Vajtai says his colleagues are working on improving the ink preparation and conductivity of the images. He believes that the technology could be used in RFID tags in about a year. RFID tags cost a few cents and are silicon-based, consisting of an integrated circuit chip and a simple antenna circuit. With the new method, one could make more durable antennas with carbon nanotubes, printed out in bulk, Vajtai says.

Conductive inks for flexible substrates are currently made of metal nanoparticles, which, unlike the carbon nanotubes, need to be annealed, a process that requires time and special chemicals. "But the final result pays off because you have features that are as conductive as conventional metals," says Ana Arias, a research associate at the Palo Alto Research Center (PARC), where researchers use polymer thin-film transistors and silver nanoparticle ink to make large flexible displays.

According to Arias, Eikos, a company based in Franklin, MA, already makes transparent carbon nanotube inks for flat-panel displays. That company has already used the inks to make organic solar cells, and claims the coatings could also be used in flexible displays.