By Darrell J. Pehr
Electronic ‘skin’ could lead to flexible screens, other devices
Picture this: a television with a screen that is so thin, flexible and portable that you can hang it on the wall or hold it in your lap, watch a program, then roll it up and take it with you when you leave. The day’s newspaper could be a single sheet of electronic paper that displays pages, one-by-one, as you scroll through, updating itself through wireless technology. The color of your car could be as varied as your imagination.
The building blocks for this technology and other applications are based on “nano skin,” an ultra-thin array of nanotubes encased in a flexible polymer film that is being developed by a group of researchers from New Mexico State University and other institutions.
Nanotechnology, the science of building materials one atom at a time, includes nanotubes – long, cylindrical carbon structures consisting of hexagonal graphite molecules attached at the edges.
Seamus Curran, an assistant professor of physics and an adjunct faculty member in chemical engineering at NMSU, came up with the idea to create nano skin about four years ago when he was at Rensselaer Polytechnic Institute in New York.
“I had a thought, even at that stage, that it might be possible, by using composite formation, to make an effective field emission device,” Curran said. “I didn’t expect it to be as great a success as it actually was. I thought it was going to work, but I didn’t think it was going to work great.”
Curran and Aditya Avadhanula, an NMSU alumnus who completed his master’s thesis in chemical engineering and now works for Micron, worked with scientists at Rensselaer and Northwestern University to turn the idea into reality. Their results were published in the journal Nano Letters in March. The journal Nature dedicated an article to the project in May.
“The current configuration we came up with is very different from what everyone else is working on,” Curran said. “While my thoughts were three years old, fortunately this is one of those rare occasions where people in the research world just did not see where I wanted to go with this.”
The technology has many advantages. Nanotubes can be set up in any configuration, which is retained after the polymer is added. The nano skin is flexible while maintaining the ability to conduct electricity, and holds up well to being stretched or compressed.
Nano skin could be used to measure stress in a building, by being imbedded in a wall or other structural element to sense any movement or imperfections. The material could be used as a gas sensor or as a field emission device for a flexible, flat panel display, and Curran said his group’s nano skin technique provides the highest field emission intensity of any nanotube system.
“I think in terms of potential application, it is incredibly important, very significant,” Curran said. “It’s very significant for the field of nanotubes because it brings nanotubes one step closer to application. I think it’s very important technologically because you’re now looking at a flat panel display potentially.”
Curran’s next step is to look at channeling emissions and the use of color, which will require some imaginative thought.
“There are some physics to be sorted out in my head first before I can actually build it. So I have to reason it out for myself, where to go next,” he said.
The project was partially supported by the Department of Defense, which funded Curran’s Agile Response Coatings research project with a grant of $1.5 million in 2004.
In that effort between NMSU, Wake Forest University and the University of Florida, scientists worked to develop high-tech coatings that would allow stealthy military aircraft to change colors. Other researchers were supported in the nano skin research by the National Science Foundation.
Curran hopes this and other developments help attract more funding to the physics department at NMSU.
“Unfortunately for us here at NMSU, we don’t have the traditional facilities built up over a decade that are required to build these things,” Curran said. As a result, NMSU researchers must do a significant amount of the work elsewhere and they must rely on good collaborations developed through personal friendships with researchers at other universities that do possess the proper facilities. Avadhanula, for example, spent most of last summer at Rensselaer growing nanotubes for their project.
“What we need is a significant investment in terms of equipment and infrastructure to be able to continue to compete on the world stage,” Curran said.