Have you ever seen an Advent Calendar of the size of a red blood cell? Of course it’s hard to see it in a glimpse, but it’s even harder to built it without the help of precise equipment. A group of scientists, in Germany, created a Calendar that measures 8.4µm by 12.4µm, with nice Christmas images in each day of December, where each image can measure about 20 nm.  

The construction was made with the help of electron microscope, making the etching of a semi-conducting gallium arsenide wafer coated with Poly(methyl-methacrylate - PMMA).

Based on a joke, but is serious science!      

Maria José Machado