Webinar
28.05.2025 – 31.12.2025
On demand: Rheodialysis - An Experimental Platform for Changing a Sample’s Chemical Environment during Rheological Testing
English
Available on demand at any time!
Many soft structured materials are highly sensitive both to shear forces an changes in chemical environment. Examples include hydrogels that re-polymerise under StrainStrain describes a deformation of a material, which is loaded mechanically by an external force or stress. Rubber compounds show creep properties, if a static load is applied.strain [1], biopolymer capsules whose size depends on shear [2] and living materials such as blood clots that degrade upon removal of tension [3]. In each of these cases, mechanical forces and chemical stimuli act not individually, but in synergy.
In this presentation we will discuss a technique known as rheodialysis, which extends the capabilities of standard rheology by incorporating a customised flow cell with a porous membrane into a parallel plate rheometer [4]. We have shown that this approach allows a sample’s chemical environment to be exchanged, while simultaneously probing its mechanical properties.
We will demonstrate experimental results that apply this technique to alginate biopolymer hydrogels assembled through diffusion of calcium ions. By probing alginate hydrogels at different plate separations, we shown that the resulting hydrogels have different properties owing to the slow diffusion calcium ions through the incipient gel network. We also show that the fractal dimension of these hydrogels varies with the distance from the source of ion diffusion and we model this process using reaction diffusion models.
We will also present some results on extending the rheodialysis technique to microrheology, by using microfluidic flow chambers with embedded microspheres that report the local mechanics of the sample through passive brownian motion. We have successfully applied this technique to samples constructed from protein filament hydrogels and have shown that their assembly pathway, as controlled by ion diffusion, has a significant influence on their mechanical properties. These techniques have broad applications across food science, biological science and soft matter physics and I will also outline some of the potential applications that are currently being pursued.
Our special guest:
Dr. Anders Aufderhorst-Roberts (please find biography below)
Lecturer in Soft Condensed Matter Physics
Department of Physics
Durham University
Register now free of charge!
Dr. Anders Aufderhorst-Roberts
Anders Aufderhorst-Roberts is a Lecturer in Soft Condensed Matter Physics at the University of Durham. He completed PhD in the group of Athene Donald at the University of Cambridge, in collaboration with Unilever R&D, working on microrheology of peptide hydrogels for food and personal care applications. He subsequently carried out postdoctoral research at the University of Leeds and AMOLF, in the Netherlands, focussing on the rheological properties of biological and bioinspired materials. The group he leads at Durham is focussed on hydrogel rheology, bioinspired materials and developing new shear rheology techniques to probe material properties in changing chemical environments.
[1] Matsuda, T., Kawakami, R., Namba, R., Nakajima, T., & Gong, J. P. (2019). Science, 363(6426), 504-508.
[2] Farr ́es, I. F., & Norton, I. T. (2014). Food Hydrocolloids, 40, 76-84.
[3] Weisel, J. W., & Litvinov, R. I. (2017), 405-456.
[4] Inman, J.S., Smith, A., Aufderhorst-Roberts, A. (2023) Rheology Bulletin, 64 (3), 74-79
