Browsing by Subject "Capillarity"

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    Capillary origami as a new method for obtaining folded structures with interior nanoparticle coating
    (Elsevier, 2020) Özkazanç, Gökçe; Erdem, E. Yegan
    We introduce capillary origami as a new method to obtain 3D enclosures with coated nanoparticles on their inner surfaces. When a liquid droplet that contains nanoparticles is placed on the surface of a thin and flexible membrane, the membrane folds around the droplet. As the droplet evaporates nanoparticles deposit on folded surfaces and eventually a 3D enclosure is obtained. In this study, both magnetic iron-oxide (Fe3O4) and gold (Au) nanoparticles are used and it is shown that with both types of nanoparticles the enclosures remain closed after the complete evaporation of the droplet. It is also demonstrated that the magnetic nanoparticles can be concentrated at a chosen location on the folded geometry by using a magnet during evaporation. The origami based coating method is applied on different geometries and distribution of nanaparticles depending on the surface orientation is quantified. As part of the study, the capillary origami behavior of liquids with and without nanoparticles is compared.
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    The magical world of metamaterials
    (IEEE, 2009-10) Özbay, Ekmel
    In recent years, there has been a burgeoning interest in rapidly growing field of metamaterials due to their unprecedented properties unattainable from ordinary materials. Veselago pointed out that a material exhibiting negative values of dielectric permittivity (ε) and magnetic permeability (μ) would have a negative refractive index [1]. Generally speaking, the dielectric permittivity (ε) and the magnetic permeability (μ) are both positive for natural materials. In fact it is possible to obtain negative values for ε and μ by utilizing proper designs of metamaterials. Left-handed electromagnetism and negative refraction are achievable with artificially structured metamaterials exhibiting negative values of permittivity and permeability simultaneously at a certain frequency region. The first steps to realize these novel type of materials were taken by Smith et al., where they were able to observe a left-handed propagation band at frequencies where both dielectric permittivity and magnetic permeability of the composite metamaterial are negative [2]. Soon after, left-handed metamaterials with an effective negative index of refraction are successfully demonstrated by various groups [3].