Washington, September 18 : A Penn State researcher of Indian origin has announced such a scientific advance that may one day help create cars with the metallic finish of some insects or the deep black of a butterfly's wing, and reflectors patterned on a fly's eyes.
Akhlesh Lakhtakia, the Charles Godfrey Binder (Endowed) Professor of Engineering Science and Mechanics, has revealed that his team has developed a method to rapidly and inexpensively copy biological surface structures.
"Only a small fraction of mutations in evolutionary processes are successful. But, evolution has gone on for at least a billion years. A huge range of biological surface architectures have been created and are available," he says.
He and his colleagues used the conformal evaporated film by rotation (CEFR) technique, to produce coatings that capture the micro- and nano-structure of biological surfaces in a thin coating of glass.
In the CEFR technique, the researchers thermally evaporated the material that formed the coating in a vacuum chamber. The object receiving the coating is fixed to a holder and rotated about once every two seconds.
Lakhtakia has revealed that his team has thus far coated butterfly wings and a fly, creating replicas of these templates with identical surface characteristics.
He says that chalcogenide glasses composed of varying combinations of germanium, antimony, and selenium are used for the purpose.
"With the right temperature, which is room temperature, and the right pressure and rotation speed, the coating process takes about 10 minutes and deposits a 500- nanometer layer," says Lakhtakia.
The researchers point out that many things in the natural world are coloured not by pigment, but by surface structure. It is the way light interacts with the surface that creates the colour, they say.
Lakhtakia's team has devised a way to create a replica template that can be used to create a mould in a harder, less damageable material to make many copies
The researchers say that moulds can be combined and multiplied to create the desired surfaces.
They have revealed that they initially looked at surfaces with optical properties because they are easy to see and identify, but the structural black of some butterflies invites investigation of thermal properties as well.
According to them, creating surfaces that have micro or nanoscale patterns on solar cells, heat exchangers, reflectors and lenses can produce devices that work more efficiently.
"The whole world of biomimetics and bioinspiration is just beginning to emerge. Butterfly wings come in a large variety of surface structures. Eventually we may be able to take these biological structures and modify them to create other properties that do not already exist on biological surfaces," says Raul J. Mart¡n-Palma, visiting professor at Penn State, and a professor in the Department of Applied Physics at Universidad Autonomia de Madrid.
The team are continuing experimenting with butterfly wings, and want to use CEFR on lotus leaves because they are super hydrophobic. They also plan to look at other plant materials as potential surfaces for solar cells.
A research article describing their work has been published in the journals Applied Physics Letters and Nanotechnology.