The Experts below are selected from a list of 93177 Experts worldwide ranked by ideXlab platform
Sunghoon Ahn - One of the best experts on this subject based on the ideXlab platform.
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Low cost fabrication of wo3 films using a room temperature and Low Vacuum air spray based deposition system for inorganic electrochromic device applications
Thin Solid Films, 2015Co-Authors: Sungik Park, Jungoh Choi, Sooyeun Kim, Ji Hyeon Song, Minoru Taya, Sunghoon AhnAbstract:Abstract We report the deposition of tungsten oxide (WO3) thin films on fluorine-doped tin oxide (FTO) and indium-doped tin oxide (ITO) glass substrates by using a room-temperature deposition system based on Low-Vacuum air-spray for the fabrication of inorganic electrochromic windows. The structure of the WO3 films was characterized using X-ray diffraction, and the surface morphology and film thickness were investigated using scanning electron microscopy and atomic force microscopy. The color of the prepared WO3 films changed from slight yelLow to dark blue under applied voltages, demonstrating electrochromism. The WO3 film coated FTO glass exhibited a large electrochromic contrast of up to 50% at a wavelength of 800 nm. The electrochemical properties of the films were examined using cyclic voltammetry and chronocoulometry.
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nano particle deposition system npds Low energy solvent free dry spray process for direct patterning of metals and ceramics at room temperature
International Journal of Precision Engineering and Manufacturing, 2012Co-Authors: Dooman Chun, Jungoh Choi, Caroline Sunyong Lee, Isaku Kanno, Hidetoshi Kotera, Sunghoon AhnAbstract:With increasing concerns of environmental issues in manufacturing process, energy efficient and waste free manufacturing processes have been widely studied. In the field of nano/micro manufacturing, many research results of direct writing processes such as ink jet printing, gravure printing, and rapid prototyping processes have been reported to remove waste-producing conventional lift-off process for patterning. In addition, the use of toxic solvents such as acetone, toluene, xylene and so on has been decreased. At the same time, energy efficiency becomes one of environmental issues in manufacturing process. In this research, Nano particle deposition system (NPDS), a dry spray deposition process for fabrication of meta and ceramic direct patterning at room temperature, was introduced according to the environmental aspects. In previous studies, NPDS has shown the feasibility of the depositions of metals such as Sn and Ni, and the depositions of ceramics such as Al2O3, and TiO2 by spraying powders under Low Vacuum condition. The advantages of NPDS are 1) solvent free dry deposition process, 2) relatively Low energy consumption with room temperature and Low Vacuum process condition, and 3) direct patterning process. The energy consumption in NPDS was briefly compared with similar processes including aerosol deposition and cold spray. The direct patterning results with 200μm width line pattern using micro-nozzle were fabricated without any post-processes. These results confirmed NPDS can become a solvent-free energy efficient direct patterning process for metals and ceramics.
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Nano particle deposition system (NPDS) for ceramic and metal coating at room temperature and Low Vacuum condition
2008 International Conference on Smart Manufacturing Application, 2008Co-Authors: Dooman Chun, Minhyeng Kim, Jaechul Lee, Sunghoon AhnAbstract:Nano particle deposition system (NPDS) is the newly developed ceramic and metal coating process. Nano and micro sized powders are sprayed through the supersonic nozzle at room temperature and Low Vacuum condition and deposited on various substrates. In this research, ceramic titanium dioxide (TiO2) coatings were deposited on metal substrates (SUS, Cu, Al) and polymer substrates (PET, PMMA), and metal tin (Sn) coating was deposited on SUS substrate. Coatings were fabricated with rectangular and line shapes at high deposition rate and without causing thermal damage on the substrates. Deposition images and material properties such as chemical composition and morphology were measured. The test results showed that the NPDS provides a new coating method of ceramic and metal materials with large surface area.
