The small print

Using an off-the-shelf inkjet printer, a team of scientists has developed a simple technique for printing patterns of carbon nanotubes on paper and plastic surfaces. The method could lead to a new process for manufacturing a wide range of nanotube-based devices, from flexible electronics and conducting fabrics to sensors for detecting chemical agents.

Most current techniques for making nanotube-based devices require complex and expensive equipment.

‘Our results suggest new alternatives for fabricating nanotube patterns by simply printing the dissolved particles on paper or plastic surfaces,’ said Robert Vajtai, a researcher with the Rensselaer Nanotechnology Center at Rensselaer Polytechnic Institute.

Vajtai and his colleagues at Rensselaer, along with a group of researchers at the University of Oulu in Finland, used a commercial inkjet printer to deposit nanotubes onto various surfaces. They filled a conventional ink cartridge with a solution of carbon nanotubes dissolved in water, and then the printer produced 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, Vajtai said. The researchers printed different samples, some of which show sensitivity to the vapours of several chemicals, which also could make them useful as gas sensors.