ACTIVEDYNAMICS · Dynamics of Active Suspensions
FP7 — People (Marie Curie Actions)
- Duration
- 2011-09-01 → 2014-02-01
- EU contribution
- €211,093
- Participants
- 1
- Scheme
- MC-IIF
Lines connect the coordinator with its partners.
Results in brief
Dynamics of Active Suspensions
The proposed research programme is about the investigation of the dynamics of active (self-propelled) particles suspensions using mainly natural motile particles (swimming bacteria). We employ a new method, ‘differential dynamic microscopy’ (DDM), which uses everyday laboratory apparatus (a microscope and a camera) to generate comprehensive information on the dynamics of suspended particles (in the form of the so-called ‘intermediate scattering function’). Compared to single-particle tracking, the standard tool in active colloids and bacterial motility research to date, DDM yields much better averages and is orders of magnitude quicker to perform. A second goal of the proposed work is to develop DDM into a versatile tool for studying active particles of all kinds, at a range of concentrations. The project is divided into three main objectives: PART A: Methodology establishment PART B: Dynamics of active suspensions in 3D PART C: Dynamics of active suspensions in polymer solution in 3D The success of investigating the collective dynamics of active suspension (dense active suspension) is first based on the development of a careful methodology (Part A) and the understanding of the dynamics of dilute active suspensions (partly Part B and C). The researcher has successfully developed a careful protocol and methodology to investigate the dynamics of suspensions of swimming bacteria as function of bacterial concentration and polymer concentration. Several key results have been obtained. First, a detailed experimental investigation of the dynamics of tracer particles (non-motile bacteria) in a bath of swimming bacteria has been done in three-dimension for the first time. In addition, a theory, based on hydrodynamic interactions considering the flow field created by swimming bacteria, has been developed that allows a quantitative description of the experimental data. Secondly, an extensive investigation of bacteria swimming in polymer solution has been performed. This has brought new insights in our understanding of microorganisms swimming in complex polymeric environment, e.g. bacteria swimming in intestinal mucus. Thirdly, the methodology developed primarily for swimming bacteria during this project has also been applied successfully to other i) microorganisms such as swimming algae, sperm cells, or synthetic self-propelled particles such as active Janus particles; and ii) systems with anisotropic dynamics, e.g. magnetic colloidal suspensions or magnetotactic bacteria. These results have brought interests from not only a broad area of academic science but also industrial research.
Data: CORDIS, © European Union
Project objective
Collective behaviour is ubiquitous in nature: from crystallization through to animal swarming. Such phenomena are ubiquitous in colloids– 0.1-1micron particles suspended in liquids by Brownian motion – and are responsible for their amazing ability to ‘self assemble’. The self assembly of colloids is now an established route to new materials, e.g. photonic crystals. Recently, active colloidal particles capable of self propulsion have been synthesized. Their collective behaviour is completely unknown. The researcher proposes a research programme into collective phenomena in active suspensions. While synthetic active colloids have only recently been synthesized, ‘natural active colloids’ have existed for billions of years – motile bacteria. Therefore the candidate proposes to investigate both natural motile particles (bacteria) as well as synthetic ones. The bacterial results should have significant biological relevance, although the primary goal is to generate new, fundamental physics insights, which will lead to ‘design principles’ for a completely new type of self-assembled structures based on active colloids. We will use a new method, ‘differential dynamic microscopy’ (DDM), which uses everyday laboratory apparatus (a microscope and a camera) to generate comprehensive dynamical information on the collective motion of suspended particles (in the form of the so-called ‘intermediate scattering function’). Compared to single-particle tracking, the standard tool in active colloids and bacterial motility research to date, DDM yields much better averages and is orders of magnitude quicker to perform. The researcher and co-workers have demonstrated recently the use of DDM for the high-throughput characterisation of the motility of dilute populations of bacteria. A second goal of the proposed work is to develop DDM into a versatile tool for studying active particles of all kinds, at a range of concentrations.""
Original text from CORDIS.
Participants
- THE UNIVERSITY OF EDINBURGH · EdinburghCoordinatorUnited Kingdom
Links
Data: CORDIS, © European Union