Size-tuned silver nanoparticles by a non-gassing electro-osmotic pump-driven microfluidic device

Abstract

Silver nanoparticles (AgNPs) are extensively used in various fields, but conventional synthesis techniques often face limitations in achieving precise control over particle size and morphology. To address this challenge, we explored the use of a microfluidic approach for synthesizing size-tuned AgNPs. Scaling down the reactor dimensions provides better control of the process of AgNPs synthesis and enables a low consumption and a high conversion of the reagents. The study aimed to utilize non-gassing electro-osmotic pumps (EOPs) connected to a three-way Y-junctioned microfluidic device for achieving controlled nanoparticle synthesis. The EOP design features a silica frit sandwiched between two flow-through electrodes composed of an Ag–Fe–O composite material. Performance evaluations revealed that the electro-osmotic flux was linearly dependent on applied voltage, with a maximum flow rate of 175.16 μL min⁻¹ cm⁻² achieved at 5.0 V. Optimized device parameters demonstrated effective nanoparticle synthesis, producing uniform AgNPs with sizes ranging from 10 to 15 nm at the maximum flow rate. Furthermore, particle size was found to vary directly with the voltage applied to the individual pumps. The synthesized nanoparticles were extensively characterized, and a long-term stability study confirmed their dispersion remained aggregation-free over 210 days. This research highlights the successful integration of microfluidic technology and EOPs for controlled AgNP synthesis, offering a scalable and precise platform for applications requiring consistent nanoparticle size and stability.