The eye's many lenses and curved shape give it a wide field of view, as well as super-fast motion detection and image recognition, the researchers reported in the April 28 issue of the journal Science.
Minute cameras and motion sensors with these types of lenses could have medical, industrial and military applications, according to the researchers.
Insects have multiple imaging units called "ommatidia" that are pointed in different directions. The researchers used flexible polymers to build artificial ommatidia, each with a tiny lens connected to a tube-like "waveguide" that directs the light down to an opt electronic imaging device.
Then, they arranged the ommatidia around a dome, projecting outwards in all directions. Of the many different types of insect eyes, a bee's eye is most similar to the new mechanical eye, they said.
Just like pins in a pincushion or a dragonfly's 30,000 ommatidia, the team's artificial ommatidia are each oriented at a slightly different angle. The researchers have shown that the lenses and waveguides of the artificial eyes focus and conduct light in the same way as an insect's eye.
"The lenses and waveguides are the most important part of the system," said Luke Lee, the principal investigator of the study.
"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," Lee said.
While conventional micro fabrication 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.
These eyes can eventually be used as cameras or sensory detectors to capture visual or chemical information from a wider field of vision than previously possible, even with the best fish-eye lens, according to Lee.
The researchers speculate that the artificial compound eyes will be put to use within a few years. Their first applications may be in ultra-thin camera phones, and then in camcorders for omnidirectional surveillance imaging and such uses as small, hidden, wearable cameras. Enditem
| | Editor: Pliny Han |