Active gels

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Physics and Astronomy


Active gels are prepared by the addition of a polymer depletant to an active colloid, here Escherichia coli. In this work, we use a strain of AB1157 modified so that it swims in intense green/blue light (in the absence of other nutrients). The resulting material has unusual phase behaviour and sedimentation properties induced by the activity of the E.coli. This project aims to quantify the macroscopic and microscopic properties of the system, to develop an understanding of the physics at play.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509644/1 01/10/2016 30/09/2021
1861845 Studentship EP/N509644/1 01/10/2016 31/03/2020 Samuel Griffiths
Description To better understand the original system studied in this work (a 3D bacterial gel), we developed a 2D colloidal system, doped with self-propulsive bacteria. This allows us to observe the entire system at once.

The effect of active swimmers on phase transitions is a topic of recent interest. In attractive passive systems, the addition of active swimmers suppresses the formation of solid phases and the activity is often likened to an effective temperature. We have shown that this "effective temperature" is a simplification of the systems behaviour. Instead, the origin of the phase transition stays the same, but the transition becomes more continuous with added active swimmers.
Exploitation Route Since active matter is inherently far from equilibrium, they are often not well described by general statistical physics descriptions. Our work builds on our understanding of this complex field. Enhancing our understanding of active systems, like the system studied in our work, paves the way to designer soft materials with unusual properties.
Sectors Other