] (ABPBI) was evaluated with respect to its capacity to increased proton conductivity and contact between separator and electrodes. The overall performance of the MFC with ABPBI was improved by enhancing the ion conductivity and steric contact, producing 766 mW/m(3) at optimum loading of 50 mg ABPBI/cm(2).

  7. High-performance flexible Ag nanowire electrode with low-temperature atomic-layer-deposition fabrication of conductive-bridging ZnO film

    NASA Astrophysics Data System (ADS)

    Duan, Ya-Hui; Duan, Yu; Chen, Ping; Tao, Ye; Yang, Yong-Qiang; Zhao, Yi

    2015-02-01

    As material for flexible transparent electrodes for organic photoelectric devices, the silver nanowires (AgNWs) have been widely studied. In this work, we propose a hybrid flexible anode with photopolymer substrate, which is composed of spin-coating-processed AgNW meshes and of zinc oxide (ZnO) prepared by low-temperature (60°C) atomic layer deposition. ZnO effectively fills in the voids of the AgNW mesh electrode, which is thus able to contact to the device all over the active area, to allow for efficient charge extraction/injection. Furthermore, ZnO grown by low temperature mainly relies on hole conduction to make the anode play a better role. Hole-only devices are fabricated to certify the functionality of the low-temperature ZnO film. Finally, we confirm that the ZnO film grown at a low temperature bring a significant contribution to the performance of the modified AgNW anode.

  8. Reprocessable squeezing electrode fabrication of olive-like Fe/Co/O nanoparticle@three dimensional nitrogen-doped reduced graphene oxides for high performance lithium batteries.

    PubMed

    Qi, Li-Ya; Zhang, Yi-Wei; Xin, Yue-Long; Zuo, Zi-Cheng; Wu, Bin; Zhang, Xin-Xiang; Zhou, Heng-Hui

    2015-05-01

    A one step in situ synthesis approach is developed to construct 3D nitrogen-doped reduced graphene oxides, in which olive-like multi-component metal oxides are homogeneously dispersed. The novel hybrid nanoarchitecture shows some particular properties derived from synergistic effects. The size of Fe/Co/O oxides is reduced and better controlled compared to that of individual oxides due to mutual dispersant interactions. Furthermore, the positive synergistic interaction between heterogeneous oxides and graphene nanosheets has effective control on the particle size and dispersion of nanoparticles. Taking advantage of the flexibility and the cohesiveness of graphene nanosheets, the obtained composite can be directly processed into a binder-free electrode through a unique time-saving "squeezing" process. The obtained electrode possesses a reprocessable feature, which provides possibilities for convenient storage and quick fabrication at any time and presents attractive electrochemical performance of robust long-term capability retention (562 mA h g(-1) after 300 cycles at 10 A g(-1)) and superior rate performances (1162 mA h g(-1) at 0.5 A g(-1), 737 mA h g(-1) at 5 A g(-1), and 585 mA h g(-1) at 10 A g(-1)).

  9. Fabrication of wide-bandgap transparent electrodes by using conductive filaments: performance breakthrough in vertical-type GaN LED.

    PubMed

    Kim, Su Jin; Kim, Hee-Dong; Kim, Kyeong Heon; Shin, Hee Woong; Han, Il Ki; Kim, Tae Geun

    2014-01-01

    For realizing next-generation solid-state lighting devices, performance breakthroughs must be accomplished for nitride-based light-emitting diodes (LEDs). Highly transparent conductive electrodes (TCEs) may be key to achieving this goal, as they provide uniform current injection and distribution across a large device area, eventually increasing the light output power. However, the trade-off between electrical conductivity and optical transmittance of LEDs must be addressed. Herein, we introduce a novel strategy based on TCEs fabricated using wide-bandgap (WB) materials such as SiNx, incorporated beneath the n-type electrode of vertical-type LEDs, and show the feasibility of this strategy. We employ a novel electrical breakdown (EBD) technique to form conductive filaments (or current paths) between a TCE and n-GaN (GaN: gallium nitride). By employing the EBD process, we obtain both ohmic behavior for SiNx TCE/n-GaN and a current spreading effect across n-GaN. These results demonstrate the tremendous potential of WB-TCEs for use in high-performance optoelectronic devices. PMID:25059757

  10. Chitosan/bovine serum albumin co-micropatterns on functionalized titanium surfaces and their effects on osteoblasts.

    PubMed

    Li, Dan; Lu, Xiong; Lin, Hong; Ren, Fuzeng; Leng, Yang

    2013-02-01

    Chitosan (CS)/bovine serum albumin (BSA) micropatterns were prepared on functionalized Ti surfaces by micro-transfer molding (μ-TM). μ-TM realized the spatially controlled immobilization of cells and offered a new way of studying the interaction between micropatterns and cells. Two kinds of micropatterns were produced: (1) microgrooves representing a discontinuously grooved co-micropattern, with the rectangular CS region separated by BSA walls; (2) microcylinders representing a continuously interconnected co-micropattern, with the net-like CS region separated by BSA cylinders. A comparison of cell behaviors on the two types of micropatterns indicated that the shape rather than the size had a dominant effect on cell proliferation. The micropattern size in the same range of cell diameters favored cell proliferation. However, cell differentiation was more sensitive to the size rather than to the shape of the micropatterns. In conclusion, cell behavior can be regulated by micropatterns integrating different materials. PMID:23132401

  11. An Easily Fabricated Electrochemical Sensor Based on a Graphene-Modified Glassy Carbon Electrode for Determination of Octopamine and Tyramine

    PubMed Central

    Zhang, Yang; Zhang, Meiqin; Wei, Qianhui; Gao, Yongjie; Guo, Lijuan; Al-Ghanim, Khalid A.; Mahboob, Shahid; Zhang, Xueji

    2016-01-01

    A simple electrochemical sensor has been developed for highly sensitive detection of octopamine and tyramine by electrodepositing reduced graphene oxide (ERGO) nanosheets onto the surface of a glassy carbon electrode (GCE). The electrocatalytic oxidation of octopamine and tyramine is individually investigated at the surface of the ERGO modified glassy carbon electrode (ERGO/GCE) by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Several essential factors including the deposition cycle of reduced graphene oxide nanosheets and the pH of the running buffer were investigated in order to determine the optimum conditions. Furthermore, the sensor was applied to the quantification of octopamine and tyramine by DPV in the concentration ranges from 0.5 to 40 μM and 0.1 to 25 μM, respectively. In addition, the limits of detection of octopamine and tyramine were calculated to be 0.1 μM and 0.03 μM (S/N = 3), respectively. The sensor showed good reproducibility, selectivity and stability. Finally, the sensor successfully detected octopamine and tyramine in commercially available beer with satisfactory recovery ranges which were 98.5%–104.7% and 102.2%–103.1%, respectively. These results indicate the ERGO/GCE based sensor is suitable for the detection of octopamine and tyramine. PMID:27089341

  12. Fabrication of Binder-Free Pencil-Trace Electrode for Lithium-Ion Battery: Simplicity and High Performance.

    PubMed

    Park, Hyean-Yeol; Kim, Min-Sik; Bae, Tae-Sung; Yuan, Jinliang; Yu, Jong-Sung

    2016-05-10

    A binder-free and solvent-free pencil-trace electrode with intercalated clay particles (mainly SiO2) is prepared via a simple pencil-drawing process on grinded Cu substrate with rough surface and evaluated as an anode material for lithium-ion battery. The pencil-trace electrode exhibits a high reversible capacity of 672 mA h g(-1) at 100 mA g(-1) after 100 cycles, which can be attributed to the unique multilayered graphene particles with lateral size of few micrometers and the formation of LixSi alloys generated by interaction between Li(+) and an active Si produced in the electrochemical reduction of nano-SiO2 in the clay particles between the multilayered graphene particles. The multilayered graphene obtained by this process consists of 1 up to 20 and occasionally up to 50 sheets and thus can not only help accommodating the volume change and alleviating the structural strain during Li ion insertion and extraction but also allow rapid access of Li ions during charge-discharge cycling. Drawing with a pencil on grinded Cu substrate is not only very simple but also cost-effective and highly scalable, easily establishing graphitic circuitry through a solvent-free and binder-free approach.

  13. Programmable gradational micropatterning of functional materials using maskless lithography controlling absorption

    PubMed Central

    Jung, Yushin; Lee, Howon; Park, Tae-Joon; Kim, Sungsik; Kwon, Sunghoon

    2015-01-01

    The demand for patterning functional materials precisely on surfaces of stimuli-responsive devices has increased in many research fields. In situ polymerization technology is one of the most convenient ways to place the functional materials on a desired location with micron-scale accuracy. To fabricate stimuli-responsive surfaces, controlling concentration of the functional material is much as important as micropatterning them. However, patterning and controlling concentration of the functional materials simultaneously requires an additional process, such as preparing multiple co-flow microfluidic structures and numbers of solutions with various concentrations. Despite applying these processes, fabricating heterogeneous patterns in large scale (millimeter scale) is still impossible. In this study, we propose an advanced in situ polymerization technique to pattern the surface in micron scale in a concentration-controlled manner. Because the concentration of the functional materials is manipulated by self-assembly on the surface, a complex pattern could be easily fabricated without any additional procedure. The complex pattern is pre-designed with absorption amount of the functional material, which is pre-determined by the duration of UV exposure. We show that the resolution reaches up to 2.5 μm and demonstrate mm-scale objects, maintaining the same resolution. We also fabricated Multi-bit barcoded micro particles verify the flexibility of our system. PMID:26490360

  14. A room-temperature process for fabricating a nano-Pt counter electrode on a plastic substrate for efficient dye-sensitized cells

    NASA Astrophysics Data System (ADS)

    Hsieh, Tsung-Yu; Wei, Tzu-Chien; Zhai, Peng; Feng, Shien-Ping; Ikegami, Masashi; Miyasaka, Tsutomu

    2015-06-01

    We present a method for depositing polyvinylpyrrolidone-capped platinum nanoparticles (PVP-nPt) on a plastic substrate as the counter electrode (CE) for dye-sensitized cells. This method was implemented using a modified two-step dip-coating process performed under ambient conditions. In particular, a short UV-ozone exposure period was adopted to replace conventional annealing, rendering the whole process feasible for plastic substrates. The surfactant required for deposition was confirmed by analyzing a Fourier transform infrared spectroscopy spectrum; however, we discovered that the surfactant jeopardized charge transfer between the PVP-nPt CE and the substrate. Furthermore, the UV-ozone treatment efficiently decomposed the surfactant, and the electrochemical-catalytic property improved considerably. When the CE was combined with a dye-sensitized photoanode fabricated on a plastic substrate, the power conversion efficiency (PCE) reached 6.24%. To further prove that the PCE is limited by the plastic photoanode instead of the proposed plastic PVP-nPt CE, a photoanode fabricated on FTO glass and the proposed plastic PVP-nPt CE with a PCE of 8.80% was demonstrated. Finally, thermal aging (conducted at 60 °C, 1000 h) test on this device indicated excellent durability, and the PCE was only 1% lower than its initial value.

  15. Fabrication of conducting-filament-embedded indium tin oxide electrodes: application to lateral-type gallium nitride light-emitting diodes.

    PubMed

    Kim, Hee-Dong; Kim, Kyeong Heon; Kim, Su Jin; Kim, Tae Geun

    2015-11-01

    A novel conducting filament (CF)-embedded indium tin oxide (ITO) film is fabricated using an electrical breakdown method. To assess the performance of this layer as an ohmic contact, it is applied to GaN (gallium nitride) light-emitting diodes (LEDs) as a p-type electrode for comparison with typical GaN LEDs using metallic ITO. The operating voltage and output power of the LED with the CF embedded ITO are 3.93 V and 8.49 mW, respectively, at an injection current of 100 mA. This is comparable to the operating voltage and output power of the conventionally fabricated LEDs using metallic ITO (3.93 V and 8.43 mW). Moreover, the CF-ITO LED displays uniform and bright light emission indicating excellent current injection and spreading. These results suggest that the proposed method of forming ohmic contacts is at least as effective as the conventional method. PMID:26561146

  16. Controlled porosity in electrodes

    SciTech Connect

    Chiang, Yet-Ming; Bae, Chang-Jun; Halloran, John William; Fu, Qiang; Tomsia, Antoni P.; Erdonmez, Can K.

    2015-06-23

    Porous electrodes in which the porosity has a low tortuosity are generally provided. In some embodiments, the porous electrodes can be designed to be filled with electrolyte and used in batteries, and can include low tortuosity in the primary direction of ion transport during charge and discharge of the battery. In some embodiments, the electrodes can have a high volume fraction of electrode active material (i.e., low porosity). The attributes outlined above can allow the electrodes to be fabricated with a higher energy density, higher capacity per unit area of electrode (mAh/cm.sup.2), and greater thickness than comparable electrodes while still providing high utilization of the active material in the battery during use. Accordingly, the electrodes can be used to produce batteries with high energy densities, high power, or both compared to batteries using electrodes of conventional design with relatively highly tortuous pores.

  17. Enhanced performance of sulfate reducing bacteria based biocathode using stainless steel mesh on activated carbon fabric electrode.

    PubMed

    Sharma, Mohita; Jain, Pratiksha; Varanasi, Jhansi L; Lal, Banwari; Rodríguez, Jorge; Lema, Juan M; Sarma, Priyangshu M

    2013-12-01

    An anoxic biocathode was developed using sulfate-reducing bacteria (SRB) consortium on activated carbon fabric (ACF) and the effect of stainless steel (SS) mesh as additional current collector was investigated. Improved performance of biocathode was observed with SS mesh leading to nearly five folds increase in power density (from 4.79 to 23.11 mW/m(2)) and threefolds increase in current density (from 75 to 250 mA/m(2)). Enhanced redox currents and lower Tafel slopes observed from cyclic voltammograms of ACF with SS mesh indicated the positive role of uniform electron collecting points. Differential pulse voltammetry technique was employed as an additional tool to assess the redox carriers involved in bioelectrochemical reactions. SRB biocathode was also tested for reduction of volatile fatty acids (VFA) present in the fermentation effluent stream and the results indicated the possibility of integration of this system with anaerobic fermentation for efficient product recovery.

  18. Enhanced performance of sulfate reducing bacteria based biocathode using stainless steel mesh on activated carbon fabric electrode.

    PubMed

    Sharma, Mohita; Jain, Pratiksha; Varanasi, Jhansi L; Lal, Banwari; Rodríguez, Jorge; Lema, Juan M; Sarma, Priyangshu M

    2013-12-01

    An anoxic biocathode was developed using sulfate-reducing bacteria (SRB) consortium on activated carbon fabric (ACF) and the effect of stainless steel (SS) mesh as additional current collector was investigated. Improved performance of biocathode was observed with SS mesh leading to nearly five folds increase in power density (from 4.79 to 23.11 mW/m(2)) and threefolds increase in current density (from 75 to 250 mA/m(2)). Enhanced redox currents and lower Tafel slopes observed from cyclic voltammograms of ACF with SS mesh indicated the positive role of uniform electron collecting points. Differential pulse voltammetry technique was employed as an additional tool to assess the redox carriers involved in bioelectrochemical reactions. SRB biocathode was also tested for reduction of volatile fatty acids (VFA) present in the fermentation effluent stream and the results indicated the possibility of integration of this system with anaerobic fermentation for efficient product recovery. PMID:24161648

  19. Method of fabricating electrode catalyst layers with directionally oriented carbon support for proton exchange membrane fuel cell

    DOEpatents

    Liu, Di-Jia; Yang, Junbing

    2010-07-20

    A method of making a membrane electrode assembly (MEA) having an anode and a cathode and a proton conductive membrane there between. A bundle of longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated in the nanotubes forms at least one portion of the MEA and is in contact with the membrane. A combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas is introduced into a first reaction zone maintained at a first reaction temperature for a time sufficient to vaporize material therein. The vaporized material is transmitted to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes. The nanotubes are in contact with a portion of the MEA at production or being positioned in contact thereafter. Methods of forming a PEMFC are also disclosed.

  20. Ninety-six-well planar lipid bilayer chip for ion channel recording fabricated by hybrid stereolithography.

    PubMed

    Suzuki, Hiroaki; Le Pioufle, Bruno; Takeuchi, Shoji

    2009-02-01

    We present a micro fluidic chip for parallel ion channel recording in a large array of artificial planar lipid bilayer membranes. To realize a composite structure that features an array of recording wells with free-standing microapertures for lipid bilayer reconstitution, the device was fabricated by the hybrid stereolithography technology, in which a Parylene film with pre-formed microapertures was inserted during the rapid stereolithography process. We designed and tested a hybrid chip that has 96 (12x8) addressable recording wells to demonstrate recording of ion channel current in high-throughput manner. Measurement was done by sequentially moving the recording electrode, and, as a result, the channel current of model membrane protein was detected in 44 wells out of 96. We also showed that this hybrid fabrication process was capable of integrating micropatterned electrodes suitable for automated recording. These results support the efficiency of our present architecture of the parallel ion channel recording chip toward realization of the high-throughput screening of ion channel proteins in the artificial lipid bilayer system.

  1. A Lithographically-Patterned, Elastic Multi-electrode Array for Surface Stimulation of the Spinal Cord

    PubMed Central

    Meacham, Kathleen W.; Giuly, Richard J.; Guo, Liang; Hochman, Shawn; DeWeerth, Stephen P.

    2008-01-01

    A new, scalable process for microfabrication of a silicone-based, elastic multi-electrode array (MEA) is presented. The device is constructed by spinning poly(dimethylsiloxane) (PDMS) silicone elastomer onto a glass slide, depositing and patterning gold to construct wires and electrodes, spinning on a second PDMS layer, and then micropatterning the second PDMS layer to expose electrode contacts. The micropatterning of PDMS involves a custom reactive ion etch (RIE) process that preserves the underlying gold thin film. Once completed, the device can be removed from the glass slide for conformal interfacing with neural tissue. Prototype MEAs feature electrodes smaller than those known to be reported on silicone substrate (60 μm diameter exposed electrode area) and were capable of selectively stimulating the surface of the in vitro isolated spinal cord of the juvenile rat. Stretchable serpentine traces were also incorporated into the functional PDMS-based MEA, and their implementation and testing is described. PMID:17914674

  2. Micropattern-Guided Assembly of Overlapping Pairs of Dynamic Microtubules

    PubMed Central

    Fourniol, Franck J.; Li, Tai-De; Bieling, Peter; Mullins, R. Dyche; Fletcher, Daniel A.; Surrey, Thomas

    2014-01-01

    Interactions between antiparallel microtubules are essential for the organization of spindles in dividing cells. The ability to form immobilized antiparallel microtubule pairs in vitro, combined with the ability to image them via TIRF microscopy, permits detailed biochemical characterization of microtubule cross-linking proteins and their effects on microtubule dynamics. Here, we describe methods for chemical micropatterning of microtubule seeds on glass surfaces in configurations that specifically promote the formation of antiparallel microtubule overlaps in vitro. We demonstrate that this assay is especially well suited for reconstitution of minimal midzone overlaps stabilized by the antiparallel microtubule cross-linking protein PRC1 and its binding partners. The micropatterning method is suitable for use with a broad range of proteins, and the assay is generally applicable to any microtubule cross-linking protein. PMID:24630116

  3. Phase emerging from intramonolayer cycloaddition on micro-patterned monolayer

    SciTech Connect

    Tajuddin, Hairul A.; Manning, Robert J.; Leggett, Graham J.; Williams, Nicholas H.

    2012-11-27

    Cu(I)-catalyzed cycloaddition between azide and acetylene, followed by hydrolysis of ester were performed on micro-patterned self-assembled monolayer to produce smaller features. The reactions were initially performed on mixed monolayers and analysed by water contact angle (CA) and confirmed by X-ray Photoelectron Spectroscopy (XPS). The contact angle measurement has shown a drastic wetting of water on the surface of mixed monolayer indicating that the terminal groups on mixed monolayer has changed into carboxylic acid and hydroxyl terminals. The reactions work in a similar way on micro-patterned SAM and analyzed by using friction force microscope. The emerging of the new lines with high friction force on the border suggested a successful intramonolayer reactions on the border of the patterned SAM.

  4. Phase emerging from intramonolayer cycloaddition on micro-patterned monolayer

    NASA Astrophysics Data System (ADS)

    Tajuddin, Hairul A.; Manning, Robert J.; Leggett, Graham J.; Williams, Nicholas H.

    2012-11-01

    Cu(I)-catalyzed cycloaddition between azide and acetylene, followed by hydrolysis of ester were performed on micro-patterned self-assembled monolayer to produce smaller features. The reactions were initially performed on mixed monolayers and analysed by water contact angle (CA) and confirmed by X-ray Photoelectron Spectroscopy (XPS). The contact angle measurement has shown a drastic wetting of water on the surface of mixed monolayer indicating that the terminal groups on mixed monolayer has changed into carboxylic acid and hydroxyl terminals. The reactions work in a similar way on micro-patterned SAM and analyzed by using friction force microscope. The emerging of the new lines with high friction force on the border suggested a successful intramonolayer reactions on the border of the patterned SAM.

  5. Fabrication of electric papers of graphene nanosheet shelled cellulose fibres by dispersion and infiltration as flexible electrodes for energy storage

    NASA Astrophysics Data System (ADS)

    Kang, Yan-Ru; Li, Ya-Li; Hou, Feng; Wen, Yang-Yang; Su, Dong

    2012-05-01

    An electrically conductive and electrochemically active composite paper of graphene nanosheet (GNS) coated cellulose fibres was fabricated via a simple paper-making process of dispersing chemically synthesized GNS into a cellulose pulp, followed by infiltration. The GNS nanosheet was deposited onto the cellulose fibers, forming a coating, during infiltration. It forms a continuous network through a bridge of interconnected cellulose fibres at small GNS loadings (3.2 wt%). The GNS/cellulose paper is as flexible and mechanically tough as the pure cellulose paper. The electrical measurements show the composite paper has a sheet resistance of 1063 Ω □-1 and a conductivity of 11.6 S m-1. The application of the composite paper as a flexible double layer supercapacitor in an organic electrolyte (LiPF6) displays a high capacity of 252 F g-1 at a current density of 1 A g-1 with respect to GNS. Moreover, the paper can be used as the anode in a lithium battery, showing distinct charge and discharge performances. The simple process for synthesising the GNS functionalized cellulose papers is attractive for the development of high performance papers for electrical, electrochemical and multifunctional applications.An electrically conductive and electrochemically active composite paper of graphene nanosheet (GNS) coated cellulose fibres was fabricated via a simple paper-making process of dispersing chemically synthesized GNS into a cellulose pulp, followed by infiltration. The GNS nanosheet was deposited onto the cellulose fibers, forming a coating, during infiltration. It forms a continuous network through a bridge of interconnected cellulose fibres at small GNS loadings (3.2 wt%). The GNS/cellulose paper is as flexible and mechanically tough as the pure cellulose paper. The electrical measurements show the composite paper has a sheet resistance of 1063 Ω □-1 and a conductivity of 11.6 S m-1. The application of the composite paper as a flexible double layer supercapacitor

  6. Adhesion of Resist Micropatterns during Drying after Water Rinse

    NASA Astrophysics Data System (ADS)

    Kawai, Akira

    1995-08-01

    The variation of residual strain in photoresist thin films can be detected by a strain gauge with high sensitivity. The adhesion of resist micropattern during drying after water rinse is studied in terms of the residual strain variation. The residual strain of a resist film varies markedly as water is evaporated from the resist surface. In order to improve the resist adhesion, it is important to decrease the residual strain during the drying process.

