World's Tiniest Christmas Card (Invisible to the Naked Eye) - best toothbrush in the world

A group of nanometers
Scientists at the University of Glasgow have produced the world's smallest Christmas card in size 200
290 m widemeters tall. (BTW, a micro-
The meter is one millionth of 1 m, and the width of human hair is about 100 micro. meters. )
You can put 8,276 of the "Christmas cards" in the area of the first class stamp size to make a card invisible to the naked eye.
"Professor Cumming said: 'We have the best nanotechnology in the world, but sometimes the ability to explain this technology to the public can be a bit tricky.
We decided to make this Christmas card a simple way to show how accurate our technology is.
The process of making cards took only 30 minutes.
Production is very simple because the process is highly repeatable-the design of the card is much longer than the production time of the card itself.
You can install more than ten million cards on a standard A5 Christmas card-but signing them will prove a challenge. . . '" (Read more)