One of these is Claude Monet's famous painting "Impression, Sunrise." The other is a replica, constructed using an aluminium nanostructure, measuring around 300 microns in width. But can you tell which is the real deal?
Printing, at whatever scale, is simply a case of laying down lots of small dots which, when observed at the correct distance, make sense as an image to our brains. Broadly speaking, Monet daubed paint on a canvas in much the same way that scientists have built nanometre-scale pillars to create an image at the microscopic level.
So how did the scientists do it? Well, they chose to eschew colour or pigment, instead opting for nanoscale metal structures. The idea is that they act as tunable resonators: electrons on the metal surface oscillate at certain frequencies, depending on the structure's size, giving out light of a different colour.
To create the image of "Impression, Sunrise," the team created pixels, each made up of four aluminium-topped pillars of hydrogen silsequioxane, atop on a silicon substrate. By varying the diameters of each of the four pillars making each pixel, from 80 to 220 nanometres, they were able to create a colour palette of over 300 colours.
The pixels were then combined, painstakingly, to form the images. The researchers reckon it could be used to create intricate, advanced patterning on metals in the future.