  7. Fabrication of tin-cobalt/carbon composite electrodes by electrodeposition using cationic surfactant for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Lee, Cho-Long; Nam, Do-Hwan; Eom, Ji-Yong; Kwon, Hyuk-Sang

    2016-07-01

    Sn-Co alloy and Sn-Co/C composite are fabricated on the nodule-type Cu substrate by co-electrodeposition process using the pulse current in the pyrophosphate bath, and then their cycling performances are examined. To modify the surface property of carbon (acetylene black) particles and improve the dispersion of agglomerated carbon particles, CTAB (Cetrimonium bromide (C16H33)N(CH3)3Br) as a cationic surfactant is added into the electrodeposition bath.10.1007/s13391-016-6077-2 By addition of the CTAB, the amount of the carbon content in the Sn-Co/C composite is increased, and also the carbon particles are uniformly distributed in the Sn-Co electrodeposit. The Sn0.6Co0.4 alloy and (Sn0.6Co0.4)0.71/C0.29 composite are obtained after annealing as the final products. The (Sn0.6Co0.4)0.71/C0.29 composite anode exhibits better the capacity retention than the Sn0.6Co0.4 alloy anode due primarily to the role of the well-dispersed carbon particles as the second buffer phase and electrical conductive path in the Sn-Co/C composite during cycling.

  8. Design, Fabrication and Characterization of a Low-Impedance 3D Electrode Array System for Neuro-Electrophysiology

    PubMed Central

    Kusko, Mihaela; Craciunoiu, Florea; Amuzescu, Bogdan; Halitzchi, Ferdinand; Selescu, Tudor; Radoi, Antonio; Popescu, Marian; Simion, Monica; Bragaru, Adina; Ignat, Teodora

    2012-01-01

    Recent progress in patterned microelectrode manufacturing technology and microfluidics has opened the way to a large variety of cellular and molecular biosensor-based applications. In this extremely diverse and rapidly expanding landscape, silicon-based technologies occupy a special position, given their statute of mature, consolidated, and highly accessible areas of development. Within the present work we report microfabrication procedures and workflows for 3D patterned gold-plated microelectrode arrays (MEA) of different shapes (pyramidal, conical and high aspect ratio), and we provide a detailed characterization of their physical features during all the fabrication steps to have in the end a reliable technology. Moreover, the electrical performances of MEA silicon chips mounted on standardized connector boards via ultrasound wire-bonding have been tested using non-destructive electrochemical methods: linear sweep and cyclic voltammetry, impedance spectroscopy. Further, an experimental recording chamber package suitable for in vitro electrophysiology experiments has been realized using custom-design electronics for electrical stimulus delivery and local field potential recording, included in a complete electrophysiology setup, and the experimental structures have been tested on newborn rat hippocampal slices, yielding similar performance compared to commercially available MEA equipments. PMID:23208555

  9. Fabrication of electric papers of graphene nanosheet shelled cellulose fibres by dispersion and infiltration as flexible electrodes for energy storage.

    PubMed

    Kang, Yan-Ru; Li, Ya-Li; Hou, Feng; Wen, Yang-Yang; Su, Dong

    2012-05-21

    An electrically conductive and electrochemically active composite paper of graphene nanosheet (GNS) coated cellulose fibres was fabricated via a simple paper-making process of dispersing chemically synthesized GNS into a cellulose pulp, followed by infiltration. The GNS nanosheet was deposited onto the cellulose fibers, forming a coating, during infiltration. It forms a continuous network through a bridge of interconnected cellulose fibres at small GNS loadings (3.2 wt%). The GNS/cellulose paper is as flexible and mechanically tough as the pure cellulose paper. The electrical measurements show the composite paper has a sheet resistance of 1063 Ω□(-1) and a conductivity of 11.6 S m(-1). The application of the composite paper as a flexible double layer supercapacitor in an organic electrolyte (LiPF(6)) displays a high capacity of 252 F g(-1) at a current density of 1 A g(-1) with respect to GNS. Moreover, the paper can be used as the anode in a lithium battery, showing distinct charge and discharge performances. The simple process for synthesising the GNS functionalized cellulose papers is attractive for the development of high performance papers for electrical, electrochemical and multifunctional applications.

  10. Towards the fabrication of the top-contact electrode in molecular junctions by photoreduction of a metal precursor.

    PubMed

    Martín, Santiago; Pera, Gorka; Ballesteros, Luz M; Hope, Adam J; Marqués-González, Santiago; Low, Paul J; Pérez-Murano, Francesc; Nichols, Richard J; Cea, Pilar

    2014-03-17

    Langmuir films of 4-{[4-({4-[(trimethylsilyl)ethynyl]phenyl}ethynyl)phenyl]ethynyl} benzenaminium chloride ([1 H]Cl) undergo anion metathesis when assembled on an aqueous auric acid (HAuCl4 ) subphase. Subsequent transfer to solid supports gives well-formed Langmuir-Blodgett (LB) monolayers of [1 H]AuCl4 in which the trimethylsilyl group serves as the surface contacting group. Photoreduction of the aurate on these monolayers leads to the formation of metallic gold nanoislands, which were distributed over the surface of the film. Electrical properties of these nascent devices were determined by recording current-voltage (I-V) curves with conductive atomic force microscopy (c-AFM) using the PeakForce tunneling AFM (PF-TUNA) mode. This gives consistent sigmoidal I-V curves that are indicative of well-behaved junctions free of metallic filaments and short circuits. The photoreduction of a metal precursor incorporated onto monomolecular films is therefore proposed as an effective method for the fabrication of molecular junctions.

  11. Towards the fabrication of the top-contact electrode in molecular junctions by photoreduction of a metal precursor.

    PubMed

    Martín, Santiago; Pera, Gorka; Ballesteros, Luz M; Hope, Adam J; Marqués-González, Santiago; Low, Paul J; Pérez-Murano, Francesc; Nichols, Richard J; Cea, Pilar

    2014-03-17

    Langmuir films of 4-{[4-({4-[(trimethylsilyl)ethynyl]phenyl}ethynyl)phenyl]ethynyl} benzenaminium chloride ([1 H]Cl) undergo anion metathesis when assembled on an aqueous auric acid (HAuCl4 ) subphase. Subsequent transfer to solid supports gives well-formed Langmuir-Blodgett (LB) monolayers of [1 H]AuCl4 in which the trimethylsilyl group serves as the surface contacting group. Photoreduction of the aurate on these monolayers leads to the formation of metallic gold nanoislands, which were distributed over the surface of the film. Electrical properties of these nascent devices were determined by recording current-voltage (I-V) curves with conductive atomic force microscopy (c-AFM) using the PeakForce tunneling AFM (PF-TUNA) mode. This gives consistent sigmoidal I-V curves that are indicative of well-behaved junctions free of metallic filaments and short circuits. The photoreduction of a metal precursor incorporated onto monomolecular films is therefore proposed as an effective method for the fabrication of molecular junctions. PMID:24532391

  12. Fabrication of electric papers of graphene nanosheet shelled cellulose fibres by dispersion and infiltration as flexible electrodes for energy storage.

    PubMed

    Kang, Yan-Ru; Li, Ya-Li; Hou, Feng; Wen, Yang-Yang; Su, Dong

    2012-05-21

    An electrically conductive and electrochemically active composite paper of graphene nanosheet (GNS) coated cellulose fibres was fabricated via a simple paper-making process of dispersing chemically synthesized GNS into a cellulose pulp, followed by infiltration. The GNS nanosheet was deposited onto the cellulose fibers, forming a coating, during infiltration. It forms a continuous network through a bridge of interconnected cellulose fibres at small GNS loadings (3.2 wt%). The GNS/cellulose paper is as flexible and mechanically tough as the pure cellulose paper. The electrical measurements show the composite paper has a sheet resistance of 1063 Ω□(-1) and a conductivity of 11.6 S m(-1). The application of the composite paper as a flexible double layer supercapacitor in an organic electrolyte (LiPF(6)) displays a high capacity of 252 F g(-1) at a current density of 1 A g(-1) with respect to GNS. Moreover, the paper can be used as the anode in a lithium battery, showing distinct charge and discharge performances. The simple process for synthesising the GNS functionalized cellulose papers is attractive for the development of high performance papers for electrical, electrochemical and multifunctional applications. PMID:22535335

  13. Fabrication of tin-cobalt/carbon composite electrodes by electrodeposition using cationic surfactant for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Lee, Cho-Long; Nam, Do-Hwan; Eom, Ji-Yong; Kwon, Hyuk-Sang

    2016-09-01

    Sn-Co alloy and Sn-Co/C composite are fabricated on the nodule-type Cu substrate by co-electrodeposition process using the pulse current in the pyrophosphate bath, and then their cycling performances are examined. To modify the surface property of carbon (acetylene black) particles and improve the dispersion of agglomerated carbon particles, CTAB (Cetrimonium bromide (C16H33)N(CH3)3Br) as a cationic surfactant is added into the electrodeposition bath.10.1007/s13391-016-6077-2 By addition of the CTAB, the amount of the carbon content in the Sn-Co/C composite is increased, and also the carbon particles are uniformly distributed in the Sn-Co electrodeposit. The Sn0.6Co0.4 alloy and (Sn0.6Co0.4)0.71/C0.29 composite are obtained after annealing as the final products. The (Sn0.6Co0.4)0.71/C0.29 composite anode exhibits better the capacity retention than the Sn0.6Co0.4 alloy anode due primarily to the role of the well-dispersed carbon particles as the second buffer phase and electrical conductive path in the Sn-Co/C composite during cycling.

  14. Micropatterning of Aptamer Beacons to Create Cytokine-Sensing Surfaces.

    PubMed

    Tuleuova, Nazgul; Revzin, Alexander

    2010-12-01

    Aptamer beacons are DNA or RNA probes that bind proteins or small molecules of interest and emit signal directly upon interaction with the target analyte. This paper describes micropatterning of aptamer beacons for detection of IFN-γ-an important inflammatory cytokine. The beacon consisted of a fluorophore-labeled aptamer strand hybridized with a shorter, quencher-carrying complementary strand. Cytokine molecules were expected to displace quenching strands of the beacon, disrupting FRET effect and resulting in fluorescence signal. The glass substrate was first micropatterned with poly(ethylene glycol) (PEG) hydrogel microwells (35 μm diameter individual wells) so as to define sites for attachment of beacon molecules. PEG microwell arrays were then incubated with avidin followed by biotin-aptamer-fluorophore constructs. Subsequent incubation with quencher-carrying complementary strands resulted in formation of DNA duplex and caused quenching of fluorescence due to FRET effect. When exposed to IFN-γ, microwells changed fluorescence from low (quencher hybridized with fluorophore-carrying strand) to high (quenching strand displaced by cytokine molecules). The fluorescence signal was confined to microwells, was changing in real-time and was dependent on the concentration of IFN-γ. In the future, we plan to co-localize aptamer beacons and cells on micropatterned surfaces in order to monitor in real-time cytokine secretion from immune cells in microwells.

  15. Improved fullerene nanofiber electrodes used in direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Q.; Zhang, Y.; Miyazawa, K.; Kato, R.; Hotta, K.; Wakahara, T.

    2009-04-01

    Platinum supported on fullerene nanofibers as possible electrodes for direct methanol fuel cells (DMFC) were studied. Fullerene nanofiber with 20 wt% Pt loading was mixed with 5 wt% Nafion solution. The mixture paste was coated on Nafion 117 membrane and sandwiched with silicon plates. To increase the surface reaction area of catalyst, nanoimprint was used to fabricate micro-patterns in the Nafion proton exchange membrane. Nanoimprint pattern consisted of dots of 500 nm-in-diameter, 140 nm-in-depth and 1 μm-in-spacing. The nanoimprint of the treated proton exchange membrane (PEM) was carried out in a desktop thermal nanoimprint system (NI273, Nano Craft Tech. Corp., Japan) at the optimized conditions of 130 °C and pressure of 3 MPa for 6 min. Then the Pt-coated PEM was sandwiched with micro-channelled silicon plates to form a micro-DMFC. With passively feeding of 1 M methanol solution and air at room temperature, the as-prepared cell had the open circuit voltage of 0.34 V and the maximum power density of 0.30 mW/cm2. Compared with a fresh cell, the results shows that nanofibers used in nanoimprinted PEM have an improvement on the performance of micro fuel cells.

  16. Two-step approach of fabrication of three-dimensional MnO2-graphene-carbon nanotube hybrid as a binder-free supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Xiong, Chuanyin; Li, Tiehu; Dang, Alei; Zhao, Tingkai; Li, Hao; Lv, Huiqin

    2016-02-01

    This paper describes the fabrication and characterization of a three-dimensional (3D) MnO2-graphene (GR)-CNT hybrid obtained by combining electrochemical deposition (ELD)-electrophoretic deposition (EPD) and chemical vapor deposition (CVD). Firstly, 3D MnO2-graphene oxide (GO) is fabricated via ELD-EPD. Secondly, the catalyst and xylene are mixed with solution of certain concentration. Thirdly, catalyst is loaded on the surface of MnO2-GO when the solution is sprayed into the furnace. Forth, MnO2-GO is restored to MnO2-GR at high temperature, meanwhile, MnO2-GR is served as a substrate to grow CNT, which is beneficial to provide high speed channel for carrier and obtain pseudocapacitance of MnO2. The as-prepared hybrid is characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray Diffraction (XRD) and Raman spectroscopy (Raman), and their supercapacitor properties are also investigated. The results show that a high specific capacitance of 330.75 F g-1 and high energy density of 36.68 Wh kg-1 while maintaining high power density of 8000 W kg-1 at a scan rate of 200 mV s-1. Furthermore, the hybrid displays a high specific capacitance of 187.53 F g-1 at ultrahigh scan rate of 400 mV s-1. These attractive results demonstrate that the hybrid is a promising electrode material for high performance supercapacitors.

  17. Alternative methods to fabricate and evaluate copper zinc tin sulfide based absorber layers on transparent conducting electrodes

    NASA Astrophysics Data System (ADS)

    Sarswat, Prashant Kumar

    This study is focused on fabrication and characterization of Cu 2ZnSnS4 (CZTS) films on transparent conducting substrate. CZTS films were synthesized using solution based methods. A specially designed sequential and single stage electrochemical method as well as spin coating method was used to grow layers of precursors. Deposition of constituent metallic layers was carried out on SnO2/F (Fluorinated tin oxide or FTO) coated glass substrates. The electrodeposited/spin coated layers were annealed in a sulfur environment to obtain CZTS. Structural, morphological and optical characterization experiments were performed using several techniques including x-ray diffraction, Raman and UV-visible spectroscopy, scanning electron microscopy, and atomic force microscopy. All characterization experiments indicated the films are single phase with a measured direct band gap of ˜1.5 eV. Photocurrent response of CZTS film grown on FTO substrate was measured using alternating front illumination and rear illumination in a Eu 3+/Eu2+ solution environment. The photoelectrochemical response exhibited during rear illumination is comparable to that obtained for front illumination. The promising photocurrent data for CZTS films suggest these films have potential application in a variety of photovoltaic devices. A comparative study revealed that photoelectrochemical response exhibited by the films grown on molybdenum substrate is greater than that obtained for film grown on FTO substrate. A modified form of the Gartner model to explain J-V characteristics for CZTS-electrolyte solution has been proposed. Fundamental information such as energy band gap-temperature relationship and temperature dependent study of Raman 'A' mode for CZTS thin films were also investigated in this research.

  18. Positive and negative TiO2 micropatterns on organic polymer substrates.

    PubMed

    Yang, Peng; Yang, Min; Zou, Shengli; Xie, Jingyi; Yang, Wantai

    2007-02-14

    Ordered titanium dioxide (TiO2) films have received increasing attention because of their great potential in photocatalysis, energy conversion, and electrooptical techniques. Such films are often fabricated as coatings on various substrates such as silicon or a variety of polymers. Liquid-phase deposition (LPD) of TiO2 films is especially promising for organic substrates due to its very mild reaction conditions. In the present paper, LPD is conducted on a wettability-patterned polypropylene surface to fabricate positive and negative TiO2 micropatterns. A thin layer of ammonium persulfate in an aqueous solution was sandwiched between two biaxially oriented polypropylene (BOPP) films, and a photomask was employed to control the irradiation region. Within a short time interval, a high hydrophilicity could be obtained on the irradiation region, and an effective wettability contrast between the irradiated and unirradiated regions could be created to further induce the formation of two types of TiO2 micropatterns. Up until now, most approaches for micropatterning have been based on self-assembled monolayers on surfaces of gold (or other noble metals), silicon, and various polyesters. With the present method, however, there is no longer any limitation in the type of substrate used. Our work demonstrates that an anatase TiO2 film could be selectively deposited on a hydrophilic region, giving rise to a positive pattern with significant bonding strength and good line edge acuity, providing an effective solution toward the microfabrication on various inert polymer substrates. More surprisingly, we find, for the first time, that TiO2 could also be selectively retained on a hydrophobic region to form a negative pattern by simply adjusting the reaction conditions. Further analysis of the mechanism shows that, independent of the deposition conditions, the TiO2 deposition pattern changes gradually, from being initially negative to becoming positive as the deposition time increases

  19. Facile fabrication of magnetic gold electrode for magnetic beads-based electrochemical immunoassay: application to the diagnosis of Japanese encephalitis virus.

    PubMed

    Li, Fang; Mei, Li; Li, Yaoming; Zhao, Kaihong; Chen, Huanchun; Wu, Peng; Hu, Yonggang; Cao, Shengbo

    2011-06-15

    A novel magnetic beads-based electrochemical immunoassay strategy has been developed for the detection of Japanese encephalitis virus (JEV). The magnetic gold electrode was fabricated to manipulate magnetic beads for the direct sensing applications. Gold-coated magnetic beads were employed as the platforms for the immobilization and immunoreaction process, and horseradish peroxidase was chosen as an enzymatic tracer. The proteins (e.g., antibodies or immunocomplexes) attached on the surface of magnetic beads were found to induce a significant decline in their electric conductivity. Multiwalled carbon nanotubes were introduced to improve sensitivity of the assay. The envelope (E) protein, a major immunogenic protein of JEV, was utilized to optimize the assay parameters. Under the optimal conditions, the linear response range of E protein was 0.84 to 11,200 ng/mL with a detection limit of 0.56 ng/mL. When applied for detection of JEV, the proposed method generated a linear response range between 2×10(3) and 5×10(5) PFU/mL. The detection limit for JEV was 2.0×10(3) PFU/mL, which was 2 orders of magnitude lower than that of immunochromatographic strip and similar to that obtained from RT-PCR. This method was also successfully applied to detect JEV in clinical specimens.

  20. Fabrication of electrodes with ultralow platinum loading by RF plasma processing of self-assembled arrays of Au@Pt nanoparticles

    NASA Astrophysics Data System (ADS)

    Banerjee, Ipshita; Kumaran, V.; Santhanam, Venugopal

    2016-07-01

    Conductive, carbon-free, electrocatalytically active, nanostructured electrodes with ultra-low platinum loading were fabricated using self-assembly of octadecanethiol-coated Au@Pt nanoparticles followed by RF plasma treatment. Bilayer arrays of Au@Pt nanoparticles with platinum loadings of 0.50, 1.04, 1.44, and 1.75 μg cm‑2 (corresponding to 0.5, 1, 1.5 and 2 atomic layer coverage of platinum on nominally 5 nm gold core) were subjected to RF argon plasma treatment for various durations and their electrical conductivity, morphological evolution, and electrocatalytic activity characterized. Samples with monolayer and above platinum coverages exhibit maximum electrochemically active surface areas values of ∼100 m2/gpt and specific activities that are ∼4× to 6× of a reference platinum nanoparticle bilayer array. The underlying gold core influences the structural evolution of the samples upon RF plasma treatment and leads to the formation of highly active Pt(110) facets on the surface at an optimal plasma treatment duration, which also corresponds to the onset of a sharp decline in lateral sheet resistance. The sample having a two atom thick platinum coating has the highest total mass activity of 48 ± 3 m2/g(pt+au), corresponding to 44% Pt atom utilization, while also exhibiting enhanced CO tolerance as well as high methanol oxidation reaction and oxygen reduction reaction activity.

  1. Facile fabrication of highly efficient carbon nanotube thin film replacing CuS counter electrode with enhanced photovoltaic performance in quantum dot-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Gopi, Chandu V. V. M.; Venkata-Haritha, Mallineni; Kim, Soo-Kyoung; Kim, Hee-Je

    2016-04-01

    An ideal counter electrode (CE), with high electrocatalytic activity, high performance stability, cost-efficient and applicable fabrication simplicity, is necessary to give full play to the advantages of quantum dot-sensitized solar cells (QDSSCs). Herein, we report a facile one-step preparation for carbon nanotubes (CNTs) have been explored as an electrocatalyst and low-cost alternative to platinum (Pt) and cuprous sulfide (CuS) CEs for polysulfide reduction in QDSSCs. QDSSC using this newly prepared CNT as a CE achieves a higher power conversion efficiency of 4.67% than those with a CuS (3.67%) or Pt CE (1.56%). Besides, a preliminary stability test reveals that the new CNT CE exhibits good stability. The results of Tafel polarization and electrochemical impedance spectroscopy measurements revealed that the CNTs had higher electrocatalytic activity for the polysulfide redox reaction and a smaller charge transfer resistance (8.61 Ω) at the CE/electrolyte interface than the CuS (21.87 Ω) and Pt (54.99 Ω) CEs. These results indicate that the CNT CE has superior electrocatalytic activity and can potentially replace CuS and Pt as CEs in QDSSCs. The preparation method of the CNT CE is simple and shows much promise as an efficient, stable, cost-effective and environmentally friendly CE for QDSSCs.

