Source-linked AI summary
Targeted Assembly and Synchronization of Self-Spinning Microgears
Antoine Aubret, Mena Youssef, Stefano Sacanna, Jérémie Palacci
TL;DR
The paper addresses using dissipative building blocks to control self-assembly beyond equilibrium constraints. It develops phototactic swimmers and models their diffusiophoretic coupling, producing self-spinning microgears and synchronized dynamical superstructures. The authors report quantitative agreement with experiments and demonstrate hierarchical micromachine assembly.
Problem
Dissipative colloidal building blocks had become available but had not been used to control self-assembly, which is constrained by unfavorable entropy costs at equilibrium.
Method
The authors engineer hematite-based phototactic swimmers and use spatiotemporal light patterns together with a stochastic description of diffusio-phoretic oscillators coupled by chemical gradients.
Results
Self-spinning microgears assemble from active particles, co-rotating gears exhibit an edge current at Ω∼0.1 rad/s, and the rotors form dynamical superstructures.
Takeaways & Limitations
The findings demonstrate non-equilibrium control of interactions for hierarchical self-assembly of dynamical architectures and synchronized micro-machinery.
Takeaways & Limitations
The experiments assume that hydrogen peroxide decomposition and optical forces from the light are not observed, while the pair model neglects effects guided by phase-lag persistence.
Abstract
from arXiv · showhide
Self-assembly is the autonomous organization of components into patterns or structures: an essential ingredient of biology and a desired route to complex organization. At equilibrium, the structure is encoded through specific interactions, at an unfavorable entropic cost for the system. An alternative approach, widely used by Nature, uses energy input to bypass the entropy bottleneck and develop features otherwise impossible at equilibrium. Dissipative building blocks that inject energy locally were made available by recent advance in colloidal science but have not been used to control self-assembly. Here we show the robust formation of self-powered rotors and dynamical superstructures from active particles and harness non-equilibrium phoretic phenomena to tailor interactions and direct self-assembly. We use a photoactive component that consumes fuel, hematite, to devise phototactic microswimmers that form self-spinning microgears following spatiotemporal light patterns. The gears are coupled via their chemical clouds and constitute the elementary bricks of synchronized superstructures, which autonomously regulate their dynamics. The results are quantitatively rationalized on the basis of a stochastic description of diffusio-phoretic oscillators dynamically coupled by chemical gradients to form directional interactions. Our findings demonstrate that non-equilibrium phenomena can be harnessed to shape interactions and program hierarchical constructions. It lays the groundwork for the self-assembly of dynamical architectures and synchronized micro-machinery.