Structural color printing of 3-D microscale objects by
shrinking photonic crystals

In a report recently published in Nature
Communications, a research group led by Associate Professor Joel
Yang from the Singapore University of Technology and Design (SUTD)
printed probably the smallest colorful 3-D model of the Eiffel
Tower. Impressively, no pigments or inks were used. Instead, the
3-D-printed model of the Eiffel Tower, measuring less than half the
width of a human hair at 39 micrometers, exhibits multiple colors
due to the manner in which light interacts with the nanostructures
that hold up the model. The 3-D models are made of a finely printed
mesh of transparent polymer, forming photonic crystals. These
mostly hollow designs remarkably shrink down in size by about 5
times when heated to produce a wide range of colors.