High-frequency surface acoustic wave atomizer

High-frequency surface acoustic wave (SAW) atomizers, with resonance frequencies in the range from 50 to 95 MHz, were newly constructed and tested. Atomization characteristics were evaluated in terms of atomization speed and deposited dry particle diameter distribution. Dry nano-sized particles formed from atomized droplets were collected by means of electrostatic force and the size distribution was measured by field-emission-type scanning electron microscopy. Mean diameters of original droplets formed by atomization were estimated to be 5.7 μm (50 MHz), 4.4 μm (75 MHz) and 2.7 μm (95 MHz), respectively, from the dry particle diameter distribution. By collecting dried nanoparticles, it was confirmed that atomization by high-frequency SAW device occurred rather than thermal evaporation. The drop size was slightly larger than Lang's estimation predicting the relationship between drop size and atomization frequency.