By using stretchable optoelectronics scientists have created an amazing imaging device based on the human eye, which brings us yet another step closer to the possibilities of a bionic eye similar to that seen in sci-fi movies like Hollywood's "Terminator".
The high performance hemispherical eye camera which uses an array of single crystalline silicon detectors and electronics based on the layout of the human eye is the creation of scientists at the University of Illinois and Northwestern University.
The team made the camera by molding a thin rubber membrane into a shape of a hemisphere which is then stretched with a specialized mechanical stage to create a flat drumhead.
A prefabricated focal plane array and associated electronics is then created by conventional planar processing and transferred from a silicon wafer to the tensioned drumhead membrane. 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, confirm researchers at Northwestern.
The array package is then transfer printed to a matching hemispherical glass substrate. A lens is then attached and the camera is connected to external electronics - the camera is the size and shape of a human eye.
Schematic illustration of steps for using compressible silicon focal plane arrays and hemispherical, elastomeric transfer elements to fabricate electronic eye cameras
Source: John Rogers
John Rogers, the Flory-Founder Chair Professor of Materials Science and Engineering at Illinois said that these systems provide a broader field of view, improved illumination uniformity and fewer aberrations than flat cameras with similar imaging lenses. He also said that this approach allows electronics to be put in places where they couldn't before - for the first time device design can be moved beyond the flatland constraints of conventional wafer-based systems.
He believes some of the most compelling areas of future application involve the intimate, conformal integration of electronics with the human body in ways that are inconceivable using established technology.
For the last 20 years researchers have looked at electronic eye systems. The most recent include University of Washington who used manufacturing techniques at microscopic scales to combine a flexible contact lens with an imprinted electronic circuit and lights, Fraunhofer Institute for Microelectric Circuits integrated a 2.5 by 2.6 millimeter sensor in an artificial lens and Moorfield Eye Hospital implanted an artificial electronic retinal device developed by University of Southern California and Second Sight Medical Products - The array is attached to the retina and used in conjunction with an external camera and video processing system to provide a rudimentary form of sight to implanted subjects - none has achieved a working camera.
Printed electronics is likely to be used in later versions to reduce cost and thickness and improve biocompatibility, in the opinion of IDTechEx.
Reference and images: University of Illinois