Q: what’s the working principle of ultrasonic cleaners? 

     The cleaning theory of the ultrasonic cleaner is called “cavitation”. “cavitation” is rapid formation and collapse of tiny bubbles in a liquid. Cavitation is produced by the alternating high and low pressure waves generated by high frequency ultrasonic sound. During the low pressure phase, these bubbles grow from microscopic size unit, during the high pressure phase, the bubbles are compressed and implode, releasing enormous amount of energy.