Séminaire d’Antoine Aubret (LOMA)

Sur le thème « Light-driven assembly of active colloids ». Le Jeudi 2 Février 2023 en salle Margaux à 9h30.

Cells are prototypical examples of Active Matter, converting energy at small scale to organize at large scale. This biological complexity challenges our ability to engineer synthetic analogs. In this talk, I will show how we can carve non-equilibrium pathways to control the assembly of active microparticles, using light as a generic tool.

I will first present our work using photocatalytic colloidal microparticles as building blocks, and light cues to control self-assembly [1]. Following sequential light-patterns, the particles autonomously assemble into robust self-spinning microgears, which interact and synchronize their motion through their catalytic activity. We describe the dynamics of the gears using a stochastic treatment based on the Langevin equation of their motion, and show that the gears can form the fundamental components of larger micro-machineries, with spin-dependent dynamics.

In a second part, I will present a novel approach that couples activity to optical forces to generate a zoology of colloidal architectures [2,3]. The novel structures are rationally designed using templates of optical traps. Once freed, they remain stable and exhibit a shape-dependent motility, explained with simple geometrical arguments.

Our study demonstrate the potential of light to manipulate non-equilibrium interactions and program the self-assembly of dynamical colloidal architectures beyond static, equilibrium assemblies.

[1] Aubret, A., Youssef, M., Sacanna, S. et al. Targeted assembly and synchronization of self-spinning microgears. Nature Phys 14, 1114–1118 (2018). https://doi.org/10.1038/s41567-018-0227-4

[2] Aubret, A., Martinet, Q. & Palacci, J. Metamachines of pluripotent colloids. Nat Commun 12, 6398 (2021). https://doi.org/10.1038/s41467-021-26699-6

[3] Martinet, Q., Aubret, A. and Palacci, J. (2023), Rotation Control, Interlocking, and Self-Positioning of Active Cogwheels. Adv. Intell. Syst. 2200129. https://doi.org/10.1002/aisy.202200129