Tests showed little effect on the spores from the transient cavitation in plain water, or from cavitation of the alcohol solution at standard atmospheric pressure.
As part of their evaluation, researchers subjected a test vial of fluid containing bacterial spores in the alcohol solution to short bursts of cavitation over a period of 10-15 minutes. When the power was applied, the test vial appeared to be filled with foam that subsided when the power was switched off, Cunefare said. The cavitation was active for up to 60 seconds of the test period.
Because acoustic disinfection could be carried out more quickly than existing heat and chemical techniques, Carter believes it could offer significant cost advantages by reducing the amount of time that expensive equipment is out of service. And it would also have the potential for minimizing the risk of cross transmission of infection caused by contaminated instruments, he added.
The idea for using transient cavitation to disinfect instruments originated with Carter, who had been interested in a new approach for sterilizing the growing number of instruments that are vulnerable to damage from traditional heat disinfection. He reasoned that rapid decompression might be able to kill microbes by breaking their cell walls, and obtained a patent for the idea in 1994.
Subsequent testing, however, showed that even "explosive decompression" failed to kill the hardiest of bacterial spores, so Carter sought to enhance the technique by combining pressure with powerful cycles of ultrasonic energy. Though he obtained a patent for that approach in 1997, it still was unable to kill the toughest of microbes. Undaunted, he approached Georgia Tech for help.
A professor in the School of Mechanical Engineering and a specialist in acoustics, Cunefare determi
Contact: John Toon
Georgia Institute of Technology Research News