Microfluidic self assembly

TL;DR

This paper introduces a novel hydrodynamic effect in microfluidics that enables rapid, controlled self-assembly of complex colloidal structures, potentially revolutionizing material manufacturing.

Contribution

It uncovers a hydrodynamic mechanism that significantly increases the speed and control of colloidal self-assembly in microfluidic systems.

Findings

Discovered a hydrodynamic effect based on dipolar flow interactions.

Achieved continuous formation of diverse monodisperse colloidal clusters.

Enabled high-throughput production of building blocks for advanced materials.

Abstract

Recent progress in colloidal science has led to elaborate self-assembled structures whose complexity raises hopes for elaborating new materials. However, the throughputs are extremely low and consequently, the chance to produce materials of industrial interest, for instance, groundbreaking optical devices, harnessing complete three-dimensional band gaps, is markedly low. We discovered a novel hydrodynamic effect that may unlock this bottleneck. It is based on the dipolar flow interactions that build up when droplets are slowed down by the microchannel walls along which they are transported. Coupled with depletion forces, we succeeded to form, via a continuous flow process, at unprecedented speeds and under exquisite control, a rich ensemble of monodisperse planar and tridimensional clusters, such as chains, triangles, diamonds, tetahedrons, heterotrimers, possessing geometrical, chemical, and/or magnetic anisotropies enabling directional bonding. Continuous productions of millions of building blocks per second for elaborating new functional materials can be envisioned.