Visual perception of white color stems from multiple scattering of broadband light in random structures. Such structures are found in diverse organisms including beetles, butterflies, spiders, cuttlefish, squids, and clams. White beetle scales contain an interconnected fibrillar nanostructure, while the others possess structures that are based on particles or compartmentalized units such as spheres, ellipsoids, prisms, and multilayer aggregates. The fibrillar nanostructure in the scales of a white beetle genus, Cyphochilus, is strongly anisotropic, which makes it one of the most efficient light-scattering biological structures known to us today. Despite their effectiveness in nature, the intricate optical fibrillar network of nanostructures inside the scales has been difficult to mimic without using complicated templating techniques. Thus, there is a need to uncover fabrication techniques that are amenable to mass production, while also preserving the scattering strength by mimicking the key structural characteristics of the white beetle scales.
Researchers at the University of New Mexico have achieved fibrous nanostructures that surpass Cyphochilus scales in light scattering strength. Essentially, they have replicated the characteristic structural parameters inside Cyphochilus scales – fiber diameter, diameter distribution, filling fraction, and structural anisotropy – in synthetic nanofibrous materials to functionally mimic the biological material. To fabricate the synthetic nanostructure, electrospinning was chosen because this conventional technique is amenable to nanomanufacturing. To maximize scattering strength in the electrospun nanofibers, optical modeling was performed based on effective medium theory and the structural parameters were optimized by modeling calculations. Electrospun structures exhibit even stronger optical scattering than Cyphochilus scales, as confirmed by experimental measurements that match well with modeling calculations. These results support that controllable fibrous nanostructures, that exceed the exceptionally strong broadband optical scattering found among living organisms, can be volume-produced.
- Increases optical scattering characteristics of nonwoven silk nanofibers
- When appropriately structured, can surpass Cyphochilus scales in scattering strength for the entire visible spectrum
- Enables mass production of biomimicking nanostructures
- Shows how the key structural parameters affect scattering properties in the electrospun films
- Optical Scattering
- Thermal Insulation
- Solar Rejection
Name: Andrew Roerick