Objective
The Eiser Group has established a Soft Matter Laboratory, enabling us to design and create nano- and microporous materials with well-defined pore-size distributions to study both, their viscoelastic properties and the flow of complex fluids and gases through them.
Homepage of the Eiser Group: https://sites.google.com/view/eisergroup/home
Google Scholar: https://scholar.google.com/citationshl=en&user=ipgdVbgAAAAJ&view_op=list_works&sortby=pubdate
Figure: A Schematic of a 3D-printed flow cell with two identical porous structures. We study the reversibility of 2-phase flow in these. Below is the averaged steady-state fluid distribution for the porous medium composed of randomly positioned and oriented triangular pillars (porosity ϕ = 0.82) for a flow from the left to right. White regions represents an equal presence of liquid and air, red tones show air-dominated zones and blue tones correspond to liquid-dominated areas (see Master thesis of Julie Delhaie). B Schematic of a thin cylindrical cavity filled with an aqueous suspension of micron-sized, charge stabilized colloidal particles synthesized in the Eiser lab. Under slow evaporation conditions we observe a sudden transition from a colloidal monolayer deposition to a rapidly forming labyrinth structure. Here the white fingers are the dry colloid depositions (Beechy-Newman et al. PNAS 122 (32), e2508363122 (2025)).
Description
Understanding the flow of binary fluids through media with completely random pore-size distributions remains challenging, because it is both difficult to design such systems in the laboratory and often 3D porous systems are opaque. Examples of nano-porous media are for instance bioengineered membranes mimicking natural filtration systems to provide smart, implantable drug-delivery systems, bioartificial organs, and other medical devices, but they also constitute the cathode material in rechargeable lithium-ion batteries, membranes for desalination or even in the development of random lasers. Presently we mainly focus on:
- 3D-resin printing of flow-cells with well-defined porosity: We study the thermodynamics of 2-phase flow in porous media (see Figure A) using machine learning to analyse the flow patterns.
- Colloidal art: Recently, we discovered that when we strongly confine a droplet of a colloidal suspension, such that it dries at very slowly evaporation rates, the receding drop shows a sudden transition from a continuous colloidal monolayer deposition to a fingering instability. The resulting pattern is a labyrinth of colloidal deposition as shown in Figure B (https://doi.org/10.1073/pnas.2508363122 ).
- Building colloidal networks with well-defined pore-size distribution: Using our experience using short strands of DNA attached to colloids as highly selective, thermo-reversive glue to build transparent, model-porous networks (Sousa et al., Phys. Rev. Res. 7, L022067 (2025)) embedded in a microfluidic channel and employing confocal microscopy to study binary flow through them as function of pore-size distribution, wettability, flow pressure and other properties.
- Sustainable stabilization of clay-rich ground: Clay suspensions/gels as nanoporous colloidal systems will be further developed to study transport through them when exposed to freeze-thaw cycles mimicking for instance thawing in permafrost. In particular, we will use the interactions and results from mechanical measurements (e.g. microrheology) relating to the nanoscale to develop up-scaling models to understand the large-scale behaviour of clay-rich soils.
- Highly selective bio-sensors: Exploiting the concept of multivalency and superselectivity we use our DNA-functionalized colloidal systems to develop highly sensitive and selective diagnostic tools for easy pathogen-DNA detection (https://doi.org/10.1073/pnas.2305995120).
- Microrheology: We use Diffusing Wave spectroscopy and optical-tweezers based microrheology to explore the viscoelastic properties of colloidal gels, shake gels (Stoev et al., Rheologica Acta 64, 241 (2025)) and biopolymers (Vanin et al., Carbohydrate Polymers 352, 123168 (2025)) as function of temperature, time, concentration, crosslink-density and other physical parameters.
Principal Investigator for Research Theme 4: Professor Erika Eiser
Partners:
Alex Hansen, Eirik Flekkøy, Sayed Ali Ghoreishian Amiri, Klarartje de Weerdt, Dag Breiby, Astrid de Wijn, Hans Herrman, Anasua Mukhopadhyay, Iliya Stoev.
Publications:
See Google Scholar: https://scholar.google.com/citations?hl=en&user=ipgdVbgAAAAJ&view_op=list_works&sortby=pubdate
News & Views on Research Articles
See the Homepage of the Eiser Group here: https://sites.google.com/view/eisergroup/home