Development of Iridium-bismuth-oxide Coatings for Use in Neural Stimulating Electrodes PDF Download
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Author: Xingge Xu
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Languages : en
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"Implantable neural prosthetics with stimulating electrodes is an increasingly-employed medical practice to treat neural disability. Further development of prosthetics to recover complex neuron function requires electrodes with higher capacity to delivery charge to neuron. Ir-oxide is currently considered as state-of-the-art stimulating electrode material. However, further improvement of its properties is needed. Consequently, in this work, addition of bismuth to Ir-oxide to produce IrxBi1-x-oxide coatings of various composition (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) were fabricated by thermal deposition of their salts on a titanium substrate, and their charge-storage/delivery capacity, surface morphology, crystalline structure and biocompatibility was evaluated. The mixed metal oxides were characterized as consisting of multi-oxide states of Ir and Bi. It was found that only a 20mol.% addition of bismuth to Ir-oxide to produce Ir0.8Bi0.2-oixde yielded superior properties to Ir-oxide. This electrode exhibited a five-fold increase in charge storage capacity over the Ir-oxide electrode, yielding 26.8 mC/cm2. At the same time, this electrode yielded the lowest impedance at 1 kHz. The superior performance of Ir0.8Bi0.2-oixde was explained to originate from change in lattice structure upon introduction of Bi to Ir-oxide, which enables better access of H+ and OH- ions deeper into the oxide structure, thus yielding a higher charge storage capacity. The Ir0.8Bi0.2-oixde electrode also showed good stability and biocompatibility, which makes potentially a better candidate for neural stimulating electrodes than the current state-of-the-art Ir-oxide." --
Author: Xingge Xu
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Languages : en
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"Implantable neural prosthetics with stimulating electrodes is an increasingly-employed medical practice to treat neural disability. Further development of prosthetics to recover complex neuron function requires electrodes with higher capacity to delivery charge to neuron. Ir-oxide is currently considered as state-of-the-art stimulating electrode material. However, further improvement of its properties is needed. Consequently, in this work, addition of bismuth to Ir-oxide to produce IrxBi1-x-oxide coatings of various composition (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) were fabricated by thermal deposition of their salts on a titanium substrate, and their charge-storage/delivery capacity, surface morphology, crystalline structure and biocompatibility was evaluated. The mixed metal oxides were characterized as consisting of multi-oxide states of Ir and Bi. It was found that only a 20mol.% addition of bismuth to Ir-oxide to produce Ir0.8Bi0.2-oixde yielded superior properties to Ir-oxide. This electrode exhibited a five-fold increase in charge storage capacity over the Ir-oxide electrode, yielding 26.8 mC/cm2. At the same time, this electrode yielded the lowest impedance at 1 kHz. The superior performance of Ir0.8Bi0.2-oixde was explained to originate from change in lattice structure upon introduction of Bi to Ir-oxide, which enables better access of H+ and OH- ions deeper into the oxide structure, thus yielding a higher charge storage capacity. The Ir0.8Bi0.2-oixde electrode also showed good stability and biocompatibility, which makes potentially a better candidate for neural stimulating electrodes than the current state-of-the-art Ir-oxide." --
Author: James David Weiland
Publisher:
ISBN:
Category :
Languages : en
Pages : 290
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Author: Bitan Chakraborty
Publisher:
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Category : Iridium oxide
Languages : en
Pages : 0
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Electrode coatings form an integral part of implantable microelectrode arrays (MEAs) which are the basis for chronic neural interfaces capable of providing feedback though neural recording and eliciting functional response through electrical stimulation in patients with lost or impaired neurological functionality. The aim of this dissertation was to develop and assess chronically stable electrode materials with low-impedance and high charge-injection capacity for neural recording and stimulation respectively. To this end, we have investigated three types of transition metal oxide thin-films, iridium oxide, ruthenium oxide and a mixed ruthenium/titanium oxide formed by a DC magnetron reactive sputtering process. We have characterized these films in terms of their microstructure, composition and electrochemistry in order to establish the relationship between film properties and electrochemical charge-injection capacities. Sputtered iridium oxide films (SIROF) and ruthenium oxide films (RuOx) were deposited by