  2. Fabrication of electrodes with ultralow platinum loading by RF plasma processing of self-assembled arrays of Au@Pt nanoparticles

    NASA Astrophysics Data System (ADS)

    Banerjee, Ipshita; Kumaran, V.; Santhanam, Venugopal

    2016-07-01

    Conductive, carbon-free, electrocatalytically active, nanostructured electrodes with ultra-low platinum loading were fabricated using self-assembly of octadecanethiol-coated Au@Pt nanoparticles followed by RF plasma treatment. Bilayer arrays of Au@Pt nanoparticles with platinum loadings of 0.50, 1.04, 1.44, and 1.75 μg cm-2 (corresponding to 0.5, 1, 1.5 and 2 atomic layer coverage of platinum on nominally 5 nm gold core) were subjected to RF argon plasma treatment for various durations and their electrical conductivity, morphological evolution, and electrocatalytic activity characterized. Samples with monolayer and above platinum coverages exhibit maximum electrochemically active surface areas values of ˜100 m2/gpt and specific activities that are ˜4× to 6× of a reference platinum nanoparticle bilayer array. The underlying gold core influences the structural evolution of the samples upon RF plasma treatment and leads to the formation of highly active Pt(110) facets on the surface at an optimal plasma treatment duration, which also corresponds to the onset of a sharp decline in lateral sheet resistance. The sample having a two atom thick platinum coating has the highest total mass activity of 48 ± 3 m2/g(pt+au), corresponding to 44% Pt atom utilization, while also exhibiting enhanced CO tolerance as well as high methanol oxidation reaction and oxygen reduction reaction activity.

  3. Cell-micropatterning by micromolding in capillary technique based on UV polymerization

    NASA Astrophysics Data System (ADS)

    Park, Min J.; Choi, Won M.; Park, O. O.

    2006-01-01

    Although optical lithography or photolithography is one of the most well-established techniques for micro, nano-fabrication, its usage with proteins and cells is restricted by steps that must be carried out in harsh organic solvents. Here, we present simple methods for cell-micropatterning using poly(dimethylsiloxane) (PDMS) as a mold. Cell non-adhesive surface or nonfouling surface providing a physico-chemical barrier to cell attachment was introduced for biomaterial pattering, where cells fail to interact with the surface over desired periods of time determined by each application. Poly(ethylene glycol) (PEG) was selected as nonfouling material to inhibit protein adsorption from biological media. The fouling resistance of PEG polymer is often explained by a steric repulsion interaction, resulting from the compression of PEG chains as proteins approach the surface. We also chose fibronectin to direct cell attachment because it is an extracellular matrix protein that is involved in the adhesion and spreading of anchorage-dependent cells. In our experiment, we propose two methods by application of micromolding in capillary (MIMIC) method based on UV polymerization to obtain a surface of alternating PEG and fibronectin. First to fabricate PEG microstructure via MIMIC method, a pre-patterned PDMS mold is placed on a desired substrate, and then the relief structure in the mold forms a network of empty channels. A drop of ethylene glycol monomer solution containing initiator for UV polymerization is placed at the open ends of the network of channels, which is then polymerized by exposure to UV light at room temperature. Once PEG microstructure is fabricated, incubation of the patterned surface in a fibronectin-containing solution allows back-filling of only the bare regions with fibronectin via adsorption. In the alternative method, a substrate is first incubated in a fibronectin-containing solution, leading to the adsorption of fibronectin over the entire surface, and

  4. Stencil Micropatterning of Human Pluripotent Stem Cells for Probing Spatial Organization of Differentiation Fates.

    PubMed

    Sahni, Geetika; Yuan, Jun; Toh, Yi-Chin

    2016-01-01

    Human pluripotent stem cells (hPSCs), including embryonic stem cells and induced pluripotent stem cells, have the intrinsic ability to differentiate into all three germ layers. This makes them an attractive cell source for regenerative medicine and experimental modeling of normal and diseased organogenesis. However, the differentiation of hPSCs in vitro is heterogeneous and spatially disordered. Cell micropatterning technologies potentially offer the means to spatially control stem cell microenvironments and organize the resultant differentiation fates. Micropatterning hPSCs needs to take into account the stringent requirements for hPSC survival and maintenance. Here, we describe stencil micropatterning as a method that is highly compatible with hPSCs. hPSC micropatterns are specified by the geometries of the cell stencil through-holes, which physically confine the locations where hPSCs can access and attach to the underlying extracellular matrix-coated substrate. Due to this mode of operation, there is greater flexibility to use substrates that can adequately support hPSCs as compared to other cell micropatterning methods. We also highlight critical steps for the successful generation of hPSC micropatterns. As an example, we demonstrate that stencil micropatterning of hPSCs can be used to modulate spatial polarization of cell-cell and cell-matrix adhesions, which in turn determines mesoendoderm differentiation patterns. This simple and robust method to micropattern hPSCs widens the prospects of establishing experimental models to investigate tissue organization and patterning during early embryonic development. PMID:27340925

  5. Unidirectional signal propagation in primary neurons micropatterned at a single-cell resolution

    NASA Astrophysics Data System (ADS)

    Yamamoto, H.; Matsumura, R.; Takaoki, H.; Katsurabayashi, S.; Hirano-Iwata, A.; Niwano, M.

    2016-07-01

    The structure and connectivity of cultured neuronal networks can be controlled by using micropatterned surfaces. Here, we demonstrate that the direction of signal propagation can be precisely controlled at a single-cell resolution by growing primary neurons on micropatterns. To achieve this, we first examined the process by which axons develop and how synapses form in micropatterned primary neurons using immunocytochemistry. By aligning asymmetric micropatterns with a marginal gap, it was possible to pattern primary neurons with a directed polarization axis at the single-cell level. We then examined how synapses develop on micropatterned hippocampal neurons. Three types of micropatterns with different numbers of short paths for dendrite growth were compared. A normal development in synapse density was observed when micropatterns with three or more short paths were used. Finally, we performed double patch clamp recordings on micropatterned neurons to confirm that these synapses are indeed functional, and that the neuronal signal is transmitted unidirectionally in the intended orientation. This work provides a practical guideline for patterning single neurons to design functional neuronal networks in vitro with the direction of signal propagation being controlled.

  6. Combined nano- and micro-scale topographic cues for engineered vascular constructs by electrospinning and imprinted micro-patterns.

    PubMed

    Moffa, Maria; Sciancalepore, Anna Giovanna; Passione, Laura Gioia; Pisignano, Dario

    2014-06-25

    The major cause of synthetic vessel failure is thrombus and neointima formation. To prevent these problems the creation of a continuous and elongated endothelium inside lumen vascular grafts might be a promising solution for tissue engineering. Different micro- and nano-surface topographic cues including grooved micro-patterns and electrospun fibers have been previously demonstrated to guide the uniform alignment of endothelial cells (ECs). Here, with a very simple and highly versatile approach we combined electrospinning with soft lithography to fabricate nanofibrous scaffolds with oriented fibers modulated by different micro-grooved topographies. The effect of these scaffolds on the behavior of the ECs are analyzed, including their elongation, spreading, proliferation, and functioning using unpatterned random and aligned nanofibers (NFs) as controls. It is demonstrated that both aligned NFs and micro-patterns effectively influence the cellular response, and that a proper combination of topographic parameters, exploiting the synergistic effects of micro-scale and sub-micrometer features, can promote EC elongation, allowing the creation of a confluent ECs monolayer in analogy with the natural endothelium as assessed by the positive expression of vinculin. Combining different micro- and nano-topographic cues by complementary soft patterning and spinning technologies could open interesting perspectives for engineered vascular replacement constructions.

  7. Combined nano- and micro-scale topographic cues for engineered vascular constructs by electrospinning and imprinted micro-patterns.

    PubMed

    Moffa, Maria; Sciancalepore, Anna Giovanna; Passione, Laura Gioia; Pisignano, Dario

    2014-06-25

    The major cause of synthetic vessel failure is thrombus and neointima formation. To prevent these problems the creation of a continuous and elongated endothelium inside lumen vascular grafts might be a promising solution for tissue engineering. Different micro- and nano-surface topographic cues including grooved micro-patterns and electrospun fibers have been previously demonstrated to guide the uniform alignment of endothelial cells (ECs). Here, with a very simple and highly versatile approach we combined electrospinning with soft lithography to fabricate nanofibrous scaffolds with oriented fibers modulated by different micro-grooved topographies. The effect of these scaffolds on the behavior of the ECs are analyzed, including their elongation, spreading, proliferation, and functioning using unpatterned random and aligned nanofibers (NFs) as controls. It is demonstrated that both aligned NFs and micro-patterns effectively influence the cellular response, and that a proper combination of topographic parameters, exploiting the synergistic effects of micro-scale and sub-micrometer features, can promote EC elongation, allowing the creation of a confluent ECs monolayer in analogy with the natural endothelium as assessed by the positive expression of vinculin. Combining different micro- and nano-topographic cues by complementary soft patterning and spinning technologies could open interesting perspectives for engineered vascular replacement constructions. PMID:24623539

  8. Micropatterning strategies to engineer controlled cell and tissue architecture in vitro.

    PubMed

    D'Arcangelo, Elisa; McGuigan, Alison P

    2015-01-01

    Micropatterning strategies, which enable control over cell and tissue architecture in vitro, have emerged as powerful platforms for modelling tissue microenvironments at different scales and complexities. Here, we provide an overview of popular micropatterning techniques, along with detailed descriptions, to guide new users through the decision making process of which micropatterning procedure to use, and how to best obtain desired tissue patterns. Example techniques and the types of biological observations that can be made are provided from the literature. A focus is placed on microcontact printing to obtain co-cultures of patterned, confluent sheets, and the challenges associated with optimizing this protocol. Many issues associated with microcontact printing, however, are relevant to all micropatterning methodologies. Finally, we briefly discuss challenges in addressing key limitations associated with current micropatterning technologies.

  9. Fabrication and characterization of PbO2 electrode modified with [Fe(CN)6](3-) and its application on electrochemical degradation of alkali lignin.

    PubMed

    Hao, Xu; Quansheng, Yuan; Dan, Shao; Honghui, Yang; Jidong, Liang; Jiangtao, Feng; Wei, Yan

    2015-04-01

    PbO2 electrode modified by [Fe(CN)6](3-) (marked as FeCN-PbO2) was prepared by electro-deposition method and used for the electrochemical degradation of alkali lignin (AL). The surface morphology and the structure of the electrodes were characterized by scanning electronic microscopy (SEM) and X-ray diffraction (XRD), respectively. The stability and electrochemical activity of FeCN-PbO2 electrode were characterized by accelerated life test, linear sweep voltammetry, electrochemical impedance spectrum (EIS) and AL degradation. The results showed that [Fe(CN)6](3-) increased the average grain size of PbO2 and formed a compact surface coating. The service lifetime of FeCN-PbO2 electrode was 287.25 h, which was longer than that of the unmodified PbO2 electrode (100.5h). The FeCN-PbO2 electrode showed higher active surface area and higher oxygen evolution potential than that of the unmodified PbO2 electrode. In electrochemical degradation tests, the apparent kinetics coefficient of FeCN-PbO2 electrode was 0.00609 min(-1), which was higher than that of unmodified PbO2 electrode (0.00419 min(-1)). The effects of experimental parameters, such as applied current density, initial AL concentration, initial pH value and solution temperature, on electrochemical degradation of AL by FeCN-PbO2 electrode were evaluated.

  10. Material Stiffness Effects on Neurite Alignment to Photopolymerized Micropatterns

    PubMed Central

    2015-01-01

    The ability to direct neurite growth into a close proximity of stimulating elements of a neural prosthesis, such as a retinal or cochlear implant (CI), may enhance device performance and overcome current spatial signal resolution barriers. In this work, spiral ganglion neurons (SGNs), which are the target neurons to be stimulated by CIs, were cultured on photopolymerized micropatterns with varied matrix stiffnesses to determine the effect of rigidity on neurite alignment to physical cues. Micropatterns were generated on methacrylate thin film surfaces in a simple, rapid photopolymerization step by photomasking the prepolymer formulation with parallel line–space gratings. Two methacrylate series, a nonpolar HMA-co-HDDMA series and a polar PEGDMA-co-EGDMA series, with significantly different surface wetting properties were evaluated. Equivalent pattern periodicity was maintained across each methacrylate series based on photomask band spacing, and the feature amplitude was tuned to a depth of 2 μm amplitude for all compositions using the temporal control afforded by the UV curing methodology. The surface morphology was characterized by scanning electron microscopy and white light interferometry. All micropatterned films adsorb similar amounts of laminin from solution, and no significant difference in SGN survival was observed when the substrate compositions were compared. SGN neurite alignment significantly increases with increasing material modulus for both methacrylate series. Interestingly, SGN neurites respond to material stiffness cues that are orders of magnitude higher (GPa) than what is typically ascribed to neural environments (kPa). The ability to understand neurite response to engineered physical cues and mechanical properties such as matrix stiffness will allow the development of advanced biomaterials that direct de novo neurite growth to address the spatial signal resolution limitations of current neural prosthetics. PMID:25211120

  11. Micropatterning and Assembly of 3D Microvessels.

    PubMed

    Roberts, Meredith A; Kotha, Surya S; Phong, Kiet T; Zheng, Ying

    2016-01-01

    In vitro platforms to study endothelial cells and vascular biology are largely limited to 2D endothelial cell culture, flow chambers with polymer or glass based substrates, and hydrogel-based tube formation assays. These assays, while informative, do not recapitulate lumen geometry, proper extracellular matrix, and multi-cellular proximity, which play key roles in modulating vascular function. This manuscript describes an injection molding method to generate engineered vessels with diameters on the order of 100 µm. Microvessels are fabricated by seeding endothelial cells in a microfluidic channel embedded within a native type I collagen hydrogel. By incorporating parenchymal cells within the collagen matrix prior to channel formation, specific tissue microenvironments can be modeled and studied. Additional modulations of hydrodynamic properties and media composition allow for control of complex vascular function within the desired microenvironment. This platform allows for the study of perivascular cell recruitment, blood-endothelium interactions, flow response, and tissue-microvascular interactions. Engineered microvessels offer the ability to isolate the influence from individual components of a vascular niche and precisely control its chemical, mechanical, and biological properties to study vascular biology in both health and disease. PMID:27685466

  12. Highly compliant transparent electrodes

    NASA Astrophysics Data System (ADS)

    Shian, Samuel; Diebold, Roger M.; McNamara, Alena; Clarke, David R.

    2012-08-01

    Adaptive optical devices based on electric field induced deformation of dielectric elastomers require transparent and highly compliant electrodes to conform to large shape changes. Electrical, optical, and actuation properties of acrylic elastomer electrodes fabricated with single-walled carbon nanotubes (SWCNTs) and silver nanowires (AgNWs) have been evaluated. Based on these properties, a figure of merit is introduced for evaluating the overall performance of deformable transparent electrodes. This clearly indicates that SWCNTs outperform AgNWs. Under optimal conditions, optical transparency as high as 91% at 190% maximum actuation strain is readily achievable using SWCNT electrodes.

  13. Stencil Micropatterning for Spatial Control of Human Pluripotent Stem Cell Fate Heterogeneity.

    PubMed

    Yuan, Jun; Sahni, Geetika; Toh, Yi-Chin

    2016-01-01

    Human pluripotent stem cells (hPSCs) have the intrinsic ability to differentiate and self-organize into distinct tissue patterns, although this requires the presentation of spatial environmental cues, i.e., biochemical and mechanical gradients. Cell micropatterning technologies potentially offer the means to spatially control stem cell microenvironments and organize the resultant differentiation fates. Here, we describe stencil micropatterning as a simple and robust method to generate hPSC micropatterns for controlling hPSC differentiation patterns. hPSC micropatterns are specified by the geometries of the cell stencil through-holes, which physically confine the locations where the underlying extracellular matrix and hPSCs can access and attach to the substrate. This confers the unique capability of stencil micropatterning to work with a variety of culture substrates and extracellular matrices for optimal hPSC culture. We present the detailed steps of stencil micropatterning to successfully generate hPSC micropatterns, which can be used to investigate how spatial polarization of cell adhesion results in cell fate heterogeneity. PMID:27032943

  14. "Artificial mitotic spindle" generated by dielectrophoresis and protein micropatterning supports bidirectional transport of kinesin-coated beads.

    PubMed

    Uppalapati, Maruti; Huang, Ying-Ming; Aravamuthan, Vidhya; Jackson, Thomas N; Hancock, William O

    2011-01-01

    The mitotic spindle is a dynamic assembly of microtubules and microtubule-associated proteins that controls the directed movement of chromosomes during cell division. Because proper segregation of the duplicated genome requires that each daughter cell receives precisely one copy of each chromosome, numerous overlapping mechanisms have evolved to ensure that every chromosome is transported to the cell equator during metaphase. However, due to the inherent redundancy in this system, cellular studies using gene knockdowns or small molecule inhibitors have an inherent limit in defining the sufficiency of precise molecular mechanisms as well as quantifying aspects of their mechanical performance. Thus, there exists a need for novel experimental approaches that reconstitute important aspects of the mitotic spindle in vitro. Here, we show that by microfabricating Cr electrodes on quartz substrates and micropatterning proteins on the electrode surfaces, AC electric fields can be used to assemble opposed bundles of aligned and uniformly oriented microtubules as found in the mitotic spindle. By immobilizing microtubule ends on each electrode, analogous to anchoring at centrosomes, solutions of motor or microtubule binding proteins can be introduced and their resulting dynamics analyzed. Using this "artificial mitotic spindle" we show that beads functionalized with plus-end kinesin motors move in an oscillatory manner analogous to the movements of chromosomes and severed chromosome arms during metaphase. Hence, features of directional instability, an established characteristic of metaphase chromosome dynamics, can be reconstituted in vitro using a pair of uniformly oriented microtubule bundles and a plus-end kinesin functionalized bead.

  15. Micro-patterning and characterization of PHEMA-co-PAM-based optical chemical sensors for lab-on-a-chip applications

    PubMed Central

    Zhu, Haixin; Zhou, Xianfeng; Su, Fengyu; Tian, Yanqing; Ashili, Shashanka; Holl, Mark R.; Meldrum, Deirdre R.

    2012-01-01

    We report a novel method for wafer level, high throughput optical chemical sensor patterning, with precise control of the sensor volume and capability of producing arbitrary microscale patterns. Monomeric oxygen (O2) and pH optical probes were polymerized with 2-hydroxyethyl methacrylate (HEMA) and acrylamide (AM) to form spin-coatable and further crosslinkable polymers. A micro-patterning method based on micro-fabrication techniques (photolithography, wet chemical process and reactive ion etch) was developed to miniaturize the sensor film onto glass substrates in arbitrary sizes and shapes. The sensitivity of fabricated micro-patterns was characterized under various oxygen concentrations and pH values. The process for spatially integration of two sensors (Oxygen and pH) on the same substrate surface was also developed, and preliminary fabrication and characterization results were presented. To the best of our knowledge, it is the first time that poly (2-hydroxylethyl methacrylate)-co-poly (acrylamide) (PHEMA-co-PAM)-based sensors had been patterned and integrated at the wafer level with micron scale precision control using microfabrication techniques. The developed methods can provide a feasible way to miniaturize and integrate the optical chemical sensor system and can be applied to any lab-on-a-chip system, especially the biological micro-systems requiring optical sensing of single or multiple analytes. PMID:23175599

  16. Solvent annealing of Micropatterned PS-b-PEO copolymer films

    NASA Astrophysics Data System (ADS)

    Kim, Tae Hee; Acharya, Himadri; Joeng, Hee June; Park, Cheolmin

    2009-03-01

    Solvent annealing of block copolymer thin films have been known as an effective way to control both orientation of microdomains with respect to the surface and their registration into a well ordered periodic lattice structure. We have recently demonstrated hierarchically ordered microdomains in a thin poly(styrene-b-ethylene oxide)(PS-b-PEO) film combined with microcontact printing. The solvent annealing gave rise to well ordered spherical PEO microdomains in large area by the confined dewetting of thin PS-b-PEO films which had been micropatterned on chemically modified surface during solvent annealing. In this presentation, we intentionally prepare a micropatterned dewet film of PS-b-PEO by spincoating a block copolymer solution on a topographic PDMS pre-pattern. Convex lens shaped spherical caps of PS-b-PEO individually located on each PDMS mesa were successfully transferred to a Si substrate by a conventional transfer printing technique. We investigate the effect of solvent on not only film wettability but also formation of hierarchical nanostructures.

  17. Micro-Pattern Gaseous Detector Technologies and RD51 Collaboration

    NASA Astrophysics Data System (ADS)

    Titov, Maxim; Ropelewski, Leszek

    2013-04-01

    Discoveries in particle physics vitally depend on parallel advances in radiation-detector technologies. A true innovation in detector instrumentation concepts came in 1968, with the development of a fully parallel readout for a large array of sensing elements — the Multi-Wire Proportional Chamber (MWPC), which earned Georges Charpak a Nobel Prize in Physics in 1992. This invention revolutionized particle detection which moved from optical-readout devices (cloud chamber, emulsion or bubble chambers) to the electronics era. Over the past two decades advances in photo-lithography, microelectronics and printed-circuit board (PCB) techniques triggered a major transition in the field of gas detectors from wire structures to the Micro-Pattern Gas Detector (MPGD) concepts. The excellent spatial and time resolution, high rate capability, low mass, large active areas, and radiation hardness make them an invaluable tool to confront future detector challenges at the frontiers of research. The design of the new micro-pattern devices appears suitable for industrial production. Novel devices where MPGDs are directly coupled to the CMOS pixel readout serve as an "electronic bubble chamber" allowing to record space points and tracks in 3D. In 2008, the RD51 collaboration at CERN has been established to further advance technological developments of MPGDs and associated electronic-readout systems, for applications in basic and applied research. This review provides an overview of the state-of-the-art of the MPGD technologies and summarizes ongoing activities within the framework of the RD51 collaboration.

  18. Novel Micropatterned Cardiac Cell Cultures with Realistic Ventricular Microstructure

    PubMed Central

    Badie, Nima; Bursac, Nenad

    2009-01-01

    Systematic studies of cardiac structure-function relationships to date have been hindered by the intrinsic complexity and variability of in vivo and ex vivo model systems. Thus, we set out to develop a reproducible cell culture system that can accurately replicate the realistic microstructure of native cardiac tissues. Using cell micropatterning techniques, we aligned cultured cardiomyocytes at micro- and macroscopic spatial scales to follow local directions of cardiac fibers in murine ventricular cross sections, as measured by high-resolution diffusion tensor magnetic resonance imaging. To elucidate the roles of ventricular tissue microstructure in macroscopic impulse conduction, we optically mapped membrane potentials in micropatterned cardiac cultures with realistic tissue boundaries and natural cell orientation, cardiac cultures with realistic tissue boundaries but random cell orientation, and standard isotropic monolayers. At 2 Hz pacing, both microscopic changes in cell orientation and ventricular tissue boundaries independently and synergistically increased the spatial dispersion of conduction velocity, but not the action potential duration. The realistic variations in intramural microstructure created unique spatial signatures in micro- and macroscopic impulse propagation within ventricular cross-section cultures. This novel in vitro model system is expected to help bridge the existing gap between experimental structure-function studies in standard cardiac monolayers and intact heart tissues. PMID:19413993

  19. Structural and molecular micropatterning of dual hydrogel constructs for neural growth models using photochemical strategies

    PubMed Central

    Horn-Ranney, Elaine L.; Curley, J. Lowry; Catig, Gary C.; Huval, Renee M.; Moore, Michael J.

