The National Physical Laboratory (NPL) in the UK has created the world’s smallest Christmas card, and at a mere 15 microns wide by 20 microns tall (0.015 by 0.020 millimeters), it out-miniaturizes last season’s 30-micron (0.030 millimeter) World’s Smallest Snowman. To apply a sense of scale, a human hair is about 50 to 80 microns (0.05 to 0.08 mm) wide.
The microscopic greeting on the 200 nanometer-thick (0.0002 mm) card includes a picture of a smiling cartoon snowman, and the inscription "Season’s Greetings", etched into the platinum-coated silicon nitride card using a focused ion beam. "From NPL" is the inscription signed inside the card.
NPL created the greeting card to showcase the equipment and techniques their labs use in their line of research. "We are using the tools that created the card to accurately measure the thickness of extremely small features in materials, helping to unlock new battery and semiconductor technologies," explains research fellow and microscopic greeting card creator, David Cox.
"It’s a genuinely exciting development that could help to make new technologies and techniques a reality."