Broadband antireflection (AR) is essential for improving the photocurrent generation of photovoltaic modules or the enhancement of visibility in optical devices. Beyond conventional AR coating methods, moth eye mimicking nanostructures give new directions to enhance broadband antireflection through the selection of geometrical parameters, such as height, periodic distance, shape, and arrangement. This study numerically and experimentally investigates the behavior of light on complex nanostructures designed to mimic the surface of the moth eye with mixed shapes and various arrangements. To obtain broadband AR, we rigorously study the design parameters, such as height, periodic distance, shape, and arrangement, on a transparent quartz substrate. Several kinds of nanopillar arrays are elaborately fabricated including mixed nanostructures comprising pointy and round shapes in ordered and random arrangements via colloidal lithography. The optimal morphology of moth eye nanostructure arrays for broadband antireflection is suggested in view of reflectance and average weight transmittance.

The sub-wavelength structures in moth eyes exhibit fascinating antireflective properties over the broadband wavelength region and at large incident angle by generating an air-mixed heterogeneous optical interface. In this work, antireflective behavior of transparent glass is observed with the elaborate controls of the nanopillar morphology. The reflectance spectrum shows a red shift and a notable light scattering with increase of the height of the nanopillars. The nanopillar arrays with a pointed cone shape have better optical performance in visible range than the rounded cone shape which is typical antireflective nanostructures in nature. Based on the observed antireflective behaviors, the flat and low value reflectance spectrum in the visible wavelength range is demonstrated by moth eye mimicking nanostructures on both sides of a glass surface. It is a unique strategy to realize a flat and broadband spectrum in the visible range showing 99% transparency via the appropriate matching of nanopillar height on the front and back sides of glass. The controlled reflection based color tuning on the antireflective and transparent glass is also obtained by adjusting the height of the nanopillar arrays on both sides. The visibility and self-cleaning ability of moth eye mimicking glass are examined for practical applications such as antireflection and self-cleaning.

We report the development of a novel quartz nanopillar (QNP) array cell separation system capable of selectively capturing and isolating a single cell population including primary CD4(+) T lymphocytes from the whole pool of splenocytes. Integrated with a photolithographically patterned hemocytometer structure, the streptavidin (STR)-functionalized-QNP (STR-QNP) arrays allow for direct quantitation of captured cells using high content imaging. This technology exhibits an excellent separation yield (efficiency) of ~95.3 ± 1.1% for the CD4(+) T lymphocytes from the mouse splenocyte suspensions and good linear response for quantitating captured CD4(+) T-lymphoblasts, which is comparable to flow cytometry and outperforms any non-nanostructured surface capture techniques, i.e. cell panning. This nanopillar hemocytometer represents a simple, yet efficient cell capture and counting technology and may find immediate applications for diagnosis and immune monitoring in the point-of-care setting.

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