Nanotubes as printed

Conductive nanotube surfaces made with standard inkjet printer

Einstein Portrait of a Conductive Nanotube Pattern Rensselaer Polytechnic Institute
Read out

Carbon nanotubes are considered to be promising "building blocks" for many nano applications of the future. But there are still difficulties to arrange them as they are needed. Now researchers have developed a seemingly simple technique and successfully tested it: they used a standard inkjet printer to print nanotube patterns on paper and plastic surfaces.

According to researchers from the US Rensselaer Nanotechnology Center, the method published in the current issue of the journal "Small" could be applied to a wide range of nanotube-based applications, including flexible electronics, flexible conductor surfaces and sensors for chemical measurements. "Our results show new alternatives for generating nanotube patterns by simply printing the dissolved particles on paper or plastic surfaces, " explains Robert Vajta, co-author of the study.

Ink from nanotubes

Vajta and his colleagues simply filled a commercial ink cartridge with a solution of nanotubes in water for their process. The printer then created a pattern similar to the tube, a normal image. With one key difference: Because the nanotubes are good conductors, conductive coatings can be printed in this way. "One major benefit of our process is that the printed patterns do not have to be cured, which is required in many conventional conductive ink applications, " Vajta explains. "And because our ink is a simple aqueous solution of nanotubes, it's also environmentally friendly and easy to handle and store."

Since normal equipment and utensils are used, the nanotubes themselves are the only major cost factor. The scientists themselves produced the multi-walled carbon tubes used for their experiments. According to the researchers, however, similar cheaper ones can be used and, in addition, the price of nanotubes will fall in the future as demand increases.

Banknotes, newspaper, flexible displays

For example, the new technology could be used to print optical markers on banknotes or other securities that could then be electronically tracked. Even an electronic newspaper whose text can be changed without having to flip the paper, the researchers consider quite feasible. In their experiments, they generated various pressure samples that responded to the vapors of specific chemicals and thus would be suitable as sensors. display

"Printed nanotube structures can be useful in many ways, " explains Vajta. "Some potential applications based on their conductivity include flexible electronics for displays, antennas, and batteries that can be integrated into paper or fabric." In the future, it could carry the battery for his laptop or mobile phone in the form of clothing.

As a next step, the researchers want to further improve the quality of the nanotube ink and the conductivity of the resulting patterns. At the moment, the paper has to go through the printing process several times to get sufficient conductivity. The researchers also want to test the possibility of using different "inks", each with different properties.

(Rensselaer Polytechnic Institute, 01.09.2006 - NPO)