Imagine a soldier's uniform made of a special fabric that allows him to look in all directions and identify threats that are to his side or even behind him. In work that could turn such science fiction into reality, MIT researchers have developed light-detecting fibers that, when weaved into a web, act as a flexible camera. Fabric composed of these fibers could be joined to a computer that could provide information on a small display screen attached to a visor, providing the soldier greater awareness of his surroundings.
This is the first time that anybody has demonstrated that a single plane of fibers, or 'fabric,' can collect images just like a camera but without a lens.
The team starts with a macroscopic cylinder, or preform, of these elements. That preform is placed into a special furnace that melts the components, carefully drawing them into miniscule fibers that retain the original orientation of the various layers. The process can produce many meters of fiber.
Fink's team demonstrated the power of their approach by placing an object - a smiley face - between a light source and a small swatch of fabric composed of the fibers that was in turn connected to an external amplifying electrical circuit and computer.
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.
In the current work, the smiley face was illuminated with light at two separate wavelengths. This generated a distinct pattern on the fabric mesh that was then fed into a computer. From there, an algorithm described earlier by the Fink team in Nature Materials assimilates the data to create a black-and-white image of the object on a computer screen.
First author Fabien Sorin, a postdoctoral associate in RLE, DMSE and ISN, said that 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.
Abstract: Exploiting Collective Effects of Multiple Optoelectronic Devices Integrated in a Single Fiber
The opportunities and challenges of realizing sophisticated functionality by assembling many nanoscale devices, while covering large areas, remain for the most part unrealized and unresolved. In this work, we demonstrate the successful fabrication of an eight-device cascaded optoelectronic fiber structure in which components down to 100 nm are individually electrically addressed and can operate collectively to deliver novel functionality over large area coverage. We show that a tandem arrangement of subwavelength photodetecting devices integrated in a single fiber enables the extraction of information on the direction, wavelength, and potentially even color of incident radiation over a wide spectral range in the visible regime. Finally, we fabricated a 0.1 square meter single plane fiber assembly which uses polychromatic illumination to extract images without the use of a lens, representing an important step toward ambient light imaging fabrics.