Researchers at Utrecht University have quantitatively mapped the three-dimensional structure of photonic supraparticles for the first time. Supraparticles are microscopic spheres composed of thousands of smaller colloidal particles. Until now, researchers could only examine the outer surface of these structures. Using a combination of super-resolution microscopy and machine learning, the team shows that particles that appear disorganized on the outside are often almost perfectly crystalline on the inside.

The paper is published in the journal Advanced Materials.

Blue morpho butterflies owe their vibrant color to the internal structure of their wings, rather than pigment. The arrangement of particles on a microscopic scale causes light to be reflected in such a way that the butterflies appear intensely blue, and that the color looks the same from every viewing angle.