Anisotropic wettability manipulation via capturing architected liquid bridge shapes

Abstract

Liquid-mediated patterning, which is a fabrication method exploiting the nature of liquids, has achieved great advances in unconventional micro- and nano-fabrication techniques. The easily deformable nature of liquids enables template-based liquid morphing, and the surface tension of the liquid allows for numerous variations of droplet microfluidics. A liquid bridge, which is formed when a droplet of liquid meets two solid surfaces, exhibits the characteristics of both; therefore, it can produce expanded variations in microfabrication and related applications. In this study, liquid bridge-shaped microstructures on a target substrate and template are exhibited. Through the synergy of theoretical investigations and novel construction with elastomeric spacers, the geometry of liquid bridges can be modeled as a function of the solid and liquid properties, separation distance, and morphology of solid surfaces. This study provides various derivatives of structures with tunable sizes, morphologies, and compositions. In particular, the re-entrant morphology of the liquid bridge-shaped microstructures exhibits liquid-repellent characteristics; therefore, it can be exploited for isotropic and anisotropic wettability manipulation. The advances in this research related to semi-confined patterning toward scale-down and controllability unfold a new route for microfabrication, surface engineering, and liquid manipulation.