Steady state of electrohydrodynamic patterning of micro/nanostructures on thin polymer films

This paper presents a nonlinear numerical study of the electrohydrodynamic (EHD) patterning process as a micro/nanostructuring approach for a thin polymer film. Special interest is focused on the steady state (or equilibrium state) in this study. Numerical results show that the polymer nanostructure height depends strongly on the applied voltage, rising higher with an increasing electric field. Moreover, a critical electric field intensity is discovered, above which the deformed film can grow continuously into a final contact with the template to form a nanostructure conformal the pattern premade on the template. An electric field intensity larger than the critical value is necessary for a faithful replica in EHD patterning; however, breakdown may occur for polymer film under a strong electric field and thus fail the process. In this study, the scale limitation is investigated and some methods are then proposed for scaling down the feature size of the structure.