[Lab on a chip] Combination of microfluidic high-throughput production and parameter screening for a
Metal nanoparticles and their special optical properties, the so-called localized surface plasmon resonance (LSPR), facilitate many applications in various fields. Due to the strong dependency of the LSPR on particle geometry the synthesis is a challenging and time-consuming procedure especially for non-spherical shapes. In contrast, micromixers offer new experimental approaches and enable therefore a simplification of several processes. By using a zigzag micromixer (Dean-Flow-Mixer, DFM) that induces Dean-flow secondary flow patterns we theoretically and experimentally show the mixing efficiency. Thus, we highlight the advantages for using it in the multistep synthesis of Au nanoparticles. Based on a narrow size distribution for Au nanocube and an increased yield in combination with higher reproducibility, we depict the need and advantage of the DFM to control the incubation times during the growth process. We further show that using the DFM an easy and very fast Au nanocube edge length tuning (53 nm, 58 nm, 70 nm and 75 nm) is possible by simultaneously reducing the consumed material up to 95 %. We finally demonstrate the versatile abilities by using the DFM for parameter screening on the example of different halides and accessible bromide in the growth solution. Therefore we highlight the optimal concentration for the different growth regimes and the influences on the Au nanoparticle morphology (spheres, cubes and rods) and their shaping.
Matthias Thiele, Andrea Knauer, Daniéll Malsch, Andrea Csáki, Thomas Henkel, Johann Michael Kohler and Wolfgang Fritzsche
Lab Chip, 2017, Accepted Manuscript DOI: 10.1039/C7LC00109F