Liquid Surfaces with Chaotic Capillary Waves Exhibit an Effective Surface Tension.

The influence of chaotic capillary waves on the time-averaged shape of a liquid volume is studied experimentally and theoretically. In that context, a liquid film containing a stable hole is subjected to Faraday waves. The waves induce a shrinkage of the hole compared to the static film, which can be described using the Young-Laplace equation by incorporating an effective capillary length.

Isotachophoresis with Oscillating Sample Zones to Control the Spatial Overlap of Co-focused Species.

Microfluidic isotachophoresis (ITP) is a powerful technique that can significantly increase the reaction rate of homogeneous chemical reactions by cofocusing reactants in a narrow sample zone. Correspondingly, ITP has been utilized to reduce the reaction time in various bioanalytical assays. However, in conventional ITP, it is hardly possible to control the reaction rate in real time, i.

Disorder-to-order transition of long fibers contained in evaporating sessile drops.

A liquid drop containing a long fiber is a complex system whose configuration is determined by an interplay of elastic stresses in the fiber and capillary forces due to the liquid. We study the morphological evolution of fibers that are much longer than the drop diameter in evaporating sessile drops. After insertion, the fibers are either found in an ordered or disordered state, with increasing disorder for increasing fiber length.

Detecting Isotachophoresis Zones Hidden in Noise Using Signal Processing.

Lowering the limit of detection in chemical or biochemical analysis is key to extending the application scope of sensing schemes. Usually, this is related to an increased instrumentation effort, which in turn precludes many commercial applications. We demonstrate that the signal-to-noise ratio of isotachophoresis-based microfluidic sensing schemes can be substantially increased merely by postprocessing of recorded signals.

Optimal Control of Droplets on a Solid Surface Using Distributed Contact Angles.

Controlling the shape and position of moving and pinned droplets on a solid surface is an important feature often found in microfluidic applications. However, automating them, e.g.