Scientists have developed a new form of high-resolution “printing” which could have wide-ranging applications in data storage, anti-counterfeiting measures, and digital imaging.
New research from the University of Glasgow, published in the journal Advanced Functional Materials, outlines how engineers have developed nano-scale plasmonic color filters that display different colors depending on the orientation of the light which hits it.
Essentially, this new technique allows the “printing” of two entirely different, but exceptionally detailed, full-color images within the same surface area — something which has never been done before using “structural color” techniques.
Instead of relying on dyes and pigments, as in traditional printing, structural color uses specially structured nanomaterials to render colors. The nanomaterials allow for much higher-resolution prints which do not fade over time. A typical printed image in a magazine, for example, might consist of around 300 colored dots per inch of page, or 300 DPI. A page “printed” with structural color techniques, however, could reach a resolution of 100,000 DPI or more.
The University of Glasgow team’s breakthrough comes from including an additional nanoscale element in the structural color process, created at the University’s James Watt Nanofabrication Centre.
Biomedical engineering lecturer Dr. Alasdair Clark is the lead author of the research paper. Clark says, “We’ve discovered that if we make color pixels from tiny cross-shaped indents on a strip of aluminum film, the color they display becomes polarization-dependent, allowing us to encode two colors into a single pixel, and then select which color is displayed by shining different polarizations of light at the surface.
“By changing the size and shape of the nanoscale indent, we can create a wide range of different colors at very high resolutions.”
The team, from the University’s School of Engineering, have demonstrated their technique with several examples, including a nanoscale image which shows the University’s crest when the light reaches it in one orientation, and an image of the famous University tower when the orientation of the light is reversed.
Clark adds, “There are a lot of potential applications for our plasmonic color technology, which we’re really excited about.
“It’s ideal for long-term data archival due to its ultra-high resolution, and because the colors won’t fade even when exposed long-term to the harshest sunlight. We’ve worked out that we could store 1.46 Gb per square centimeter, so a single A4 sheet could hold more than 900 Gb of data.
“Secondly, the process to produce the plasmonic colors is difficult to replicate without access to dedicated facilities, so it could be ideal for creating a new kind of anti-counterfeiting material for banknotes.
“Lastly, it offers the possibility of developing new types of color filters for digital photography.”
The paper, titled “Plasmonic color filters as dual-state nano-pixels for high density micro-image encoding,” is published in Advanced Functional Materials.
Source: University of Glasgow
