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Articles 1 - 22 of 22
Full-Text Articles in Physical Sciences and Mathematics
Pegylation Of Platinum Bio-Electrodes, Zhilian Yue, Paul J. Molino, Xiao Liu, Gordon G. Wallace
Pegylation Of Platinum Bio-Electrodes, Zhilian Yue, Paul J. Molino, Xiao Liu, Gordon G. Wallace
Gordon Wallace
Controlling protein interactions at the implanted electrode interface is becoming an important strategy for the management of foreign body responses that have proven to be detrimental to the long-term performance of neural prosthesis. In this study, PEGylation was conducted on platinum bio-electrodes to render the surface protein-resistant. The PEGylated electrode was investigated using a quartz crystal microbalance-dissipation, electrochemical impedance spectroscopy and cyclic voltammetiy.
Conducting Polymer Coated Neural Recording Electrodes, Alexander R. Harris, Simon Morgan, Jun Chen, Robert M. Kapsa, Gordon G. Wallace, Antonio Paolini
Conducting Polymer Coated Neural Recording Electrodes, Alexander R. Harris, Simon Morgan, Jun Chen, Robert M. Kapsa, Gordon G. Wallace, Antonio Paolini
Gordon Wallace
Neural recording electrodes suffer from poor signal to noise ratio, charge density, biostability and biocompatibility. This paper investigates the ability of conducting polymer coated electrodes to record acute neural response in a systematic manner, allowing in depth comparison of electrochemical and electrophysiological response. Approach. Polypyrrole (Ppy) and poly-3,4-ethylenedioxythiophene (PEDOT) doped with sulphate (SO4) or para-toluene sulfonate (pTS) were used to coat iridium neural recording electrodes. Detailed electrochemical and electrophysiological investigations were undertaken to compare the effect of these materials on acute in vivo recording. Main results. A range of charge density and impedance responses were seen with each respectively doped …
The Nanostructure Of Three-Dimensional Scaffolds Enhances The Current Density Of Microbial Bioelectrochemical Systems, Victoria Flexer, Jun Chen, Bogdan C. Donose, Peter C. Sherrell, Gordon G. Wallace, Jurg Keller
The Nanostructure Of Three-Dimensional Scaffolds Enhances The Current Density Of Microbial Bioelectrochemical Systems, Victoria Flexer, Jun Chen, Bogdan C. Donose, Peter C. Sherrell, Gordon G. Wallace, Jurg Keller
Gordon Wallace
Bioelectrochemical systems encompass a range of electrochemical systems wherein microorganisms are used as biocatalysts. These range from classical microbial fuel cells to novel microbial electrosynthesis processes. The future of practical applications relies on increased performance. In all cases the development of new electrode materials is essential to overcome the low current densities of bioelectrochemical systems. Here we describe a new biocompatible, highly conductive three-dimensional scaffold electrode, NanoWeb-RVC, with a hierarchical porous structure, synthesized by direct growth of carbon nanotubes on a macroporous substrate. The nanostructure of these electrodes enhances the rate of bacterial extracellular electron transfer while the macrostructure ensures …
Preparation And Characterisation Of Graphene Composite Hydrogels, Nicholas J. Whiteside, Gordon G. Wallace, Marc In Het Panhuis
Preparation And Characterisation Of Graphene Composite Hydrogels, Nicholas J. Whiteside, Gordon G. Wallace, Marc In Het Panhuis
Gordon Wallace
Stable dispersions containing graphene and gellan gum are used to form composite films. Incorporation of graphene into the gellan gum matrix results in mechanical reinforcement and electrical conductivity at low and high graphene loading fractions, respectively. Graphene-containing gellan gum hydrogel films are prepared by immersion of composite films in Ca2+ cross-linking solutions. The resulting hydrogels are electrically conducting and exhibit reinforcement compared to the corresponding gellan gum hydrogels. 2013 Elsevier B.V.
