Contact Angle Hysteresis Characterization of Textured Super-Hydrophobic Surfaces

This paper presents the fabrication of rough super-hydrophobic surfaces, dynamic high-speed measurements of sliding angles of water droplets, and develops a mechanistic understanding of contact angle hysteresis—the major dissipative mechanism in droplet based microfluidic systems. We investigate texture-dependence of hysteresis, evaluate the current model, propose a modification, and observe that the two models—current and proposed—are useful bounds on hysteresis of the surface except in ultra- hydrophobic regime where observed hysteresis is significantly higher than predictions of either model.