Microfluidic Fabrication of Functional Micro-/Nanoparticles: From Structural Regulation to Scalable Integration

Functional particles play critical roles in biomedicine, sensing, catalysis, energy storage and conversion, and environmental remediation. Conventional bulk synthesis can provide limited control over local reaction environments when narrow size distributions, complex morphologies, or hierarchical architectures are required. Microfluidic synthesis addresses these limitations by confining reactions within microscale channels, droplets, or flow segments, thereby enabling controlled multiphase flow, rapid heat and mass transfer, and precise regulation of local reaction conditions. This review is organized around a particle formation/process control/particle properties/scale-up framework, linking microfluidic design and operating parameters to nucleation, growth, phase separation, interfacial assembly, and solidification, and subsequently to particle size, morphology, dispersity, and hierarchical structure. Representative strategies, including droplet microfluidics, hydrodynamic focusing, co-flow systems, structured microchannels, and integrated microreactors, are critically compared in terms of particle-quality control and manufacturing feasibility. Particular attention is given to scalability, productivity, process robustness, clogging, downstream processing, and internal and external integration. Although microfluidic processing can improve control and reproducibility, many reported systems remain at the proof-of-concept or laboratory scale. Future development therefore requires quantitative process-structured relationships, robust device engineering, in-line monitoring, feedback control, and validated scale-up strategies.