4 research outputs found

    Porous Gold Surfaces for Implantable Neural Electrodes

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    Neural electrodes used for measurements of action potentials in brain cells are often made of gold. These electrodes need to be suciently small to cover only one brain cell, but this induces the problem of increased impedance since impedance scales inversely with surface area. This means that if the surface area is too small, only noise will be measured. One way to overcome this problem is to try to enlarge the real surface area by making the gold nanoporous. In this way, the geometric surface area can be kept small while the real surface area becomes several times larger. In this project, attempts to increase the surface area by anodization has been made. First, a silicon wafer with a large number of chips containing six electrodeseach was fabricated using techniques such as evaporation, UV exposure and etching. Then the chips were diced out of the wafer and each chip was glued onto a circuit board. The copper and gold were connected by a thin aluminum wire and covered by silicone for protection and isolation. Different anodization modes and times were tested on the electrodes, and the results were evaluated by both an optical microscope and a SEM. At the best combination of anodization mode and time, the impedance was measured both before and after anodization. Also, cyclic voltammetry was used in order to calculate the real surface area of the electrodes. The results of the measurements show an increase of the real surface area with up to approximately seven times. This was conrmed by the impedance measurements, which clearly showed that the impedance sharply decreased after anodization compared to the impedance measured before anodization. This indicates that surface enlargement of gold electrodes by anodization is a viable method, but it should be carried out on more electrodes in order to get reliable results

    Sodium-Ion Battery Electrolytes: Modeling and Simulations

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    The authors review the efforts made from a modeling and simulation perspective in order to assist both the fundamental understanding as well as the development of higher performance sodium-ion battery (SIB) electrolytes. Depending on the type of the electrolyte studied, liquid, ionic liquid, polymer, glass, solid-state, etc., the simulation methods applied and the research questions in focus differ, but all contribute to more rational progress. Furthermore, the authors create cases of meta-analysis using literature data. A historical perspective is applied and the focus clearly is on more recent work and novel electrolyte materials. Finally, the authors outline a few prospective areas for where SIB electrolyte simulations can/should be extended for maximum impact in the field
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