They simply fill a conventional ink cartridge with a solution of carbon nanotubes dissolved in water, and then the printer produces a pattern just as if it was printing with normal ink. Because nanotubes are good conductors, the resulting images also are able to conduct electricity.
"Printed carbon nanotube structures could be useful in many ways," Vajtai said. "Some potential applications based on their electrical conductivity include flexible electronics for displays, antennas, and batteries that can be integrated into paper or cloth." Printing electronics on cloth could allow people to actually "wear" the battery for their laptop computer or the entire electronic system for their cell phone, according to Vajtai.
The technique could be used to print optical tags on money and other paper items that need to be tracked, and it could even lead to an electronic newspaper where the text can be switched without changing the paper, he said. The researchers printed different samples, some of which show sensitivity to the vapors of several chemicals, which also could make them useful as gas sensors.
The approach is simple, versatile, and inexpensive, which makes it superior to other methods for producing conductive surfaces, according to Vajtai. "A great advantage of our process is that the printed patterns do not require curing, which is known to be a limiting factor for conventional conductive ink applications," he said. "And since our ink is a simple water-based dispersion of nanotubes, it is environmentally friendly and easy to handle and store."