A Battery Composed Of A Polypyrrole Cathode And A Magnesium Alloy Anode-Toward A Bioelectric Battery, Yong Kong, Caiyun Wang, Yang Yang, Chee O. Too, Gordon G. Wallace
A Battery Composed Of A Polypyrrole Cathode And A Magnesium Alloy Anode-Toward A Bioelectric Battery, Yong Kong, Caiyun Wang, Yang Yang, Chee O. Too, Gordon G. Wallace
Gordon Wallace
A bioelectric battery can be implanted into the human body and relies on oxygen in the internal body fluid to produce electrical energy. In this work, a battery that uses polypyrrole doped with a biological polyelectrolyte (dextran sulfate, an anti-coagulant) as the cathode and bioresorbable Mg alloy (AZ61) as the anode was developed. This battery exhibited a discharge capacity of 565 mA h g-1 in phosphate buffered saline (PBS, pH = 7.4), a commonly used electrolyte in biological research; offering a specific energy density of similar to 790W h kg-1. The electrochemical properties of the cathode, anode and battery itself …
The Mechanical And The Electrical Properties Of Conducting Polypyrrole Fibers, Javad Foroughi, Shaban R. Ghorbani, Germanas Peleckis, Geoffrey M. Spinks, Gordon G. Wallace, Xiaolin Wang, S X. Dou
The Mechanical And The Electrical Properties Of Conducting Polypyrrole Fibers, Javad Foroughi, Shaban R. Ghorbani, Germanas Peleckis, Geoffrey M. Spinks, Gordon G. Wallace, Xiaolin Wang, S X. Dou
Gordon Wallace
The mechanical and the electrical properties of polypyrrole (PPy) fibers and electrochemically deposited PPy films were studied. It was found that the PPy fibers showed a significantly higher strength than the PPy films due to better orientation of the molecular structure. The electrochemically prepared PPy films had a higher electrical conductivity than that of the fibers at high temperature. At low temperature, the PPy fibers showed the higher conductivity. The conductivity results were analyzed in the frame of the three-dimensional variable range hopping model. The results showed that at room temperature the average hopping distance for the fibers was about …
Polypyrrole Coated Nylon Lycra Fabric As Stretchable Electrode For Supercapacitor Applications, Binbin Yue, Caiyun Wang, Xin Ding, Gordon G. Wallace
Polypyrrole Coated Nylon Lycra Fabric As Stretchable Electrode For Supercapacitor Applications, Binbin Yue, Caiyun Wang, Xin Ding, Gordon G. Wallace
Gordon Wallace
Wearable electronics offer the combined advantages of both electronics and fabrics. Being an indispensable part of these electronics, lightweight, stretchable and wearable power sources are strongly demanded. Here we describe a daily-used nylon lycra fabric coated with polypyrrole as electrode for stretchable supercapacitors. Polypyrrole was synthesized on the fabric via a simple chemical polymerization process with ammonium persulfate (APS) as an oxidant and naphthalene-2,6-disulfonic acid disodium salt (Na2NDS) as a dopant. This material was characterized with FESEM, FTIR, tensile stress, and studied as a supercapacitor electrode in 1.0 M NaCl. This conductive textile could endure 1000 stretching cycles with 100% …
Printing Nanomaterials Using Non-Contact Printing, Charles Mire, Marc In Het Panhuis, Paul D. Calvert, Gordon G. Wallace
Printing Nanomaterials Using Non-Contact Printing, Charles Mire, Marc In Het Panhuis, Paul D. Calvert, Gordon G. Wallace
Gordon Wallace
We report on the use of inkjet, extrusion, and capillary printing of poly(3,4 ethylenedioxythiophene)/ poly(sodium 4-styrene-sulfonate) (PEDOT/PSS) to create structures that could be used in a flexible, implantable bionic device. Resistance values as low as 250 kΩ are demonstrated, with little deviation under as much as 1.5% strain. The results show PEDOT/PSS can be a suitable material for printed bionic devices.