    2013-01-01

    Chemotactic and haptotactic cues guide neurite growth toward appropriate targets by eliciting attractive or repulsive responses from the neurite growth cones. Here we present an integrated system allowing both structural and molecular micropatterning in dual hydrogel 3D tissue culture constructs for directing in vitro neuronal growth via structural, immobilized, and soluble guidance cues. These tissue culture constructs were fabricated into specifiable geometries using UV light reflected from a digital micromirror device acting as a dynamic photomask, resulting in dual hydrogel constructs consisting of a cell growth-restrictive polyethylene glycol (PEG) boundary with a cell growth-permissive interior of photolabile α-carboxy-2-nitrobenzyl cysteine agarose (CNBC-A). This CNBC-A was irradiated in discrete areas and subsequently tagged with maleimide-conjugated biomolecules. Fluorescent microscopy showed biomolecule binding only at the sites of irradiation in CNBC-A, and confocal microscopy confirmed 3D binding through the depth of the construct. Neurite outgrowth studies showed contained growth throughout CNBC-A. The diffusion rate of soluble fluorescein-bovine serum albumin through the dual hydrogel construct was controlled by PEG concentration and the distance between the protein source and the agarose interior; the timescale for a transient protein gradient changed with these parameters. These findings suggest the dual hydrogel system is a usefulplatform for manipulating a 3D in vitro microenvironment with patterned structural and molecular guidance cues for modeling neural growth and guidance. PMID:22903647

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

    PubMed

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

    2015-02-01

    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.

  1. Addressable micropatterning of multiple proteins and cells by microscope projection photolithography based on a protein friendly photoresist.

    PubMed

    Kim, Miju; Choi, Jong-Cheol; Jung, Hong-Ryul; Katz, Joshua S; Kim, Min-Gon; Doh, Junsang

    2010-07-20

    We report a new method for the micropatterning of multiple proteins and cells with micrometer-scale precision. Microscope projection photolithography based on a new protein-friendly photoresist, poly(2,2-dimethoxy nitrobenzyl methacrylate-r-methyl methacrylate-r-poly(ethylene glycol) methacrylate) (PDMP), was used for the fabrication of multicomponent protein/cell arrays. Microscope projection lithography allows precise registration between multiple patterns as well as facile fabrication of microscale features. Thin films of PDMP became soluble in near-neutral physiological buffer solutions upon UV exposure and exhibited excellent resistance to protein adsorption and cell adhesion. By harnessing advantages in microscope projection photolithography and properties of PDMP thin films, we could successfully fabricate protein arrays composed of multiple proteins. Furthermore, we could extend this method for the patterning of two different types of immune cells for the potential study of immune cell interactions. This technique will in general be useful for protein chip fabrication and high-throughput cell-cell communication study.

  2. Preparation and surface characterization of plasma-treated and biomolecular-micropatterned polymer substrates

    NASA Astrophysics Data System (ADS)

    Langowski, Bryan Alfred

    A micropatterning process creates distinct microscale domains on substrate surfaces that differ from the surfaces' original chemical/physical properties. Numerous micropatterning methods exist, each having relative advantages and disadvantages in terms of cost, ease, reproducibility, and versatility. Polymeric surfaces micropatterned with biomolecules have many applications, but are specifically utilized in tissue engineering as cell scaffolds that attempt to controlled tissue generation in vivo and ex vivo. As the physical and chemical cues presented by micropatterned substrates control resulting cellular behavior, characterization of these cues via surface-sensitive analytical techniques is essential in developing cell scaffolds that mimic complex in vivo physicochemical environments. The initial focus of this thesis is the chemical and physical characterization of plasma-treated, microcontact-printed (muCP) polymeric substrates used to direct nerve cell behavior. Unmodified and oxygen plasma-treated poly(methyl methacrylate) (PMMA) substrates were analyzed by surface sensitive techniques to monitor plasma-induced chemical and physical modifications. Additionally, protein-micropattern homogeneity and size were microscopically evaluated. Lastly, poly(dimethylsiloxane) (PDMS) stamps and contaminated PMMA substrates were characterized by spectroscopic and microscopic methods to identify a contamination source during microcontact printing. The final focus of this thesis is the development of microscale plasma-initiated patterning (muPIP) as a versatile, reproducible micropatterning method. Using muPIP, polymeric substrates were micropatterned with several biologically relevant inks. Polymeric substrates were characterized following muPIP by surface-sensitive techniques to identify the technique's underlying physical and chemical bases. In addition, neural stem cell response to muPIP-generated laminin micropatterns was microscopically and biologically evaluated

  3. Defining the origins of electron transfer at screen-printed graphene-like and graphite electrodes: MoO2 nanowire fabrication on edge plane sites reveals electrochemical insights.

    PubMed

    Rowley-Neale, Samuel J; Brownson, Dale A C; Banks, Craig E

    2016-08-18

    Molybdenum (di)oxide (MoO2) nanowires are fabricated onto graphene-like and graphite screen-printed electrodes (SPEs) for the first time, revealing crucial insights into the electrochemical properties of carbon/graphitic based materials. Distinctive patterns observed in the electrochemical process of nanowire decoration show that electron transfer occurs predominantly on edge plane sites when utilising SPEs fabricated/comprised of graphitic materials. Nanowire fabrication along the edge plane sites (and on edge plane like-sites/defects) of graphene/graphite is confirmed with Cyclic Voltammetry, Scanning Electron Microscopy (SEM) and Raman Spectroscopy. Comparison of the heterogeneous electron transfer (HET) rate constants (k°) at unmodified and nanowire coated SPEs show a reduction in the electrochemical reactivity of SPEs when the edge plane sites are effectively blocked/coated with MoO2. Throughout the process, the basal plane sites of the graphene/graphite electrodes remain relatively uncovered; except when the available edge plane sites have been utilised, in which case MoO2 deposition grows from the edge sites covering the entire surface of the electrode. This work clearly illustrates the distinct electron transfer properties of edge and basal plane sites on graphitic materials, indicating favourable electrochemical reactivity at the edge planes in contrast to limited reactivity at the basal plane sites. In addition to providing fundamental insights into the electron transfer properties of graphite and graphene-like SPEs, the reported simple, scalable, and cost effective formation of unique and intriguing MoO2 nanowires realised herein is of significant interest for use in both academic and commercial applications. PMID:27487988

  4. Defining the origins of electron transfer at screen-printed graphene-like and graphite electrodes: MoO2 nanowire fabrication on edge plane sites reveals electrochemical insights.

    PubMed

    Rowley-Neale, Samuel J; Brownson, Dale A C; Banks, Craig E

    2016-08-18

    Molybdenum (di)oxide (MoO2) nanowires are fabricated onto graphene-like and graphite screen-printed electrodes (SPEs) for the first time, revealing crucial insights into the electrochemical properties of carbon/graphitic based materials. Distinctive patterns observed in the electrochemical process of nanowire decoration show that electron transfer occurs predominantly on edge plane sites when utilising SPEs fabricated/comprised of graphitic materials. Nanowire fabrication along the edge plane sites (and on edge plane like-sites/defects) of graphene/graphite is confirmed with Cyclic Voltammetry, Scanning Electron Microscopy (SEM) and Raman Spectroscopy. Comparison of the heterogeneous electron transfer (HET) rate constants (k°) at unmodified and nanowire coated SPEs show a reduction in the electrochemical reactivity of SPEs when the edge plane sites are effectively blocked/coated with MoO2. Throughout the process, the basal plane sites of the graphene/graphite electrodes remain relatively uncovered; except when the available edge plane sites have been utilised, in which case MoO2 deposition grows from the edge sites covering the entire surface of the electrode. This work clearly illustrates the distinct electron transfer properties of edge and basal plane sites on graphitic materials, indicating favourable electrochemical reactivity at the edge planes in contrast to limited reactivity at the basal plane sites. In addition to providing fundamental insights into the electron transfer properties of graphite and graphene-like SPEs, the reported simple, scalable, and cost effective formation of unique and intriguing MoO2 nanowires realised herein is of significant interest for use in both academic and commercial applications.

  5. Nanoscale Electrodes for Flexible Electronics by Swelling Controlled Cracking.

    PubMed

    Zhao, Qiang; Wang, Wenjun; Shao, Jinyou; Li, Xiangming; Tian, Hongmiao; Liu, Lu; Mei, Xuesong; Ding, Yucheng; Lu, Bingheng

    2016-08-01

    Nanogap electrodes are realized using pre-patterned electrodes and a swelling controlled cracking method. Parallel fabrication of nanogap electrodes on flexible substrates can be achieved using this method. This swelling-controlled cracking method is promising for fabricating high-performance flexible electronics. UV photodetectors with ZnO nanoparticle-bridged nanogap electrodes exhibit high responsivity and external quantum efficiency.

  6. Nanoscale Electrodes for Flexible Electronics by Swelling Controlled Cracking.

    PubMed

    Zhao, Qiang; Wang, Wenjun; Shao, Jinyou; Li, Xiangming; Tian, Hongmiao; Liu, Lu; Mei, Xuesong; Ding, Yucheng; Lu, Bingheng

    2016-08-01

    Nanogap electrodes are realized using pre-patterned electrodes and a swelling controlled cracking method. Parallel fabrication of nanogap electrodes on flexible substrates can be achieved using this method. This swelling-controlled cracking method is promising for fabricating high-performance flexible electronics. UV photodetectors with ZnO nanoparticle-bridged nanogap electrodes exhibit high responsivity and external quantum efficiency. PMID:27197807

  7. Controlling condensation and frost growth with chemical micropatterns.

    PubMed

    Boreyko, Jonathan B; Hansen, Ryan R; Murphy, Kevin R; Nath, Saurabh; Retterer, Scott T; Collier, C Patrick

    2016-01-01

    In-plane frost growth on chilled hydrophobic surfaces is an inter-droplet phenomenon, where frozen droplets harvest water from neighboring supercooled liquid droplets to grow ice bridges that propagate across the surface in a chain reaction. To date, no surface has been able to passively prevent the in-plane growth of ice bridges across the population of supercooled condensate. Here, we demonstrate that when the separation between adjacent nucleation sites for supercooled condensate is properly controlled with chemical micropatterns prior to freezing, inter-droplet ice bridging can be slowed and even halted entirely. Since the edge-to-edge separation between adjacent supercooled droplets decreases with growth time, deliberately triggering an early freezing event to minimize the size of nascent condensation was also necessary. These findings reveal that inter-droplet frost growth can be passively suppressed by designing surfaces to spatially control nucleation sites and by temporally controlling the onset of freezing events. PMID:26796663

  8. Controlling condensation and frost growth with chemical micropatterns.

    PubMed

    Boreyko, Jonathan B; Hansen, Ryan R; Murphy, Kevin R; Nath, Saurabh; Retterer, Scott T; Collier, C Patrick

    2016-01-22

    In-plane frost growth on chilled hydrophobic surfaces is an inter-droplet phenomenon, where frozen droplets harvest water from neighboring supercooled liquid droplets to grow ice bridges that propagate across the surface in a chain reaction. To date, no surface has been able to passively prevent the in-plane growth of ice bridges across the population of supercooled condensate. Here, we demonstrate that when the separation between adjacent nucleation sites for supercooled condensate is properly controlled with chemical micropatterns prior to freezing, inter-droplet ice bridging can be slowed and even halted entirely. Since the edge-to-edge separation between adjacent supercooled droplets decreases with growth time, deliberately triggering an early freezing event to minimize the size of nascent condensation was also necessary. These findings reveal that inter-droplet frost growth can be passively suppressed by designing surfaces to spatially control nucleation sites and by temporally controlling the onset of freezing events.

  9. Reversible switching of hydrogel-actuated nanostructures into complex micropatterns.

    PubMed

    Sidorenko, Alexander; Krupenkin, Tom; Taylor, Ashley; Fratzl, Peter; Aizenberg, Joanna

    2007-01-26

    Responsive behavior, which is intrinsic to natural systems, is becoming a key requirement for advanced artificial materials and devices, presenting a substantial scientific and engineering challenge. We designed dynamic actuation systems by integrating high-aspect-ratio silicon nanocolumns, either free-standing or substrate-attached, with a hydrogel layer. The nanocolumns were put in motion by the "muscle" of the hydrogel, which swells or contracts depending on the humidity level. This actuation resulted in a fast reversible reorientation of the nanocolumns from tilted to perpendicular to the surface. By further controlling the stress field in the hydrogel, the formation of a variety of elaborate reversibly actuated micropatterns was demonstrated. The mechanics of the actuation process have been assessed. Dynamic control over the movement and orientation of surface nanofeatures at the micron and submicron scales may have exciting applications in actuators, microfluidics, or responsive materials.

  10. Controlling condensation and frost growth with chemical micropatterns

    NASA Astrophysics Data System (ADS)

    Boreyko, Jonathan B.; Hansen, Ryan R.; Murphy, Kevin R.; Nath, Saurabh; Retterer, Scott T.; Collier, C. Patrick

    2016-01-01

    In-plane frost growth on chilled hydrophobic surfaces is an inter-droplet phenomenon, where frozen droplets harvest water from neighboring supercooled liquid droplets to grow ice bridges that propagate across the surface in a chain reaction. To date, no surface has been able to passively prevent the in-plane growth of ice bridges across the population of supercooled condensate. Here, we demonstrate that when the separation between adjacent nucleation sites for supercooled condensate is properly controlled with chemical micropatterns prior to freezing, inter-droplet ice bridging can be slowed and even halted entirely. Since the edge-to-edge separation between adjacent supercooled droplets decreases with growth time, deliberately triggering an early freezing event to minimize the size of nascent condensation was also necessary. These findings reveal that inter-droplet frost growth can be passively suppressed by designing surfaces to spatially control nucleation sites and by temporally controlling the onset of freezing events.

  11. Controlling condensation and frost growth with chemical micropatterns

    DOE PAGESBeta

    Boreyko, Jonathan B.; Hansen, Ryan R.; Murphy, Kevin R.; Nath, Saurabh; Retterer, Scott T.; Collier, C. Patrick

    2016-01-22

    Frost growth on chilled hydrophobic surfaces is an inter-droplet phenomenon, where frozen droplets harvest water from supercooled liquid droplets to grow ice bridges that propagate across the surface in a chain reaction. To date, no surface has been able to passively prevent the in-plane growth of frost across the population of supercooled condensate. Here, we demonstrate that when the nucleation sites for supercooled condensate are properly controlled with chemical micropatterns, the speed of frost growth can be slowed and even halted entirely. This stoppage of frost growth is attributed to the large interdroplet separation between condensate upon the onset ofmore » freezing, which was controlled by the pitch of the chemical patterns and by deliberately triggering an early freezing event. Lastly, these findings reveal that frost growth can be passively suppressed by designing surfaces to spatially control nucleation sites and/or temporally control the onset of freezing events.« less

  12. Adhesive micropatterns to study intermediate filament function in nuclear positioning.

    PubMed

    Dupin, Isabelle; Elric, Julien; Etienne-Manneville, Sandrine

    2015-01-01

    The nucleus is generally found near the cell center; however its position can vary in response to extracellular or intracellular signals, leading to a polarized intracellular organization. Nuclear movement is mediated by the cytoskeleton and its associated motors. While the role of actin and microtubule cytoskeletons in nuclear positioning has been assessed in various systems, the contribution of intermediate filaments is less established due in part to the lack of tools to study intermediate filament functions. The methods described here use micropatterned substrates to impose reproducible cell shape and nucleus position. Intermediate filament organization can be perturbed using gene downregulation or upregulation; intermediate filaments can also be visualized using fluorescent intermediate filament proteins. This protocol is valuable for characterizing the role of intermediate filaments in a variety of live or fixed adherent cells.

  13. Controlling condensation and frost growth with chemical micropatterns

    PubMed Central

    Boreyko, Jonathan B.; Hansen, Ryan R.; Murphy, Kevin R.; Nath, Saurabh; Retterer, Scott T.; Collier, C. Patrick

    2016-01-01

    In-plane frost growth on chilled hydrophobic surfaces is an inter-droplet phenomenon, where frozen droplets harvest water from neighboring supercooled liquid droplets to grow ice bridges that propagate across the surface in a chain reaction. To date, no surface has been able to passively prevent the in-plane growth of ice bridges across the population of supercooled condensate. Here, we demonstrate that when the separation between adjacent nucleation sites for supercooled condensate is properly controlled with chemical micropatterns prior to freezing, inter-droplet ice bridging can be slowed and even halted entirely. Since the edge-to-edge separation between adjacent supercooled droplets decreases with growth time, deliberately triggering an early freezing event to minimize the size of nascent condensation was also necessary. These findings reveal that inter-droplet frost growth can be passively suppressed by designing surfaces to spatially control nucleation sites and by temporally controlling the onset of freezing events. PMID:26796663

  14. Microfluidics-based laser cell-micropatterning system.

    PubMed

    Erdman, Nick; Schmidt, Lucas; Qin, Wan; Yang, Xiaoqi; Lin, Yongliang; DeSilva, Mauris N; Gao, Bruce Z

    2014-09-01

    The ability to place individual cells into an engineered microenvironment in a cell-culture model is critical for the study of in vivo relevant cell-cell and cell-extracellular matrix interactions. Microfluidics provides a high-throughput modality to inject various cell types into a microenvironment. Laser guided systems provide the high spatial and temporal resolution necessary for single-cell micropatterning. Combining these two techniques, the authors designed, constructed, tested and evaluated (1) a novel removable microfluidics-based cell-delivery biochip and (2) a combined system that uses the novel biochip coupled with a laser guided cell-micropatterning system to place individual cells into both two-dimensional (2D) and three-dimensional (3D) arrays. Cell-suspensions of chick forebrain neurons and glial cells were loaded into their respective inlet reservoirs and traversed the microfluidic channels until reaching the outlet ports. Individual cells were trapped and guided from the outlet of a microfluidic channel to a target site on the cell-culture substrate. At the target site, 2D and 3D pattern arrays were constructed with micron-level accuracy. Single-cell manipulation was accomplished at a rate of 150 μm s(-1) in the radial plane and 50 μm s(-1) in the axial direction of the laser beam. Results demonstrated that a single-cell can typically be patterned in 20-30 s, and that highly accurate and reproducible cellular arrays and systems can be achieved through coupling the microfluidics-based cell-delivery biochip with the laser guided system.

  15. Fabrication of 3D core-shell multiwalled carbon nanotube@RuO2 lithium-ion battery electrodes through a RuO2 atomic layer deposition process.

    PubMed

    Gregorczyk, Keith E; Kozen, Alexander C; Chen, Xinyi; Schroeder, Marshall A; Noked, Malachi; Cao, Anyuan; Hu, Liangbing; Rubloff, Gary W

    2015-01-27

    Pushing lithium-ion battery (LIB) technology forward to its fundamental scaling limits requires the ability to create designer heterostructured materials and architectures. Atomic layer deposition (ALD) has recently been applied to advanced nanostructured energy storage devices due to the wide range of available materials, angstrom thickness control, and extreme conformality over high aspect ratio nanostructures. A class of materials referred to as conversion electrodes has recently been proposed as high capacity electrodes. RuO2 is considered an ideal conversion material due to its high combined electronic and ionic conductivity and high gravimetric capacity, and as such is an excellent material to explore the behavior of conversion electrodes at nanoscale thicknesses. We report here a fully characterized atomic layer deposition process for RuO2, electrochemical cycling data for ALD RuO2, and the application of the RuO2 to a composite carbon nanotube electrode scaffold with nucleation-controlled RuO2 growth. A growth rate of 0.4 Å/cycle is found between ∼ 210-240 °C. In a planar configuration, the resulting RuO2 films show high first cycle electrochemical capacities of ∼ 1400 mAh/g, but the capacity rapidly degrades with charge/discharge cycling. We also fabricated core/shell MWCNT/RuO2 heterostructured 3D electrodes, which show a 50× increase in the areal capacity over their planar counterparts, with an areal lithium capacity of 1.6 mAh/cm(2).

  16. Fabrication of novel coated pyrolytic graphite electrodes for the selective nano-level monitoring of Cd²⁺ ions in biological and environmental samples using polymeric membrane of newly synthesized macrocycle.

    PubMed

    Sahani, Manoj Kumar; Singh, A K; Jain, A K; Upadhyay, Anjali; Kumar, Amit; Singh, Udai P; Narang, Shikha

    2015-02-20

    Novel 5-amino-1,3,4-thiadiazole-2-thiol unit based macrocyclic ionophore 5,11,17-trithia-1,3,7,9,13,15,19,20,21-nonaazatetracyclo[14.2.1.1(4,7).1(10,13)]henicosa-4(20),10(21),16(19)-triene-6,12,18-trithione (M1), was synthesized and characterized. Preliminary studies on M1 have showed that it has more the affinity toward Cd(2+) ion. Thus, the macrocyclic ionophore (M1) was used as electroactive material in the fabrication of PVC-membrane electrodes such as polymeric membrane electrode (PME), coated graphite electrode (CGE) and coated pyrolytic graphite electrode (CPGE) were prepared and its performance characteristic were compared with. The electroanalytical studies performed on PME, CGE and CPGE revealed that CPGE having membrane composition M1:PVC:1-CN:NaTPB in the ratio of 7:37:54:2 exhibits the best potentiometric characteristics in terms of detection limit of 7.58×10(-9) mol L(-1), Nernstian slope of 29.6 mV decade(-1) of activity. The sensor was found to be independent of pH in the range 2.5-8.5. The sensor showed a fast response time of 10s and could be used over a period of 4 months without any significant divergence in its potentiometric characteristics. The sensor has been employed for monitoring of the Cd(2+) ion in real samples and also used as an indicator electrode in the potentiometric titration of Cd(2+) ion with EDTA.

  17. Nano-level monitoring of Er(III) by fabrication of coated graphite electrode based on newly synthesized Schiff base as neutral carrier.

