Researchers in Singapore are pushing the boundaries of printed color. In a recent issue of Nature Nanotechnology, Joel Wang and coworkers report a method of printing diffraction-limited pixels using the structural color of metallic nanostructures. Structural color refers to materials which derive their pigment from the interaction of tiny mico- or nanometer structures with light, rather than the absorption of light that occurs in most organic dyes. The light scattered by silver, for examples, can be different colors depending on the structure (size, shape, aspect ratio) of the metal at the nano-scale. In this recent paper, the idea of structural color is refined to create extremely high resolution printing. Specifically, arrays of nanometer-scale glass posts are coated with silver; the size and spacing of the posts controls the color of each pixel consisting of a 2×2 post subarray. The result is a remarkably reproduced Lena image, a standard test in the imaging community.
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