A University of Cincinnati professor is doing research for the U.S. Air Force, attempting to bring salmon sperm into the mix of biological materials used to intensify light-emitting diodes.
Andrew Steckl, a leading expert on LEDs and an Ohio Eminent Scholar at UC's Department of Electrical and Computer Engineering, is considering salmon sperm as an optional biological material that could manipulate the mobility of electrons, which create light in LEDs.
Steckl's work on BioLEDs, devices that incorporate DNA thin films as electron-blocking layers, has a strong environmental incentive. His research on DNA-based devices is being done in collaboration with the U.S. Air Force Research Laboratory.
Most LEDs existing today are based on inorganic materials, such as silicon. Over the last decade, researchers have been exploring the possibility of using naturally occurring materials in devices like diodes and transistors.
"The driving force, of course, is cost; cost to the producer, cost to the consumer and cost to the environment, but performance has to follow," he said.
LEDS, which some scientists see as the unsung heroes of the electronics world, do dozens of different jobs and are found in a host of devices. They form the numbers on digital clocks, transmit information from remote controls and light up watches. Collected together, they can form images on a jumbo television screen or illuminate a traffic light.
Basically, LEDs are tiny light bulbs that fit easily into an electrical circuit. Unlike ordinary incandescent bulbs, they don't have a filament that will burn out, and they don't get very hot. LEDs are illuminated solely by movement of electrons in a semiconductor material and last as long as a standard transistor.
Electrons move constantly, rather like tiny particles with a negative charge and attention deficit disorder. It is through the movement of these electrons that electric current flows and light is created.
After much research Steckl felt that if electrons' mobility could be manipulated, then new properties could be revealed. His attention was drawn to salmon sperm.
"Biological materials have many technologically important qualities - electronic, optical, structural, magnetic," Steckl said. "But certain materials are hard to duplicate, such as DNA and proteins."
He also wanted a source that was widely available, would not have to be mined, and was not subject to any organization or country's monopoly.
The answer, he concluded, was salmon sperm.
"Salmon sperm is considered a waste product of the fishing industry," Steckl said. "It's thrown away by the ton. It's natural, renewable and perfectly biodegradable."
The light reborn
To date, Steckl said his source of wild salmon sperm is from a professor at Chitose Institute of Science and Technology in Chitose, Hokkaido, Japan. He said he did not know which salmon species the sample sperm was coming from.
His research team has also begun to investigate the DNA of sperm from farmed Chilean salmon. Steckl said he would be interested in obtaining salmon sperm DNA from Alaska, particularly if he could have samples selected by salmon species.
"The Air Force had already been working with DNA for other applications when they came to us and said, OWe know that you know how to make devices,'" Steckl said. "They also knew that they had a good source of salmon DNA.
"DNA has certain optical properties that make it unique," he said. "It allows improvements in one to two orders of magnitude in terms of efficiency, light, brightness - because we can trap electrons longer."
When electrons collide with oppositely charged particles, they produce very tiny packets of light called photons.
"Some of the electrons rushing by have a chance to say Ohello' and get that photon out before they pass out," Steckl said. "The more electrons we can keep around, the more photons we can generate."
That's where the DNA comes in, thanks to the salmon sperm.
"DNA serves as a barrier that affects the motion of the electrons," Steckl said. "The next step is to now replace some other materials that go into an LED with biomaterials. The long-term goal is to be able to make Ogreen' devices that use only natural, renewable and biodegradable materials.
"We all know that the DNA molecule is special in many ways," Steckl said. "For our work in electronic and photonic devices, we have found that the ability to form high-quality DNA thin films enables us to take advantage of DNA chemical, electronic and optical properties.
"The incorporation of DNA thin films in LED structures has led to significant improvements in brightness and efficiency. We have also been able to fabricate very efficient optically pumped lasers which use light emitting dyes incorporated in DNA thin films."