    PubMed

    Bandi, Koteswara Rao; Upadhyay, Anjali; Singh, Ashok K; Jain, A K

    2016-05-01

    Plasticized membranes using N-(-3-((thiazol-2-ylimino)methyl)benzylidene)thiazol-2-amine (S1) and 5-((-3-((5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl)benzylidene)amino)-1,3,4-thiadiazole-2-thiol (S2) have been prepared and explored as Er (III) selective electrodes. Effect of various plasticizers viz. dibutylphthalate, tri-n-butylphosphate, dioctylphthalate, acetophenone, 1-chloronapthalene, o-nitrophenyloctylether, and anion excluders viz. sodium tetraphenylborate and potassium tetrakis-p-(chlorophenyl)borate was studied in detail and improved performance was observed. Optimum performance was observed for the membrane electrode having a composition of S2: PVC: o-NPOE: KTpClPB in the ratio of 4: 38: 55: 3 (w/w, mg). The performance of the PME based on S2 was compared with CGE. The electrodes exhibit Nernstian slope for Er (III) ion with detection limit 5.4 × 10(-8)mol L(-1) for PME and 6.1 × 10(-9)mol L(-1) for CGE. The response time for PME and CGE was found to be 12s and 9s respectively. The practical utility of the CGE has been demonstrated by its usage as an indicator electrode in potentiometric titration of EDTA with Er (III) solution and determination of fluoride ions in mouthwash solution. The proposed electrode was also applied to the determination of added Er(3+) ion in water and binary mixtures. It is found that the electrode could be able to recover the Er(3+) ion in 96.2-99.5%. PMID:26952392

  18. Flexible electrode belt for EIT using nanofiber web dry electrodes.

    PubMed

    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.

  19. Flexible electrode belt for EIT using nanofiber web dry electrodes.

    PubMed

    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. PMID:22945587

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

    PubMed

    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. PMID:25546837

  1. Micro-fabrication of Piezo-composite materials on the flexible substrates.

    PubMed

    Shin, Dong-Jin; Koh, Jung-Hyuk

    2013-09-01

    In this study, we have presented micro-scaled flexible energy harvesters fabricated by the Micro-electromechanical systems (MEMS) process. The flexible energy harvesters were prepared by a pillar structure with a diameter size of 100-500 microm. We will describe a micro-pattern of fine scale ceramic structures utilizing an SU-8 negative photoresist by standard UV lithography. SU-8 processing was developed to implement low-stress SU-8 structures as permanent and functional material incorporated with silicon-on-insulator technologies. The micro-patterns of fine scale (Pb, Zr) TiO3 ceramics of the pillar shape were prepared by this MEMS method. We have studied the micro-pattern of fine scale PZT pillar structures through scanning electron microscope (SEM) analysis and several analysis methods.

  2. Fabrication of Metal Nanoparticle-Modified Screen Printed Carbon Electrodes for the Evaluation of Hydrogen Peroxide Content in Teeth Whitening Strips

    ERIC Educational Resources Information Center

    Popa, Adriana; Abenojar, Eric C.; Vianna, Adam; Buenviaje, Czarina Y. A.; Yang, Jiahua; Pascual, Cherrie B.; Samia, Anna Cristina S.

    2015-01-01

    A laboratory experiment in which students synthesize Ag, Au, and Pt nanoparticles (NPs) and use them to modify screen printed carbon electrodes for the electroanalysis of the hydrogen peroxide content in commercially available teeth whitening strips is described. This experiment is designed for two 3-h laboratory periods and can be adapted for…

  3. Co- and distinct existence of Tris-NTA and biotin functionalities on individual and adjacent micropatterned surfaces generated by photo-destruction.

    PubMed

    Biswas, Atanu; Saha, Abhijit; Ghosh, Dhruba; Jana, Batakrishna; Ghosh, Surajit

    2014-04-14

    Micropatterned surfaces with Tris-NTA and biotin functionalities both in the same micropattern as well as individually in adjacent micropatterns are generated by UV light illumination through photo-masks. These surfaces are extremely useful for the immobilization of oligohistidine and biotin tagged multiple biomolecules/proteins. PMID:24623362

  4. Jointed Holder For Welding Electrodes

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.

    1991-01-01

    Adjustable-angle holder enables use of standard straight electrode with custom-fabricated bent gas cup for welding in difficult-to-reach places. Electrode replaced easily, without removing cup, with aid of tool loosening miniature collet nut on holder. Consumes fewer electrodes for given amount of welding. Angle of holder continuously adjustable to fit angle of gas cup or geometry of part welded. Holder made double-jointed to accommodate gas cup having compound angles.

  5. Electrodynamic Arrays Having Nanomaterial Electrodes

    NASA Technical Reports Server (NTRS)

    Trigwell, Steven (Inventor); Biris, Alexandru S. (Inventor); Calle, Carlos I. (Inventor)

    2013-01-01

    An electrodynamic array of conductive nanomaterial electrodes and a method of making such an electrodynamic array. In one embodiment, a liquid solution containing nanomaterials is deposited as an array of conductive electrodes on a substrate, including rigid or flexible substrates such as fabrics, and opaque or transparent substrates. The nanomaterial electrodes may also be grown in situ. The nanomaterials may include carbon nanomaterials, other organic or inorganic nanomaterials or mixtures.

  6. Making EDM Electrodes By Stereolithography

    NASA Technical Reports Server (NTRS)

    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.

  7. Oleophobicity of Biomimetic Micropatterned Surface and Its Effect on the Adhesion of Frozen Oil.

    PubMed

    Pan, Zihe; Zhang, Wei; Kowalski, Andrew; Zhao, Boxin

    2015-09-15

    The relationship between the oleophobicity of micropatterned surfaces and the reduction of oil adhesion at low temperatures was explored by using siloxane elastomer surfaces as a model system. Polydimethylsiloxane (PDMS) surfaces were fabricated with varying oleophobicity from oleophilic to superoleophobic by combing the blending of trichloro(1H,1H,2H,2H-perfluorooctyl)silane (FDTS) into PDMS with the construction of bioinspired micropillars. The oil contact angles of micropillars were >130°, with the largest contact angle measured to be 146°. The micropillared surface showed remarkable self-cleaning properties; the contact angle hysteresis was <15°. The transparent oil droplets on PDMS surfaces of varied oleophobicity were frozen into a white-colored solid at -25 °C with the aid of a cooling system. Adhesion forces of the frozen oil droplets were obtained from the knock-off tests, showing that the adhesion forces dropped with the increased oleophobicity. The largest adhesion force was observed on the oleophilic flat surface, while the lowest adhesion force was on the highest oleophobic micropillared surface. The relative effectiveness of chemical and physical modifications on adhesion strength reduction was studied in terms of FDTS and micropillars, respectively. The results showed that a reduction of adhesion strength by 4% was reached by blending FDTS into flat PDMS, while a much more pronounced reduction of frozen oil adhesion strength by 60% was achieved by blending FDTS into PDMS micropillars; these results suggested a possible synergic effect of the FDTS chemistry and micropillar on the reduction of adhesion strength of frozen oil droplets. PMID:26300446

  8. Salivary gland cell differentiation and organization on micropatterned PLGA nanofiber craters.

    PubMed

    Soscia, David A; Sequeira, Sharon J; Schramm, Robert A; Jayarathanam, Kavitha; Cantara, Shraddha I; Larsen, Melinda; Castracane, James

    2013-09-01

    There is a need for an artificial salivary gland as a long-term remedy for patients suffering from salivary hypofunction, a leading cause of chronic xerostomia (dry mouth). Current salivary gland tissue engineering approaches are limited in that they either lack sufficient physical cues and surface area needed to facilitate epithelial cell differentiation, or they fail to provide a mechanism for assembling an interconnected branched network of cells. We have developed highly-ordered arrays of curved hemispherical "craters" in polydimethylsiloxane (PDMS) using wafer-level integrated circuit (IC) fabrication processes, and lined them with electrospun poly-lactic-co-glycolic acid (PLGA) nanofibers, designed to mimic the three-dimensional (3-D) in vivo architecture of the basement membrane surrounding spherical acini of salivary gland epithelial cells. These micropatterned scaffolds provide a method for engineering increased surface area and were additionally investigated for their ability to promote cell polarization. Two immortalized salivary gland cell lines (SIMS, ductal and Par-C10, acinar) were cultured on fibrous crater arrays of various radii and compared with those grown on flat PLGA nanofiber substrates, and in 3-D Matrigel. It was found that by increasing crater curvature, the average height of the cell monolayer of SIMS cells and to a lesser extent, Par-C10 cells, increased to a maximum similar to that seen in cells grown in 3-D Matrigel. Increasing curvature resulted in higher expression levels of tight junction protein occludin in both cell lines, but did not induce a change in expression of adherens junction protein E-cadherin. Additionally, increasing curvature promoted polarity of both cell lines, as a greater apical localization of occludin was seen in cells on substrates of higher curvature. Lastly, substrate curvature increased expression of the water channel protein aquaporin-5 (Aqp-5) in Par-C10 cells, suggesting that curved nanofiber substrates

  9. Oriented growth and transdifferentiation of mesenchymal stem cells towards a Schwann cell fate on micropatterned substrates.

    PubMed

    Sharma, Anup D; Zbarska, Svitlana; Petersen, Emma M; Marti, Mustafa E; Mallapragada, Surya K; Sakaguchi, Donald S

    2016-03-01

    While Schwann cells (SCs) have a significant role in peripheral nerve regeneration, their use in treatments has been limited because of lack of a readily available source. To address this issue, this study focused on the effect of guidance cues by employing micropatterned polymeric films to influence the alignment, morphology and transdifferentiation of bone marrow-derived rat mesenchymal stem cells (MSCs) towards a Schwann cell-like fate. Two different types of polymers, biocompatible polystyrene (PS) and biodegradable poly(lactic acid) (PLA) were used to fabricate patterned films. Percentages of transdifferentiated MSCs (tMSCs) immunolabeled with SC markers (α-S100β and α-p75(NTR)) were found to be similar on patterned versus smooth PS and PLA substrates. However, patterning had a significant effect on the alignment and elongation of the tMSCs. More than 80% of the tMSCs were oriented in the direction of microgrooves (0°-20°), while cells on the smooth substrates were randomly oriented. The aspect ratio [AR, ratio of length (in direction of microgrooves) and breadth (in direction perpendicular to microgrooves)] of the tMSCs on patterned substrates had a value of approximately five, as compared to cells on smooth substrates where the AR was one. Understanding responses to these cues in vitro helps us in understanding the behavior and interaction of the cells with the 3D environment of the scaffolds, facilitating the application of these concepts to designing effective nerve guidance conduits for peripheral nerve regeneration.

  10. Crosslinking of micropatterned collagen-based nerve guides to modulate the expected half-life.

    PubMed

    Salvatore, L; Madaghiele, M; Parisi, C; Gatti, F; Sannino, A

    2014-12-01

    The microstructural, mechanical, compositional, and degradative properties of a nerve conduit are known to strongly affect the regenerative process of the injured peripheral nerve. Starting from the fabrication of micropatterned collagen-based nerve guides, according to a spin-casting process reported in the literature, this study further investigates the possibility to modulate the degradation rate of the scaffolds over a wide time frame, in an attempt to match different rates of nerve regeneration that might be encountered in vivo. To this aim, three different crosslinking methods, that is, dehydrothermal (DHT), carbodiimide-based (EDAC), and glutaraldehyde-based (GTA) crosslinking, were selected. The elastically effective degree of crosslinking, attained by each method and evaluated according to the classical rubber elasticity theory, was found to significantly tune the in vitro half-life (t1/2 ) of the matrices, with an exponential dependence of the latter on the crosslink density. The high crosslinking efficacy of EDAC and GTA treatments, respectively threefold and fourfold when compared to the one attained by DHT, led to a sharp increase of the corresponding in vitro half-lives (ca., 10, 172, and 690 h, for DHT, EDAC, and GTA treated matrices, respectively). As shown by cell viability assays, the cytocompatibility of both DHT and EDAC treatments, as opposed to the toxicity of GTA, suggests that such methods are suitable to crosslink collagen-based scaffolds conceived for clinical use. In particular, nerve guides with expected high residence times in vivo might be produced by finely controlling the biocompatible reaction(s) adopted for crosslinking.

  11. Oleophobicity of Biomimetic Micropatterned Surface and Its Effect on the Adhesion of Frozen Oil.

    PubMed

    Pan, Zihe; Zhang, Wei; Kowalski, Andrew; Zhao, Boxin

    2015-09-15

    The relationship between the oleophobicity of micropatterned surfaces and the reduction of oil adhesion at low temperatures was explored by using siloxane elastomer surfaces as a model system. Polydimethylsiloxane (PDMS) surfaces were fabricated with varying oleophobicity from oleophilic to superoleophobic by combing the blending of trichloro(1H,1H,2H,2H-perfluorooctyl)silane (FDTS) into PDMS with the construction of bioinspired micropillars. The oil contact angles of micropillars were >130°, with the largest contact angle measured to be 146°. The micropillared surface showed remarkable self-cleaning properties; the contact angle hysteresis was <15°. The transparent oil droplets on PDMS surfaces of varied oleophobicity were frozen into a white-colored solid at -25 °C with the aid of a cooling system. Adhesion forces of the frozen oil droplets were obtained from the knock-off tests, showing that the adhesion forces dropped with the increased oleophobicity. The largest adhesion force was observed on the oleophilic flat surface, while the lowest adhesion force was on the highest oleophobic micropillared surface. The relative effectiveness of chemical and physical modifications on adhesion strength reduction was studied in terms of FDTS and micropillars, respectively. The results showed that a reduction of adhesion strength by 4% was reached by blending FDTS into flat PDMS, while a much more pronounced reduction of frozen oil adhesion strength by 60% was achieved by blending FDTS into PDMS micropillars; these results suggested a possible synergic effect of the FDTS chemistry and micropillar on the reduction of adhesion strength of frozen oil droplets.

  12. Chitooligomer-Immobilized Biointerfaces with Micropatterned Geometries for Unidirectional Alignment of Myoblast Cells

    PubMed Central

    Poosala, Pornthida; Kitaoka, Takuya

    2016-01-01

    Skeletal muscle possesses a robust capacity to regenerate functional architectures with a unidirectional orientation. In this study, we successfully arranged skeletal myoblast (C2C12) cells along micropatterned gold strips on which chitohexaose was deposited via a vectorial chain immobilization approach. Hexa-N-acetyl-d-glucosamine (GlcNAc6) was site-selectively modified at its reducing end with thiosemicarbazide, then immobilized on a gold substrate in striped micropatterns via S–Au chemisorption. Gold micropatterns ranged from 100 to 1000 µm in width. Effects of patterning geometries on C2C12 cell alignment, morphology, and gene expression were investigated. Unidirectional alignment of C2C12 cells having GlcNAc6 receptors was clearly observed along the micropatterns. Decreasing striped pattern width increased cell attachment and proliferation, suggesting that the fixed GlcNAc6 and micropatterns impacted cell function. Possibly, interactions between nonreducing end groups of fixed GlcNAc6 and cell surface receptors initiated cellular alignment. Our technique for mimicking native tissue organization should advance applications in tissue engineering. PMID:26784249

  13. Infrared face recognition based on intensity of local micropattern-weighted local binary pattern

    NASA Astrophysics Data System (ADS)

    Xie, Zhihua; Liu, Guodong

    2011-07-01

    The traditional local binary pattern (LBP) histogram representation extracts the local micropatterns and assigns the same weight to all local micropatterns. To combine the different contributions of local micropatterns to face recognition, this paper proposes a weighted LBP histogram based on Weber's law. First, inspired by psychological Weber's law, intensity of local micropattern is defined by the ratio between two terms: one is relative intensity differences of a central pixel against its neighbors and the other is intensity of local central pixel. Second, regarding the intensity of local micropattern as its weight, the weighted LBP histogram is constructed with the defined weight. Finally, to make full use of the space location information and lessen the complexity of recognition, the partitioning and locality preserving projection are applied to get final features. The proposed method is tested on our infrared face databases and yields the recognition rate of 99.2% for same-session situation and 96.4% for elapsed-time situation compared to the 97.6 and 92.1% produced by the method based on traditional LBP.

  14. Flexible binder free functionalized carbon nanotube electrodes for ultracapacitor

    NASA Astrophysics Data System (ADS)

    Bhat, Badekai Ramachandra; Aravinda, L. S.; Bhat, K. Udaya

    2014-03-01

    The Flexible supercapacitor electrode material was prepared by simple spray coating technique. This will provide a greener alternative for the fabrication of binder free composite electrode for supercapacitor applications. A symmetric double layer super capacitor stack was fabricated by using flexible electrodes. The investigation of the capacitance property of the fabricated super capacitor stack was investigated using cyclic voltammetry, chronopotentiometry and electrical impedance spectroscopy studies. The flexible electrode material shows a specific capacitance of 50 Fg-1 with good cyclibility.

  15. Transformation of medical grade silicone rubber under Nd:YAG and excimer laser irradiation: First step towards a new miniaturized nerve electrode fabrication process

    NASA Astrophysics Data System (ADS)

    Dupas-Bruzek, C.; Robbe, O.; Addad, A.; Turrell, S.; Derozier, D.

    2009-08-01

    Medical grade silicone rubber, poly-dimethylsiloxane (PDMS) is a widely used biomaterial. Like for many polymers, its surface can be modified in order to change one or several of its properties which further allow this surface to be functionalized. Laser-induced surface modification of PDMS under ambient conditions is an easy and powerful method for the surface modification of PDMS without altering its bulk properties. In particular, we profit from both UV laser inducing surface modification and of UV laser micromachining to develop a first part of a new process aiming at increasing the number of contacts and tracks within the same electrode surface to improve the nerve selectivity of implantable self sizing spiral cuff electrodes. The second and last part of the process is to further immerse the engraved electrode in an autocatalytic Pt bath leading in a selective Pt metallization of the laser irradiated tracks and contacts and thus to a functionalized PDMS surface. In the present work, we describe the different physical and chemical transformations of a medical grade PDMS as a function of the UV laser and of the irradiation conditions used. We show that the ablation depths, chemical composition, structure and morphology vary with (i) the laser wavelength (using an excimer laser at 248 nm and a frequency-quadrupled Nd:YAG laser at 266 nm), (ii) the conditions of irradiation and (iii) the pulse duration. These different modified properties are expected to have a strong influence on the nucleation and growth rates of platinum which govern the adhesion and the thickness of the Pt layer on the electrodes and thus the DC resistance of tracks.

  16. Centrifugal spinning: A novel approach to fabricate porous carbon fibers as binder-free electrodes for electric double-layer capacitors

    NASA Astrophysics Data System (ADS)

    Lu, Yao; Fu, Kun; Zhang, Shu; Li, Ying; Chen, Chen; Zhu, Jiadeng; Yanilmaz, Meltem; Dirican, Mahmut; Zhang, Xiangwu

    2015-01-01

    Carbon nanofibers (CNFs), among various carbonaceous candidates for electric double-layer capacitor (EDLC) electrodes, draw extensive attention because their one-dimensional architecture offers both shortened electron pathways and high ion-accessible sites. Creating porous structures on CNFs yields larger surface area and enhanced capacitive performance. Herein, porous carbon nanofibers (PCNFs) were synthesized via centrifugal spinning of polyacrylonitrile (PAN)/poly(methyl methacrylate) (PMMA) solutions combined with thermal treatment and were used as binder-free EDLC electrodes. Three precursor fibers with PAN/PMMA weight ratios of 9/1, 7/3 and 5/5 were prepared and carbonized at 700, 800, and 900 °C, respectively. The highest specific capacitance obtained was 144 F g-1 at 0.1 A g-1 with a rate capability of 74% from 0.1 to 2 A g-1 by PCNFs prepared with PAN/PMMA weight ratio of 7/3 at 900 °C. These PCNFs also showed stable cycling performance. The present work demonstrates that PCNFs are promising EDLC electrode candidate and centrifugal spinning offers a simple, cost-effective strategy to produce PCNFs.

  17. Simulations of Droplets on Micro-patterned Surfaces

    NASA Astrophysics Data System (ADS)

    Liu, Banglin; Grigola, Michael; Li, Huan; Hilgenfeldt, Sascha; Hsia, K. Jimmy

    2013-11-01

    The behavior of liquid droplets on micro-patterned surfaces made from arrays of micropillars is important for applications in self-cleaning surfaces, refrigeration, or pore filtration. Properties like droplet contact angles and their hysteresis have been described in macroscopic terms from coarse-grained variables like pillar density. However, for accurate modeling of the droplet shape and dynamical behavior, microscopic parameters like pillar positioning and the topography of the contact line are crucial. We have developed an energy-based model of a water droplet on a PDMS substrate in the Cassie-Baxter state using Surface Evolver. We assess the changes in droplet energy upon deformation and displacement, with particular attention to the pinning and depinning from individual pillars. The majority of shape distortion and energy change is found to occur in close proximity to the substrate, encouraging a simplified theoretical description using concepts of 2D contact-line pinning. The versatile simulation tool can be used to study the effects of pillar position pattern, pillar orientation, substrate symmetry, and many more general problems of contact-line statics and dynamics.

  18. Signal Propagation between Neuronal Populations Controlled by Micropatterning

    PubMed Central

    Albers, Jonas; Offenhäusser, Andreas

    2016-01-01

    The central nervous system consists of an unfathomable number of functional networks enabling highly sophisticated information processing. Guided neuronal growth with a well-defined connectivity and accompanying polarity is essential for the formation of these networks. To investigate how two-dimensional protein patterns influence neuronal outgrowth with respect to connectivity and functional polarity between adjacent populations of neurons, a microstructured model system was established. Exclusive cell growth on patterned substrates was achieved by transferring a mixture of poly-l-lysine and laminin to a cell-repellent glass surface by microcontact printing. Triangular structures with different opening angle, height, and width were chosen as a pattern to achieve network formation with defined behavior at the junction of adjacent structures. These patterns were populated with dissociated primary cortical embryonic rat neurons and investigated with respect to their impact on neuronal outgrowth by immunofluorescence analysis, as well as their functional connectivity by calcium imaging. Here, we present a highly reproducible technique to devise neuronal networks in vitro with a predefined connectivity induced by the design of the gateway. Daisy-chained neuronal networks with predefined connectivity and functional polarity were produced using the presented micropatterning method. Controlling the direction of signal propagation among populations of neurons provides insights to network communication and offers the chance to investigate more about learning processes in networks by external manipulation of cells and signal cascades. PMID:27379230

  19. Micropatterned solid-supported membranes formed by micromolding in capillaries.

    PubMed

    Janshoff, A; Künneke, S

    2000-01-01

    The formation of individually addressable micropatterned solid-supported lipid bilayers has been accomplished by means of micromolding in capillaries. Small unilamellar vesicles were spread on glass slides to form planar supported membranes along microscopic capillaries molded as trenches into a polydimethylsiloxane (PDMS) elastomer. PDMS provides an elastic and transparent carrier for microcapillaries molded from silicon wafers displaying the desired inverse trenches. The so-called master structure has been conventionally etched into silicon by photolithography. The cured PDMS elastomer was briefly exposed to an oxygen plasma, rendering the surface hydrophilic, and subsequently attached to a glass surface in order to form hydrophilic capillaries equipped with flow-promoting pads on either side. One flowpad acts as a reservoir to be filled with the vesicle suspension, while the other one serves as a collector to ensure a sufficient capillary flow to cover the substrate completely. Formation of planar lipid bilayers on the glass slide along the capillaries was followed by imaging the flow and spreading of fluorescently labeled DMPC liposomes with confocal laser scanning microscopy. By means of scanning force microscopy in aqueous solution the formed lipid structures were identified and the height of the lipid bilayers was accurately determined. With both techniques, it was shown that the patterned bilayers remain separated and persist for several hours on the substrate in aqueous solution.

