Two-color barcodes: Dynamic duo to fight crime, cancer
So-called lanthanide-doped upconversion materials are highly promising for applications against crime and cancer as they have adjustable morphologies and tunable output wavelengths — they can also be fabricated by inexpensive processes that are easily scaled up. To date, single-crystal nanocrystals made from these materials have been impractical as multicolor barcodes because their tiny size makes them too small to be observed using conventional optical microscopes. …