A Model to Guide Template-Based Nanoparticle Printing Development

Advective molding in vapor-permeable templates is an evaporation-driven process for submicron molding of nanoparticles with high fidelity. In this process, nanoparticle ink is drawn through channels in a vapor permeable template. The ink solvent is sorbed into the channel walls and evaporated through the template. As the complexity (e.g., width variation and turns in a channel) of the desired features increases, so does the likelihood of incompletely patterned nanoparticles. Patterning difficulties arise from dry-out, a condition where the nanoparticle ink dries before reaching the end of the channel and blocks the flow of more ink. Predicting dry-out during the template development stage is a critical step in patterning complex features. In this work, we present a method for predicting dry-out by incorporating two layers of finite element analysis. First, models for ink fluid flow and solvent diffusion through the template are used to determine wall sorption rate correlations. Fluid flow through complex templates is then modeled in a fluid-only model, with the flux rate into the template walls determined by the sorption rate correlations. The fluid velocities and wall sorption rates are then used to determine the likelihood of dry-out. The linked simulations successfully predict points of improper nanoparticle patterning in real templates.