Surface Interactions and Nanostructures

Casimir effect

Casimir forces between macroscopic surfaces have the same physical origin as atom-surface interactions (Casimir-Polder forces) and van der Waals (vdW) forces between two atoms or molecules. In general, Casimir forces result from selective confinement of long-range fluctuations of any field, regardless of its quantum or classical nature, which are encountered in a variety of systems, such as in mixed liquids where it is named the critical Casimir effect, or in the vdW interactions between protein molecules or cellular membranes. vdW forces are crucial in bioassembling including virus-like type objects. Casimir forces have also important technological potential for Micro- and Nano-ElectroMechanical Systems (MEMS/NEMS) like switches, accelerometers, quantum levitation systems etc. They have surface areas large enough but gaps small enough for the Casimir force to draw components together and affect their actuation dynamics. In our research we investigate how surface roughness and material optical properties affect Casimir forces and as a result actuation dynamics of these systems.

Nanoparticles

Nowadays monometallic and bimetallic nanoparticles (NPs) have emerged as key materials for important modern applications in plasmonics, catalysis, biodiagnostics, energy storage, and magnetics. Consequently the control of NP structural motifs with specific shapes provides increasing functionality and selectivity for related applications. However, producing bimetallic NPs with well controlled structural motifs still remains a formidable challenge.  In our research we investigate NPs for hydrogen storage, wetting, magnetism, solar cells, and phase change materials.

Wetting of surface nanostructures

Wetting of liquids over material surfaces is a topic studied for the last 200 years from both the fundamental and application point of view.Just to mention a few examples, wetting is important for self-cleaning, anti-icing, the adhesion of material surfaces, stiction issues in microelectromechanical systems (MEMS), capillarity phenomena, reduced fluid drug in micro/nanofluidic systems etc. Moreover, trapping of water drops by modification of surface wettability can play important role for the efficiency of drop condensation from vapor in heat exchangers and fog harvesters.The surface wettability is measured by the contact angle θ between a water droplet and the surface it is attached to. A surface that gives a contact angle (CA) smaller than 90° is termed as hydrophilic, while one with larger than 90° is termed as hydrophobic.The creation also of superhydrophobic surfaces has attracted enormous attention, where examples in nature include the feathers of ducks, butterfly’s wings or the leaves of the lotus plant. In our research we investigate how surface roughness effects the wetting state of surfaces.