Ultrasonic cleaners use very high frequencies to shake dirt loose from small delicate objects.

The longer version

A transducer drives the wall of a tank at a rate far above hearing, sending pressure waves through the liquid. Millions of microscopic bubbles form and collapse with each cycle, and the collapse scrapes contamination off surfaces, including inside narrow cracks a brush cannot reach. The liquid couples the vibration efficiently, since air would reflect most of it.

The process is cavitation, and it cleans by mechanical action rather than by dissolving dirt, so gentle chemistry suffices. High rates are used because tiny bubbles respond to fast pressure changes, and the same mechanism can pit metal if a cycle runs too long.

Where this entry sits

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