Say what you will about the 1990’s, the decade produced some severely under-appreciated and entirely too short-lived cultural moments: I mean, Hammer pants? Titanic? Come on – you know you loved it!  Another phenomenon of the 1990’s that in some ways is slightly less exciting than the OJ Simpson trial, but which has stayed with us to this day is: green-tinted glass.

Image courtesy metaefficient.com

No one knows exactly how it started, but I imagine that sometime in the 1990’s, an architect somewhere in the world specified green-tinted glass for the fenestration on a prominent building. This building was probably published in a print magazine that a lot of other architects read, and somehow, without even knowing what was happening, they all suddenly wanted to use green glass on their projects too.  I completely understand: the exact same thing happened to me when I was reading Elle and saw that Heidi Klum decided to cut bangs (and yes, mine are still growing out).

Image courtesy instyle.com

What if there was a way to have your green glass cake when it felt trendy, and then not have the same cake twenty years later when it was moldy and dated, and kind of sad looking?  I think perhaps there is!

I recently learned that a University of Connecticut scientist has developed a method that allows films and displays to change color.  The obvious application for this technology is sunglasses, and everyone from Hollywood stars to the U.S. military are interested in lenses that respond to changes in the environment to make it easier to see (or be seen).

Typical transition lenses use photochromic films, which are sheets of polymers that change color when light hits them. The new color-changing technology uses electrochromic lenses; these are controlled by an electric current passing through them that adjusts when triggered by a stimulus such as light (Physorg.com). The arrangement is similar to a double-pane window with a gel sandwiched between the glass.

Image courtesy physorg.com

That’s what got me thinking that this material, which can change color as quickly as electricity can travel through it (ie instantaneously) could be great for buildings.  The polymer used by the scientists creates less waste and is less expensive to produce than previous mixtures, which is good because for an architectural application, you’d need a lot of it!

WU XING:

I have filed this under fire because electricity creates the color change, and under wood, because it’s a polymer.

Cited:

“A Better Way to Photo Gray: New Technology Allows Lenses to Change Color Rapidly.” Physorg.com 07/12/11. Accessed 07/15/11. URL.

Images courtesy amnh.org and vipnyc.org 

Pinned up along one side of the wall was a row of brilliantly colored butterflies.  They were so glittery and shiny and their patterns so vivid in color that I wanted to sew a coat out of their wings and wear it for the rest of my life.  But I abandoned the idea, reasoning that the colors would probably fade with time and also because a coat made of insect parts is gross.

Fast forward to today and the butterfly wing coat idea is still gross.  However, I did find out that the colors on butterfly wings don’t fade because … wait for it … they are made of crystal nanostructures called gyroids.  “These are ‘mind-bendingly weird’ three-dimensional curving structures that selectively scatter light,” according to Richard Prum, chair and the William Robertson Coe Professor in the Department of Ornithology, Ecology and Evolutionary Biology at Yale (Source: Physorg.com). Geometrically speaking, a gyroid is “an infinitely connected triply periodic minimal surfacediscovered by Alan Schoen in 1970″ (Wikipedia) and it’s highly awesome.  You can think of it as a network of “three bladed boomerangs” if that helps (Physorg.com). 

Image courtesy Wikipedia

The gyroids on butterfly wings are made of chitin, which is a tough starchy material that forms the exterior of insects and crustaceans.  The chitin that makes up the exoskeletons of crabs and scorpions is typically deposited on the outer membranes of cells, and it doesn’t usually take the form of a gyroid. 

The Yale research team used an X-ray scattering technique at the Argonne National Laboratory in Illinois to determine that, “essentially, the outer membranes of the butterfly wing scale cells grow and fold into the interior of the cells. The membranes then form a double gyroid — or two, mirror-image networks shaped by the outer and inner cell membranes. The latter are easier to grow but are not as good at scattering light. Chitin is then deposited in the outer gyroid to create a single solid crystal. The cell then dies, leaving behind the crystal nanostructures on the butterfly wing” (Physorg.com). 

Okay, so the crystal nanostructures come in pretty colors and they’re durable.  But the most exciting aspect of this line of research has to do with solar cells.  Gyroid shapes can improve the efficiency of solar cells and other optical devices. 

Image Credit: Michael Apel, Wikipedia Commons

Researcher Di Zhang and colleagues are turning to the microscopic solar scales on butterfly wings in their search for materials that may improve the already high efficiency of light-harvesting in dye-sensitized solar cells, also known as Grätzel cells after inventor Michael Grätzel. These solar cells can convert 10% of the light energy that strikes them into electricity (Source: ACS). 

Di Zhang and co. used natural butterfly wings as a mold or template to make copies of the solar collectors, and transferred those light-harvesting structures to Grätzel cells. “Laboratory tests showed that the butterfly wing solar collector absorbed light more efficiently than conventional dye-sensitized cells. The fabrication process is simpler and faster than other methods, and could be used to manufacture other commercially valuable devices, the researchers say” (ACS).  The more efficient our solar cells become, the fewer of them we’ll need to manufacture – meaning less waste, less space, less time, and more betterness.

WU XING:

I’m always distracted by things that are shiny. I’m placing this post in the fire category.

Cited:

“Novel Photoanode Structure Templated from Butterfly Wing Scales”, Chemistry of Materials. Provided by ACS via Physorg.com.  Accessed 06/15/10.  URL.

“Colors of Butterfly Wing Yield Clues to Light-Altering Structures” Provided by Yale University via Physorg.com.  Accessed 06/15/10.  URL.