Moth’s Inner Eye


Evolutionary Edge
The deep black interior of a moth’s eye is one of the least reflective surfaces in nature. Scientists believe the texture is responsible for the moth’s sensitive night vision. It also minimizes reflections that could signal dinner to predators.

Why Engineers Want It
Simple: The less light reflected by the surface of a solar cell, the more it can convert to electricity.

State of the Tech
Engineers in Japan used a mold to replicate the nanoscale structure of the moth’s eye in an acrylic resin film. In January the researchers reported that applying the film to solar cells increased efficiency by 6 percent. A commercial version is on the way.

Stripes of the Oriental Hornet


Evolutionary Edge
A pigment called xanthopterin, which gives the hornet’s abdominal stripes their yellow color, may power a biological heat pump to keep the hornet cool.

Why Engineers Want It
Xanthopterin is arguably nature’s best solar panel—it naturally converts sunlight into energy.

State of the Tech
Last December researchers from Israel and the United Kingdom dipped the electrodes of a solar cell in a solution of xanthopterin harvested from hornets. Disappointingly, the cell achieved an efficiency of less than 1 percent. Researchers say adding an antireflective surface, which exists in the hornet’s exoskeleton, could improve that performance. In the meantime, they are searching for other natural solar panels worth imitating.

Swallowtail Butterfly Wings


Evolutionary Edge
The black scales of this butterfly’s wings 
reflect virtually no sunlight, perhaps as an adaptation to help regulate the butterfly’s body temperature.

Why Engineers Want It
Like the moth eye, butterfly wings can improve sunlight absorption, and their relatively flat structure may make it even easier to apply the feature to solar cells.

State of the Tech
In 2009 a team of researchers from China and Japan created a titanium dioxide cast of the wing scales that improved the power output of solar cells by 10 percent. They hope to have a version ready for commercial use within five years.