Researchers at North Carolina State University have developed a cheap and easy method for assembling nanowires, controlling their alignment and density. The researchers hope the findings will foster additional research into a range of device applications using nanowires, from nanoelectronics to nanosensors, especially on unconventional substrates such as rubber, plastic and paper.
"Alignment is a critical first step for developing devices that use nanowires," says Dr. Yong Zhu, an assistant professor of mechanical and aerospace engineering at NC State and co-author of a paper describing the research. "Hopefully our simple and cost-effective method will facilitate research in this field."
Aligning nanowires is challenging because, when they are created, the user is faced with a profusion of randomly oriented nanoscale wires that are, by definition, incredibly small. For example, the nanowires are between 10 and 100 nanometers in diameter, whereas a white blood cell is approximately 10,000 nanometers in diameter. Before any practical applications can be pursued, the user must assemble the nanowires in an orderly way. Specifically, users need to align the nanowires in a common direction and define their density meaning the number of nanowires in a given area. Controlling both alignment and density is commonly called "assembling" the nanowires.
In the new method, Zhu's team deposited the nanowires on a stretched rubber substrate, and then released the tension on the substrate. When the nanowires settled, they aligned at a right angle to where the tension was coming from. Picture a rubber band being stretched to the east and west. If nanowires were placed on the rubber band, and the band was allowed to snap back to its original shape, the nanowires would be oriented to the north and south. The more the rubber substrate is stretched, the more aligned the nanowires will be, and the greater the nanowire density will be.
|Contact: Matt Shipman|
North Carolina State University