Lightning sparks scientists’ design of ultraviolet-C device for food disinfection

Scientists at the University of Illinois at Urbana-Champaign have developed a portable, self-powered ultraviolet C device called the Tribo-sanitizer, which can inactivate two of the bacteria responsible for many food-borne illnesses and deaths.

The Tribo-sanitizer’s UVC lamp is powered by the triboelectric effect, i.e. the electricity generated when two different materials come into contact. In tests, the Tribo-sanitizer successfully inactivated two potentially deadly foodborne bacteria, Escherichia coli O157:H7 and Listeria monocytogenes, primarily by damaging their DNA, according to results published in the journal. Nanoenergy.

The bacteria selected as testing targets are two of the most common causes of serious foodborne illness outbreaks in the United States. Escherichia coli produces toxins that can cause severe abdominal cramps, fever, bloody diarrhea, and kidney failure, and Listeria monocytogenes can cause listeriosis, which has the highest hospitalization and mortality rates of any disease of food origin.

The team evaluated the Tribo-sanitizer’s decontamination ability with bacteria found in liquids and on three solids: fresh apple peels, romaine lettuce, and polyethylene terephthalate, commonly known as PET, a popular packaging material. food and beverages.

Results indicated that the Tribo-sanitizer had strong potential to meet Food and Drug Administration disinfection standards. Specifically, the device “achieved reductions of at least 99.999% on the E. coli strain in the buffer solution and on the PET, demonstrating the excellent decontamination capacity of the Tribo-sanitizer,” said l Corresponding author Yi-Cheng Wang, professor of food safety and engineering. .

On products, the device made it possible to obtain smaller but nevertheless useful reductions of approximately 99.98% for the E. coli bacteria, 99.9% for L. monocytogenes on apple peels, and 99.8 % for E. coli and 98% for L. monocytogenes on romaine lettuce. according to the newspaper.

These results “are comparable to those reported in other studies that used UV light with a commercial energy source for decontamination of fresh produce,” said doctoral student Zachary (Zhenhui) Jin, co-first author of the paper. article with former student Fujunzhu. Zhao. Graduate student Longwen Li also participated in the study.

The Tribo-sanitizer’s triboelectric power source can convert mechanical energy from the surrounding environment, for example from human movements and wind, which would otherwise be wasted. That’s why the research team describes it as “self-sustaining,” Wang said.

An air gap that the team incorporated into the design of their triboelectric power source mimics lightning by breaking down air electrostatically. This innovation increased the power of the Tribo-sanitizer to more than 4,000 volts and significantly increased the brightness of its UVC lamp, according to the study.

Although light-based technologies like the Tribo-sanitizer lamp “can be very effective when surfaces are directly exposed to the light source,” Wang said they may not adequately decontaminate areas that are not directly lit, such as uneven or rough surfaces on lettuce and apples. peels.

“This problem could be solved by incorporating other decontamination methods or using multiple light sources from different angles,” he said. “This is one of the future directions we are working on. And if properly integrated into existing facilities such as transport or storage units, the Tribo-sanitizer could potentially provide continuous decontamination throughout supply chain without the need for commercial power.”

Although the time required to achieve a 99.999% reduction in E. coli bacteria is long (currently 90 minutes), Jin said the device’s potential to achieve continuous decontamination, such as in trucks on the highway, means that this extended time should not be considered a major inconvenience. The team is continuing its efforts to improve the Tribo-sanitizer, and “we can expect this time to be much shorter in the future,” he said.

According to the World Health Organization, foodborne illnesses affect nearly 600 million people each year and cause 420,000 deaths. The economic cost of dealing with the consequences of food contamination is more than $15.6 billion per year in the United States and $110 billion in low- and middle-income countries, according to ministry estimates. Department of Agriculture and WHO, respectively. Wang said the Tribo-sanitizer represents a new way to alleviate these problems.

Consumers could use Tribo sanitizers at home to disinfect surfaces, food and more, as “the estimated cost of materials used to construct the device is less than $70,” Jin said.

The self-powered nature of the device also gives it “excellent potential for use in low-resource settings such as natural disaster areas and conflict zones where electricity is absent or unreliable,” said Mr. Li.