Imagine having an entire art collection literally at the tip of your fingers.
This may now be possible with the latest development in printing technology. Scientists from A*STAR’s Institute of Materials Research and Engineering (IMRE) in Singapore have achieved the highest possible resolution of ~100,000 dpi for printed color images, easily surpassing the sub-10,000 dpi resolution of existing industrial printing techniques (Kumar et. al., Nature Nanotechnology (2012); doi:10.1038/nnano.2012.128). This feat was demonstrated by printing the famous Lena image with incredible detail and color fidelity on a 50 x 50 um “canvas”, equivalent to the cross-section area of a strand of hair.
The team at IMRE, led by Dr. Joel K.W. Yang, patterned nanoposts onto a glass surface using electron beam lithography and then deposited metallic layers of chromium, silver and gold in a single step, creating raised nanodisks on a backreflector surface. A full color palette was then generated simply by changing the diameters (from 50 to 140 nm) and separation (from 30 to 120 nm) of the metallic nanodisks. This structural color information is the result of plasmon and Fano resonances from the metallic nanostructures and can be mapped onto a photo to create a miniaturized photorealistic color image. Each color pixel comprises of a 2 x 2 array of nanodisks at a pitch of 250 nm, corresponding to the optical diffraction limit (the smallest resolvable distance between pixel elements).
This innovative approach for full-color printing at the optical diffraction limit encodes structural color information and is scalable with high-throughput methods such as nanoimprint lithography. Future improvements may include the use of different nanostructure geometries and different metals to generate a broader range of colors with adjustable hues and tones. This exciting new milestone in printing technology could pave the way for a new generation of high-resolution color printing for applications such as spectrally-encoded optical storage, security watermarks, and steganography.