Nanotube ink: Desktop printing of carbon nanotube patterns

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, which is described in the August 2006 issue of the journal Small, 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.

Carbon nanotubes have enticed researchers since their discovery in 1991, offering an impressive combination of high strength, low weight, and excellent conductivity. But most current techniques to make 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 and corresponding author of the paper.

Vajtai and his colleagues at Rensselaer - along with a group of researchers led by Krisztiбn Kordбs and Gйza Tуth at the University of Oulu in Finland - have developed an approach that uses a commercial inkjet printer to deposit nanotubes onto various surfaces. 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."

Because the process uses off-the-shelf printers, cartridges, and paper or plastic surfaces, the only real expense is the cost of the nanotubes. For this experiment, the researchers made their own multi-walled carbon nanotubes, which were then chemically modified to allow them to dissolve in water. But similar nanotubes can be purchased for as little as a tenth of the price of the more expensive single-walled variety of carbon nanotubes, Vajtai said. And the cost of nanotubes should continue to drop as commercial demand for higher volumes grows.

The researchers plan to continue optimizing the process to improve the quality of the nanotube ink and the conductivity of the printed images. At present, the paper or plastic must be run through the printer multiple times to get an electrically conductive pattern, with the conductivity increasing after each repetition. They also hope to experiment with different chemical modifications to produce a diversity of ink "colors," each producing surface patterns with different properties, Vajtai said.

Source: Rensselaer Polytechnic Institute

Related stories:

Beyond batteries: Storing power in a sheet of nanocomposite paper
Researchers at Rensselaer Polytechnic Institute have developed a new energy storage device that easily could be mistaken for a simple sheet of black paper.
Nanotubes could improve thermal management in electronics
As the electronics industry continues to churn out smaller and slimmer portable devices, manufacturers have been challenged to find new ways to combat the persistent problem of thermal management. New research published in the March 19 issue of Applied Physics Letters suggests that carbon nanotubes may soon be integrated into ever-shrinking cell phones, digital audio players, and personal digital assistants to help ensure the equipment does not overheat, malfunction, or fail.
Hybrid Structures Combine Strengths of Carbon Nanotubes and Nanowires
A team of researchers at Rensselaer Polytechnic Institute has created hybrid structures that combine the best properties of carbon nanotubes and metal nanowires. The new structures, which are described in a recent issue of Applied Physics Letters, could help overcome some of the key hurdles to using carbon nanotubes in computer chips, displays, sensors, and many other electronic devices.
New Techniques Pave Way for Carbon Nanotubes in Electronic Devices
Many of the vaunted applications of carbon nanotubes require the ability to attach these super-tiny cylinders to electrically conductive surfaces, but to date researchers have only been successful in creating high-resistance interfaces between nanotubes and substrates. Now a team from Rensselaer Polytechnic Institute reports two new techniques, each following a different approach, for placing carbon nanotube patterns on metal surfaces of just about any shape and size.

Scientists create DNA tubes with programmable sizes for nanoscale manufacturing
Scientists at the California Institute of Technology (Caltech) have developed a simple process for mass producing molecular tubes of identical--and precisely programmable--circumferences. The technological feat may allow the use of the molecular tubes in a number of nanotechnology applications.
Study Details How Platinum Nanocages 'Cook' Cancer Cells
Platinum-based anticancer agents have a long history as proven therapeutic agents, but their toxicity and short lifetime in the body and the ability of tumors to develop resistance to these drugs limit the ultimate utility of these agents.
True properties of carbon nanotubes measured
For more than 15 years, carbon nanotubes (CNTs) have been the flagship material of nanotechnology. Researchers have conceived applications for nanotubes ranging from microelectronic devices to cancer therapy. Their atomic structure should, in theory, give them mechanical and electrical properties far superior to most common materials.
Slipping through cell walls, nanotubes deliver high-potency punch to cancer tumors in mice
(PhysOrg.com) -- The problem with using a shotgun to kill a housefly is that even if you get the pest, you'll likely do a lot of damage to your home in the process. Hence the value of the more surgical flyswatter.

News discussion:

Nanotechnology news