A team of US researchers at Rutgers – the State University of New Jersey – has invented an inexpensive, effective way to kill bacteria and sanitise surfaces with devices made of paper.
“Paper is an ancient material, but it has unique attributes for new, high-tech applications,” said Aaron Mazzeo, an assistant professor in Rutgers’ Department of Mechanical and Aerospace Engineering. “We found that by applying high voltage to stacked sheets of metallised paper, we were able to generate plasma, which is a combination of heat, ultraviolet radiation and ozone that kill microbes.”
The researchers have detailed their invention in a study published in the Proceedings of the National Academy of Sciences1.
In the future, paper-based sanitisers may be suitable for clothing that sterilises itself, devices that sanitise laboratory equipment and smart bandages to heal wounds, among other uses, the study says.
The motivation for this study was to create personal protective equipment that might contain the spread of infectious diseases, such as the devastating 2014 outbreak of Ebola in West Africa.
The researchers’ invention consists of paper with thin layers of aluminium and hexagon/honeycomb patterns that serve as electrodes to produce the plasma, or ionized gas. The fibrous and porous nature of the paper allows gas to permeate it, fuelling the plasma and facilitating cooling.
“To our knowledge, we’re the first to use paper as a base to generate plasma,” said Jingjin Xie, the study’s lead author and a doctoral candidate in the Department of Mechanical and Aerospace Engineering.
In experiments, the paper-based sanitisers killed more than 99% of Saccharomyces cerevisiae (a yeast species) and more than 99.9% of E. coli cells.
“Preliminary results showed that our sanitisers can kill spores from bacteria, which are hard to kill using conventional sterilisation methods,” said Qiang (Richard) Chen, study coauthor and a doctoral candidate in the Department of Plant Biology in Rutgers’ School of Environmental and Biological Sciences.
“Our next phase is to vigorously test how effective our sanitiser system is in killing spores,” said James F. White Jr., study coauthor and professor of plant pathology in the Department of Plant Biology.
Mazzeo said one of the goals of their ongoing research is to make sensors that resemble how human and animal skin provides protection from external microbes and bacteria, while detecting input (touch, force, temperature and moisture) from environmental surroundings. Such sensors might cover parts of prosthetics, buildings or vehicles. It also might be possible to sterilize vehicles, robots or devices before they enter contamination-prone environments and when they come out to keep them from contaminating people and clean environments.
Study authors also include Poornima Suresh, an electrical and computer engineering major and undergraduate researcher in the Department of Mechanical and Aerospace Engineering, along with Subrata Roy, a professor in the Department of Mechanical and Aerospace Engineering at the University of Florida in Gainesville, Florida.
1. Jingjin Xie el al., "Paper-based plasma sanitizers," PNAS (2017). www.pnas.org/cgi/doi/10.1073/pnas.1621203114
