Designing active colloidal architectures from diffusiophoretic interactions

In Nature, energy input is needed to develop advanced features, e.g. self-healing or self-regulation. I will show how we can extend this principle to the artificial world, using light to carve non-equilibrium interactions between synthetic microswimmers. Following sequential light-patterns, they autonomously assemble into robust self-spinning structures, or microgears. A rotor constitutes a dissipative building block that creates a repulsive, anisotropic potential of diffusiophoretic origin, which we characterize using Highly Inclined Laminated Optical
sheets microscopy (HILO). The results agree with analytical and numerical predictions of a simple model of a rotor forming a hexapolar sink of fuel. We show that gears act as contactless ‘teeth’, synchronizing their motion, and constitute the fundamental components of synchronized micro-machineries that auto-regulate and whose dynamics is tuned by the spins of their internal components.
The study demonstrate the potential of non-equilibrium interactions to program self-assembly and control dynamical colloidal architectures beyond static, equilibrium assemblies.