Templated assembly of self-propelled particles in targeted micromachines*

In this talk, I will show how we can carve non-equilibrium pathways for the controlled self-assembly of active microparticles using light as a tool.
We previously demonstrated the light-triggered self-assembly of self-propelled particles in robust geared micromachines [Aubret et al., Nature Physics 2018]. The gears constitute the fundamental components of synchronized micro-machineries, whose dynamics is tuned by the spins of their internal components.
Here, we demonstrate a new approach -templated assembly- which exploits optical forces and the activity of the colloids to create larger ensembles of self-spinning microgears. Thanks to our approach, the chirality of the gears can be selected and changed over time. It allows us to finely examine the interaction between multiple gears depending on their precise arrangement, and to explore the non-equilibrium interaction potential of the gears, which is due to both hydrodynamics and phoretic phenomena. Our study demonstrate the potential of light to manipulate and image the non-equilibrium interactions between dynamical colloidal architectures.