Formation of Gradient Particle Pattern Via Electric Field Guided Electrospray Deposition

Electrospray and electric-hydrodynamic atomization have been investigated in recent years for the production of pharmaceutical particles. Furthermore, there were literature report on the electrospray deposition for fabrication of various patterns based on different types of materials such as living cells, proteins, and pharmaceutical particles. In this project, the effect of the configuration of grounded electrode used in electrospray was investigated. Three types of grounded electrode, namely, point, line and plane electrode were placed under a glass slide. The electric field and particle deposition were simulated by solving the Poisson’s equation and the force balance equation for the charged particle during the electrospraying process. It was found that the particle patterns with graded size can be obtained when the additional point or line electrode was used. The formation of gradient patterns was ascribed to the gradient of electric field and the corresponding focusing effect. By changing the electric field, the feature size of the gradient patterns can be controlled. In addition, an analysis of the particle patterns obtained by using different collecting substrates, e.g. normal glass slide, Polydimethylsiloxane (PDMS) coated glass slide, showed that the particle pattern size is much more uniform on PDMS –coated glass slide under the same condition. This kind of gradient patterns may be promising for applications in high throughput drug screening or biomaterial screening for studying cell material interactions.