Scientists in Singapore have developed a nanoprinting technology that can achieve a record high color resolution of 100,000 dots per inch (dpi), without inks or dyes.
Optical micrographs of an image before and after metal deposition, along with and enlargement (c) and resolution test patterns. Image: Nature Nanotechnology
Researchers at the Institute of Materials Research and Engineering in Singapore accidentally stumbled upon the possibility of using nanostructures for producing images during an experiment in nanoplasmonics. Examined under a microscope, the materials exhibited a range of colors; intrigued, the team replicated a photo using the material.
Published in the August 12 edition of Nature Nanotechnology, the research outlines how the team achieved bright-field color prints with resolutions up to the optical diffraction limit by encoding the information in metal nanostructures. By tuning their plasmon resonance, the researchers could determine the color of individual pixels.
“The resolution of printed color images very much depends on the size and spacing between individual ‘nanodots’ of color,” said Karthik Kumar, one of the researchers. “The closer the dots are together and because of their small size, the higher the resolution of the image. With the ability to accurately position these extremely small color dots, we were able to demonstrate the highest theoretical print colour resolution of 100,000 dpi.”
According to the article:
Our colour-mapping strategy produces images with both sharp colour changes and fine tonal variations, is amenable to large-volume colour printing via nanoimprint lithography, and could be useful in making microimages for security, steganography, nanoscale optical filters and high-density spectrally encoded optical data storage.
Pixels of different colors can be placed extremely close together by encoding the color information in the nanostructures, then applying a uniform metal (silver in this case) on top to produce the colors. Because of the high resolution at the nano-scale, the technology could be used for anti-counterfeiting techniques, for instance.
The researchers are currently investigating how to scale the images to be seen with the human eye, and expanding the color palette.
Source: Nature Nanotechnology
100,000 DPI Nanoprinting