Microfluidic enhancement of self-assembly systems

Dynamic, kinetically-controlled, self-assembly processes are commonly observed in nature and are capable of creating intricate, functional architectures from simple precursors. However, notably, much of the research into molecular self-assembly has been performed using conventional bulk techniques where the resultant species are dictated by thermodynamic stability to yield relatively simple assemblies. Whereas, the environmental control offered by microfluidic systems offers methods to achieve non-equilibrium reaction conditions capable of increasingly sophisticated self-assembled structures. Alterations to the immediate microenvironment during the assembly of the molecules is possible, providing the basis for kinetically-controlled assembly. This review examines the key mechanism offered by microfluidic systems and the architectures required to access them. The mechanisms include diffusion-led mixing, shear gradient alignment, spatial and temporal confinement, and structural templates in multiphase systems. The works are selected and categorised in terms of the microfluidic approaches taken rather than the chemical constructs which are formed.

Self-assembly of colloids based on microfluidics

Self-assembly of colloids provides a powerful way for the construction of complex multi-scale materials. Microfluidic techniques possess great potential to precisely control the assembly of micro- and nano-scale building blocks via the rational design of various microfluidic environments. In this review, we first discuss the self-assembly of colloids without templates by using the laminar microfluidic technique. The self-assembly of colloids based on a droplet as a template was subsequently summarized and discussed via droplet microfluidic technique. Moreover, the evaporation-driven self-assembly of colloids in microfluidic channels has been discussed and analysed. Finally, the representative applications in this field have been pointed out. The aim of this review is to summarize the state-of-art on the self-assembly of colloids based on various microfluidic techniques, exhibit their representative applications, and point out the current challenges in this field, hoping to inspire and guide future work.