Morphology of liquid microstructures on chemically patterned surfaces

Abstract

We study the equilibrium conformations of liquid microstructures on flat but chemically heterogeneous substrates using energy minimization computations. The surface patterns, which establish regions of different surface energy, induce deformations of the liquid-solid contact line. Depending on the geometry, these deformations either promote or impede capillary breakup and bulge formation. The contact angles of the liquid on the hydrophilic and hydrophobic regions, as well as the pattern geometry and volume of liquid deposited, strongly affect the equilibrium shapes. Moreover, due to the small scale of the liquid features, the presence of chemical or topological surface defects significantly influence the final liquid shapes. Preliminary experiments with arrays of parallel hydrophilic strips produce shapes resembling the simulated forms. These encouraging results provide a basis for the development of high resolution lithography by direct wet printing.

Controlling Drop Size and Polydispersity Using Chemically Patterned Surfaces

“…The behaviour of fluids spreading and moving across such surfaces is extremely rich, and is only just beginning to be explored [1,2,3,4,5,6,7,8,9,10,11]. Biosystems have evolved to use hydrophobic and hydrophilic patches to direct the motion of fluids at surfaces [12,13].…”

Liquid Nanodroplets Spreading on Chemically Patterned Surfaces

“…Depending on the size of the pattern and the contact angle in the two domains, wetting transitions can occur in which the liquid droplet can change its shape or morphology [12,13]. The equilibrium shapes of liquid droplets on a variety of chemically patterned surfaces has been studied both experimentally and theoretically [14,15,16,17,18,19,20].…”

Geometry-Dependent Electrostatics near Contact Lines

“…Modern microfluidic and patterning applications call for directed fluid flow and wetting on treated surfaces often exhibiting complex surface chemistry [1,2,3,4]. Mechanisms of differential wetting of small droplets of electrolytes have also been exploited as electrically activated switches and micropumps [5].…”