Electrically Conductive, Tough Hydrogels With Ph Sensitivity, Sina Naficy, Joselito M. Razal, Geoffrey M. Spinks, Gordon G. Wallace, Philip G. Whitten
Electrically Conductive, Tough Hydrogels With Ph Sensitivity, Sina Naficy, Joselito M. Razal, Geoffrey M. Spinks, Gordon G. Wallace, Philip G. Whitten
Gordon Wallace
Electrically conductive, mechanically tough hydrogels based on a double network (DN) comprised of poly(ethylene glycol) methyl ether methacrylate (PPEGMA) and poly(acrylic acid) (PAA) were produced. Poly(3,4-ethylenedioxythiophene) (PEDOT) was chemically polymerized within the tough DN gel to provide electronic conductivity. The effects of pH on the tensile and compressive mechanical properties of the fully swollen hydrogels, along with their electrical conductivity and swelling ratio were determined. Compressive and tensile strengths as high as 11.6 and 0.6 MPa, respectively, were obtained for hydrogels containing PEDOT with a maximum conductivity of 4.3 S cm-1. This conductivity is the highest yet reported for hydrogel …
Nanostructured Electrically Conducting Biofibres Produced Using A Reactive Wet-Spinning Process, Javad Foroughi, Geoffrey M. Spinks, Gordon G. Wallace
Nanostructured Electrically Conducting Biofibres Produced Using A Reactive Wet-Spinning Process, Javad Foroughi, Geoffrey M. Spinks, Gordon G. Wallace
Gordon Wallace
Electrically conducting, robust fibres comprised of both an alginate (Alg) biopolymer and a polypyrrole (PPy) component have been produced using reactive wet-spinning. Using this approach polypyrrole-biopolymer fibres were also produced with single-walled carbon nanotubes (CNTs), added to provide additional strength and conductivity. The fibres produced containing CNTs show a 78% increase in ultimate stress and 25% increase in elongation to break compared to PPy-alginate fibre. These properties are essential for studies involving the use of electrical stimulation to promote nerve regrowth and/or muscle regeneration. The resultant a novel fibres had been evaluated to develop a viable system in incorporating biological …
Vapor Phase Polymerization Of Edot From Submicrometer Scale Oxidant Patterned By Dip-Pen Nanolithography, Cathal D. O'Connell, Michael J. Higgins, Hiroshi Nakashima, Simon E. Moulton, Gordon G. Wallace
Vapor Phase Polymerization Of Edot From Submicrometer Scale Oxidant Patterned By Dip-Pen Nanolithography, Cathal D. O'Connell, Michael J. Higgins, Hiroshi Nakashima, Simon E. Moulton, Gordon G. Wallace
Gordon Wallace
Some of the most exciting recent advances in conducting polymer synthesis have centered around the method of vapor phase polymerization (VPP) of thin films. However, it is not known whether the VPP process can proceed using significantly reduced volumes of oxidant and therefore be implemented as part of nanolithography approach. Here, we present a strategy for submicrometer scale patterning of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) via in situ VPP. Attolitre (10-18 L) volumes of oxidant "ink" are controllably deposited using dip-pen nanolithography (DPN). DPN patterning of the oxidant ink is facilitated by the incorporation of an amphiphilic block copolymer thickener, …
Polypyrrole Stretchable Actuators, Wen Zheng, Gursel Alici, Phillip R. Clingan, Bridget Munro, Geoffrey M. Spinks, Julie R. Steele, Gordon G. Wallace
Polypyrrole Stretchable Actuators, Wen Zheng, Gursel Alici, Phillip R. Clingan, Bridget Munro, Geoffrey M. Spinks, Julie R. Steele, Gordon G. Wallace
Gordon Wallace
Here, we report a simple way to prepare stretchable polypyrrole (PPy)-based actuator materials that can be operated over a wide dynamic strain range and generate useable actuation displacements and pressures. The stretchable actuators were prepared as a laminated composite of PPy and a gold-coated roughened rubber sheet. By manipulating the corrugated surface of the rubber substrate, the stretchability of PPy was greatly improved. Gold-coated rubbers could be stretched to 30 percent without significant change in electrical resistance. The corrugated PPy/gold/rubber laminates successfully showed - 1 percents of actuation strain even when prestretched to 24 percent. The actuation strains were smaller …
