While an insect's ommatidia each end in a photoreceptor cell that transmits a light signal to the creature's optic nerve, Lee plans to couple his team's ommatidia with CCD photodiodes, the light-capturing units used in digital cameras and camcorders. He also has plans to link them to spectroscopes for chemical detection and analysis.
"The lenses and waveguides are the most important part of the system," Lee said. "People have said that it would be totally impossible to create them with an angle, but now that we've done it, we're ready to integrate imaging or chemical sensing into the eyes."
While conventional microfabrication techniques are expensive and use high temperatures, Lee and his team borrowed from nature, using a low temperature system, photopolymerization, and self-aligning, self-writing technology.
To create the artificial eye, the team first needed to construct a hemispherical mold of the eye's outer layer, a structure consisting of thousands of microlenses. Using existing technology, they made a flat array of these tiny, domed lenses arranged in the hexagonal honeycomb pattern. On top of this, they applied a thin slab of an elastic polymer called polydimethylsiloxane, or PDMS, creating a concave pattern of the lenses in the polymer. By affixing the PDMS membrane over the opening of a vacuum chamber and applying negative air pressure, they pulled it into the dome shapes they needed, controlling its form by using different pressures.
They then had a hemisphere-shaped cup pocked with some 8,700 indentations: a compound-eye mold that could be used over and over again using soft lithography technology, a set of methods developed over the last decade to replicate
Source:University of California - Berkeley