Deposition of charged aerosol particles on a substrate by collimating through an electric field assisted coaxial flow nozzle

Abstract

Electroaerodynamic (EAD) jet printing, where aerodynamic force is coupled with electrostatic force in order to obtain a wide range of controlled pattern sizes, is introduced. Charged and sheathed aerosol particles yield a high deposition rate even at low velocity owing to the force of their electrostatic attraction to the substrate. In this study, two coaxial nozzles (inner diameters of 6 mm and 100 μm) were designed and tested theoretically and experimentally in order to observe the effects of electrostatic force, particle size, and air flow rate on particle trajectory and dot pattern size. A higher sheath air flow rate (higher Stokes number) caused the aerosol jet stream to be focused. For Stokes numbers higher than 1, the effect of applied voltage on pattern size was less than that of the sheath air flow rate. However, for Stokes number lower than 1, the pattern size was affected by both the applied voltage and the sheath air flow rate. After incorporating all data, the diameter of the particle deposition area (Wp) was expressed as a function of nozzle diameter (W), sheath air flow rate (Qsheath), aerosol flow rate (Qaerosol), Stokes number (Stk), and Electrostatic number (Es). Three different equations were obtained for Stk < 1, for 1 ≤ Stk < 5, and for Stk ≥ 5, respectively. These equations would be used to predict pattern width for given conditions of aerosol and sheath flow rates, particle size, electric field, and nozzle size. © 2013 American Association for Aerosol Research.