22 June 2017
A way to store digital data in half the space has been found by chemists at Case Western Reserve University (CWRU).
To reduce storage space, engineers have traditionally used existing technology but made it smaller.
The CWRU researchers, however, demonstrate how commonly used polymer films containing two dyes can optically store data in a four-symbol code, potentially requiring about half as much space.
“We’re using chemistry instead of engineering to address data storage, but it’s complementary to what engineers are doing,” said assistant professor Emily Pentzer.
To take advantage of the quaternary storage, computer programs would need to be written in quaternary code instead of binary code, which Pentzer said would be easy with the system they used.
Instead of numerals, the optical-storage system uses the absence of colour and three colours produced by the dyes as the symbols representing information.
To create the system, the researchers loaded a small amount of the two dye molecules into a flexible sheet of poly(methyl methacrylate), or PMMA. PMMA is clear and colourless in ambient light and temperature.
Cyano-substituted oligo(p-phenyene vinylene) fluoresces green when exposed to heat. The second dye, o-nitrobenzyl ester of benzoic acid, fluoresces ultramarine when exposed to ultraviolet light. When the overlapping dyes are exposed to both heat and UV light, they fluoresce as cyan.
The team wrote the code by laying metal or wood templates over the dye-containing film, then applying heat and ultraviolet light.
The code proved durable, remaining legible even after the film had been rolled, bent, written on with permanent marker, submerged in boiling water and half the surface had been rubbed away with sandpaper.
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