The successful demonstration of a technique capable of producing color images with a record-breaking resolution of 100,000 dots per inch (dpi) could guide the printing industry into uncharted territory. The resolution provided by the new method, which is based on the tailored scattering of light by nanostructures, surpasses commercial techniques by more than a factor of ten and reaches the fundamental limit set by the laws of optics.
Currently leading technologies for color printing, such as the inkjet and laserjet methods, deposit tiny dots of dye on a surface. The size of these dots is typically in the micrometer range, which means that the highest attainable resolution for these techniques is below 10,000 dpi. Approaches that yield finer dots have been demonstrated in research laboratories, but these techniques are so far limited to producing monochrome images and are not scalable. The method now developed at the A*STAR Institute of Materials Research and Engineering (IMRE), with the participation of the Institute of High Performance Computing (IHPC), provides a fundamentally different approach that is free of the technological limitations of colorant-based methods. “We use tiny metal nanostructures to create color,” explains Joel Yang, the lead researcher on this project. “This is somewhat similar to staining glass, where different colors are produced by using different metals. We use only one metal, however, which we deposit in a thin, uniform layer on tiny posts of varying diameter.”
The posts are only a few tens of nanometers in size, and Yang and his co-workers1 have now shown that, depending on the disks’ diameter and density, different colors can be generated through a mechanism known as plasmon resonance. To demonstrate the power of their technique, Yang’s team has created a 50 micrometer × 50 micrometer photorealistic full-color image with pixels at 250 nanometer pitch (see top image). This resolution is at the so-called optical diffraction limit, which is the fundamental resolution limit of any optical imaging system.
This new method now pushes the door for commercial uses wide open. “At the current stage, we can think already of a number of applications, including branding and brand protection for products meant for viewing under a microscope — bio-assays or microscope calibration kits, for instance — or the production of anti-counterfeit features,” says Yang. “Following further development, there should be the potential for applications such as high-density optical data storage or coating all sorts of surfaces with colors that won't fade.”
Importantly, with a view to commercial applications, the new technique can be scaled up. The creation of the nanostructures that make up the image may be quite involved. Once a master template is made, however, pattern-replication methods such as nano-imprint or photolithography can be used to mass-produce micro-images. Furthermore, technologies for imprinting large areas are available, too.
Indeed, first steps from laboratory to market have already been taken: One Singapore provisional patent is filed and another is pending. Furthermore, the team is working with Exploit Technologies Pte Ltd (ETPL), A*STAR’s technology-transfer arm, to assess the interest of companies for collaborations, and to explore opportunities for licensing the technology.
About the A*STAR Institute of Materials Research and Engineering
The Institute of Materials Research and Engineering (IMRE) is a research institute of A*STAR. The Institute has capabilities in materials analysis and characterization, design & growth, patterning and fabrication, and synthesis and integration. We house a range of state-of-the-art equipment for materials research including development, processing and characterization. The IMRE conducts a wide range of research, which includes novel materials for organic solar cells, photovoltaics, printed electronics, catalysis, bio-mimetics, microfluidics, quantum dots, heterostructures, sustainable materials, atom technology, etc. We collaborate actively with other research institutes, universities, public bodies, and a wide spectrum of industrial companies, both globally and locally.
About Exploit Technologies Pte Ltd
Exploit Technologies Pte Ltd (ETPL) [link] is the technology transfer arm of A*STAR. Its mission is to support A*STAR in transforming Singapore’s economy by commercializing research and development. Exploit Technologies turns A*STAR’s inventions into marketable products or processes. Through licensing deals and spin-offs with industry partners, Exploit Technologies is a key driver of technology transfer in Singapore. It actively engages industry leaders and players to commercialize A*STAR’s technologies and capabilities, bridging the gap from Mind to Market.
- Kumar K., Duan, H., Hegde, R. S., Koh, S. C. W., Wei, J. N. & Yang, J. K. W. Printing colour at the optical diffraction limit. Nature Nanotechnology advance online publication, 12 August 2012 (doi: 10.1038/NNANO.2012.128) | article
© 2012 Nature Publishing Group