coffee stains

Ivan Vakarelski at the Institute of Chemical and Engineering Sciences in Singapore was inspired by the rings left behind by spilled coffee to create a new way to make ultrathin coatings for LCD and plasma flat-screens.

In LCDs, transparent conductive coatings are used to form an electrode on the surface of the screen, while in plasma TVs they provide a shield that prevents electromagnetic fields from straying.

Traditionally to make such coatings it’s necessary to sputter a fine layer of highly conductive and transparent indium tin oxide onto the surface. This takes place in cost-intensive clean rooms and vacuum chambers.

Vakearelsk noted that when coffee is spilled, the evaporating liquid drives coffee particles to the edges of the spill -- which ultimately produces the circular stain. The coffee granules are being "assembled" by the varying evaporation and convection rates in the fluid.

Vakarelski and his colleagues figured that if they could mimic the process in a controlled fashion, they could create a pattern of granules of other materials to form a nanoscale conductive coating.

Instead of coffee they used a suspension of gold particles »

Shamelessly plagiarized and paraphrased from Anil Ananthaswamy’s Future TV screens seen in coffee stains in the 1 March issue of NewScientist.