Characterization of Microreactors for Nanoparticle Synthesis

This paper reports the characterization and demonstration of two, sub-millisecond microfluidic mixing reactors for the controllable synthesis of ultra-small nanoparticles (USNPs), i.e. particles with diameters in the range of 1–3 nm. The properties of USNPs are determined by their size. Therefore, controlling size is of the upmost importance for applications such as electronics, catalysis, and photonics [1]–[2]. Of the noble metal particles, ultra-small silver nanoparticles (AgNPs) are particularly difficult to controllably synthesize due to their sub-millisecond reaction kinetics. Experimental determination of flow profiles, mixing times, and resulting nanoparticle size distributions are presented here for a microturbine and a micro-maelstrom reactor. USNPs were reliably produced with both, however the microturbine provided a higher degree of control over mixing time and NP size.