Diffusion; Thermal fluctuations; Hydrodynamic vortex; Superhydrophobicity; Slip-length; Atomic force microscopy; Brownian sphere; Optical trapping; Nanostructured surfaces
Butykai Adam, Mor Flavio M., Gaal Richard, Dominguez-Garcia Pablo, Forró László, Jeney Sylvia (2015), Calibration of optical tweezers with non-spherical probes via high-resolution detection of Brownian motion, in Computer Physics Communications
, 196, 599-610.
Schleicher Kai D., Dettmer Simon L., Kapinos Larisa E., Pagliara Stefano, Keyser Ulrich F., Jeney Sylvia, Lim Roderick Y. H. (2014), Selective transport control on molecular velcro made from intrinsically disordered proteins., in Nature Nanotechnology
, 9, 525-530.
Mor Flavio M., Sienkiewicz Andrzej, Forró László, Jeney Sylvia (2014), Upconversion particle as a local luminescent Brownian probe: A Photonic Force Microscopy Study, in ACS Photonics
, 1, 1251-1257.
Mor Flavio M., Sienkiewicz Andrzej, Magrez Arnaud, Forró László, Jeney Sylvia, Single potassium niobate nano/microsized particles as local mechano-optical Brownian probes, in Nanoscale
Inspired by the lotus effect, the development of self-cleaning and other functional surfaces with tunable and/or biomimetic properties has attracted intense research interest in the last decades. Smart coatings are now routinely engineered, in particular by supramolecular self-assembly of hydrophobic and hydrophilic patches on a nano- and micro scale. For characterization of liquid-substrate interactions, typically macroscopic methods are used, such as contact angle measurements of a water droplet. At microscopic scale, fluid flow can be observed by different microscopy techniques and computer simulations. It could be shown that fluid flow is mainly affected by the slip-length at the solid/liquid interface, which is defined as an extrapolated distance relative to the wall where the tangential velocity component vanishes. With the advent of micro- and nanofluidics, multidimensional measurements of fluid dynamics at the solid/liquid interface down to the nano-scale have become a necessity. However, up to now only few experiments and theoretical predictions allow for quantitative studies in directions parallel and perpendicular to the surface with high enough spatial and temporal resolution. Recently, we and another group of researchers proposed that, by observing, very locally and at shortest time, Brownian motion of a sphere immersed in a fluid at a given distance from a surface could give information on surface properties. The suggested approach exploits the firstly observed effects of the hydrodynamic vortex intrinsically propagating around the Brownian sphere and reflecting at the surface. As a result, anisotropic long-time correlations in the sphere’s Brownian fluctuations can be detected in the direction parallel and perpendicular to the wall. According to latest theoretical predictions, these correlations should depend on boundary conditions at both surfaces, and be a measure for slip-length. Surprisingly, the hydrodynamic backflow carries detectable information on the characteristics of the wall over distances as long as 10 times the sphere’s radius R.In this project, we would like to develop experimental protocols to systematically characterize various kinds of surfaces, ranging from nanostructured surfaces to living cells. We should be able to gain information on short- and long-ranged effects of surface properties, and provide new insights in biological as well as physico-chemical diffusion mechanisms in confined geometries.