About us

We use theory and experiment to study surface phenomena and mass transport. We study mass and ion transport phenomena in the presence of seismic waves and ultrasound as well as the structure and properties of complex fluids. In current projects we investigate mass transfer in the in thin liquid films and porous media and electrokinetic spectroscopy of ions near electrically charged surfaces. Our work on mass transfer in porous media explains observations of underground water movement following seismic waves; the technology is widely used for enhancing material transfer processes and chemical reactions in unit operations in the chemical industry and for actuating microfluidic systems. In our work on electrokinetic spectroscopy, we are developing a new spectroscopic methodology for studying ion dynamics in electric double layers – one of the most common and fundamental mechanisms in biochemistry,  colloid science, and membrane technology. In addition, we use Classical Density Functional Theory — a mathematical formulation of the Gibbs and Helmholtz energy of complex fluids, arising from basic thermodynamic principles and statistical tools, and their solution through energy minimisation of the fluid molecular structure. This is to understand interactions and structure in complex fluids. A brief description of the projects is given below:

Electrokinetic and Surface Acoustic Wave Phenomena in Fluids

Electrical double layers (EDLs) are a surface phenomenon. These are ion structures that appear at the interface between charged surfaces and electrolyte (ion) solutions and are one of the most fundamental and abundant mechanisms in nature. They are nano-meter thick, react to changes within nano-seconds, and give rise to the complexity of biology and to life as well as to countless industrial processes and products. Examples to the latter commence with the stability of toothpaste and shampoo and continue to membranes, water desalination, and energy applications such as batteries and super-capacitors. We impose a field effect­ on the ions in EDLs, an evanescent viscous wave, by generating a MHz-frequency surface acoustic wave (SAW) in a neighboring solid substrate. The excited EDLs leak residual electrical fields that we translate to ion composition, structure, and dynamics. We use experiment and theory to develop this new science and to identify ion electro-mechnical resonance in EDLs, identify the presence of ions in electrolyte solutions, and identify the intrinsic rate energy systems may charge and discharge by specific ions.

Breaking liquid mixtures using Surface Acoustic Waves and Film Dynamics

Miniatuzising equipment for breaking oil in water mixtures into their constituent phases using MHz-frequency surface acoustic waves (SAWs) offers several advantages over existing mixture breaking methods that are employed in large water recovery facilities. This is particularly true for the recovery of gray water in domestic housing and small industry. SAWs traveling in a solid substrate discriminate between oil and water by their different surface chemistry and by their ability to wet the solid surface. The SAWs are capable of pulling oil films off oil in water mixtures and onto the solid substrate. However, the physics of liquid mixture breaking by SAW comes with many peculiarities: We observe multiple types of flow instabilities that are connected to the interplay between acoustic, viscous, and capillary interactions in multiphase liquid mixtures and in liquid films. Here, we use both theory and experiment to investigate the interactions between MHz-frequency SAWs, liquid mixtures, wetting phenomena, and film dynamics.

Acoustic Flow in Porous Media

The transport of fluids in porous media under an acoustic stimulus is ubiquitous in geology, employed in unit operations in the chemical and mechanical industry, and is used in microfluidic applications. At high acoustic frequency, this is a promising technology for lab-on-a-chip platforms, especially for medical point of care and domestic detection kits. We use both theory and experiment to study the transport of mass along the path of an acoustic stimulus (acoustofluidics) in porous media. We study contributions to mass transport in porous media from MHz-frequency ultrasound waves that propagate along porous media and from MHz-frequency surface acoustic waves (SAWs) that travel in solid substrates in contact with porous media. The solid substrates in our experiments are piezoelectric transducers that we design in lab to gain control over mass transport. We are especially interested in using acoustic stimuli for the transport of multiphase liquid systems and facilitating chemical and biochemical reactions within porous media.

Student and Postdoc recruitment

  We are always looking for bright and motivated students and postdocs that are interested in theory and experiment. Useful academic backgrounds for the research in our lab are Physics and Chemical, Mechanical, Electrical, Biomedical and Material Engineering. We are further happy to to consider interested candidates of different academic backgrounds. Currently, we are especially looking for people with interest in Electrokinetics and Surface Acoustic Waves.

Publications