The Importance of Dean Flow in Microfluidic Nanoparticle Synthesis: A ZIF‐8 Case Study

• Published in: Small methods Vol. 8; no. 1; pp. e2300603 - n/a
• Main Authors: Yu, Xiangjiang, Andreo, Jacopo, Walden, Madeline, Campo, Javier F., Basabe‐Desmonts, Lourdes, Benito‐Lopez, Fernando, Burg, Thomas P., Wuttke, Stefan
• Format: Journal Article
• Language: English
• Published: Germany 01-01-2024
• Subjects: Dean Flow; Dean Number; metal‐organic frameworks; microfluidics; ZIF‐8; Dean Flow; ZIF-8; microfluidics; Dean Number; metal-organic frameworks
• ISSN: 2366-9608; 2366-9608
• DOI: 10.1002/smtd.202300603

The Dean Flow, a physics phenomenon that accounts for the impact of channel curvature on fluid dynamics, has great potential to be used in microfluidic synthesis of nanoparticles. This study explores the impact of the Dean Flow on the synthesis of ZIF‐8 particles. Several variables that influence the Dean Equation (the mathematical expression of Dean Flow) are tested to validate the applicability of this expression in microfluidic synthesis, including the flow rate, radius of curvature, channel cross sectional area, and reagent concentration. It is demonstrated that the current standard of reporting, providing only the flow rate and crucially not the radius of curvature, is an incomplete description that will invariably lead to irreproducible syntheses across different laboratories. An alternative standard of reporting is presented and it is demonstrated how the sleek and simple math of the Dean Equation can be used to precisely tune the final dimensions of high quality, monodisperse ZIF‐8 nanoparticles between 40 and 700 nm.
The Dean Number, and in particular the often omitted variable radius of curvature, is a crucial metric that must be reported to ensure synthetic reproducibility. A systematic comparison of the effects of straight, coiled, and serpentine reactors on particle size and size distribution of ZIF‐8 particles is conducted, producing particles of any size between 40 and 700 nm.