The gap between science fiction and reality is narrowing further. Scientists always desire to replicate nature, and they at times come close to doing it. The latest being an effort by the researchers at the University of Illinois and Northwestern University who have developed a high-performance, hemispherical 'eye' camera using an array of single-crystalline silicon detectors and electronics, configured in a stretchable, interconnected mesh. By combining stretchable optoelectronics and biologically inspired design, scientists have created a remarkable imaging device, with a layout based on the human eye.
The work opens new possibilities for advanced camera
design. It also foreshadows artificial retinas for bionic eyes similar
in concept to those in the movie 'The Terminator' and other popular
science fiction.
''Conformally wrapping
surfaces with stretchable sheets of optoelectronics provides a
practical route for integrating well-developed planar device
technologies onto complex curvilinear objects,'' said John Rogers, the
Flory-founder chair professor of materials science and engineering at
Illinois, and corresponding author of the paper which was published in
the the 7 August issue of the journal Nature.
The
camera's design is based on that of the human eye, which has a simple,
single-element lens and a hemispherical detector. The camera integrates
such a detector with a hemispherical cap and imaging lens, to yield a
system with the overall size, shape and layout of the human eye.
To
make the camera, the researchers begin by molding a thin rubber
membrane in the shape of a hemisphere. The rubber membrane is then
stretched with a specialised mechanical stage to form a flat drumhead.
Next, a prefabricated focal plane array and associated electronics --
created by conventional planar processing -- are transferred from a
silicon wafer to the tensioned, drumhead membrane.
| Schematic
illustration of steps for using compressible silicon focal plane arrays and hemispherical, elastomeric transfer elements to fabricate electronic eye cameras. |
When the tension is released, the membrane returns to
its original shape. This process compresses the focal plane array,
causing specially designed electrical interconnects to delaminate from
the rubber surface and form arcs, pinned on the ends by detector
pixels.
These deformations accommodate strains associated with the
planar to hemispherical transformation, without stressing the silicon,
as confirmed by mechanics modeling performed by researchers at
Northwestern.
The array package is then transfer printed to a matching hemispherical glass substrate. Attaching a lens and connecting the camera to external electronics completes the assembly. The camera has the size and shape of a human eye.
(The camera
was designed by John Rogers (back left), the Flory-Founder Chair
Professor of Materials Science and Engineering, and his research group:
(clockwwise from back right) Joe Geddes, Mark Stoykovich, Heung Cho Ko
and Viktor Malyarchuk, all postdoctoral researchers.)
Over the last 20 years, many research groups have pursued electronic eye systems of this general type, but none has achieved a working camera.
''This approach allows us to put electronics in places where we couldn't before,'' Rogers said. ''We can now, for the first time, move device design beyond the flatland constraints of conventional wafer-based systems.
So, keep an eye on the eye of The Terminator!
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