StaMACS · Statistical Mechanics and transport phenomena in Active Colloidal Solids
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2021-10-01 → 2023-09-30
- EU contribution
- €171,473
- Participants
- 1
- Scheme
- MSCA-IF
Lines connect the coordinator with its partners.
Results in brief
Statistical Mechanics and transport phenomena in Active Colloidal Solids
Active solids, or self-propelling units elastically coupled on a lattice, are recently of growing interest and are predicted to show emerging out-of-equilibrium behaviour, while they can inspire the design of numerous applications. However, experimental studies have been few and limited due to the difficulty of practically realising systems of hundreds of confined active particles. The results of StaMACS show for the first time an experimental realisation of a large ordered active solid with activity and confinement tuneable in-situ and on- command. This two-dimensional active solid is composed of repulsive magnetic particles activated by a photokinetic bacterial bath. In this way, our crystal is in contact with two effective temperature reservoirs: 1) the thermal or magnetic temperature, related to the strength of the inter-particle repulsion and controlled by the magnetic field, and the active temperature, related to the power of the light-driven bacterial bath and controlled by green light. We tuned both independently and show that there is a regime in which these two temperatures are not equivalent. We drew an off-equilibrium phase diagram depending on the two temperatures of the system and discovered some unexpected differences between melting in the passive system and active melting. Furthermore, we studied this active system when the active temperature changes in space. The results of StaMACS provide a novel testbed for active solids with an unprecedented degree of tunability. By revealing new complex dynamics, the project expands the physics of active matter to the realm of non-equilibrium colloidal solids, bringing the field closer to the practical realization of new soft materials with distinctive properties and high tunability.
Data: CORDIS, © European Union
Project objective
The objective of StaMACS is to uncover the dynamics of an active and loosely packed magnetic colloidal crystal. This system will consist of repulsive paramagnetic particles immersed in a bath of light-driven bacteria. We will have two independent ways to tune the interactions: 1) An external magnetic field will control the strength of the dipolar repulsion between colloids. 2) The intensity of light will control the motility of bacteria and thus the particle’s induced activity, both locally and globally. By combining experiments with simulations and theoretical analysis, we will reach a general understanding of this system’s dynamics, study its melting and crystallization transitions and examine how a local change in activity propagates throughout the crystal. Our findings will unveil the properties of a novel out-of-equilibrium system: an active colloidal solid. Furthermore, this work will stimulate theoretical investigation related to the kinetics of such systems, with strong implications on understanding the fundamental process of crystallization in the presence of activity. By a two-way transfer of knowledge, StaMACS will bring numerous mutual benefits to both the researcher and the host institution. Its results will represent a major contribution to the soft and active matter field with direct applications in physics, biology and material science.Descriptors: Active Matter, Soft Matter, Statistical Mechanics, Magnetic Colloids
Original text from CORDIS.
Participants
- UNIVERSITA DEGLI STUDI DI ROMA LA SAPIENZA · RomaCoordinatorItaly
Links
Data: CORDIS, © European Union