Nano-LampEvery day scientists continue to surprises us with the new discoveries; however, the most noted and admired by the vast majority of folks as well as science professionals are the achievements and developments in the field of nanotechnology. We all get easily amused when we see the next “nano” research headline because the “nanotech world” is not yet fully understood or explored.

Recently Craighead Research Group at Corenll University reported their next “nano” breakthrough. They created a so-called “Nano-Lamp” – a microscopic collection of light-emitting fibers with dimensions of only a few hundred nanometers.

According to the research article published in “Nano Letters”, the scientists were able to create one of the smallest manmade source of light that world has ever seen. The light-emitting spots on the fibers measure less than 250 nm in diameter which makes this light source smaller than the wavelength of light that they emit – 600nm. The fibers are made from a polymer with ruthenium-based molecules using a complex technique called – electrospinning – when a small droplet of polymer solution is placed on a metal needle tip followed by application of a high voltage between the tip and gold electrodes in a silicon base placed a few millimeters away.

A light-emitting nanofiber spans gold electrodes that are 500 nm apart and ruthenium-based molecules embedded in the fiber light up when exposed to an electric field of 3-4 V. An interesting fact is that when researches applied a high voltage of 100 volts, the orange light was bright enough to be seen by a human eye in the dark.

“I would say this is a breakthrough in the way nanosize light sources are made,” says Stefan Bernhard, a chemistry professor at Princeton University.

Because the fibers made of polymer they can be potentially used in flexible displays and clothing. The device of this size could also be easily integrated into lab-on-a-chip modules for detection of chemical and biological molecules.

    References: “Electrospun Light-Emitting Nanofibers” Moran-Mirabal, J. M.; Slinker, J. D.; DeFranco, J. A.; Verbridge, S. S.; Ilic, R.; Flores-Torres, S.; Abruna, H.; Malliaras, G. G.; Craighead, H. G. Nano Lett.; (Letter); 2007; 7(2); 458-463. DOI: 10.1021/nl062778+
    Abstract: We have electrospun light-emitting nanofibers from ruthenium(II) tris(bipyridine)/polyethylene oxide mixtures. The electroluminescent fibers were deposited on gold interdigitated electrodes and lit in a nitrogen atmosphere. The fibers showed light emission at low operating voltages (3-4 V), with turn-on voltages approaching the band gap limit of the organic semiconductor. Because of the fiber size, emission from electrospun light-emitting nanofibers is confined to nanoscale dimensions, an attractive feature for sensing applications and lab-on-a-chip integration where highly localized excitation of molecules is required.

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