Physicochemical Study Of Spiropyran-Terthiophene Derivatives: Photochemistry And Thermodynamics, Michele Zanoni, Simon Coleman, Kevin J. Fraser, Robert P. Byrne, Klaudia K. Wagner, Sanjeev Gambhir, David L. Officer, Gordon G. Wallace, D Diamond
Physicochemical Study Of Spiropyran-Terthiophene Derivatives: Photochemistry And Thermodynamics, Michele Zanoni, Simon Coleman, Kevin J. Fraser, Robert P. Byrne, Klaudia K. Wagner, Sanjeev Gambhir, David L. Officer, Gordon G. Wallace, D Diamond
Gordon Wallace
The photochemistry and thermodynamics of two terthiophene (TTh) derivatives bearing benzospiropyran (BSP) moieties, 1-(3,3''-dimethylindoline-6'-nitrobenzospiropyranyl)-2-ethyl 4,4''-didecyloxy-2,2':5',2''-terthiophene-30-acetate (BSP-2) and 1-(3,3''-dimethylindoline-6'- nitrobenzospiropyranyl)-2-ethyl 4,4''-didecyloxy-2,2':5',2''-terthiophene-30-carboxylate (BSP-3), differing only by a single methylene spacer unit, have been studied. The kinetics of photogeneration of the equivalent merocyanine (MC) isomers (MC-2 and MC-3, respectively), the isomerisation properties of MC-2 and MC-3, and the thermodynamic parameters have been studied in acetonitrile, and compared to the parent, non-TTh-functionalised, benzospiropyran derivative, BSP-1. Despite the close structural similarity of BSP-2 and BSP-3, their physicochemical properties were found to differ significantly; examples include activation energies (Ea(MC-2) = 75.05 kJ mol-1, Ea(MC-3) = 100.39 …
Additive Bio Fabrication: Impact, Opportunities And Challenges, Gordon G. Wallace, Stephen Beirne
Additive Bio Fabrication: Impact, Opportunities And Challenges, Gordon G. Wallace, Stephen Beirne
Gordon Wallace
In recent years we have outrun our ability to fabricate structures from the amazing materials that we can now create. While this can be said of many areas of materials research it is particularly so in the area of biomaterials. Here, we are often confronted with delicate compositions with nano- to microscopic features that will not survive the traditional (hammer and chisel) approach to fabrication. There is good reason why nature “grows” complex, highly functional structures. Such structures with functionality determined by the spatial distribution of composition with nanodimensional resolution can not be chiselled from a slab of material. Additive …
All-Polymer Battery System Based On Polypyrrole (Ppy)/Para (Toluene Sulfonic Acid) (Pts) And Polypyrrole (Ppy)/Indigo Carmine (Ic) Free Standing Films, Irin Sultana, Md. Mokhlesur Rahman, Jiazhao Wang, Caiyun Wang, Gordon G. Wallace, Hua-Kun Liu
All-Polymer Battery System Based On Polypyrrole (Ppy)/Para (Toluene Sulfonic Acid) (Pts) And Polypyrrole (Ppy)/Indigo Carmine (Ic) Free Standing Films, Irin Sultana, Md. Mokhlesur Rahman, Jiazhao Wang, Caiyun Wang, Gordon G. Wallace, Hua-Kun Liu
Gordon Wallace
In this study, we introduce a novel all-polymer battery system based on conducting polymer (polypyrrole, PPy) doped with dopants of para (toluene sulfonic acid) (pTS) and indigo carmine (IC), respectively. The performance of the systems consisting of polypyrrole-para (toluene sulfonic acid) (PPy-pTS) as cathode and polypyrrole-indigo carmine (PPy-IC) as anode in conjunction with either a polymer based electrolyte or a commercial organic electrolyte of 1M LiPF6 in a 50:50 (v/v) mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) was evaluated. In the system, all the free-standing PPy-pTS and PPy-IC films were directly used without needing any metal substrate support …
Actuating Individual Electrospun Hydrogel Nanofibres, Adrian Gestos, Philip G. Whitten, Gordon G. Wallace, Geoffrey Maxwell Spinks
Actuating Individual Electrospun Hydrogel Nanofibres, Adrian Gestos, Philip G. Whitten, Gordon G. Wallace, Geoffrey Maxwell Spinks
Gordon Wallace
The actuation of a single hydrogel nanofibre is measured for the first time by AFM. The actuation stress generated was comparable to that produced by skeletal muscle and the actuation rate was significantly increased by the nanoscale dimensions of the fibre.
