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  • Silica Nanospheres as Photonic Nanostructure Found in the ‘Disco’ Clam Ctennoides Ales

    Scientists from UC Berkeley have recently discovered that a strange naturally occurring bright display of the ‘disco’ or ‘electric’ clam Ctenoides ales is actually a photonic display created by a layer of silica nanospheres. The display functions solely by reflecting light.

    An article was published in the Journal of The Royal Society titled “A Dynamic Broadband Reflector Built from Microscopic Silica Spheres in the ‘Disco’ Clam Ctenoides Ales“, where the researchers shared their findings.

    Laboratory elemental analysis of the reflective nanospheres showed that they are indeed composed of amorphous silica. Both the outer shells and the cores are composed of silica. Silica nanospheres are secreted by the animal and used as a light scattering structure in a behavior modulated reflective photonic display.

    The measurements show that the diameter of the silica nanospheres is at around 300nanometers, an optimal particle size for scattering visible light, especially the shorter blue-green wavelengths of 400-500nm that predominate at 3-50m underwater, which is typically the clam’s habitat. In addition to the diameter, the highly organized packing structure of the nanospheres aid in the scattering of the visible light at the shorter wavelengths.

    The display is so bright that it has been mistakenly thought of as bioluminescent, but the findings show that it is actually based on light scattered by photonic nanostructures.

    Silica has a high index of refraction at n=1.43 at 589nm.

    Silica Nanospheres - 300nm in diameter

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    This study is extremely interesting to scientists in many different fields because it opens their minds up to many creative uses of silica nanospheres that have not been known before. The findings show a practical way to manipulate light in low light situations. Among its other advantages, silica, similar to glass, is a very durable material, with high melt point. Using silica nanospheres in tightly packed arrays to create photonic nanostructures seems like a great idea.

    Highly precise and spherical silica nanospheres with narrow size distribution, diameters around 300nm and sphericity of greater than 99% in dry powder from can be purchased from CosphericNano—a new website specializing in precise silica nanospheres.