Physics of Complex Fluids Group

The research goal of PCF is to understand and to control liquids and their interfaces from molecular to macroscopic scales. Our research connects fundamental phenomena in static and dynamic wetting, nanofluidics, microfluidic two-phase flow, functional surfaces, drop impact, and drop evaporation to practically relevant applications such as enhanced oil recovery, lab-on-a-chip systems, analytical chemistry (MALDI-MS), optofluidics, and inkjet printing.

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Experimental methods and tools: electrowetting, high resolution Atomic Force Microscopy and spectroscopy, (high speed) video microscopy, contact angle goniometry, particle tracking microrheology, macroscopic rheometry, (imaging) ellipsometry, quartz crystal microbalance, Langmuir trough and Langmuir-Blodgett deposition.

Latest news

Resolving clay mineral surfaces – from periodic atomic structure to surface defects. New publication in Nanoscale

Atomic scale details of surface structure play a crucial role for solid-liquid interfaces. While macroscopic characterization techniques provide averaged information about bulk and interfaces, high resolution real space imaging reveals unique insights into the role of defects that are believed to dominate many aspects of surface chemistry and physics. Here, we use high resolution dynamic Atomic Force Microscopy (AFM) to visualize and characterize in ambient water the morphology and atomic scale structure of a variety of nanoparticles of common clay minerals adsorbed to flat solid surfaces. Atomically resolved images of the (001) basal planes are obtained on all materials investigated, namely gibbsite, kaolinite, illite, and Na-montmorillonite of both natural and synthetic origin. Next to regions of perfect crystallinity, we routinely observe extended regions of various types of defects on the surfaces, including vacancies of one or few atoms, vacancy islands, atomic steps, apparently disordered regions, as well as strongly adsorbed seemingly organic and inorganic species. While their exact nature is frequently difficult to identify, our observations clearly highlight the ubiquity of such defects and their relevance for the overall physical and chemical properties of clay nanoparticle-water interfaces. ... read more

Congratulations Bijoy

On Friday, February 12, Bijoy Bera successfully defended his PhD thesis entitled “Ion and Surfactant Induced Wetting Transition”. The project was a great success and delivered new insights into the mechanisms how cations of variable valency affect the relative wettability of water and oil on mineral surfaces. The findings provided a microscopic explanation of empirical findings by oil companies in their macroscopic core flooding experiments.
We wish Bijoy all the best for his future career, which has already started at the University of Amsterdam. ... read more

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Congratulations, Dr. Somnath!

On Thursday 10 December, Somnath Ghosh successfully defended his PhD thesis entitled “Colloidal Dynamics in Flow and Confinement”. Key element of his research was the use of a Confocal Scanning Laser Microscope and Particle Tracking algorithms to measure individual displacements of silica spheres dispersed in viscous liquid. Microfluidic chips were used to study the effect of inhomogeneous flow and cylindrical confinement on the diffusive behavior of the particles. This has resulted in 4 publications, all in 2015. We wish Somnath success in his new job at the University of Lund! ... read more

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A Review on Droplet manipulations in two-phase flow microfluidics

In this review by A.M. Pit et al., we discuss the most recent and promising techniques for manipulating droplets in microchannels. The physical principles are explained, and (potential) advantages and drawbacks of different methods in the sense of versatility, flexibility, tunability and durability are discussed; firstly per technique and also per droplet protocol: generation, transport, sorting, coalescence and splitting. ... read more