Jun 2 2020
Scientists at Penn State, the University of Minnesota, and two Japanese universities have now reported that it is possible to create a personal, handheld device that emits ultraviolet light of high-intensity to disinfect areas by destroying the novel coronavirus.
Using ultraviolet light to disinfect public spaces is preferable to using harsh chemicals. Image Credit: Jennifer M. McCann/Penn State.
Ultraviolet radiation exposure or chemicals are the two common methods used to disinfect and sanitize areas from viruses and bacteria. UV radiation with a wavelength in the range of 200–300 nm is known to kill the virus, rendering the virus unable to reproduce and infect.
With the current pandemic situation, the large-scale adoption of this efficient UV method is much needed. However, it necessitates UV radiation sources with the ability to emit high enough doses of UV light. Although there already exist devices with such high doses, the UV radiation source is usually a high-cost mercury-containing gas discharge lamp, which is bulky, needs high power, and has a comparatively short service life.
The solution is to create UV light-emitting diodes (LEDs) that exhibit high performance and would be much more durable, portable, environmentally benign, and energy-efficient. Although such LEDs already exist, it is highly difficult to apply a current to them for light emission since it is essential for the electrode material also to be transparent to UV light.
You have to ensure a sufficient UV light dose to kill all the viruses. This means you need a high-performance UV LED emitting a high intensity of UV light, which is currently limited by the transparent electrode material being used.
Roman Engel-Herbert, Associate Professor of Materials Science, Physics and Chemistry, Penn State
It has already been difficult to find transparent electrode materials that work in the visible spectrum for smartphones, displays, and LED lighting, and it is even more challenging to find such materials for ultraviolet light.
There is currently no good solution for a UV-transparent electrode. Right now, the current material solution commonly employed for visible light application is used despite it being too absorbing in the UV range. There is simply no good material choice for a UV-transparent conductor material that has been identified.
Joseph Roth, Doctoral Candidate in Materials Science and Engineering, Penn State
It is crucial to find a new material with the optimal composition to improve the performance of UV LEDs. Working together with materials theorists from the University of Minnesota, the Penn State researchers found out very early that the solution for the challenge might be in a new class of transparent conductors that were discovered recently.
Theoretical predictions suggested strontium niobate as a promising material. Thus, the researchers obtained strontium niobate films from their Japanese collaborators and instantly tested their performance as UV transparent conductors. These films were found to meet the theoretical predictions, and thus the researchers sought a deposition technique to scalably integrate these films.
“We immediately tried to grow these films using the standard film-growth technique widely adopted in industry, called sputtering,” added Roth. “We were successful.”
This is a key step toward technology advancement that enables integration of this new material into UV LEDs at high quantity and reduced cost. Both Engel-Herbert and Roth consider that this is essential during the ongoing crisis.
While our first motivation in developing UV transparent conductors was to build an economic solution for water disinfection, we now realize that this breakthrough discovery potentially offers a solution to deactivate COVID-19 in aerosols that might be distributed in HVAC systems of buildings.
Joseph Roth, Doctoral Candidate in Materials Science and Engineering, Penn State
Virus disinfection can be applied to other areas such as densely and frequently populated areas, like sports arenas, theaters, and public transportation vehicles, including subways, buses, and airplanes.
The study outcomes were recently reported in the Nature Group publication Physics Communications.
This study was supported by the National Science Foundation through the DMREF program and a Graduate Research Fellowship, as well as the Japan Society for the Promotion of Science KAKENHI program.
Journal Reference:
Park, Y., et al. (2020) SrNbO3 as a transparent conductor in the visible and ultraviolet spectra. Communications Physics. doi.org/10.1038/s42005-020-0372-9.
Source: https://www.psu.edu/