Domain Wall Conductivity In Oxygen Deficient Multiferroic Ymno3 Single Crystals, Yi Du, Xiaolin Wang, Dapeng Chen, S X. Dou, Z. Cheng, Michael J. Higgins, Gordon G. Wallace, Jiazhao Wang
Domain Wall Conductivity In Oxygen Deficient Multiferroic Ymno3 Single Crystals, Yi Du, Xiaolin Wang, Dapeng Chen, S X. Dou, Z. Cheng, Michael J. Higgins, Gordon G. Wallace, Jiazhao Wang
Gordon Wallace
The transport properties of domain walls in oxygen deficient multiferroic YMnO3 single crystals have been probed using conductive atomic force microscopy and piezoresponse force microscopy. Domain walls exhibit significantly enhanced conductance after being poled in electric fields, possibly induced by oxygen vacancy ordering at domain walls. The electronic conduction can be understood by the Schottky emission and Fowler-Nordheim tunnelling mechanisms. Our results show that the domain wall conductance can be modulated through band structure engineering by manipulating ordered oxygen vacancies in the poling fields.
Control Of Biodegradation Of A Mg Alloy In Simulated Body Fluid, Yafei Zhang, Maria Forsyth, Bruce Hinton, Gordon G. Wallace
Control Of Biodegradation Of A Mg Alloy In Simulated Body Fluid, Yafei Zhang, Maria Forsyth, Bruce Hinton, Gordon G. Wallace
Gordon Wallace
Mg alloy AZ31 is an attractive candidate for coronary artery stents, as it possesses excellent biocompatibility in human body and good mechanical properties. However, AZ31 magnesium alloys generally have poor corrosion resistance in the body environment. This paper reports on the early stages of an investigation into the corrosion mechanism and the morphology of corrosion of AZ31 in simulated body fluid (SBF), The investigation will also consider ways of improving corrosion resistance of this alloy in SBF through the use of ionic liquids. The results to date have shown that AZ31 suffers severe localized pitting corrosion in SBF. The pits …
The Role Of Unbound Oligomers In The Nucleation And Growth Of Electrodeposited Polypyrrole And Method For Preparing High Strength, High Conductivity Films, Wen Zheng, Joselito M. Razal, Geoffrey M. Spinks, Van-Tan Truong, Philip G. Whitten, Gordon G. Wallace
The Role Of Unbound Oligomers In The Nucleation And Growth Of Electrodeposited Polypyrrole And Method For Preparing High Strength, High Conductivity Films, Wen Zheng, Joselito M. Razal, Geoffrey M. Spinks, Van-Tan Truong, Philip G. Whitten, Gordon G. Wallace
Gordon Wallace
Polypyrrole is a material with immensely useful properties suitable for a wide range of electrochemical applications, but its development has been hindered by cumbersome manufacturing processes. Here we show that a simple modification to the standard electrochemical polymerization method produces polypyrrole films of equivalently high conductivity and superior mechanical properties in one-tenth of the polymerization time. Preparing the film as a series of electrodeposited layers with thorough solvent washing between layering was found to produce excellent quality films even when layer deposition was accelerated by high current. The washing step between the sequentially polymerized layers altered the deposition mechanism, eliminating …
Collaborate Or Commiserate !, Gordon G. Wallace
Collaborate Or Commiserate !, Gordon G. Wallace
Gordon Wallace
