Paper-Metal Antimicrobial Layers Designed

E. coli bacteria (National Institute of Allergy and Infectious Diseases)

2 May 2017. A lab at Rutgers University devised a method for sending an electric current through inexpensive paper and metal layered surfaces, which in lab tests kills harmful microbes. The team led by engineering professor Aaron Mazzeo published its findings in yesterday’s issue of Proceedings of the National Academy of Sciences (paid subscription required).

Mazzeo and colleagues are seeking practical ways of creating protective gear for people facing disease-causing microbes, such as public health workers in epidemics. In fact, the researchers say this project was inspired in part by the Ebola outbreak in 2014-15. That outbreak in caused a serious public health emergency in West Africa, with nearly 29,000 cases reported in Liberia, Sierra Leone, and Guinea, leading to more than 11,000 deaths.

In these circumstances, protective surfaces need to be inexpensive and flexible enough to be made into garments. The Rutgers team’s solution is to create plasma gas that releases ionizing molecules killing microbes with ozone, heat, and ultraviolet radiation. But instead of a separate device to generate plasma gas, the researchers produce the gas through layers of paper and aluminum.

“Paper is an ancient material,” says Mazzeo in a university statement, “but it has unique attributes for new, high-tech applications.” Among those attributes is paper’s porosity that allows the plasma gas produced to flow through the layers, as well as allowing heat to dissipate. The researchers use aluminum in a hexagonal honeycomb pattern that serves as electrodes for an electric current.

Tests of the paper-metal material show with an oscillating current, the material can produce high levels of plasma, particularly ozone, sufficient to kill microbes. The team also tested the material in lab dishes with two types of microbes: Saccharomyces cerevisiae or brewer’s yeast, and Escherichia coli  or E. coli bacteria, some of which can cause food poisoning and skin infections. The results show the electrified material kills more than 99 percent of the fungi and bacteria encountered.

With these proof-of-concept findings, the researchers next plan to expand their tests into other types of microbes. The team envisions adapting the technology to uses beyond protective clothing. Mazzeo’s lab is studying sensors that work like human skin to protect against microbes, as well as sense pressure and temperature from the outside. These sensors, say the researchers could be made with plasma-generating paper and built into shared surfaces to prevent contamination, such as in public computer kiosks, as well as prosthetic devices, robots, and vehicles.

The authors say patent applications were filed for the technology in February 2016 and February 2017. The team tells more about its research in the following video.

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