A novel printing method that involves positioning individual nanoparticles with great accuracy could make smaller electronic circuits, and might eventually help prevent banknote counterfeiting, researchers say.

The method could perhaps provide a way to foil counterfeiters by marking banknotes with carefully positioned nanoparticles, which could be detected with the right equipment. "This is an interesting application for an every small-scale, advanced printing method," Wolf says, "although it was not the motivation behind our research."

The researchers are able to precisely control where the particles stick to their printing plate by patterning it with tiny indentations – dots or grooves – not much larger than the particles themselves. These grooves were created using established silicon-chip manufacturing techniques.