Solar Technology Muse: The Papilios paris Butterfly

Hmm…butterflies and solar technology? How could there possibly be any correlation, one might wonder? Nature actually brims with its own cutting edge technology. In fact, researchers recently discovered that the Papilio paris species of butterfly have tiny solar collectors on their wings, which trap heat from the sun and insulate the butterfly in colder weather.

The Papilio paris species of butterfly has tiny solar collectors on their wings.

Figure 1. The Papilio paris species of butterfly has tiny solar collectors on their wings. On the most basic level, Papilio paris is indeed a visual spectacle. The beautiful swallowtail butterfly, found in South China, flutters about on black wings irorated with dark green scales on the upper wing. On the hind wing, there is a conspicuous upper discal shining blue patch.

Because their wings can absorb more heat at faster rapid, their wings increase the butterfly’s body temperatures faster and plentier. This mechanism could enhance the survival chances of the butterfly individuals in cold climates or high-altitude areas.  Thus, the microstructures on the wings surface are effective solar collectors. And scientists at Shanghai Jiao Tong University agree. [1]  They have imitated the honeycomb-like structures of the solar collectors, which help to scatter and absorb sunlight. By doing so, they have improved the efficiency of the dye-sensitized cells enough to compete with traditional photovoltaic cells.

How, you might ask? Well, the secret lies with the scales of the honeycomb structure, which are on average significantly less reflective than those with cross-ribbing structure. The honeycomb-like pattern scales take advantage of refraction on trapping light, much like a fiber-optic cable. The scales on the wings have a relatively high refractive index, so they take advantage of total internal reflection. That is, the light enters the material, but whenever the light meets another part of the surface, instead of crossing, it is reflected back into the material. So nearly all the incident light could be adsorpted.

Dye-sensitized cells could be turn out to be the hero of solar energy because they are inexpensive to make, can be used on many surfaces and can be used in both high heat and low light settings. The The quasi-honeycomb structure titania replica photoanode has a perfect light absorptivity and higher surface area, which give great advantages to the light harvesting efficiency and dye sorption. The successfully synthesized butterfly wing microstructure titania photoanode we obtained not only gives us new ideas to DSC researches in technology and theory but also offers simplified fabrication of the photothermal, photocatalyzed, and photosensitized devices. Potentially, the fabrication method may be applied to other chitin substrate template and metal oxide systems that could eventually lead to the production of optical, magnetic. or electric devices or components as building blocks for nanoelectronic, magnetic, or photonic integrated systems.

Now, isn’t that cool? One little tiny butterfly can do all this. Imagine all the nature-inspired possibilities!


[1] Zhang, W. et al. Chem. Mater., 2009, 21 (1), pp 33–40