  20. Signal Propagation between Neuronal Populations Controlled by Micropatterning.

    PubMed

    Albers, Jonas; Offenhäusser, Andreas

    2016-01-01

    The central nervous system consists of an unfathomable number of functional networks enabling highly sophisticated information processing. Guided neuronal growth with a well-defined connectivity and accompanying polarity is essential for the formation of these networks. To investigate how two-dimensional protein patterns influence neuronal outgrowth with respect to connectivity and functional polarity between adjacent populations of neurons, a microstructured model system was established. Exclusive cell growth on patterned substrates was achieved by transferring a mixture of poly-l-lysine and laminin to a cell-repellent glass surface by microcontact printing. Triangular structures with different opening angle, height, and width were chosen as a pattern to achieve network formation with defined behavior at the junction of adjacent structures. These patterns were populated with dissociated primary cortical embryonic rat neurons and investigated with respect to their impact on neuronal outgrowth by immunofluorescence analysis, as well as their functional connectivity by calcium imaging. Here, we present a highly reproducible technique to devise neuronal networks in vitro with a predefined connectivity induced by the design of the gateway. Daisy-chained neuronal networks with predefined connectivity and functional polarity were produced using the presented micropatterning method. Controlling the direction of signal propagation among populations of neurons provides insights to network communication and offers the chance to investigate more about learning processes in networks by external manipulation of cells and signal cascades. PMID:27379230

  1. Fabrication and characterization of Meldola's blue/zinc oxide hybrid electrodes for efficient detection of the reduced form of nicotinamide adenine dinucleotide at low potential.

    PubMed

    Kumar, S Ashok; Chen, Shen-Ming

    2007-05-29

    We report the synthesis and the electrochemical properties of hybrid films made of zinc oxide (ZnO) and Meldola's blue dye (MB) using cyclic voltammetry (CV). MB/ZnO hybrid films were electrochemically deposited onto glassy carbon, gold and indium tin oxide-coated glass (ITO) electrodes at room temperature (25+/-2 degrees C) from the bath solution containing 0.1 M Zn(NO3)2, 0.1 M KNO3 and 1x10(-4) MMB. The surface morphology and deposition kinetics of MB/ZnO hybrid films were studied by means of scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrochemical quartz crystal microbalance (EQCM) techniques, respectively. SEM and AFM images of MB/ZnO hybrid films have revealed that the surfaces are well crystallized, porous and micro structured. MB molecules were immobilized and strongly fixed in a transparent inorganic matrix. MB/ZnO hybrid films modified glassy carbon electrode (MB/ZnO/GC) showed one reversible redox couple centered at formal potential (E0') -0.12 V (pH 6.9). The surface coverage (gamma) of the MB immobilized on ZnO/GC was about 9.86x10(-12) mol cm(-2) and the electron transfer rate constant (ks) was determined to be 38.9 s(-1). The MB/ZnO/GC electrode acted as a sensor and displayed an excellent specific electrocatalytic response to the oxidation of nicotinamide adenine dinucleotide (NADH). The linear response range between 50 and 300 microM NADH concentration at pH 6.9 was observed with a detection limit of 10 microM (S/N=3). The electrode was stable during the time it was used for the full study (about 1 month) without a notable decrease in current. Indeed, dopamine (DA), ascorbic acid (AA), acetaminophen (AP) and uric acid (UA) did not show any interference during the detection of NADH at this modified electrode.

  2. A practical guide for the fabrication of microfluidic devices using glass and silicon

    PubMed Central

    Iliescu, Ciprian; Taylor, Hayden; Avram, Marioara; Miao, Jianmin; Franssila, Sami

    2012-01-01

    This paper describes the main protocols that are used for fabricating microfluidic devices from glass and silicon. Methods for micropatterning glass and silicon are surveyed, and their limitations are discussed. Bonding methods that can be used for joining these materials are summarized and key process parameters are indicated. The paper also outlines techniques for forming electrical connections between microfluidic devices and external circuits. A framework is proposed for the synthesis of a complete glass/silicon device fabrication flow. PMID:22662101

  3. Laser interference lithography as a new and efficient technique for micropatterning of biopolymer surface.

    PubMed

    Yu, Fayou; Li, Ping; Shen, Hao; Mathur, Sanjay; Lehr, Claus-Michael; Bakowsky, Udo; Mücklich, Frank

    2005-05-01

    Laser interference lithography (LIL) is a straightforward technique to prepare linear micropatterns for regulating cellular adhesion behaviors on polymer substratum. This process is based on selective laser ablation directly duplicating the interference patterns of two or more coherent laser beams onto the polymer surface. Micropatterns prepared by LIL on poly(ethylene terephthalate) and Thermanox were characterized using atomic force microscopy (AFM) and white light interferometer while the chemical surface modification induced by laser was analyzed by X-ray photoelectron spectroscopy (XPS). The AFM photographs show that the micropatterns are well-defined and of great consistency. Polymer properties and laser parameters related to LIL as well as laser ablation mechanisms are discussed in this technical note.

  4. Optimizing micropattern geometries for cell shape and migration with genetic algorithms.

    PubMed

    Albert, Philipp J; Schwarz, Ulrich S

    2016-07-11

    Adhesive micropatterns have become a standard tool to control cell shape and function in cell culture. However, the variety of possible patterns is infinitely large and experiments often restrict themselves to established designs. Here we suggest a systematic method to establish novel micropatterns for desired functions using genetic algorithms. The evolutionary fitness of a certain pattern is computed using a cellular Potts model that describes cell behavior on micropattern. We first predict optimal patterns for a desired cell shape. We then optimize ratchet geometries to bias cell migration in a certain direction and find that asymmetric triangles are superior over the symmetric ones often used in experiments. Finally we design geometries which reverse the migration direction of cells when cell density increases due to cell division. PMID:27334659

  5. Hierarchic micro-patterned porous scaffolds via electrochemical replica-deposition enhance neo-vascularization.

    PubMed

    Varoni, Elena Maria; Altomare, Lina; Cochis, Andrea; GhalayaniEsfahani, Arash; Cigada, Alberto; Rimondini, Lia; De Nardo, Luigi

    2016-04-21

    Neo-vascularization is a key factor in tissue regeneration within porous scaffolds. Here, we tested the hypothesis that micro-patterned scaffolds, with precisely-designed, open micro-channels, might help endothelial cells to produce intra-scaffold vascular networks. Three series of micro-patterned scaffolds were produced via electrochemical replica-deposition of chitosan and cross-linking. All had regularly-oriented micro-channels (ϕ 500 μm), which differed for the inter-channel spacing, at 600, 700, or 900 μm, respectively. Random-pore scaffolds, using the same technique, were taken as controls. Physical-mechanical characterization revealed high water uptake and favorable elastic mechanical behavior for all scaffolds, slightly reduced in the presence of cross-linking and enhanced with the 700 μm-spaced micro-pattern. At MTT assay, mouse endothelial cell viability was >90% at day 1, 3 and 7, confirmed by visual examination with scanning electron microscopy (SEM). Intra-scaffold cell density, at fluorescence analysis, was higher for the 600 μm-spaced and the 700 μm-spaced micro-patterns over the others. The 700 μm-spaced scaffold was selected for the in vivo testing, to be compared to the random-pore one. Neither type produced an inflammatory reaction; both showed excellent tissue ingrowth. Micro-patterned scaffolds enhanced neo-vascularization, demonstrated by immunofluorescent, semi-quantitative analyses. These findings support the use of micro-patterned porous scaffolds, with adequately spaced micro-channels, to promote neo-vascularization.

  6. Fabrication of high performance flexible micro-supercapacitor arrays with hybrid electrodes of MWNT/V2O5 nanowires integrated with a SnO2 nanowire UV sensor

    NASA Astrophysics Data System (ADS)

    Kim, Daeil; Yun, Junyeong; Lee, Geumbee; Ha, Jeong Sook

    2014-09-01

    We report on the on-chip fabrication of high performance flexible micro-supercapacitor (MSC) arrays with hybrid electrodes of multi-walled carbon nanotube (MWNT)/V2O5 nanowire (NW) composites and a solid electrolyte, which could power the SnO2 NW UV sensor integrated on the same flexible substrate. The patterned MSC using hybrid electrodes of MWNT/V2O5 NW composites with 10 vol% of V2O5 NWs exhibited excellent electrochemical performance with a high volume capacitance of 80 F cm-3 at a scan rate of 10 mV s-1 in a PVA-LiCl electrolyte and good cycle performance to maintain 82% of the capacitance after 10 000 cycles at a current density of 11.6 A cm-3. The patterned MSC also showed an excellent energy density of 6.8 mW h cm-3, comparable to that of a Li-thin film battery (1-10 mW h cm-3), and a power density of 80.8 W cm-3 comparable to that of state-of-the-art MSCs. In addition, the flexible MSC array on a PET substrate showed mechanical stability over bending with a bending radius down to 1.5 mm under both compressive and tensile stress. Even after 1000 bending cycles at a bending radius of 7 mm, 94% of the initial capacitance was maintained. Furthermore, we have shown the operation of a SnO2 NW UV sensor using such a fabricated MSC array integrated into the same circuit on the PET substrate.We report on the on-chip fabrication of high performance flexible micro-supercapacitor (MSC) arrays with hybrid electrodes of multi-walled carbon nanotube (MWNT)/V2O5 nanowire (NW) composites and a solid electrolyte, which could power the SnO2 NW UV sensor integrated on the same flexible substrate. The patterned MSC using hybrid electrodes of MWNT/V2O5 NW composites with 10 vol% of V2O5 NWs exhibited excellent electrochemical performance with a high volume capacitance of 80 F cm-3 at a scan rate of 10 mV s-1 in a PVA-LiCl electrolyte and good cycle performance to maintain 82% of the capacitance after 10 000 cycles at a current density of 11.6 A cm-3. The patterned MSC also

  7. Nano-level monitoring of Yb(III) by fabrication of coated graphite electrode based on newly synthesized hexaaza macrocyclic ligand.

    PubMed

    Singh, Ashok K; Singh, Prerna

    2009-06-01

    The two macrocyclic ligands 2,12-(2-methoxyaniline)2-4,14-Me2-[20]-1,4,11,14-tetraene-1,5,8,11,15,18-N6 (L1) and 2,12-(2-methoxyaniline)(2)-4,14-Me2-8,18-dimethylacrylate-[20]-1,4,11,14-tetraene-1,5,8,11,15,18-N6 (L2) have been synthesized and explored as neutral ionophores for preparing poly(vinylchloride) (PVC) based membrane sensors selective to Yb(III) ions. Effects of various plasticizers and anion excluders were studied in detail and improved performance was observed. The best performance was obtained for the membrane sensor having a composition of L2:PVC:BA:NaTPB in the ratio of 5: 40: 52: 3 (w/w; mg). The performance of the membrane based on L2 was compared with polymeric membrane electrode (PME) as well as with coated graphite electrode (CGE). The electrodes exhibit Nernstian slope for Yb3+ ions with limits of detection of 4.3 x 10(-8) M for PME and 5.8 x 10(-9) M for CGE. The response time for PME and CGE was found to be 10 s and 8 s, respectively. The potentiometric responses are independent of the pH of the test solution in the pH range 3.0-8.0 for PME and 2.5-8.5 for CGE. The CGE has found to work satisfactorily in partially non-aqueous media upto 30% (v/v) content of methanol, ethanol and 20% (v/v) content of acetonitrile and could be used for a period of 5 months. The CGE was used as indicator electrode in the potentiometric titration of Yb3+ ions with EDTA and in determination of fluoride ions in mouthwash samples. It can be used for determination of sulfite in red and white wine samples and also in determination of Yb3+ in various binary mixtures with quantitative results. PMID:19446066

  8. Coated carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    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.

  9. Coated carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2006-12-12

    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.

  10. An analysis of electrochemical energy storage using electrodes fabricated from atomically thin 2D structures of MoS2, graphene and MoS2/graphene composites

    NASA Astrophysics Data System (ADS)

    Huffstutler, Jacob D.

    The behavior of 2D materials has become of great interest in the wake of development of electrochemical double-layer capacitors (EDLCs) and the discovery of monolayer graphene by Geim and Novoselov. This study aims to analyze the response variance of 2D electrode materials for EDLCs prepared through the liquid-phase exfoliation method when subjected to differing conditions. Once exfoliated, samples are tested with a series of structural characterization methods, including tunneling electron microscopy, atomic force microscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. A new ionic liquid for EDLC use, 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate is compared in performance to 6M potassium hydroxide aqueous electrolyte. Devices composed of liquid-phase exfoliated graphene / MoS2 composites are analyzed by concentration for ideal performance. Device performance under cold extreme temperatures for the ionic fluid is presented as well. A brief overview of by-layer analysis of graphene electrode materials is presented as-is. All samples were tested with cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy, with good capacitive results. The evolution of electrochemical behavior through the altered parameters is tracked as well.

  11. Fabrication and characterization of TiO2-NTs based hollow carbon fibers/carbon film composite electrode with NiOx decorated for capacitive application

    NASA Astrophysics Data System (ADS)

    Wei, Kajia; Wang, Yi; Han, Weiqing; Li, Jiansheng; Sun, Xiuyun; Shen, Jinyou; Wang, Lianjun

    2016-06-01

    This work designs a novel structure of TiO2 nanotubes (TiO2-NTs) based hollow carbon nanofibers (HCFs)/carbon film (CF) composite electrode with NiOx decorated for capacitive deionization application. The TiO2-NTs array is obtained through anode oxidation method on the titanium substrate, while the HCFs/CF is synthesized by thermal decomposition of a mixture of C6H12O6 and Ni(CH3COO)2·4H2O inside the nanochannels and over the caps of TiO2-NTs array, then followed by carbonization and HNO3 activation. The nickel possesses multi-functional effects during the synthesis process as carbon catalyst (Ni(II)), molecule binder (NiTi) and pseudo-capacitance supplier (NiOx). FE-SEM, XRD, Raman spectroscopy and water contact angle measurement reveal a uniform carbon distribution, favorable nickel dispersion, high stability and ideal hydrophilicity for this structure. With the addition of C6H12O6 and Ni(Ac)2·4H2O controlled at 10% (wt) and 2% (wt), respectively, a composite electrode with specific capacitance of 244.9 F·g-1, high oxygen evolution potential of 2.15 V and low water contact angle of 41.77° is obtained as well as minimum polarization impedance and efficient capacitive ability, which exhibits promising applications for practical employment.

  12. Fabrication of a chitosan/glucose oxidase-poly(anilineboronic acid)-Au(nano)/Au-plated Au electrode for biosensor and biofuel cell.

    PubMed

    Huang, Yi; Qin, Xiaoli; Li, Zou; Fu, Yingchun; Qin, Cong; Wu, Feng; Su, Zhaohong; Ma, Ming; Xie, Qingji; Yao, Shouzhuo; Hu, Jiming

    2012-01-15

    Enzyme immobilization is one of the key factors in constructing high-performance enzyme biosensors and biofuel cells (BFCs). Herein, we propose a new protocol for efficient immobilization of a glycoprotein enzyme based on the interaction of the 1, 2- or 1, 3-diols in the glycoprotein with a boronic acid functionalized monomer. Briefly, casting a mixture of glucose oxidase (GOx) and anilineboronic acid (ABA) followed by a NaAuCl(4) solution to an Au-plated Au electrode surface yielded a GOx-poly(ABA) (PABA)-gold nanoparticle (Au(nano)) bionanocomposite, and chitosan (CS) was then cast and air-dried. In the present protocol, the small-sized Au(nano) or Au subnanostructures can form near/on the enzyme molecule, which greatly promotes the electron transfer of enzymatic reaction and enhances the amperometric responses. The thus-prepared CS/GOx-PABA-Au(nano)/Au-plated Au electrode worked well in the first-/second generation biosensing modes and as a bioanode in a monopolar biofuel cell, with analytical or cell-power performance superior to those of most analogues hitherto reported. PMID:22099959

  13. One-Step Fabrication of a Multifunctional Magnetic Nickel Ferrite/Multi-walled Carbon Nanotubes Nanohybrid-Modified Electrode for the Determination of Benomyl in Food.

    PubMed

    Wang, Qiong; Yang, Jichun; Dong, Yuanyuan; Zhang, Lei

    2015-05-20

    Benomyl, as one kind of agricultural pesticide, has adverse impact on human health and the environment. It is urgent to develop effective and rapid methods for quantitative determination of benomyl. A simple and sensitive electroanalytical method for determination of benomyl using a magnetic nickel ferrite (NiFe2O4)/multi-walled carbon nanotubes (MWCNTs) nanohybrid-modified glassy carbon electrode (GCE) was presented. The electrocatalytic properties and electroanalysis of benomyl on the modified electrode were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In the phosphate-buffered saline (PBS) of pH 6.0, this constructed biosensor exhibited two linear relationships with the benomyl concentration range from 1.00 × 10(-7) to 5.00 × 10(-7) mol/L and from 5.00 × 10(-7) to 1.00 × 10(-5) mol/L, respectively. The detection limit was 2.51 × 10(-8) mol/L (S/N = 3). Moreover, the proposed method was successfully applied to determine benomyl in real samples with satisfactory results. The NiFe2O4/MWCNTs/GCE showed good reproducibility and stability, excellent catalytic activity, and anti-interference.

  14. 3D Printing of Micropatterned Anion Exchange Membranes.

    PubMed

    Seo, Jiho; Kushner, Douglas I; Hickner, Michael A

    2016-07-01

    Micropatterned anion exchange membranes (AEMs) have been 3D printed via a photoinitiated free radical polymerization and quaternization process. The photocurable formulation, consisting of diurethane dimethacrylate (DUDA), poly(ethylene glycol) diacrylate (PEGDA), dipentaerythritol penta-/hexa- acrylate, and 4-vinylbenzyl chloride (VBC), was directly cured into patterned films using a custom 3D photolithographic printing process similar to stereolithography. Measurements of water uptake, permselectivity, and ionic resistance were conducted on the quaternized poly(DUDA-co-PEGDA-co-VBC) sample series to determine their suitability as ion exchange membranes. The water uptake of the polymers increased as the ion exchange capacity (IEC) increased due to greater quaternized VBC content. Samples with IEC values between 0.98 to 1.63 mequiv/g were synthesized by varying the VBC content from 15 to 25 wt %. The water uptake was sensitive to the PEGDA content in the network resulting in water uptake values ranging from 85 to 410 wt % by varying the PEGDA fractions from 0 to 60 wt %. The permselectivity of the AEM samples decreased from 0.91 (168 wt %, 1.63 mequiv/g) to 0.85 (410 wt %, 1.63 mequiv/g) with increasing water uptake and to 0.88 (162 wt %, 0.98 mequiv/g) with decreasing IEC. Permselectivity results were relatively consistent with the general understanding of the correlation between permselectivity, water uptake, and ion content of the membrane. Lastly, it was revealed that the ionic resistance of patterned membranes was lower than that of flat membranes with the same material volume or equivalent thickness. A parallel resistance model was used to explain the influence of patterning on the overall measured ionic resistance. This model may provide a way to maximize ion exchange membrane performance by optimizing surface patterns without chemical modification to the membrane. PMID:27218137

  15. Weld electrode cooling study

    NASA Astrophysics Data System (ADS)

    Masters, Robert C.; Simon, Daniel L.

    1999-03-01

    The U.S. auto/truck industry has been mandated by the Federal government to continuously improve their fleet average gas mileage, measured in miles per gallon. Several techniques are typically used to meet these mandates, one of which is to reduce the overall mass of cars and trucks. To help accomplish this goal, lighter weight sheet metal parts, with smaller weld flanges, have been designed and fabricated. This paper will examine the cooling characteristics of various water cooled weld electrodes and shanks used in resistance spot welding applications. The smaller weld flanges utilized in modern vehicle sheet metal fabrications have increased industry's interest in using one size of weld electrode (1/2 inch diameter) for certain spot welding operations. The welding community wants more data about the cooling characteristics of these 1/2 inch weld electrodes. To hep define the cooling characteristics, an infrared radiometer thermal vision system (TVS) was used to capture images (thermograms) of the heating and cooling cycles of several size combinations of weld electrodes under typical production conditions. Tests results will show why the open ended shanks are more suitable for cooling the weld electrode assembly then closed ended shanks.

  16. The effect of negative pressure aging on the aggregation of Cu2O nanoparticles and its application to laser induced copper electrode fabrication.

    PubMed

    Lee, H S; Yang, M Y

    2015-02-14

    The aggregation and dispersion of nanoparticles are critical problems in selective laser sintering. In this study, negative pressure aging was applied to resolve the aggregation of nanoparticles and a metal oxide reduction method used to make a well-dispersed nanoparticles in solvent. As a result, metal oxide nanoparticles were synthesized according to a grade of the aggregation and aging conditions found to provide well-dispersed nanoparticles in solvent with less re-dissolution of the nanoparticles. Furthermore, a coating quality and characteristics of laser induced sintering were analyzed according to the grade of the aggregation. The coating quality was affected by the aggregation and the statistical dispersion of nanoparticles. The coating deposited by particles with a wide statistical dispersion has a better quality when compared with the coating prepared from particles with a narrow dispersion. The quality of laser sintered electrode depends on the aggregation but the dependency of the aggregation diminishes as the irradiation of the laser power is decreased.

  17. Recent developments in the NSWC composite electrode

    NASA Technical Reports Server (NTRS)

    Ferrando, W. A.

