© 2020 Elsevier B.V. Continuous synthesis of nanoparticles in microreactors is enabled by their characteristic high mass and heat transfer rates with exquisite control of the synthetic parameters. However, their laminar regime present challenges such as tendency to clogging, broad residence time distributions and concentration profiles. Multi-phase systems (liquid–liquid, gas–liquid) overcome these issues by the creation of recirculation patterns between immiscible phases however, indirectly promotes particle–particle interaction, making necessary the addition of steric organic ligands to avoid agglomeration. Over the past few years, the design of the geometry of the reactors has been presented as an alternative approach to control the hydrodynamics in single-phase system. Secondary flows such as Dean vorteces within the laminar regime are promoted on coiled and helical reactors enhancing mass transfer and narrowing residence time distributions. This approach enables the synthesis of nanoparticles in the absence of organic surface ligands with narrow size distribution opening the door to size tuneability.