- 31 August 2005 -

A fiber for electrical, magnetic or optical 'signatures'

Dr Juan Hinestroza, assistant professor of textile engineering, chemistry and science at North Carolina State University and Dr Carlos Rinaldi, assistant professor of chemical engineering at the University of Puerto Rico, Mayaguez, have created new nanoscale fibers that placed inside a garment or paper document serve as a “fingerprint” to prove garments or documents are genuine.

Image: A new nanofiber has the potential to serve anti-counterfeiting purposes

At about 150nm diameter, the fibers are designed to enclose even smaller nanoparticles with an electrical, magnetic or optical “signature” that can prove a product genuine. The product would need only be scanned, or read, by a device looking for the particular signature.

For example, Hinestroza says, name-brand clothing with nanofibers can be scanned at different points in the supply chain to ensure pirated clothing doesn’t get into retail outlets. Passports with nanofibers can be scanned to ensure their legitimacy. Ostensibly, paper money with nanofibers would help ensure against forgeries.

“The fibers can essentially serve as molecular bar codes,” Hinestroza says. “We can control the position, frequency and distribution of particles inside the fibers, and their signature.”

The process used to create the nanofibers is electrospinning, a 1930s textiles manufacturing process now being put to use to create tiny fibers. In their electrospinning research, the scientists apply electrical charges to water-based polymer solutions containing tiny nanoparticles, including magnetic particles or quantum dots, tiny particles that, depending on their size, display colors.

When enough electrical charge is applied to the solution, an unstable jet – or narrow stream of solution and nanoparticles – moving like a whip through air, is formed. The whipping motion elongates the jet while the solvent evaporates, producing a tiny fiber containing the nanoparticles. The researchers then tested the fibers and found the fibers had magnetic properties.

The research is sponsored by a National Science Foundation Nanoscale Exploratory Research grant, and by the NC State Nanotechnology Steering Committee.