    1982-01-01

    A characterization of the physical parameters and life cycle data on nickel composite electrodes was conducted. Attempts to improve the nickel composite electrodes with respect to longevity, light weight, and low cost were made. The physical characteristics of a group of electrodes were examined with emphasis on the porosity of the plaques, the thickness of the electrodes, and the potential presence of electrolytes contamination. It was concluded that the nickel composite electrodes exhibit good life cycle characteristics and that their fabrication seems to present real possibilities for the future as a method of making electrodes that are durable, lightweight, and low cost.

  18. Recent developments in the NSWC composite electrode

    NASA Astrophysics Data System (ADS)

    Ferrando, W. A.

    1982-03-01

    A characterization of the physical parameters and life cycle data on nickel composite electrodes was conducted. Attempts to improve the nickel composite electrodes with respect to longevity, light weight, and low cost were made. The physical characteristics of a group of electrodes were examined with emphasis on the porosity of the plaques, the thickness of the electrodes, and the potential presence of electrolytes contamination. It was concluded that the nickel composite electrodes exhibit good life cycle characteristics and that their fabrication seems to present real possibilities for the future as a method of making electrodes that are durable, lightweight, and low cost.

  19. Electrode compositions

    DOEpatents

    Block, Jacob; Fan, Xiyun

    1998-01-01

    An electrode composition for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C.sub.8 -C.sub.15 alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5-4.5 volts.

  20. Electrode compositions

    DOEpatents

    Block, J.; Fan, X.

    1998-10-27

    An electrode composition is described for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C{sub 8}-C{sub 15} alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5--4.5 volts.

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

    PubMed

    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.

  2. MAPLE deposition of 3D micropatterned polymeric substrates for cell culture

    NASA Astrophysics Data System (ADS)

    Paun, Irina Alexandra; Mihailescu, Mona; Calenic, Bogdan; Luculescu, Catalin Romeo; Greabu, Maria; Dinescu, Maria

    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 μm2 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.

  3. Dynamics of Cell Shape and Forces on Micropatterned Substrates Predicted by a Cellular Potts Model

    PubMed Central

    Albert, Philipp J.; Schwarz, Ulrich S.

    2014-01-01

    Micropatterned substrates are often used to standardize cell experiments and to quantitatively study the relation between cell shape and function. Moreover, they are increasingly used in combination with traction force microscopy on soft elastic substrates. To predict the dynamics and steady states of cell shape and forces without any a priori knowledge of how the cell will spread on a given micropattern, here we extend earlier formulations of the two-dimensional cellular Potts model. The third dimension is treated as an area reservoir for spreading. To account for local contour reinforcement by peripheral bundles, we augment the cellular Potts model by elements of the tension-elasticity model. We first parameterize our model and show that it accounts for momentum conservation. We then demonstrate that it is in good agreement with experimental data for shape, spreading dynamics, and traction force patterns of cells on micropatterned substrates. We finally predict shapes and forces for micropatterns that have not yet been experimentally studied. PMID:24896113

  4. Micropatterning control of tubular commitment in human adult renal stem cells.

    PubMed

    Sciancalepore, Anna G; Portone, Alberto; Moffa, Maria; Persano, Luana; De Luca, Maria; Paiano, Aurora; Sallustio, Fabio; Schena, Francesco P; Bucci, Cecilia; Pisignano, Dario

    2016-07-01

    The treatment of renal injury by autologous, patient-specific adult stem cells is still an unmet need. Unsolved issues remain the spatial integration of stem cells into damaged areas of the organ, the commitment in the required cell type and the development of improved bioengineered devices. In this respect, biomaterials and architectures have to be specialized to control stem cell differentiation. Here, we perform an extensive study on micropatterned extracellular matrix proteins, which constitute a simple and non-invasive approach to drive the differentiation of adult renal progenitor/stem cells (ARPCs) from human donors. ARPCs are interfaced with fibronectin (FN) micropatterns, in the absence of exogenous chemicals or cellular reprogramming. We obtain the differentiation towards tubular cells of ARPCs cultured in basal medium conditions, the tubular commitment thus being specifically induced by micropatterned substrates. We characterize the stability of the tubular differentiation as well as the induction of a polarized phenotype in micropatterned ARPCs. Thus, the developed cues, driving the functional commitment of ARPCs, offer a route to recreate the microenvironment of the stem cell niche in vitro, that may serve, in perspective, for the development of ARPC-based bioengineered devices. PMID:27105437

  5. Magnetohydrodynamic electrode

    DOEpatents

    Boquist, Carl W.; Marchant, David D.

    1978-01-01

    A ceramic-metal composite suitable for use in a high-temperature environment consists of a refractory ceramic matrix containing 10 to 50 volume percent of a continuous high-temperature metal reinforcement. In a specific application of the composite, as an electrode in a magnetohydrodynamic generator, the one surface of the electrode which contacts the MHD fluid may have a layer of varying thickness of nonreinforced refractory ceramic for electrode temperature control. The side walls of the electrode may be coated with a refractory ceramic insulator. Also described is an electrode-insulator system for a MHD channel.

  6. Highly transparent conductive electrode with ultra-low HAZE by grain boundary modification of aqueous solution fabricated alumina-doped zinc oxide nanocrystals

    SciTech Connect

    Nian, Qiong; Cheng, Gary J.; Callahan, Michael; Bailey, John; Look, David; Efstathiadis, Harry

    2015-06-01

    Commercial production of transparent conducting oxide (TCO) polycrystalline films requires high electrical conductivity with minimal degradation in optical transparency. Aqueous solution deposited TCO films would reduce production costs of TCO films but suffer from low electrical mobility, which severely degrades both electrical conductivity and optical transparency in the visible spectrum. Here, we demonstrated that grain boundary modification by ultra-violet laser crystallization (UVLC) of solution deposited aluminium-doped zinc oxide (AZO) nanocrystals results in high Hall mobility, with a corresponding dramatic improvement in AZO electrical conductance. The AZO films after laser irradiation exhibit electrical mobility up to 18.1 cm{sup 2} V{sup −1} s{sup −1} with corresponding electrical resistivity and sheet resistances as low as 1 × 10{sup −3} Ω cm and 75 Ω/sq, respectively. The high mobility also enabled a high transmittance (T) of 88%-96% at 550 nm for the UVLC films. In addition, HAZE measurement shows AZO film scattering transmittance as low as 1.8%, which is superior over most other solution deposited transparent electrode alternatives such as silver nanowires. Thus, AZO films produced by the UVLC technique have a combined figure of merit for electrical conductivity, optical transparency, and optical HAZE higher than other solution based deposition techniques and comparable to vacuumed based deposition methods.

  7. Shape-dependent electron transfer kinetics and catalytic activity of NiO nanoparticles immobilized onto DNA modified electrode: fabrication of highly sensitive enzymeless glucose sensor.

    PubMed

    Sharifi, Ensiyeh; Salimi, Abdollah; Shams, Esmaeil; Noorbakhsh, Abdollah; Amini, Mohammad K

    2014-06-15

    Herein we describe improved electron transfer properties and catalytic activity of nickel oxide nanoparticles (NiONPs) via the electrochemical deposition on DNA modified glassy carbon electrode (DNA/GCE) surface. NiONPs deposited on the bare and DNA-coated GCE showed different morphologies, electrochemical kinetics and catalytic activities. The atomic force microscopy (AFM) images revealed the formation of triangular NPs on the DNA/GCE that followed the shape produced by the DNA template, while the electrodeposition of NiONPs on the bare GCE surface led to the formation of spherical nanoparticles. Electrochemical impedance spectroscopy (EIS) measurements revealed lower charge-transfer resistance (Rct) of triangular NiONPs compared to spherical NPs. Furthermore, the electrocatalytic activity of triangular NiONPs compared to spherical NPs toward glucose oxidation in alkaline media was significantly improved. The amperometric oxidation of glucose at NiONP-DNA/GCE, yielded a very high sensitivity of 17.32 mA mM(-1)cm(-2) and an unprecedented detection limit of 17 nM. The enhanced electron transfer properties and electrocatalytic activity of NiONP-DNA/GCE can be attributed to the higher fraction of sharp corners and edges present in the triangular NiONPs compared to the spherical NPs. The developed sensor was successfully applied to the determination of glucose in serum samples. PMID:24525015

  8. Highly transparent conductive electrode with ultra-low HAZE by grain boundary modification of aqueous solution fabricated alumina-doped zinc oxide nanocrystals

    NASA Astrophysics Data System (ADS)

    Nian, Qiong; Callahan, Michael; Look, David; Efstathiadis, Harry; Bailey, John; Cheng, Gary J.

    2015-06-01

    Commercial production of transparent conducting oxide (TCO) polycrystalline films requires high electrical conductivity with minimal degradation in optical transparency. Aqueous solution deposited TCO films would reduce production costs of TCO films but suffer from low electrical mobility, which severely degrades both electrical conductivity and optical transparency in the visible spectrum. Here, we demonstrated that grain boundary modification by ultra-violet laser crystallization (UVLC) of solution deposited aluminium-doped zinc oxide (AZO) nanocrystals results in high Hall mobility, with a corresponding dramatic improvement in AZO electrical conductance. The AZO films after laser irradiation exhibit electrical mobility up to 18.1 cm2 V-1 s-1 with corresponding electrical resistivity and sheet resistances as low as 1 × 10-3 Ω cm and 75 Ω/sq, respectively. The high mobility also enabled a high transmittance (T) of 88%-96% at 550 nm for the UVLC films. In addition, HAZE measurement shows AZO film scattering transmittance as low as 1.8%, which is superior over most other solution deposited transparent electrode alternatives such as silver nanowires. Thus, AZO films produced by the UVLC technique have a combined figure of merit for electrical conductivity, optical transparency, and optical HAZE higher than other solution based deposition techniques and comparable to vacuumed based deposition methods.

  9. Shape-dependent electron transfer kinetics and catalytic activity of NiO nanoparticles immobilized onto DNA modified electrode: fabrication of highly sensitive enzymeless glucose sensor.

    PubMed

    Sharifi, Ensiyeh; Salimi, Abdollah; Shams, Esmaeil; Noorbakhsh, Abdollah; Amini, Mohammad K

    2014-06-15

    Herein we describe improved electron transfer properties and catalytic activity of nickel oxide nanoparticles (NiONPs) via the electrochemical deposition on DNA modified glassy carbon electrode (DNA/GCE) surface. NiONPs deposited on the bare and DNA-coated GCE showed different morphologies, electrochemical kinetics and catalytic activities. The atomic force microscopy (AFM) images revealed the formation of triangular NPs on the DNA/GCE that followed the shape produced by the DNA template, while the electrodeposition of NiONPs on the bare GCE surface led to the formation of spherical nanoparticles. Electrochemical impedance spectroscopy (EIS) measurements revealed lower charge-transfer resistance (Rct) of triangular NiONPs compared to spherical NPs. Furthermore, the electrocatalytic activity of triangular NiONPs compared to spherical NPs toward glucose oxidation in alkaline media was significantly improved. The amperometric oxidation of glucose at NiONP-DNA/GCE, yielded a very high sensitivity of 17.32 mA mM(-1)cm(-2) and an unprecedented detection limit of 17 nM. The enhanced electron transfer properties and electrocatalytic activity of NiONP-DNA/GCE can be attributed to the higher fraction of sharp corners and edges present in the triangular NiONPs compared to the spherical NPs. The developed sensor was successfully applied to the determination of glucose in serum samples.

  10. Conveniently fabricated heterojunction ZnO/TiO2 electrodes using TiO2 nanotube arrays for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Rui; Yang, Wein-Duo; Qiang, Liang-Sheng; Liu, Hsin-Yi

    2012-12-01

    TiO2 nanotube arrays with an inner average pore diameter of 83 nm and a length of 14 μm are grown on Ti foils by electrochemical anodization in ammonium fluoride-water-glycerol solution. ZnO is introduced into the TiO2 nanotube arrays by a convenient electrodeposition technique. ZnO/TiO2 nanocomposites supported on Ti substrate are used as the photo-anode electrode for dye-sensitized solar cells (DSSCs). The morphology, structure and electrochemical properties are investigated using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis diffusion reflection spectroscopy, X-ray photoelectron spectroscopy and cyclic voltammetry measurements. It is found that ZnO have been embedded in the TiO2 nanotube arrays, and changed some photoelectric properties. The conversion efficiency of the dye-sensitized solar cells is more than doubled, compared with that of bare TiO2 nanotube arrays with deposited 60 min. This improvement comes from the synergetic effect between ZnO and TiO2, which increases dye absorption, electron transport and electron lifetime.

  11. Facile fabrication of a novel anisotropic gold nanoparticle-chitosan-ionic liquid/graphene modified electrode for the determination of theophylline and caffeine.

    PubMed

    Yang, Guangming; Zhao, Faqiong; Zeng, Baizhao

    2014-09-01

    In the present study, a suspension solution containing anisotropic gold nanoparticle (GNP), chitosan (CHIT) and ionic liquid (IL, i.e. 1-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF4]), is prepared by reducing HAuCl4 with sodium citrate in CHIT-IL aqueous solution. The hybrid solution is coated on a graphene (r-GO) modified glassy carbon electrode to construct an electrochemical sensor for the determination of theophylline (TP) and caffeine (CAF). The obtained hybrid film shows rough surface, and anisotropic GNPs are well dispersed on it. The factors concerning this assay strategy are carefully investigated, including the components of the hybrid film, the concentrations of r-GO, HAuCl4 and IL, and the pH of buffer solution. Under the optimized conditions, the linear response ranges are 2.50×10(-8)-2.10×10(-6) mol L(-1) and 2.50×10(-8)-2.49×10(-6) mol L(-1) for TP and CAF, respectively; the detection limits are 1.32×10(-9) mol L(-1) and 4.42×10(-9) mol L(-1), respectively. The electrochemical sensor shows good reproducibility, stability and selectivity, and it has been successfully applied to the determination of TP and CAF in real samples.

  12. Working Electrodes

    NASA Astrophysics Data System (ADS)

    Komorsky-Lovrić, Šebojka

    In electrochemistry an electrode is an electronic conductor in contact with an ionic conductor. The electronic conductor can be a metal, or a semiconductor, or a mixed electronic and ionic conductor. The ionic conductor is usually an electrolyte solution; however, solid electrolytes and ionic melts can be used as well. The term "electrode" is also used in a technical sense, meaning the electronic conductor only. If not specified otherwise, this meaning of the term "electrode" is the subject of the present chapter. In the simplest case the electrode is a metallic conductor immersed in an electrolyte solution. At the surface of the electrode, dissolved electroactive ions change their charges by exchanging one or more electrons with the conductor. In this electrochemical reaction both the reduced and oxidized ions remain in solution, while the conductor is chemically inert and serves only as a source and sink of electrons. The technical term "electrode" usually also includes all mechanical parts supporting the conductor (e.g., a rotating disk electrode or a static mercury drop electrode). Furthermore, it includes all chemical and physical modifications of the conductor, or its surface (e.g., a mercury film electrode, an enzyme electrode, and a carbon paste electrode). However, this term does not cover the electrolyte solution and the ionic part of a double layer at the electrode/solution interface. Ion-selective electrodes, which are used in potentiometry, will not be considered in this chapter. Theoretical and practical aspects of electrodes are covered in various books and reviews [1-9].

  13. Nickel anode electrode

    DOEpatents

    Singh, Prabhakar; Benedict, Mark

    1987-01-01

    A nickel anode electrode fabricated by oxidizing a nickel alloying material to produce a material whose exterior contains nickel oxide and whose interior contains nickel metal throughout which is dispersed the oxide of the alloying material and by reducing and sintering the oxidized material to form a product having a nickel metal exterior and an interior containing nickel metal throughout which is dispersed the oxide of the alloying material.

  14. Surface modification of polydimethylsiloxane with photo-grafted poly(ethylene glycol) for micropatterned protein adsorption and cell adhesion.

    PubMed

    Sugiura, Shinji; Edahiro, Jun-ichi; Sumaru, Kimio; Kanamori, Toshiyuki

    2008-06-01

    In this study, we applied photo-induced graft polymerization to micropatterned surface modification of polydimethylsiloxane (PDMS) with poly(ethylene glycol). Two types of monomers, polyethylene glycol monoacrylate (PEGMA) and polyethylene glycol diacrylate (PEGDA), were tested for surface modification of PDMS. Changes in the surface hydrophilicity and surface element composition were characterized by contact angle measurement and electron spectroscopy for chemical analysis. The PEGMA-grafted PDMS surfaces gradually lost their hydrophilicity within two weeks. In contrast, the PEGDA-grafted PDMS surface maintained stable hydrophilic characteristics for more than two months. Micropatterned protein adsorption and micropatterned cell adhesion were successfully demonstrated using PEGDA-micropatterned PDMS surfaces, which were prepared by photo-induced graft polymerization using photomasks. The PEGDA-grafted PDMS exhibited useful characteristics for microfluidic devices (e.g. hydrophilicity, low protein adsorption, and low cell attachment). The technique presented in this study will be useful for surface modification of various research tools and devices. PMID:18242961

  15. 3D Woven-Like Carbon Micropattern Decorated with Silicon Nanoparticles for Use in Lithium-Ion Batteries.

    PubMed

    Kang, Da-Young; Kim, Cheolho; Gueon, Donghee; Park, Gyulim; Kim, Jung Sub; Lee, Joong Kee; Moon, Jun Hyuk

    2015-10-26

    Carbon/silicon composite materials are a promising anode substrate for use in lithium-ion batteries. In this study, we suggest a new architecture for a composite electrode made of a woven-like carbon material decorated with silicon nanoparticles. The 3D woven-like carbon (WLC) structure was fabricated using direct carbonization of multi-beam interference lithography polymer patterns. Subsequent solution coating was applied to decorate the WLC with silicon nanoparticles (SiNPs). The SiNP/WLC electrode exhibited a specific capacity of 930 mAh g(-1) , which is three times higher than the specific capacity of the bare electrode. Specifically, the SiNP/WLC electrode exhibited an outstanding retention capacity of 81 % after 50 cycles and a Coulombic efficiency of more than 98 %. This rate capability performance was attributed to the WLC structure and the uniform decoration of the SiNPs.

  16. Immobilization of enzyme to platinum electrode and its use as enzyme electrode

    SciTech Connect

    Kawakami, Mitsuyasu; Koya, Hidekazu; Gondo, Shinichiro

    1991-12-31

    This report describes a glucose electrode for use in biochemical analysis or perhaps for biochemical conversion technologies. A glucose electrode was fabricated by immobilizing glucose oxidase covalently onto a platinized platinum electrode. The sensor showed rapid response with response time of 2-4 s, and also the linear response to the glucose concentration, ranging from 2 x 10{sup -3} to 5 mM. The sensitivity was found to be correlated with the surface area of a base electrode used.

  17. Liquid electrode

    DOEpatents

    Ekechukwu, Amy A.

    1994-01-01

    A dropping electrolyte electrode 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.

  18. Carbon fabric-aligned carbon nanotube/MnO2/conducting polymers ternary composite electrodes with high utilization and mass loading of MnO2 for super-capacitors

    NASA Astrophysics Data System (ADS)

    Lv, Peng; Feng, Yi Y.; Li, Yu; Feng, Wei

    2012-12-01

    3D porous ternary composite electrodes have been prepared by electrodepositing MnO2 and poly(3,4-ethylenedioxythiophene) (PEDOT) successively on carbon fabric-aligned carbon nanotube (CF-ACNT) hybrids for the super-capacitors. MnO2 petal-like nano-sheets are deposited on the ACNT surface with PEDOT uniformly encapsulated and interconnected MnO2 nano-sheets and ACNTs. Cyclic voltammetry shows the MnO2 utilization of ternary composites up to 77.7%, which far exceeds that of MnO2/CNT-based materials reported recently. Moreover, the 3D porous ternary system allows large mass loading of MnO2. And the ternary composites can remain a high MnO2 utilization of 36% with the MnO2 mass loading up to 3.11 mg cm-2 while achieve a reasonable area-normalized capacitance of 1.3 F cm-2 at 0.1 mV s-1. The ternary composites with substantially high mass loading exhibit an excellent rate capability and cycling stability, retaining over 95% of its initial charge after 1000 cycles. The excellent electrochemical performances are attributed to the synergetic effect of each component with unique properties and structures: high porosity and interconnectivity of CF, aligned ion diffusion channels along ACNTs, ultrathin MnO2 nano-sheets and the improved conductivity by PEDOT.

  19. Performance of lightweight nickel electrodes

    NASA Technical Reports Server (NTRS)

    Britton, Doris L.

    1988-01-01

    The NASA Lewis Research Center is currently developing nickel electrodes for nickel-hydrogen (Ni-H2) batteries. These electrodes are lighter in weight and have higher energy densities than the heavier state-of-the-art (SOA) sintered nickel electrodes. In the present approach, lightweight materials or plaques are used as conductive supports for the nickel hydroxide active material. These plaques (fiber and felt, nickel plated plastic and graphite) are commercial products that are fabricated into nickel electrodes by electrochemically impregnating them with active material. Evaluation is performed in half cells structured in the bipolar configuration. Initial performance tests include capacity measurements at five discharge levels, C/2, 1.0C, 1.37C, 2.0C and 2.74C. The electrodes that pass the initial tests are life cycle tested in a low earth orbit regime at 80 percent depth of discharge. Different formulations of nickel fiber materials obtained from several manufacturers are currently being tested as possible candidates for nickel electrodes. One particular lightweight fiber mat electrode has accumulated over 3000 cycles to date, with stable capacity and voltage. Life and performance data of this electrode were investigated and presented. Good dimensional stability and active material adherence have been demonstrated in electrodes made from this lightweight plaque.

  20. Performance of lightweight nickel electrodes

    NASA Technical Reports Server (NTRS)

    Britton, Doris L.

    1988-01-01

    The NASA Lewis Research Center is currently developing nickel electrodes for nickel-hydrogen (Ni-H2) batteries. These electrodes are lighter in weight and have higher energy densities than the heavier state-of-the-art (SOA) sintered nickel electrodes. In the present approach, lightweight materials or plaques are used as conductive supports for the nickel hydroxide active material. These plaques (fiber and felt, nickel plated plastic and graphite) are commercial products that are fabricated into nickel electrodes by electrochemically impregnating them with active material. Evaluation is performed in half cells structured in the bipolar configuration. Initial performance tests include capacity measurements at five discharge levels, C/2, 1.0C 1.37C, 2.0C and 2.74C. The electrodes that pass the initial tests are life cycle tested in a low Earth orbit regime at 80 percent depth of discharge. Different formulations of nickel fiber materials obtained from several manufacturers are currently being tested as possible candidates for nickel electrodes. One particular lightweight fiber mat electrode has accumulated over 3000 cycles to date, with stable capacity and voltage. Life and performance data of this electrode were investigated and presented. Good dimensional stability and active material adherence have been demonstrated in electrodes made from this lightweight plaque.

