Photonic Droplets
Non-toxic Displays, Cosmetics, and Paints

Manoharan and Weitz developed a method in which small core-shell colloidal particles (200-400 nm diameter) can be encapsulated inside polymerizable shells (top image) to form "photonic droplets." These 100- micrometer droplets display colors that can be tuned by changing the small particle size (bottom images). The photonic droplets, which use no pigments or dyes, are a non-toxic way to make long-lasting colors for paints, cosmetics, and reflective displays.