Normally when you take a great shot, you want to print it nice and large. Not the nanotechnologists at Swiss university ETH Zurich, though: They just set the record for smallest inkjet-printed color image in the world. At about 80-by-115 micrometers, the picture — of clownfishes loitering around a sea anemone — would comfortably fit on a cross-section of a human hair.
But the researchers didn't use ordinary ink; this image is printed with "quantum dots," tiny particles that emit light of different colors depending on their size. Smaller dots are blue, large ones are red, and those in-between are green or some blended shade. Each dot is separated from its neighbors by just 500 nanometers, giving the image a printed resolution of 25,000 dots per inch.
Guinness was on hand to verify the record. There's not too much utility in having a picture no one can actually see without a microscope, but other applications can be imagined for such an exact method of printing.