At 8.4 x 12.4 micrometers, the world's smallest advent calendar
was created in a lab late one night in Germany. The motivation
for the work was that the researchers wanted to have "a nice
picture of Christmas to put on our homepage." "We waited until
normal business was done for the day in the clean room," said
PhD student Daniel Neumaier at the University of Regensburg, one
of the three collaborators on the project. "Then we went in and
did it. We were just having fun." He said the creation took
about two hours. On the randomly-numbered calendar, the doors
for the first six days of December are open, revealing six
different images, including Santa Claus, a bell, a snowman and a
church. The smallest images on the calendar are the glass panes
on the church windows, which measure about 20nm. At the bottom
of the calendar, the researchers finished with a wish: "Merry
Christmas wish from Nanonic" in German. It would take about 5
million of the calendars to fit on a postage stamp. Nanonic is
the start-up company f