reactive sputtering in a DC magnetron sputtering system using water-vapor as a reactive plasma constituent. The films deposited using a combination of oxygen and water-vapor showed lower impedance and higher charge-injection capacity than the films deposited using oxygen alone. The films deposited using only water-vapor as the reactive gas showed the presence of nano-sized metallic iridium and ruthenium on the SIROF and RuOx films respectively. Systematic investigation by plasma optical spectroscopy, surface characterization and electrochemical measurements revealed that the incorporation of water-vapor as a reactive gas constituent, along with oxygen, alters the reduction-oxidation (redox) state of the plasma as well as the microstructure and the electrochemical characteristics for the SIROF and RuOx films. A 3:1 water-vapor to oxygen plasma condition formed a hydrous, low-crystallinity and nodular film microstructure that enabled both electronic and ionic conduction producing an apparent optimal electrode coating with low impedance for recording and high charge-injection capacity for stimulation. Electrochemical measurements on SIROF and RuOx electrodes, deposited using a ratio of watervapor to oxygen 3:1, demonstrated that these have minimal contribution towards oxygen reduction, an unwanted side reaction and also showed rapid reversibility of their respective Faradaic processes during stimulation current pulsing. These films were found to be electrochemically stable for ~1 billion pulses at biphasic 8 nC/phase (0.4 mC/cm2 ) constant current stimulation in an inorganic model of interstitial fluid at 37o C and also showed no indication of cytotoxicity towards primary cortical neurons in a cell viability assay. Additionally, we investigated the deposition and characterization of sputtered mixed oxide films consisting of ruthenium/titanium oxide (RuTiOx) as a neural stimulation and recording electrode. This study was motivated by the observation that RuOx films deposited at optimal watervapor:oxygen gas flow ratios were more friable and thus less physically stable than SIROF deposited under the same conditions. Incorporation of titanium resulted in an increased the hardness of the film, by a factor of two with respect to RuOx films, while still maintaining an adequately low enough impedance for recording and a charge-injection capacity suitable for clinical neural stimulation.
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Category :
Languages : en
Pages : 130
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Languages : en
Pages : 0
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Author: Nehar Ullah
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Languages : en
Pages :
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"Metal-oxide (MO) coatings have been used in many electrochemistry-based applications, such as in the chloro-alkali industry, particularly, for the production of various valuable chemicals (e.g chlorine, sodium hydroxide, oxygen, etc.). MO coatings have also been employed for other purposes, such as electrodes for electrochemical supercapacitors (SCs), corrosion protection of metals, neural-stimulating electrodes, sensor electrodes, and electrodes in organic synthesis and wastewater treatment. This PhD thesis represents an attempt to contribute to the area of mixed metal-oxide (MMOs) electrodes by employing Ir/Ru-oxide coatings as electrode materials in four selected applications. The general objectives of this research were to develop bimetallic Ir/Ru-oxide coatings of various compositions on a titanium metal substrate through thermal decomposition and to investigate their properties/performance in the area of charge delivery/storage and electrocatalytic hydrogenation reactions. Electrochemical and topographical/structural/morphological properties of thermally prepared Ir-Ru-oxide coatings of various compositions formed on a Ti substrate were first investigated for its potential use as neural stimulating electrodes. All coating surfaces displayed a 'cracked-mud' morphology, yielding a high surface roughness. Among several compositions examined, the Ir0.8Ru0.2-oxide coating was found to offer the largest apparent electrochemical active surface area (1540 cm-2 per 1cm2 of geometric area) and charge storage capacity (27 mCcm-2) making it a good candidate for further optimization and possible application as a neural stimulating electrode.The Ir/Ru-oxide coating was also employed in the field of charge storage in supercapacitors (SCs). An electrochemically-activated Ir0.4Ru0.6-oxide coating yielded the highest areal capacitance value (85 mF cm-2) at a galvanostatic charging/discharging current density of 0.1 mA cm-2 (0.9 V potential window). In addition, this cycling procedure enabled a significant increase in capacitance for all coating compositions. It was shown that the areal capacitance of these coatings is strongly dependent upon the nature of the components of which the metal oxide is composed. The electrochemical reduction of CO2 on the Ir0.8Ru0.2-oxide electrode was also investigated. The results showed that the Ir/Ru-oxide