There will no longer be any need to wait until laboratory uniforms and accessories get dirty before decontaminating them. A team of researchers from State University, New Jersey, and the University of Florida in Gainesville, created a paper-based device capable of self-disinfection by killing bacteria through the action of excited material.
A Decontaminating Plasma State
The team, headed by Aaron Mazzeo, Assistant Professor at the Rutgers Department of Mechanical and Aerospace Engineering, found that when high voltage was applied to stacked sheets of metallized paper, a plasma state was generated. Plasma, discovered by chemist and physicist Irving Langmuir in 1928, is the fourth state of matter, the others being solid, liquid and gaseous states. It is a state of matter consisting of charged particles, ions and electrons that gravitate far from their original atoms, caused by thermal or electrical energy.
The plasma state generated within the paper created by the team is capable of deactivating 99% of the Saccharomyces cerevisiae and Escherichia coli bacteria in 30 seconds of treatment. E. coli is one of the most prolific microbes on the planet. Most strains are harmless and many contribute to the health of the human intestine. However, harmful E. coli types can cause diarrhea, pneumonia, urinary tract infections and other fatal diseases. According to Qiang Richard Chen, PhD student in the Department of Plant Biology at the Rutgers School of Environmental and Biological Sciences, preliminary test results of the paper sanitizer have shown that it is also capable of destroying bacterial spores that are difficult to eliminate using conventional sterilization methods.
Application and Function
The study, entitled “Paper-based plasma sanitizers“, co-written by Jingjin Xiea, Qiang Chenb, Poornima Suresha, Subrata Royc, James F. Whiteb and Aaron D. Mazzeoa, was published on May 1, 2017, in the journal Proceedings of the National Academy of Sciences of the United States of America.
In the article, the team members explain the design method for this device, whose operation does not require the use of a specific gas to induce the plasma state. Furthermore, they show that this technology is capable of conforming to curved surface shapes and can be adapted to kirigami-type extensible structures. The technology is particularly compatible with user interfaces and can also disinfect microbe-sprayed surfaces. This type of disposable plasma generator represents an advance in biodegradable devices made from renewable and flexible materials. The technology will revolutionize the future design of protective clothing and skin-like sensors for robots as well as prostheses used in contaminated environments.
The material is made of two layers of paper. The first is laminated with cellulose fibers and three polymer layers embedding a thin coat of aluminum applied using vacuum evaporation. This first layer is connected to an upper layer of paper with an adhesive. The paper of the upper layer is covered with conductive silver ink, matching the hexagonal cell patterns. The plasma state is generated when an electrical load ranging from ± 1 to ± 10 kV ionizes the air, causing a combination of heat, ultraviolet radiation and ozone that kills germs on the surface and within the device.
The fibrous nature of the paper and its porous interior provide a large area of contact with air. This contributes to maintaining the plasma state while it allows cooling of the entire device.
The team members are pursuing this research with a view to producing biomimetic devices that mimic the way skin protects us against microbes and bacteria by integrating sensors that will measure touch, pressure, temperature and humidity. They will be able to measure brain waves and sweat to determine the onset of alertness and stress situations. In fact, it will be possible to create electronic devices that will connect machines to humans. In addition, these detectors could be used to design covers for prostheses, building walls or vehicle surfaces to sterilize machines, robots or equipment before entering or exiting contaminated areas. Similarly, cleaning cycles of architectural walls could be programmed continuously in order to fight off microbes.