Droplets on substrates with oscillating wettability

Abstract

In recent decades novel solid substrates have been designed which change their wettability in response to light or an electrostatic field. Here, we investigate a droplet on substrates with oscillating...

Steering droplets on substrates using moving steps in wettability

“…In the following we reformulate our formalism to apply the boundary element method (BEM) [28] to a wetting droplet, which we developed in Refs. [14,29], and adjust its boundary condition to account for either an imposed wettability pattern or a height profile of the substrate. Because in our previous work we only studied a plane substrate [14,29], the method needed to be extended to curved substrates.…”

Wetting dynamics under periodic switching on different scales: characterization and mechanisms

“…Guided by eqn (10) one may substitute k 1 sin(y)/g(y) by k 1 sin(hyi)/g(hyi). k 3,i in eqn (19) and all corresponding formulas can be substituted by this value. Convenient is the choice of the contact angle y as calculated via coshyi = (1/2)(cos y eq (e HW ) + cos y eq (e LW )) which is the average angle for large switching times T. The resulting value is then denoted k ˜3,i which would substitute the corresponding value of k 3,i .…”

“…Theoretical investigations of the dynamical behavior of droplets on surfaces with an oscillating wettability can be performed with a variety of different models reflecting different temporal and spatial scales. For instance, the boundary element method applied to Stokes flow, [17][18][19] mesoscopic models based on the lubrication approximation 20,21 and microscopic models like molecular dynamics [22][23][24] have all been successfully applied to dynamic wetting problems. The inherent complexity in such models often makes it hard to pinpoint the physical origin of the effects in question and hence, comparison with minimal models can help to understand the physical effects at work.…”

Molecular Kinetics and Wetting Dynamics of Self-Assembled Monolayers with Fluorinated Arylazopyrazoles

“…However, it is extremely difficult to change once the liquid is in contact with the solid surface . For that reason, dynamic control of surface wettability with external stimuli such as electric fields in electrowetting experiments or light irradiation has gained considerable attention. − Applications where such control is highly desirable involve the modification of the liquid flow on surfaces (e.g., programmable − transport of a liquid or microfluidics , ), where tuning of drop formation, drop size, and drop size distribution is desired. In addition, photoswitchable thin organic films are interesting for optoelectronic devices. − …”