Characterization of deposition patterns produced by twin-nozzle electrospray

Abstract

This paper presents the characteristics of two-nozzle electrospray deposition with a capillary–extractor–substrate configuration. A three-dimensional Lagrangian model was developed to simulate the spray evolution and deposition patterns. The droplet size distribution was not affected by the extractor–substrate voltage; however, spray evolution was found to be influenced considerably by the extractor–substrate voltage. Smaller particles are deposited densely in the outer region of the spray, whereas larger particles are deposited in the core region of the spray due to the size segregation effect. The normalized thickness in the intervening region of adjacent sprays is thinner than in the core region of sprays and gradually decreases as the extractor–substrate voltage increases. The normalized surface number density of deposited particles in the intervening region of adjacent sprays also decreased with the increasing extractor–substrate voltage, whereas the surface number density of them is larger than that in the core regions of sprays at an extractor–substrate voltage below 3 kV. The deposition patterns using a diluted PSL solution and spray visualization were in good agreement with the simulation results. It is suggested that the electrical self-dispersion effect and electrical repulsive interaction between adjacent sprays play an important role in determining the characteristics of the spray evolution and deposition patterns for multiplexed electrospray deposition.