Final answer:
Ultrasonic cleaners clean dirty instruments through mechanical scrubbing caused by cavitation, which releases energy from collapsing microscopic bubbles in the cleaning fluid.
Step-by-step explanation:
An ultrasonic cleaner uses sound waves to clean dirty instruments, which causes mechanical scrubbing. This is due to the phenomenon of cavitation, where microscopic bubbles in the cleaning fluid collapse, releasing energy that results in a powerful scrubbing effect. This mechanism effectively cleans jewellery, lenses, optical parts, watches, dental and surgical instruments, and industrial parts. The frequencies typically employed in ultrasonic cleaners range from 20-40 kHz.
The energy released from the cavitation process at high intensities can cause shock pressures that assist in cleaning within tiny crevices that might otherwise be difficult to reach with cleaning fluids alone, thus making it an efficient and thorough cleaning method. Ultrasonic cleaners do not rely on chemical disinfection, heat sterilization, or UV radiation, but instead utilize a physical cleaning process.