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a nano particle deposition system for ceramic and metal coating at room temperature and Low Vacuum conditions
International Journal of Precision Engineering and Manufacturing, 2008Co-Authors: Dooman Chun, Minhyeng Kim, Jaechul Lee, Sunghoon AhnAbstract:A new nano-particle deposition system (NPDS) was developed for a ceramic and metal coating process. Nano-and micro-sized powders were sprayed through a supersonic nozzle at room temperature and Low Vacuum conditions to create ceramic and metal thin films on metal and polymer substrates without thermal damage. Ceramic titanium dioxide (TiO₂) powder was deposited on polyethylene terephthalate substrates and metal tin (Sn) powder was deposited on SUS substrates. Deposition images were obtained and the resulting chemical composition was measured using X-ray photoelectron spectroscopy. The test results demonstrated that the new NPDS provides a noble coating method for ceramic and metal materials.
Milos Toth - One of the best experts on this subject based on the ideXlab platform.
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electron flux controlled switching between electron beam induced etching and deposition
Journal of Applied Physics, 2007Co-Authors: Milos Toth, Charlene J Lobo, Gavin Hartigan, Ralph W KnowlesAbstract:Electron beam induced deposition (EBID) and etching (EBIE) are promising methods for the fabrication of three-dimensional nanodevices, wiring of nanostructures, and repair of photolithographic masks. Here, we study simultaneous EBID and EBIE, and demonstrate an athermal electron flux controlled transition between material deposition and etching. The switching is observed when one of the processes has both a higher efficiency and a Lower precursor partial pressure than the other. This is demonstrated in two technologically important systems: during XeF2-mediated etching of chrome on a photolithographic mask and during deposition and etching of carbonaceous films on a semiconductor surface. Simultaneous EBID and EBIE can be used to enhance the spatial localization of etch profiles. It plays a key role in reducing contamination buildup rates during Low Vacuum electron imaging and deposition of high purity nanostructures in the presence of oxygen-containing gases.
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secondary electron contrast in Low Vacuum environmental scanning electron microscopy of dielectrics
Journal of Applied Physics, 2005Co-Authors: B L Thiel, Milos TothAbstract:Low Vacuum scanning electron microscopy (SEM) is a high-resolution technique, with the ability to obtain secondary electron images of uncoated, nonconductive specimens. This feat is achieved by alLowing a small pressure of gas in the specimen chamber. Gas molecules are ionized by primary electrons, as well as by those emitted from the specimen. These ions then assist in dissipating charge from the sample. However, the interactions between the ions, the specimen, and the secondary electrons give rise to contrast mechanisms that are unique to these instruments. This paper summarizes the central issues with charging and discusses how electrostatically stable, reproducible imaging conditions are achieved. Recent developments in understanding the physics of image formation are reviewed, with an emphasis on how local variations in electronic structure, dynamic charging processes, and interactions between ionized gas molecules and Low-energy electrons at and near the sample surface give rise to useful contrast m...
Wanderley De Souza - One of the best experts on this subject based on the ideXlab platform.
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comparative analysis of trichuris muris surface using conventional Low Vacuum environmental and field emission scanning electron microscopy
Veterinary Parasitology, 2013Co-Authors: Wanderley De Souza, Eduardo Jose Lopes Torres, Kildare MirandaAbstract:Abstract The whipworm of the genus Trichuris Roederer, 1791, is a nematode of worldwide distribution and comprises species that parasitize humans and other mammals. Infections caused by Trichuris spp. in mammals can lead to various intestinal diseases of human and veterinary interest. The morphology of Trichuris spp. and other helminths has been mostly studied using conventional scanning electron microscopy of chemically fixed, dried and metal-coated specimens, although this kind of preparation has been shown to introduce a variety of artifacts such as sample shrinking, loss of secreted products and/or hiding of small structures due to sample coating. Low Vacuum (LVSEM) and environmental scanning electron microscopy (ESEM) have been applied to a variety of insulator samples, also used in the visualization of hydrated and/or live specimens in their native state. In the present work, we used LVSEM and ESEM to analyze the surface of T. muris and analyze its interaction with the host tissue using freshly fixed or unfixed hydrated samples. Analysis of hydrated samples showed a set of new features on the surface of the parasite and the host tissue, including the presence of the secretory products of the bacillary glands on the surface of the parasite, and the presence of mucous material and eggs on the intestinal surface. Field emission scanning electron microscopy (FESEM) was also applied to reveal the detailed structure of the glandular chambers in fixed, dried and metal coated samples. Taken together, the results show that analysis of hydrated samples may provide new insights in the structural organization of the surface of helminth parasites and its interaction with the infected tissue, suggesting that the application of alternative SEM techniques may open new perspectives for analysis in taxonomy, morphology and host–parasite interaction fields.
