Conference of Antoine Aubret (LOMA) at LOF “Light-driven assembly of active colloids” February 2nd 2023

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