|Researchers from MIT have integrated a collection of light sensors into polymer fibers, creating a new type of camera. Such a camera would be lightweight, robust and even foldable. The team from the Institute's Department of Materials Science and Engineering (DMSE) has developed light-detecting fibers that, when woven into a web, act as a flexible �camera�. Fabric made from these fibers could be joined to a computer to create a large, foldable telescope or made into a soldier�s uniform to provide greater situational awareness. Though such applications are still years away, work is progressing rapidly on developing fabrics capable of capturing images. Optical fiber webs provide a distributed imaging capability over the entire surface of a fabric, which provides a wider view and are less susceptible to damage. If one area is damaged, other fibers can still function, extracting the image.
The new fibers are less than 1mm (0.04 n.) in diameter and composed of eight nested layers of light-detecting materials. Those layers include two rings of a semiconductor material that are light sensitive, each ring only 100 billionths of a meter across. Four metal electrodes contact each of the rings, extending along the length of the fiber, for a total of eight. Each semiconductor ring with its attached electrodes is in turn encased in rings of a polymer insulator that separate it from its neighbor. To make the fibers, the researchers arrange the semiconductor glass sensors in a polymer cylinder with a diameter of 25mm (0.9 in.), controlling the sensor's spacing and angle within the fiber. Once the sensors, made of a type of semiconducting glass, are in position, the polymer cylinder was heated and then stretched so that the diameter shrank the diameter of hundreds of micrometers--a process that is identical to the way in which commercial fiber is made for telecommunication applications--retaining the orientation of the sensors. When light hits the semiconductors, it creates an electrical current. The intensity of this current from the fibers is input into algorithms, running on an attached computer, that create the image of an object placed near the sheet of fiber. The individual fibers measure the intensity of the light illuminating them and convert it to an electrical signal. Importantly, they are also designed to differentiate between light at different wavelengths or colors. A mesh of fibers is then deployed to measure light intensity distribution at different wavelengths across a large area. As the individual fibers become more sophisticated, it is possible to envision fabrics with more intriguing and complex functionalities, such as ones capable of producing crisper images in color.