Electrostatic characterization of electrohydrodynamic atomization process for particle fabrication

The electrostatics of electrohydrodynamic atomization (EHDA) process in a shuttle-chamber for polymeric particle fabrication was investigated. The electrical potential field between the spray nozzle and the ground plate inside the chamber was measured three-dimensionally and demonstrated that the electrical field strength increased with decreasing nozzle-plate distance and made more effect on liquid spraying. Four liquids, two inorganic liquids (water, KCI) and two organic liquids (PLGA + DCM (w/v = 7%), PLGA + acetonitrile (w/v = 8%)) were tested and the organic liquids were sprayed to fabricate micro-particles. For spraying inorganic liquids the current scaling was I similar to Q(1/2) but for spraying organic liquids the current scaling was I similar to Q(1/4). The accuracy of current scaling depended on the values of delta(mu)delta(1/3), which was independent of the nozzle-plate distances (electric field strength). In addition, the spray current increased with decreasing nozzle-plate distance (or increasing liquid flow rate or liquid conductivity). As a result of spraying polymer solution with volatile organic solvent, particles with size of 0.61-36.10 mu m were fabricated. Particle size decreased with decreasing nozzle-plate distance as well as increasing conductivity of polymer solution or decreasing the liquid flow rate. For all cases of particle fabrication, Rayleigh limit was never reached and no coulomb fission occurred in the experiments. (C) 2016 Published by Elsevier B.V.