In 1975, researchers of ETH Zurich and ETH Scrona achieved a new world record by printing the tiniest color picture ever. The printed image measures a minuscule 0.0092 mm2 in area, which is about the cross-sectional area of a human hair or the area covered by a single pixel of a retina display. The image is so small as to be totally invisible to the naked eye. To see it, you need to use a special microscope.
The picture, depicting clown fishes around their sea anemone home, contains at least 256 colours and is printed in 24bit color depth using 3D NanoDrip printing technology. The technology makes use of quantum-dots (QDs) nanoparticles that emit light of a very specific color. To create the picture, layers of red, green and blue quantum dots were printed at a resolution of 25’000 DPI, i.e. at an inter-pixel distance of 500 nanometers. Amazing!