The ability to build effective collaborative research activities is no longer a secondary skill for scientists. It is a skill critical to the development of a successful career. Without a demonstrated capacity to deliver on projects that mandate collaboration, a competitive position cannot be sustained. The importance of collaboration in delivering efficient, effective and high impact advances in research and innovation is well documented. See for example the position paper entitled “Australian Science in a Changing World: Innovation requires Global Engagement” published by the Australian Academy of Science in 2011. A scant search of the research literature also shows numerous …
Comparative Displacement Study Of Bilayer Actuators Comprising Of Conducting Polymers, Fabricated From Polypyrrole, Poly(3,4- Ethylenedioxythiophene) Or Poly(3,4-Propylenedioxythiophene), Babita Gaihre, Syed Ashraf, Geoffrey M. Spinks, Peter C. Innis, Gordon G. Wallace
Comparative Displacement Study Of Bilayer Actuators Comprising Of Conducting Polymers, Fabricated From Polypyrrole, Poly(3,4- Ethylenedioxythiophene) Or Poly(3,4-Propylenedioxythiophene), Babita Gaihre, Syed Ashraf, Geoffrey M. Spinks, Peter C. Innis, Gordon G. Wallace
Gordon Wallace
The stress gradient generated due to electrochemical oxidation/reduction of a conducting polymer in a bilayer actuator causes a bending movement. Here we report a comparative study of the displacement of bilayer actuators prepared using different conducting polymers. The effects of conducting polymers obtained from electrochemical or chemical synthesis route: different polymers (polypyrrole (PPy), poly(3,4-ethylenedioxythiophene) PEDOT and poly(3,3-dihexyl-3-4-dihydro-2H-thieno[3,4b][1,4]-dioxepine [PProDOT(Hx) 2]); and different electrolytes (0.1 M lithium trifluromethanesulfonate/propylenecarbonate (LiTFSI/PC) and 1-ethyl-3-methyl imidazolium trifluromethanesulfonate (EMITFSI)) on the displacement amplitude and displacement patterns of these actuators were investigated and compared. The results indicate that the bilayer actuator consisting of an electrochemically synthesized conducting polymer …
Levetiracetam-Loaded Biodegradable Polymer Implants In The Tetanus Toxin Model Of Temporal Lobe Epilepsy In Rats, Amy J. Halliday, Toni E. Campbell, Timothy S. Nelson, Karen J. Mclean, Gordon G. Wallace, Mark J. Cook
Levetiracetam-Loaded Biodegradable Polymer Implants In The Tetanus Toxin Model Of Temporal Lobe Epilepsy In Rats, Amy J. Halliday, Toni E. Campbell, Timothy S. Nelson, Karen J. Mclean, Gordon G. Wallace, Mark J. Cook
Gordon Wallace
Approximately one-third of people with epilepsy receive insufficient benefit from currently available anticonvulsant medication, and some evidence suggests that this may be due to a lack of effective penetration into brain parenchyma. The current study investigated the ability of biodegradable polymer implants loaded with levetiracetam to ameliorate seizures following implantation above the motor cortex in the tetanus toxin model of temporal lobe epilepsy in rats. The implants led to significantly shorter seizures and a trend towards fewer seizures for up to 1 week. The results of this study indicate that drug-eluting polymer implants represent a promising evolving treatment option for …