UT Plasma Sterilization Tests Successful

KNOXVILLE, Tenn. — A quicker, safer way to clean medical instruments might result from a University of Tennessee research project.

UT-Knoxville researchers are testing a sterilization process using electrically charged gases that kill surface germs faster and more safely than conventional methods.

Tests show the process does the job without the heat, poisons and harmful radiation generated by standard sterilization, the researchers said.

“We still have a long way to go, but initial tests have been more successful than we anticipated,” said Dr. Reece Roth, the UT-Knoxville electrical engineering professor who invented the process.

In the UT tests, contaminated materials are placed in a device which resembles a microwave oven and are exposed to charged gases called plasmas.

The plasmas, which Roth describes as “the fourth state of matter,” kill microorganisms at room temperature, do not harm materials and create little toxicity or radioactivity.

“We suspect that these (bacteria) are being torn apart by energetic chemical reactions of the plasma. They’re actually disassembled at the atomic level,” Roth said. “It’s the ultimate form of zapping.”

Dr. Tom Montie, a microbiology professor and member of the research team, said the process has killed bacteria on cloth, metals and plastics in as little as five seconds.

He said common industrial and hospital sterilization methods and their associated problems include:

* Ethylene oxide, a highly toxic gas used in industrial sterilization, requires careful handling and is hazardous to humans.

* Steam autoclaves, widely used in hospital sterilization, produce heat and pressure that can soften or melt some plastics and damage materials being sterilized.

* Gamma radiation, inconvenient because of strict radiation shielding requirements, can make polypropylene and other materials brittle.

Dr. Larry Wadsworth, a textiles professor, collaborated with Roth and Montie on the project. A report on their work has been presented to the American Society for Microbiology.

Contact: Dr. Reece Roth (423-974-4446)

Dr. Thomas Montie (423-974-4047

Dr. Larry Wadsworth (423-974-6298)

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