Geometry, topology and hydrodynamics of soft active matter

Lead Research Organisation: University of Bristol
Department Name: Mathematics

Abstract

Active matter has come to be broadly defined as the collective behaviour of interacting agents that have an internal source of energy; as such examples can be found in many living systems from collections of cells in tissues to collections of mammals or birds (this js sometimes called living matter). However increasingly man-made synthetic systems are providing a fruitful avenue to study the underlying principles that govern the properties and behaviour of active matter.

Living matter is highly complex and difficult to describe in a rigorous, quantitative manner. A considerable amount of insight, however, can be gained by the analysis of the overall structure of living tissues. It has been recognized that a large number of biological materials can be classified as particular examples of liquids, colloids, polymers, foams, gels, and even liquid crystals. These physical systems are usually referred to as soft matter because of their ability to deform when subject to thermal or mechanical stresses; the expression soft active matter has thus been coined to include the presence of large numbers of self-propelling units or agents like cells or bacteria, which introduce an additional (and internal) source of stress in the material.

Three key elements emerge as the basis for all possible descriptions of the mechanics of soft active matter: (1) the spontaneous motility of living motors, cells and organisms (i.e., its activity); (2) its ability to undergo a phase transition from an isotropic state to an aligned one, thus organising in ordered states (i.e., its orientational properties) and (3) its characteristic flowing motion, typical of highly viscous fluids, that it shows whenit's driven out of equilibrium.

In the language of non-equilibrium thermodynamics, these systems show two different types of transitions: one from disorder (isotropic, liquid-like states) to order (aligned states), and one from static behaviour to flowing motion.

This project aims to understand how to control local properties of such systems by applying global perturbations using new ideas from topology, continuum mechanics and statistical mechanics.

Active matter has possible applications in medical science: cancer and wound healing and also in material science: smart materials.

This project falls within EPSRC areas: biophysics and soft matter physics, mathematical sciences, fluid mechanics.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/V520287/1 30/09/2020 31/10/2025
2614888 Studentship EP/V520287/1 30/09/2021 29/09/2025 Luke Neville