Note: Electric field assisted megasonic atomization for size-controlled nanoparticles

In this study, we report the use of megasonic atomization along with an electric field to reduce the aerosol particle size. The electric field assisted megasonic atomization (EMA) was achieved by implementing mesh and an induction charging ring at the output of a megasonic atomizer. The aim was to increase the number of particles generated and reduce the size of the particles to the nanoscale regime. In the present study, the megasonically generated NaCl and TiO₂ aerosols were charged by applying an electric supply voltage up to +20 kV through the induction ring. The generated nanoparticles were evaluated by an electrical low-pressure impactor and scanning electron microscopy. It is observed that, for +15 kV, the number concentration of NaCl and TiO₂ particles was found to have increased by up to five times, and the peak size of the particles was shifted from 40 nm to 15 nm. The particle size reduction and increase in the number concentration might be due to Coulomb fission. Hence, the developed EMA system is suitable for many industrial applications where a large number of uniform-sized nanoparticles are required.