Präsentationsmaterialien
Slide electrification-spontaneous charge separation at receding contact line has been reported to result in an electrostatic potential of around 1 kV and significantly affect drop motion. In order to find out how slide electrification influences contact angle, we examined the dynamic contact angles of aqueous droplets at various salt concentrations sliding down surfaces. We compare drops...
Leveraging our established droplet model developed using the boundary element method (BEM), we investigate dynamic wetting on thin flexible sheets. One promising application arising from this research is the potential for designing tunable fluidic lenses.
Central to our study is the nuanced interplay between the mechanical attributes of the sheet and droplet behavior, with a particular...
Water drops sliding on insulating, hydrophobic substrates can become electrically charged [1–3]. Despite many decades of research, this spontaneous electrification of moving drops is still far from being understood. By precisely measuring charge and voltage, we found that moving water drops accumulate a voltage of several kilovolts after sliding for just a few centimeters. To enable an...
Conducting polymers (CPs) are discussed in a huge variety of electronic devices including organic field effect transistors, batteries, actuators and (bio)electronic sensors. Compared to other conducting materials, CPs are light-weight, low cost, non-toxic, flexible and allow easy processing, low voltage operation (around 1 Volt) and low power consumption.
Here, poly(3-hexylthiophene) (P3HT)...
The breakup dynamics of highly viscous capillary bridges on grounded hydrophobic surfaces is investigated. The breakup dynamics bears a very close resemblance to that of highly viscous free capillary bridges. However, due to the strong dependency of the dynamics on the surface properties, the wettability of the substrate must be taken into account. In this regard, it is demonstrated that under...
Nanometer thick layers of polydimethylsiloxane (PDMS) are widely applied as hydrophobic coatings because they are environmentally friendly and chemically inert. In many applications, low friction of water drops is required. While the onset of motion (static friction) has already been studied, dynamic friction is less explored. It is not understood which processes lead to energy dissipation and...
The static contact angle of a liquid droplet on a substrate is often used to describe its wetting properties, which are influenced by various factors such as the chemistry of the substrate, properties of the liquid, and environmental conditions. Our study shows that the wetting of a microscopic droplet can systematically depend on its size. This dependency can be described with consideration...
Protein condensates inside human cells are liquid-like droplets composed of protein and RNA. These condensates interact with the heterogeneous, active and dense environment of the cytoplasm, crossed by various cytoskeletal filaments such as microtubules and actin. Wetting interactions with the cytoskeleton lead to stereotypical positioning of such protein droplets inside the cell. Using...
Wetting and adhesion of lipid vesicles and biological cells are distinct from that of Newtonian fluid, because of their viscoelasticity. The use of switchable substrates based on polymer brushes and hydrogels offers a unique advantage for the adjustment of interfacial interactions on demand.
In the first of my talk, I will introduce our collaborative activities with Müller group (Göttingen)...
Soft materials can undergo irreversible shape changes when driven out of equilibrium [1,2]. When shape changes are triggered by processes at the surface, geometry-dependent feedback can arise. Motivated by the mechanochemical feedback observed in multicellular systems [1,3-5], we study incompressible droplets that adjust their interfacial tensions in response to shape-dependent signals. We...
A liquid bridge is a liquid droplet suspended between solid surfaces. We study pendent liquid bridges between two horizontally aligned cylindrical rods using experiments, direct numerical simulations and reduced-order model equations obtained by minimizing an appropriate Rayleighian according to Onsager’s variational principle. Additionally, we analyse the influence on the dynamics of perfect...
Liquid droplets on soft, solid, elastic substrates tend to deform the substrate on which they sit due to the interaction of interfacial and elastic forces. This deformation is the more pronounced the softer the substrate. Our project aims at understanding the mechanisms that determine the resulting morphology of equilibrium droplets.
To study these phenomena, we explore the dewetting of...