  1. Composite electrode/electrolyte structure

    DOEpatents

    Visco, Steven J.; Jacobson, Craig P.; DeJonghe, Lutgard C.

    2004-01-27

    Provided is an electrode fabricated from highly electronically conductive materials such as metals, metal alloys, or electronically conductive ceramics. The electronic conductivity of the electrode substrate is maximized. Onto this electrode in the green state, a green ionic (e.g., electrolyte) film is deposited and the assembly is co-fired at a temperature suitable to fully densify the film while the substrate retains porosity. Subsequently, a catalytic material is added to the electrode structure by infiltration of a metal salt and subsequent low temperature firing. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in ionic (electrochemical) devices such as fuel cells and electrolytic gas separation systems.

  2. Fabrication of tantalum and nitrogen codoped ZnO (Ta, N-ZnO) thin films using the electrospay: twin applications as an excellent transparent electrode and a field emitter.

    PubMed

    Mahmood, Khalid; Park, Seung Bin; Sung, Hyung Jin

    2013-05-01

    The realization of stable p-type nitrogen-doped ZnO thin films with durable and controlled growth is important for the fabrication of nanoscale electronic and optoelectronic devices. ZnO thin films codoped with tantalum and nitrogen (Ta, N-ZnO) were fabricated by using the electrospraying method at an atmospheric pressure. X-ray diffraction (XRD) studies demonstrated that all the prepared films were polycrystalline in nature with hexagonal wurtzite structure. In addition, a shift in the XRD patterns was observed, and the crystal orientation was changed at a certain amount of nitrogen (>6 at.%) in the starting solution. Analysis of X-ray diffraction patterns and X-ray photoelectron spectra revealed that nitrogen which was combined with the zinc atom (N-Zn) was successfully doped into the ZnO crystal lattice. It was also observed that 2 at.% tantalum and 6 at.% nitrogen (2 at.% Ta and 6 at.% N) were the optimal dopant amounts to achieve the minimum resistivity of about 9.70 × 10(-5) Ω cm and the maximum transmittance of 98% in the visible region. Consequently, the field-emission characteristics of such a Ta, N-ZnO emitter can exhibit the higher current density of 1.33 mA cm(-2), larger field-enhancement factor (β) of 4706, lower turn-on field of 2.6 V μm(-1), and lower threshold field of 3.5 V μm(-1) attributed to the enhanced conductivity and better crystallinity of films. Moreover, the obtained values of resistivity were closest to the lowest resistivity values among the doped ZnO films as well as to the indium tin oxide (ITO) resistivity values that were previously studied. We confirmed that the tantalum and nitrogen atoms substitution in the ZnO lattice induced positive effects in terms of enhancing the free carrier concentration which will further improve the electrical, optical, and field-emission properties. The proposed electrospraying method was well suitable for the fabrication of Ta, N-ZnO thin films at optimum conditions with superior electrical

  3. Direct metal micropatterning on needle-type structures towards bioimpedance and chemical sensing applications

    NASA Astrophysics Data System (ADS)

    Kim, Sanghyeok; Park, Jae-ho; Kang, Kyungnam; Park, Chong-Ook; Park, Inkyu

    2015-01-01

    Direct metal patterning methods, such as screen printing, inkjet printing and gravure/flexography printing, are widely used to form electrodes or interconnections for printed electronic devices due to their inexpensive, simple and rapid fabrication as compared to vacuum-based conventional metallization processes. Here, we present direct metal patterning by modified screen printing on the curved surface of needle-type rod structures (i.e. rods with radius of ρ < 1 mm). We achieved various microscale patterns such as straight lines, zigzag lines, wavy lines and alphabetic words with a minimum width of 70 µm on the surface of the rod. Also, four pairs of line patterns were printed on the single rod for electrical interconnection. Printed patterns on the surface of the rod were used as electrodes for the control of a light emission diode (LED) as well as the real-time electrochemical impedance spectroscopy of electrolyte solutions and solid objects by the rod insertion. Furthermore, needles with multiple pairs of microelectrodes were used to measure the electrical impedance of biological samples such as fat and muscle tissues of porcine meat. In addition, a needle-type probe sensor with gas sensing capability was demonstrated by using a needle with printed Ag electrodes and Pd thin films.

  4. Graphene oxide-based micropatterns via high-throughput multiphoton-induced reduction and ablation.

    PubMed

    Li, Yi-Cheng; Yeh, Te-Fu; Huang, Hsin-Chieh; Chang, Hsin-Yu; Lin, Chun-Yu; Cheng, Li-Chung; Chang, Chia-Yuan; Teng, Hsisheng; Chen, Shean-Jen

    2014-08-11

    In this study, a developed temporal focusing-based femtosecond laser system provides high-throughput multiphoton-induced reduction and ablation of graphene oxide (GO) films. Integrated with a digital micromirror device to locally control the laser pulse numbers, GO-based micropatterns can be quickly achieved instantly. Furthermore, the degree of reduction and ablation can be precisely adjusted via controlling the laser wavelength, power, and pulse number. Compared to point-by-point scanning laser direct writing, this approach offers a high-throughput and multiple-function approach to accomplish a large area of micro-scale patterns on GO films. The high-throughput micropatterning of GO via the temporal focusing-based femtosecond laser system fulfills the requirement of mass production for GO-based applications in microelectronic devices. PMID:25321055

  5. Stochastic Micro-Pattern for Automated Correlative Fluorescence - Scanning Electron Microscopy

    PubMed Central

    Begemann, Isabell; Viplav, Abhiyan; Rasch, Christiane; Galic, Milos

    2015-01-01

    Studies of cellular surface features gain from correlative approaches, where live cell information acquired by fluorescence light microscopy is complemented by ultrastructural information from scanning electron micrographs. Current approaches to spatially align fluorescence images with scanning electron micrographs are technically challenging and often cost or time-intensive. Relying exclusively on open-source software and equipment available in a standard lab, we have developed a method for rapid, software-assisted alignment of fluorescence images with the corresponding scanning electron micrographs via a stochastic gold micro-pattern. Here, we provide detailed instructions for micro-pattern production and image processing, troubleshooting for critical intermediate steps, and examples of membrane ultra-structures aligned with the fluorescence signal of proteins enriched at such sites. Together, the presented method for correlative fluorescence – scanning electron microscopy is versatile, robust and easily integrated into existing workflows, permitting image alignment with accuracy comparable to existing approaches with negligible investment of time or capital. PMID:26647824

  6. Dynamic three-dimensional micropatterned cell co-cultures within photocurable and chemically degradable hydrogels.

    PubMed

    Sugiura, Shinji; Cha, Jae Min; Yanagawa, Fumiki; Zorlutuna, Pinar; Bae, Hojae; Khademhosseini, Ali

    2016-08-01

    In this paper we report on the development of dynamically controlled three-dimensional (3D) micropatterned cellular co-cultures within photocurable and chemically degradable hydrogels. Specifically, we generated dynamic co-cultures of micropatterned murine embryonic stem (mES) cells with human hepatocellular carcinoma (HepG2) cells within 3D hydrogels. HepG2 cells were used due to their ability to direct the differentiation of mES cells through secreted paracrine factors. To generate dynamic co-cultures, mES cells were first encapsulated within micropatterned photocurable poly(ethylene glycol) (PEG) hydrogels. These micropatterned cell-laden PEG hydrogels were subsequently surrounded by calcium alginate (Ca-Alg) hydrogels containing HepG2 cells. After 4 days, the co-culture step was halted by exposing the system to sodium citrate solution, which removed the alginate gels and the encapsulated HepG2 cells. The encapsulated mES cells were then maintained in the resulting cultures for 16 days and cardiac differentiation was analysed. We observed that the mES cells that were exposed to HepG2 cells in the co-cultures generated cells with higher expression of cardiac genes and proteins, as well as increased spontaneous beating. Due to its ability to control the 3D microenvironment of cells in a spatially and temporally regulated manner, the method presented in this study is useful for a range of cell-culture applications related to tissue engineering and regenerative medicine. Copyright © 2013 John Wiley & Sons, Ltd.

  7. M3: Microscope-based maskless micropatterning with dry film photoresist

    PubMed Central

    Leigh, Steven Y.; Tattu, Aashay; Mitchell, Joseph S. B.

    2011-01-01

    We present a maskless micropatterning system that utilizes a fluorescence microscope with programmable X-Y stage and dry film photoresist to realize feature sizes in the sub-millimeter range (40–700 μm). The method allows for flexible in-house maskless photolithography without a dedicated microfabrication facility and is well-suited for rapid prototyping of microfluidic channels, scaffold templates for protein/cell patterning or optically-guided cell encapsulation for biomedical applications. PMID:21190086

  8. X-ray Polarimetry with a Micro-Pattern Gas Detector

    NASA Technical Reports Server (NTRS)

    Hill, Joe

    2005-01-01

    Topics covered include: Science drivers for X-ray polarimetry; Previous X-ray polarimetry designs; The photoelectric effect and imaging tracks; Micro-pattern gas polarimeter design concept. Further work includes: Verify results against simulator; Optimize pressure and characterize different gases for a given energy band; Optimize voltages for resolution and sensitivity; Test meshes with 80 micron pitch; Characterize ASIC operation; and Quantify quantum efficiency for optimum polarization sensitivity.

  9. Assessment of a micropatterned hepatocyte coculture system to generate major human excretory and circulating drug metabolites.

    PubMed

    Wang, Wendy WeiWei; Khetani, Salman R; Krzyzewski, Stacy; Duignan, David B; Obach, R Scott

    2010-10-01

    Metabolism is one of the important determinants of the overall disposition of drugs, and the profile of metabolites can have an impact on efficacy and safety. Predicting which drug metabolites will be quantitatively predominant in humans has become increasingly important in the research and development of new drugs. In this study, a novel micropatterned hepatocyte coculture system was evaluated for its ability to generate human in vivo metabolites. Twenty-seven compounds of diverse chemical structure and subject to a range of drug biotransformation reactions were assessed for metabolite profiles in the micropatterned coculture system using pooled cryopreserved human hepatocytes. The ability of this system to generate metabolites that are >10% of dose in excreta or >10% of total drug-related material in circulation was assessed and compared to previously reported data obtained in human hepatocyte suspensions, liver S-9 fraction, and liver microsomes. The micropatterned coculture system was incubated for up to 7 days without a change in medium, which offered an ability to generate metabolites for slowly metabolized compounds. The micropatterned coculture system generated 82% of the excretory metabolites that exceed 10% of dose and 75% of the circulating metabolites that exceed 10% of total circulating drug-related material, exceeds the performance of hepatocyte suspension incubations and other in vitro systems. Phase 1 and phase 2 metabolites were generated, as well as metabolites that arise via two or more sequential reactions. These results suggest that this in vitro system offers the highest performance among in vitro metabolism systems to predict major human in vivo metabolites.

  10. Post-test evaluation of the oxygen electrode from a solid oxide electrolysis stack and electrode materials development.

    SciTech Connect

    Mawdsley, J. R.; Carter, J. D.; Yildiz, B.; Call, A. V.; Kropf, A. J.; Ferrandon, M. S.; Myers, D. J.; Maroni, V. A.

    2009-05-01

    The conclusions of this paper are: (1) stack degradation analysis - significant sources of degradation have been identified, (a) oxygen electrode delamination off the electrolyte and (b) chromium contamination of the oxygen electrode and bond layer; (2) electrode materials development - improved electrode materials have been demonstrated, Pr{sub 2}NiO{sub 4} oxygen electrodes show state-of-the-art performance without optimization of fabrication parameters.

  11. Carbon material based microelectromechanical system (MEMS): Fabrication and devices

    NASA Astrophysics Data System (ADS)

    Xu, Wenjun

    silicon and metal based microsystems. In this thesis, this mature technique was exploited to generate a variety of microelectrode structures to facilitate the micropatterning and manipulation of the CNTs. Selective deposition of electrically charged CNTs onto desired locations was realized in an EPD process through patterning of electric field lines created by the microelectrodes fabricated through MEMS techniques. A variety of 2-D and 3-D micropatterns of CNTs with waferscale areas have been successfully achieved in both rigid and elastic systems. The thickness and morphology of the generated CNT patterns was found to be readily controllable through the parameters of the fabrication process. Studies also showed that for this technique, high surface hydrophobicity of the non-conductive regions in microstructures was critical to accomplish well-defined selective micropatterning of CNTs. Upon clearing the hurdles of the CNT manipulation, a patterned PDMS/CNT nanocomposite was fabricated through the aforementioned approach and was incorporated, investigated and validated in elastic force/strain microsensors. The gauge factor of the sensor exhibited a strong dependence on both the initial resistance of the device and the applied strain. Detailed analysis of the data suggests that the piezoresistive effect of this specially constructed bi-layer composite could be due to three mechanisms, and the sensing mechanism may vary when physical properties of the CNT network embedded in the polymer matrix alter. The feasibility of the PDSM/CNT composite being utilized as an elastic electret was further explored. The nanocomposite composed of these two non-traditional electret materials exhibited electret characteristics with reasonable charge storage stability when charged using a corona discharge. The power generation capacity of the corona-charged composite has been characterized and successfully demonstrated in both a ball drop experiment and cyclic mechanical load experiments

  12. Relatively uniform and accelerated degradation of pure iron coated with micro-patterned Au disc arrays.

    PubMed

    Cheng, J; Huang, T; Zheng, Y F

    2015-03-01

    Pure iron has been proven to be a potential biodegradable metal, but its degradation rate was too slow. To accelerate its biodegradation, micro-patterned Au disc films were deposited on the surface of pure iron by vacuum sputtering. The influence of Au disc films on the degradation of pure iron matrix in vitro was investigated in the present study. Electrochemical measurement results indicated that the corrosion current density of pure iron coated with micro-patterned Au disc films in Hank's solution was 4 times larger than that of the uncoated one, while the difference between the influences of micro-patterned Au discs with different diameters on the corrosion rate of pure iron was insignificant. Immersion test indicated that the corrosion depth for pure iron coated with Au disc films was about three times as that of bare pure iron. Both electrochemical test and immersion test revealed that the corrosion of pure iron matrix coated with Au disc array became more uniform.

  13. Improved-throughput traction microscopy based on fluorescence micropattern for manual microscopy.

    PubMed

    Liu, Kai; Yuan, Yuan; Huang, Jianyong; Wei, Qiong; Pang, Mingshu; Xiong, Chunyang; Fang, Jing

    2013-01-01

    Traction force microscopy (TFM) is a quantitative technique for measuring cellular traction force, which is important in understanding cellular mechanotransduction processes. Traditional TFM has a significant limitation in that it has a low measurement throughput, commonly one per TFM dish, due to a lack of cell position information. To obtain enough cellular traction force data, an onerous workload is required including numerous TFM dish preparations and heavy cell-seeding activities, creating further difficulty in achieving identical experimental conditions among batches. In this paper, we present an improved-throughput TFM method using the well-developed microcontact printing technique and chemical modifications of linking microbeads to the gel surface to address these limitations. Chemically linking the microbeads to the gel surface has no significant influence on cell proliferation, morphology, cytoskeleton, and adhesion. Multiple pairs of force loaded and null force fluorescence images can be easily acquired by means of manual microscope with the aid of a fluorescence micropattern made by microcontact printing. Furthermore, keeping the micropattern separate from cells by using gels effectively eliminates the potential negative effect of the micropattern on the cells. This novel design greatly improves the analysis throughput of traditional TFM from one to at least twenty cells per petri dish without losing unique advantages, including a high spatial resolution of traction measurements. This newly developed method will boost the investigation of cell-matrix mechanical interactions.

  14. Print-to-print: a facile multi-object micro-patterning technique.

    PubMed

    Xing, Siyuan; Zhao, Siwei; Pan, Tingrui

    2013-04-01

    In recent years, micropatterning techniques have gained increasing popularity from a broad range of engineering and biology communities for the promise to establish highly quantitative investigations on miniature biological objects (e.g., cells and bacteria) with spatially defined microenvironments. However, majority of the existing techniques rely on cleanroom-based microfabrication and cannot be easily extended to a regular biological laboratory. In this paper, we present a simple versatile printing-based method, referred to as Print-to-Print (P2P), to form multi-object micropatterns for potential biological applications, along with our recent efforts to deliver out-of-cleanroom microfabrication solutions to the general public (Zhao et al. 2009), (Xing et al. 2011), (Wang et al. 2009), (Pan and Wang 2011), (Zhao et al. 2011). The P2P method employs only a commercially available solid-phase printer and custom-made superhydrophobic films. The entire patterning process does not involve any thermal or chemical treatment. Moreover, the non-contact nature of droplet transferring and printing steps can be highly advantageous for sensitive biological uses. Using the P2P process, a minimal feature resolution of 229 ± 17 μm has been successfully demonstrated. In addition, this approach has been applied to form biological micropatterning on various substrates as well as multi-object co-patterns on the commonly used surfaces. Finally, the reusability of superhydrophobic substrates has also been illustrated.

  15. Micropatterning hydroxy-PAAm hydrogels and Sylgard 184 silicone elastomers with tunable elastic moduli.

    PubMed

    Versaevel, Marie; Grevesse, Thomas; Riaz, Maryam; Lantoine, Joséphine; Gabriele, Sylvain

    2014-01-01

    This protocol describes a simple method to deposit protein micropatterns over a wide range of culture substrate stiffness (three orders of magnitude) by using two complementary polymeric substrates. In the first part, we introduce a novel polyacrylamide hydrogel, called hydroxy-polyacrylamide (PAAm), that permits to surmount the intrinsically nonadhesive properties of polyacrylamide with minimal requirements in cost or expertize. We present a protocol for tuning easily the rigidity of "soft" hydroxy-PAAm hydrogels between ~0.5 and 50 kPa and a micropatterning method to locally deposit protein micropatterns on these hydrogels. In a second part, we describe a protocol for tuning the rigidity of "stiff" silicone elastomers between ~100 and 1000 kPa and printing efficiently proteins from the extracellular matrix. Finally, we investigate the effect of the matrix rigidity on the nucleus of primary endothelial cells by tuning the rigidity of both polymeric substrates. We envision that the complementarity of these two polymeric substrates, combined with an efficient microprinting technique, can be further developed in the future as a powerful mechanobiology platform to investigate in vitro the effect of mechanotransduction cues on cellular functions, gene expression, and stem cell differentiation.

  16. Ultra-flexible biomedical electrodes and wires

    NASA Technical Reports Server (NTRS)

    Rositano, S. A.

    1970-01-01

    Soft, flexible electrode conforms to body contour during body motion. It is fabricated from an elastomer impregnated with a conductive powder which can be configured into any required shape, including a wire shape to connect the electrode directly to an electrical instrument or to a conventional metallic wire.

  17. Striped Electrodes for Solid-Electrolyte Cells

    NASA Technical Reports Server (NTRS)

    Richter, R.

    1983-01-01

    Striped thick-film platinum electrodes help insure lower overall cell resistance by permitting free flow of gases in gaps between stripes. Thickfilm stripes are also easier to fabricate than porous thin-film electrodes that cover entire surface. Possible applications for improved cells include oxygen production from carbon dioxide, extraction of oxygen from air, small fluidic pumping, sewage treatment, and fuel cells.

  18. Liquid electrode

    DOEpatents

    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.

  19. Ceramic fabrication R D

    SciTech Connect

    Not Available

    1990-01-01

    This project is separated into three tasks. The first task is a design and modelling effort to be carried out by MSE, Inc. The purpose of this task is to develop and analyze designs for various cohesive ceramic fabrication (CCF) components, principally an MHD electrode for strategic defense initiative (SDI) applications. A high stress, low cost, ceramic component is to be selected, designed and, if possible, analyzed. The final design for the MHD electrode comprised a layered structure of molybdenum disilicide graded with quartz glass. The design demonstrates the fabrication capabilities of the CCF process. The high stress component was targeted at armor applications and will be thick alumina plate. Silicon carbide reinforcement of the alumina will be explored. Task 2 is directed at establishing a mechanical properties data base for monolithic and laminated alumina fabricated using the CCF process. Task 3 involved production of a solid oxide fuel cell model electrode; however, work ceased when it became apparent that successful integration of the electrode modules would require additional time. Currently, work is principally focused on the production of thick CCF alumina plates; three test plates were ballistically tested and showed a very satisfactory performance. Silicon carbide reinforcement of the CCF alumina is being explored. Effort on the CCF processing of molybdenum disilicide (a nonoxide material) continued at a reduced level. Sinter aids were explored, and densities of 87% theoretical density on pressureless sintered dry pressed pellets were achieved. 1 ref., 9 figs., 4 tabs.

  20. Dependency of anti-ferro-magnetic coupling strength on Ru spacer thickness of [Co/Pd]{sub n}-synthetic-anti-ferro-magnetic layer in perpendicular magnetic-tunnel-junctions fabricated on 12-inch TiN electrode wafer

    SciTech Connect

    Chae, Kyo-Suk; Shim, Tae-Hun; Park, Jea-Gun

    2014-07-21

    We investigated the Ru spacer-thickness effect on the anti-ferro-magnetic coupling strength (J{sub ex}) of a [Co/Pd]{sub n}-synthetic-anti-ferro-magnetic layer fabricated with Co{sub 2}Fe{sub 6}B{sub 2}/MgO based perpendicular-magnetic-tunneling-junction spin-valves on 12-in. TiN electrode wafers. J{sub ex} peaked at a certain Ru spacer-thickness: specifically, a J{sub ex} of 0.78 erg/cm{sup 2} at 0.6 nm, satisfying the J{sub ex} criteria for realizing the mass production of terra-bit-level perpendicular-spin-transfer-torque magnetic-random-access-memory. Otherwise, J{sub ex} rapidly degraded when the Ru spacer-thickness was less than or higher than 0.6 nm. As a result, the allowable Ru thickness variation should be controlled less than 0.12 nm to satisfy the J{sub ex} criteria. However, the Ru spacer-thickness did not influence the tunneling-magneto-resistance (TMR) and resistance-area (RA) of the perpendicular-magnetic-tunneling-junction (p-MTJ) spin-valves since the Ru spacer in the synthetic-anti-ferro-magnetic layer mainly affects the anti-ferro-magnetic coupling efficiency rather than the crystalline linearity of the Co{sub 2}Fe{sub 6}B{sub 2} free layer/MgO tunneling barrier/Co{sub 2}Fe{sub 6}B{sub 2} pinned layer, although Co{sub 2}Fe{sub 6}B{sub 2}/MgO based p-MTJ spin-valves ex-situ annealed at 275 °C achieved a TMR of ∼70% at a RA of ∼20 Ω μm{sup 2}.