electrode can efficiently be used for the electrochemical conversion of CO2 into different valuable organic molecules at high faradaic efficiency, 85% and 96% at 295 K and 277 K, respectively. Ethanol was found to be the major electrochemical reduction product remained in the liquid phase, with minor quantities of methanol, acetone and acetaldehyde. The amount of formed products and the corresponding faradaic efficiency reached its maximum at -1.70 V vs. MSE. The final study on the applicability of the Ir0.8Ru0.2-oxide coating as a cathode material concerned the direct electrochemical regeneration of enzymatically-active 1,4-NADH from its oxidized form NAD+. The results showed that the percentage of enzymatically-active 1,4 NADH present in the product mixture (i.e. the 1,4-NADH recovery) is highly dependent on the electrode potential, reaching a maximum (88 %) at -1.70 V vs. MSE." --
Author: Hiroyuki Fujiwara
Publisher: John Wiley & Sons
ISBN: 9780470060186
Category : Technology & Engineering
Languages : en
Pages : 388
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Ellipsometry is a powerful tool used for the characterization of thin films and multi-layer semiconductor structures. This book deals with fundamental principles and applications of spectroscopic ellipsometry (SE). Beginning with an overview of SE technologies the text moves on to focus on the data analysis of results obtained from SE, Fundamental data analyses, principles and physical backgrounds and the various materials used in different fields from LSI industry to biotechnology are described. The final chapter describes the latest developments of real-time monitoring and process control which have attracted significant attention in various scientific and industrial fields.
Author: Srikanth Ramaswamy
Publisher: Frontiers Media SA
ISBN: 2889745120
Category : Science
Languages : en
Pages : 347
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Author: Nitish V. Thakor
Publisher: Springer Nature
ISBN: 9811655405
Category : Technology & Engineering
Languages : en
Pages : 3686
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This Handbook serves as an authoritative reference book in the field of Neuroengineering. Neuroengineering is a very exciting field that is rapidly getting established as core subject matter for research and education. The Neuroengineering field has also produced an impressive array of industry products and clinical applications. It also serves as a reference book for graduate students, research scholars and teachers. Selected sections or a compendium of chapters may be used as “reference book” for a one or two semester graduate course in Biomedical Engineering. Some academicians will construct a “textbook” out of selected sections or chapters. The Handbook is also meant as a state-of-the-art volume for researchers. Due to its comprehensive coverage, researchers in one field covered by a certain section of the Handbook would find other sections valuable sources of cross-reference for information and fertilization of interdisciplinary ideas. Industry researchers as well as clinicians using neurotechnologies will find the Handbook a single source for foundation and state-of-the-art applications in the field of Neuroengineering. Regulatory agencies, entrepreneurs, investors and legal experts can use the Handbook as a reference for their professional work as well.
Author: Ashutosh Tiwari
Publisher: John Wiley & Sons
ISBN: 1118773683
Category : Technology & Engineering
Languages : en
Pages : 421
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Offers a comprehensive and interdisciplinary view of cutting-edge research on advanced materials for healthcare technology and applications Advanced healthcare materials are attracting strong interest in fundamental as well as applied medical science and technology. This book summarizes the current state of knowledge in the field of advanced materials for functional therapeutics, point-of-care diagnostics, translational materials, and up-and-coming bioengineering devices. Advanced Healthcare Materials highlights the key features that enable the design of stimuli-responsive smart nanoparticles, novel biomaterials, and nano/micro devices for either diagnosis or therapy, or both, called theranostics. It also presents the latest advancements in healthcare materials and medical technology. The senior researchers from global knowledge centers have written topics including: State-of-the-art of biomaterials for human health Micro- and nanoparticles and their application in biosensors The role of immunoassays Stimuli-responsive smart nanoparticles Diagnosis and treatment of cancer Advanced materials for biomedical application and drug delivery Nanoparticles for diagnosis and/or treatment of Alzheimers disease Hierarchical modelling of elastic behavior of human dental tissue Biodegradable porous hydrogels Hydrogels in tissue engineering, drug delivery, and wound care Modified natural zeolites Supramolecular hydrogels based on cyclodextrin poly(pseudo)rotaxane Polyhydroxyalkanoate-based biomaterials Biomimetic molecularly imprinted polymers
