Control of Charging and Motion of Particles using UV Irradiation and Electrostatic Field

Abstract

Particle adhesion and deposition in dry powder processes can result in low quality and productivity. In this study, to establish a method for controlling the charge and motion of particles and for removing them without using fluid and/or mechanical external forces, dielectric particles deposited on an insulating plate were charged and levitated using ultraviolet (UV) irradiation in an upward electric field. The particles in the top layer irradiated by UV light were positively charged by photoemission and levitated by the Coulomb forces. The flux and motion of the levitated particles and the charge of each levitated particle were experimentally obtained. The results showed that approximately 40% of the levitated particles descended because of the change in particle charge due to negative charge clouds formed by the photoemission from the particle layers and the levitated particles. Furthermore, applying an upward electric field after UV irradiation, all the particles were levitated without descending because the negative charge clouds were not formed. In addition, more particles were levitated due to an increase in particle charge, but the continuous levitation did not occur.

Graphical Abstract

Particles levitated from top layer. Reprinted with permission from Ref. (Shoyama M., et al., 2022). Copyright: (2022) IEEE. https://doi.org/10.1109/TIA.2021.3123930