How could the Mourning Cloak Butterfly become the source of inspiration in solar-cell technology?
Anti-reflective surface structure: Nano-nipples
I’ve always believed that butterflies hide something behind their artistic beauty. Whenever I see a butterfly in the warm days of springtime, I‘m amazed at the way they swing in the air by showing off their colorful forewings and hindwings. Although both wings are fragile, they have enough strength to keep the butterfly’s body in the air and make it easy to fly.
This mysterious creature must have had something we needed to discover!
I have cleared the questions in my mind when I encountered the study of the nanOntorio program led by Professor Uwe Erb, at the University of Ontario.
This program was aimed to teach senior school students. They would learn about both bio-inspiration phenomena and nanotechnology applications. Such a great opportunity for young prospective scientists!
According to the study of “Bio-designed Anti-reflective Surfaces”, students examined the eye structure of the Monarch and Mourning Butterflies’ which are popular North American butterflies.
The main difference between these native butterflies comes from the presence of the moth-eye effect. The eyes of those butterflies were examined by using the scanning electron microscope to obtain a high-resolution image of the surface of the eye.
First of all, I should remind you that the structure of an insect eye is quite different than an of the human eye. The type of insect eye is called compound eye due to the presence of repeating units called ommatidia. These thousands of times repeated units are closely packed together and form a semi-spherical facet structure which is the structure of an insect compound eyes.
While the surface structure of the Mourning butterfly shows the moth-eye effect, the Monarch butterfly does not. The examined high-resolution images revealed the nano-nipple-covered structure of the Mourning Cloak’s eye surface. Thanks to this special surface, a refractive index gradient occurs hence it reduces the reflection of the light by the eye. This outcome also explains why only the Mourning Cloak butterfly’s eye has the moth-eye effect, it is due to the anti-reflective surface structure.
Who could imagine that the nano-nipple structure of the beautiful butterfly’s eye would lead to the development of a special type of solar cell design!
A study on solar cells claims that the moth-eye nipple structured solar cells could absorb the light and utilize it efficiently without reflecting.
I believe when we observe, feel, and try to understand nature without losing the ability of thinking, we will definitely end up with another breathtaking discovery.
Do you agree with me? :)
