Finite Element Method Modeling of Self-Limiting Electrospray Deposition

Electrospray deposition (ESD) is a manufacturing tool that involves passing a solution through a charged capillary, allowing the solution to disperse into a spray. Some materials undergo self-limiting electrospray deposition (SLED) when sprayed, in which the charge of the spray builds up on the spray target, resulting in the deflection of further spray onto unsprayed portions, creating an even coating. To model the SLED process, COMSOL was used to create a model of the spray needle, target, and electric field, creating a particle trace representing the spray. This was used in combination with a MATLAB interpolation to calculate the surface charge based on the droplets deposited and the charge decay, and a MATLAB wrapper which ran the simulation with the interpolation over several iterations to simulate the film deposition over time. These patterns were compared to experimental polystyrene sprays to determine its charge decay constant, allowing the proper charge decay constant to be found and used to model the spray on various target geometries and conductivity patterns. This study can allow for the calculation of various spray materials’ charge decay constants and spray patterns on various geometries.