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using environmental scanning electron microscopy esem as a quantitative method to analyse the attachment of giardia duodenalis to epithelial cells
Micron, 2012Co-Authors: Claudia Maiabrigagao, Wanderley De SouzaAbstract:Abstract Giardia duodenalis is a human parasite that colonises the small intestine. In some studies, it may be necessary to estimate the parasite–host adhesion index. When working in vitro , it is very difficult to determine the relative number of parasites adhered to intestinal cells because parasites might be removed from enterocytes during specimen preparation. We have encountered such difficulties with sample analyses when using light and conventional scanning electron microscopy, including the loss of adherent cells during the processing steps. In this study, we showed that environmental scanning electron microscopy (ESEM), which alLows the examination of specimens at normal atmospheric pressure or in very Low Vacuum without any previous treatment, can be used effectively in quantitative studies of the parasite–host relationship.
B L Thiel - One of the best experts on this subject based on the ideXlab platform.
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secondary electron contrast in Low Vacuum environmental scanning electron microscopy of dielectrics
Journal of Applied Physics, 2005Co-Authors: B L Thiel, Milos TothAbstract:Low Vacuum scanning electron microscopy (SEM) is a high-resolution technique, with the ability to obtain secondary electron images of uncoated, nonconductive specimens. This feat is achieved by alLowing a small pressure of gas in the specimen chamber. Gas molecules are ionized by primary electrons, as well as by those emitted from the specimen. These ions then assist in dissipating charge from the sample. However, the interactions between the ions, the specimen, and the secondary electrons give rise to contrast mechanisms that are unique to these instruments. This paper summarizes the central issues with charging and discusses how electrostatically stable, reproducible imaging conditions are achieved. Recent developments in understanding the physics of image formation are reviewed, with an emphasis on how local variations in electronic structure, dynamic charging processes, and interactions between ionized gas molecules and Low-energy electrons at and near the sample surface give rise to useful contrast m...
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consequences of positive ions upon imaging in Low Vacuum scanning electron microscopy
Journal of Microscopy, 2002Co-Authors: J P Craven, Frank S Baker, B L Thiel, A M DonaldAbstract:Summary The effects caused by an excess quantity of ionized gas molecules within the Low Vacuum, variable pressure and environmental scanning electron microscope (ESEM) are described with reference to mechanisms by which they can influence imaging conditions. These effects can include specimen charging, recombination and development of space charge. They are demonstrated for three different classes of sample: (1) an electrically grounded conductor, (2) an electrically floating conductor, and (3) an electrical insulator. A new device is presented that will aid excess charge removal within the ESEM and help correct for some of these effects, thereby dramatically improving imaging over a wide range of operating conditions and samples. The mechanism of image enhancement is demonstrated with reference to the three classes of sample described above.
Dooman Chun - One of the best experts on this subject based on the ideXlab platform.
