Blue: Inspired by Structural Color

"Light in Nature creates the movement of colors." - Robert Delaunay

As part of our Connect with Nature series, we are going to explore how color is created in nature and how learning from organic structures that manipulate light in a prism-like manner could lead to significant nature-inspired innovations.

The majority of the mesmerizing colors we see in the natural world are a result of chemical or pigment-based coloration. The color blue, however, is rarely found as a pigment, and its emergence in the wings of butterflies and bird feathers holds an essential evolutionary secret.

Nature’s engineering ability designed an alternative coloring mechanism that uses complex microscopic structures to convey the color blue. In contrast to pigments, structural colors cause light waves to diffract and interfere, thus intensifying some colors while canceling others. 

The recent technological advances have generated an increased interest in structural colors and their great potential for creating new sustainable and durable materials to replace traditional paints and dyes in product design.

THE COLOR BLUE IN MORPHO BUTTERFLIES

Morpho Butterfly by Vincent van Zalinge

The Morpho butterfly is a species native to the rain forests of South America that have attracted the interest of researchers all over the world due to its unique appearance.

The metallic blue hues of its wings have come to be one of the most studied examples of structural colors while also illustrating nature’s ingenuity in adapting the bodies of living organisms for the ongoing survival race.

Morpho Butterfly Wing via Science Source

Despite the magnificent iridescent blue color of the Morpho butterflies, their wings contain no blue pigments. Their coloration is given instead by the actual shape of their wings or, more precisely, through the interaction of light waves within the nanometric structures on each individual scale. 

Photograph by Raoul Gonzales

On closer inspection, scientists discovered that the tiny scales on the Morpho butterfly wings present Christmas tree-shaped ridges made of chitin and air pockets. These translucent structures act like a microscopic light filter and directly influence how light waves interfere with each other.

Butterfly Wing Nanostructure via Science Source

After a light beam hits the first branch of one of those tree structures (lamellae), it then passes through every layer. The light with the right wavelength—in this case, the blue color— will be reinforced and reflected (constructive interference) while the others will be destroyed (destructive interference).

This process resembles how glass prisms refract light splitting it into rainbow-colored wavelengths.

The intricacy of these natural structures doesn’t end here as the apparently random distribution of these tree-like ridges determines what color is reflected and at which intensity. That’s why we see very slight variations in coloring when we look at the wings of the Morpho butterfly from different angles.



Image Source: what-when-how

__________

At RAA, we are permanently inspired by how nature seamlessly combines design and engineering to create unique properties in organic structures. We use biomimicry to design elegant customized products that are rooted in admiration for the natural world.


Our Wrap and Flower collections explore the potential of metal ridges to reflect the light and replicate the ever-shifting quality of natural elements in 3D printed contemporary jewelry and home accessories. However, these pieces were just the beginning of our exploration. 

In our upcoming collection titled Light, we are looking into the qualities of structural color through a series of pieces based on this principle, as a method to create color through form.

RESOURCES

Dushkina, Natalia & Lakhtakia, Akhlesh. Structural Colors

 Fu, Yulan & Tippets, Cary & Donev, Eugenii & Lopez, Rene. Structural colors: From natural to artificial systems

Radwanul Hasan Siddique, Silvia Diewald, Juerg Leuthold, and Hendrik Hölscher. Theoretical and experimental analysis of the structural pattern responsible for the iridescence of Morpho butterflies

 

Blue: Inspired by Structural Color