LEDs on metal foils purify water, sterilise equipment

Article By : Carolyn Mathas

Researchers have leveraged molecular beam epitaxy to achieve water purification, whereby vapourised elemental materials settle on a surface and move themselves into layers or nanostructures.

Researchers at Ohio State University have developed metal foil-based LEDs, which they say could be used to purify drinking water and even sterilise medical equipment in the field.

For the first time, LEDs on lightweight flexible metal foil are using the high-energy deep end of the UV spectrum that is already the basis for detection of biological agents as well as curing plastics. The lightweight foil enables easy transport compared with any other deep ultraviolet light today, such as mercury lamps. The research indicates that by making UV LEDs safe, portable and inexpensive, safe drinking water could be made wherever needed.

__Figure 1:__ *Ohio State University researchers have developed a technique to create light emitting diodes on metal foil. (Source: Brelon J. May, The Ohio State University)*

Foil-based nanotechnology whereby nanowires are grown on titanium foil in this research can foster large-scale production of an environmentally friendly deep-UV LED. The researchers, according to Roberto Myers, associate professor of materials science and engineering at OSU, are anticipating that the research can push nanophotonics into viability. In the past, the technology was not scalable, which was a huge barrier to commercial use. Now nanophotonics can possibly be used for large-scale manufacturing.

The team used the semiconductor growth technique called molecular beam epitaxy, where vapourised elemental materials settle on a surface and move themselves into layers or nanostructures. The wires measure approximately 200 nanometres tall and 20-50 nanometres in diameter. They are invisible to the naked eye and thousands of times more narrow than human hair, yet they light as brightly and are more flexible than a single-crystal silicon solution.

Research continues to make the LEDs even brighter and grow wires on steel and aluminium foils. The research was recently featured in the journal Applied Physics Letters.