Thursday, December 20, 2007

Atomic Layer Deposition Replicates Fly's Eye, Demonstrates Novel Optical Properties

Dr. Zhong Lin Wang, Regents' Professor, COE Distinguished Professor, and Director, Center for Nanostructure Characterization, at Georgia Tech, has examined the fine structure of the compound eyes of a household fly and precisely replicated its entire structure using a low-temperature atomic layer deposition technique. The results have been published in the December 6, 2007 online edition of Nanotechnology ("Bio-inspired fabrication of antireflection nanostructures by replicating fly eyes").
"Our contribution is the ability to replicate a biological structure and then measure its physical properties and find out why a particular structure exhibits unusual properties" Wang explains to Nanowerk. "By doing so, we are trying to find an effective fabrication path that follows the evolution of Nature for making extraordinary nanostructures."
"The surface of the fly eye is covered by highly packed protuberances, which potentially increases visual efficiency through increased photon capture for a given stimulus" Wang comments on his group's most recent bioinspired nano research. "We carefully examined the fine structure of the household fly compound eye and then completely replicated the entire configuration by alumina through a low-temperature atomic layer deposition process."

Insects have compound eyes – instead of one lens they see through a sphere with many hundreds or thousands of eyes, so called ommatidiums. Household flies, for instance, have a very well-developed visual system with the capacity of seeing motion, color and pattern of objects in their environment due to their advanced compound eyes.
The Georgia Tech scientists' goal has been focused on the optical properties of the fly eye's nanostructure, aiming to understand the visible light, UV light and infrared light transmission through the structures.
"We achieved the alumina replica by removing the fly compound eye template at high temperature, and the alumina coating was crystallized simultaneously" Wang describes the experimental details. "The success of our replication was not only with the morphologies but also with the optical features – the unique antireflection property of the eye was also inherited by the alumina replica. By measuring the reflective spectra of the replica, we demonstrated that the alumina replica of a fly eye was an efficient antireflection structure of visible light at an incident angle up to 80°."
Wang says that the fly eye replica with antireflection structure exhibits great potential in the applications of optical coating, sensing or lens arrays. His group is now working on developing more sophisticated replication techniques for tuning the optical response of the structure in order to optimize the performance.


Anonymous said...

"Alumina" I assume means an aluminum deposition. It would be fun to see this with other deposits such as diamond-like coatings.

Anonymous said...

I will not concur on it. I assume warm-hearted post. Specially the title-deed attracted me to review the unscathed story.

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