By Peter Weiss
Bubbles can be microbe killers. Scientists have long known that ultrasound in liquids causes gas bubbles to form and then often collapse violently. When those bubbles implode in cleaning solutions, they break up dirt and destroy some microbes. Doctors have eyed high-frequency sound as a quick, low-heat way to sterilize medical instruments, but no ultrasonic device yet has killed germs efficiently enough.
A study unveiled this week at the First Pan-American/Iberian Meeting on Acoustics in Cancun, Mexico, suggests that an effect known from submarine research may make ultrasound sterilization possible. In a liquid exposed to ultrasound, moderately increasing the pressure dramatically boosts microbe destruction, according to Kenneth A. Cunefare of the Georgia Institute of Technology in Atlanta and his colleagues.