Sessile drop technique

About: Sessile drop technique is a research topic. Over the lifetime, 2827 publications have been published within this topic receiving 68943 citations.

Droplet impact on soft viscoelastic surfaces.

Abstract: In this work, we experimentally investigate the impact of water droplets onto soft viscoelastic surfaces with a wide range of impact velocities. Several impact phenomena, which depend on the dynamic interaction between the droplets and viscoelastic surfaces, have been identified and analyzed. At low We, complete rebound is observed when the impact velocity is between a lower and an upper threshold, beyond which droplets are deposited on the surface after impact. At intermediate We, entrapment of an air bubble inside the impinging droplets is found on soft surfaces, while a bubble entrapment on the surface is observed on rigid surfaces. At high We, partial rebound is only identified on the most rigid surface at We≳92. Rebounding droplets behave similarly to elastic drops rebounding on superhydrophobic surfaces and the impact process is independent of surface viscoelasticity. Further, surface viscoelasticity does not influence drop spreading after impact-as the surfaces behave like rigid surfaces-but it does affect drop recoiling. Also, the postimpact drop oscillation on soft viscoelastic surfaces is influenced by dynamic wettability of these surfaces. Comparing sessile drop oscillation with a damped harmonic oscillator allows us to conclude that surface viscoelasticity affects the damping coefficient and liquid surface tension sets the spring constant of the system.

New Experimental Setup for Wettability Characterization under Monitored Oxygen Activity: I, Role of Oxidation State and Defect Concentration on Oxide Wettability by Gold

Abstract: A sessile drop setup has been combined with an oxygen sensor, an electrochemical pump, and a renewable oxygen getter. The oxygen activity of a metal–oxide sample can be monitored in the 10−9–1 range, in a flowing gas, that enables the control of the defect concentration in the oxide and of the oxygen content in the metal. The stoichiometry of the substrate can also be modified by electrochemical reduction, allowing the oxygen activity of the sample to be monitored down to values as low as 10−20. The dependence on oxygen activity of the wetting and the thermodynamic adhesion of gold on sapphire, titanium oxides, and yttria-stabilized zirconia is presented to illustrate the versatility of the equipment.