I found this interesting article  at NewScientistTech written by Kurt Kleiner. They have a nice approach to create a curved digital sensor (spherical) mostly using conventional photolithography. There can be endless applications since this will help to get wide-angle but less distorted images from a small camera. Also the author suggests, these can be used in military surveillance as well as in medical applications. Read on for more information on how they created the sensor.
Extracted from the Article:
Mimicking the curves of a human retina has enabled a digital image sensor to take wide-angle pictures without distortion. This is possible thanks to an improved method of transferring silicon sensors onto a curved surface.
They built their hemispherical electronic eye by first using conventional photolithography to build silicon photodiodes 500 micrometers square and 1 micrometer thick. These were then wired into a flexible 16-by-16 array using chromium and gold.
Separately, they created a 1-cm-wide hemisphere out of a stretchy plastic, and stretched it into a flat surface. That stretched surface, or “drumhead”, was then pressed against the photodiode array.
The silicon squares stuck to the stretched plastic thanks to van der Waals forces, which was then allowed to spring back to its original hemispherical shape. As the array took its new form, the photodiodes packed together tightly and the connecting wires arced away from the surface, but the array was undamaged.
The reformed array was then glued to a curved glass surface, and a conventional lens attached. It now resembled a human eye in construction, with light entering the lens from the front, and passing to the curved “retina” containing the matrix of photodiodes behind.