High-fidelity Modeling and Validation of Electrohydrodynamic Jet Printing

Abstract

High-resolution electrohydrodynamic jet (e-jet) printing has provided a new route to flexible fabrication design of electronic devices. However, there are gaps in understanding this novel micro-additive manufacturing (μ-AM) process and the key material parameters that dictate the material jetting behavior. This paper provides a framework for high-fidelity modeling of drop-on-demand high-resolution e-jet printing that addresses this knowledge gap, which currently leads to slow and costly process optimization through experimental testing. The model is implemented in COMSOL Multiphysics and based on the leaky-dielectric model for an applied pulsed voltage, where the level set method is used to track the ink-air interface. The simulation results successfully demonstrate the critical process steps including equilibrium, Taylor Cone formation, the creation of a jet, jet break, and material retraction to the nozzle. The model is validated using high-speed printing images that are taken from a similar experimental setup. Four different case studies are conducted using the simulation model to investigate the impacts of key material parameters including viscosity, surface tension, electrical conductivity, and relative permittivity on the e-jet process, where it is shown in simulation that viscosity, surface tension and electrical conductivity have a higher impact on jetting frequency and deposited droplet volume.