Ultrasonic humidification function
In order to be able to use ultrasonic waves for air humidification, electrical energy has to be converted into mechanical energy. This takes place in the piezoelectric transduce (also called transducer and oscillator).
Vibrations arise as a result of a pressure change. Repeated increases and decreases in pressure produce different sound waves. The frequencies 16 - 20,000 Hz are audible to the human ear. All higher frequencies are called ultrasound.
A vibration unit thus consists of the resonance circuit in which the high frequency of ~ 1.7 MHz is generated and the piezoelectric transducer to convert the electrical frequency into a proportional, mechanical oscillation.
The piezoceramic transducers are attached to the bottom of the humidifier´s water pan. When the transducer is exited, the water conducts the ultrasonic vibrations to the water-air boundary layer.
The constant compress / decompression of the water column above the transducer causes cavitation in the immediate vicinity of the water surface. This creates crossed capillary waves, from which the smallest mist droplets (aerosols) are released in the wave crest.
The aerosols have a very small diameter (~ 0.001-0.005 mm). They are carried out by the air flow in the humidifier and mix very quickly with the ambient air.