Every insect eye consists of lots of small units called facets. Each facet is comprised of lens, pigment, and photoreceptors. The lens is mounted on a transparent crystalline cone that allows the light to reach the photoreceptors. Black pigment isolates facets from each other and screens out background light.The hemispherical shape allows extremely wide-angle fields of view, and the other advantage of this design is that it has incredible depth of view, which keeps objects focused despite the distance from the camera.
[Image Source: University of Illinois and Beckman Institute]
John Rogers, a physical chemist and materials engineer at the University of Illinois at Urbana-Champaign and leader of the research, said “We think of the insect world as an inspiration for design, but we’re not constrained by it… It’s not bio-mimicry; it’s bio-inspiration.”
In these artificial insect eyes the tiny lenses are located on top of columns based on a flexible membrane – all made from elastic polymer also used in contact lenses. Each supporting cylindrical post protected its lens from any bending or stretching in the base membrane.The array of lenses lies on a second layer of stretchable silicon photodiodes that converted the focused light from the lenses into current or voltage, which is transported to other electronics by small serpentine wires.The final layer of “black matrix” is positioned on top of both the lens layer and the photodiode layer to protect the whole structure from background light. The black pigment of real insect eyes can adjust to changing conditions of light, but the artificial camera does these adjustments via software.
Each individual facet provides 1 pixel of resolution. A 180-pixel-resolution camera doesn’t offer the best view, but Rogers anticipates making camera designs with better resolution comparable to the eyes of praying mantises (15 000 facets) and dragonflies (28 000 facets).