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Electrochemical Performance of Few-Layer Graphene Nano-Flake Supercapacitors Prepared by the Vacuum Kinetic Spray Method
MDPI AG, 2018Co-Authors: Mohaned Mohammed Mahmoud Mohammed, Dooman ChunAbstract:A few-layer graphene nano-flake thin film was prepared by an affordable Vacuum kinetic spray method at room temperature and modest Low Vacuum conditions. In this economical approach, graphite microparticles, a few layers thick, are deposited on a stainless-steel substrate to form few-layer graphene nano-flakes using a nanoparticle deposition system (NPDS). The NPDS alLows for a large area deposition at a Low cost and can deposit various metal oxides at room temperature and Low Vacuum conditions. The morphology and structure of the deposited thin films are alterable by changing the scan speed of the deposition. These changes were verified by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. The electrochemical performances of the supercapacitors, fabricated using the deposited films and H3PO4–PVA gel electrolytes with different concentrations, were measured using a 2-electrode cell. The electrochemical performance was evaluated by cyclic voltammetry, galvanostatic Charge–discharge, and electrochemical impedance spectroscopy. The proposed affordable fabricated supercapacitors show a high areal capacitance and a small equivalent series resistance
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nano particle deposition system npds Low energy solvent free dry spray process for direct patterning of metals and ceramics at room temperature
International Journal of Precision Engineering and Manufacturing, 2012Co-Authors: Dooman Chun, Jungoh Choi, Caroline Sunyong Lee, Isaku Kanno, Hidetoshi Kotera, Sunghoon AhnAbstract:With increasing concerns of environmental issues in manufacturing process, energy efficient and waste free manufacturing processes have been widely studied. In the field of nano/micro manufacturing, many research results of direct writing processes such as ink jet printing, gravure printing, and rapid prototyping processes have been reported to remove waste-producing conventional lift-off process for patterning. In addition, the use of toxic solvents such as acetone, toluene, xylene and so on has been decreased. At the same time, energy efficiency becomes one of environmental issues in manufacturing process. In this research, Nano particle deposition system (NPDS), a dry spray deposition process for fabrication of meta and ceramic direct patterning at room temperature, was introduced according to the environmental aspects. In previous studies, NPDS has shown the feasibility of the depositions of metals such as Sn and Ni, and the depositions of ceramics such as Al2O3, and TiO2 by spraying powders under Low Vacuum condition. The advantages of NPDS are 1) solvent free dry deposition process, 2) relatively Low energy consumption with room temperature and Low Vacuum process condition, and 3) direct patterning process. The energy consumption in NPDS was briefly compared with similar processes including aerosol deposition and cold spray. The direct patterning results with 200μm width line pattern using micro-nozzle were fabricated without any post-processes. These results confirmed NPDS can become a solvent-free energy efficient direct patterning process for metals and ceramics.
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Nano particle deposition system (NPDS) for ceramic and metal coating at room temperature and Low Vacuum condition
2008 International Conference on Smart Manufacturing Application, 2008Co-Authors: Dooman Chun, Minhyeng Kim, Jaechul Lee, Sunghoon AhnAbstract:Nano particle deposition system (NPDS) is the newly developed ceramic and metal coating process. Nano and micro sized powders are sprayed through the supersonic nozzle at room temperature and Low Vacuum condition and deposited on various substrates. In this research, ceramic titanium dioxide (TiO2) coatings were deposited on metal substrates (SUS, Cu, Al) and polymer substrates (PET, PMMA), and metal tin (Sn) coating was deposited on SUS substrate. Coatings were fabricated with rectangular and line shapes at high deposition rate and without causing thermal damage on the substrates. Deposition images and material properties such as chemical composition and morphology were measured. The test results showed that the NPDS provides a new coating method of ceramic and metal materials with large surface area.
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a nano particle deposition system for ceramic and metal coating at room temperature and Low Vacuum conditions
International Journal of Precision Engineering and Manufacturing, 2008Co-Authors: Dooman Chun, Minhyeng Kim, Jaechul Lee, Sunghoon AhnAbstract:A new nano-particle deposition system (NPDS) was developed for a ceramic and metal coating process. Nano-and micro-sized powders were sprayed through a supersonic nozzle at room temperature and Low Vacuum conditions to create ceramic and metal thin films on metal and polymer substrates without thermal damage. Ceramic titanium dioxide (TiO₂) powder was deposited on polyethylene terephthalate substrates and metal tin (Sn) powder was deposited on SUS substrates. Deposition images were obtained and the resulting chemical composition was measured using X-ray photoelectron spectroscopy. The test results demonstrated that the new NPDS provides a noble coating method for ceramic and metal materials.
