Low-cost and simple FDM-based 3D-printed microfluidic device for the synthesis of metallic core–shell nanoparticles

Abstract

A fused deposition modeling-based 3D-printed microfluidic device is designed and built to synthesize core–shell metallic Au@Ag nanoparticles based on the reduction of a silver salt on gold nanoparticles seeds by sodium borohydride in a continuous flow manner. A microfluidic device consisting of three inlets for the reactants and one outlet to collect the synthesized nanoparticles is printed in less than two hours using poly(lactic acid) as the polymer, presenting channels width and height of approximately 260 µm. After synthesis, the nanoparticles samples were analyzed by UV–Vis spectroscopy and transmission electron microscopy to confirm the formation of the core–shell structure. The concentration of the silver salt was varied, while the flow rate was kept constant, and the results indicated that too high silver concentration in relation to amount of gold seeds could lead to coalescence of the synthesized nanoparticles. We obtained core–shell nanoparticles of approximately 23 nm in diameter. Finally, we employed the synthesized Au@Ag nanoparticles in the surface modification of a carbon paste electrode, which showed improved charge transfer behavior compared to the unmodified electrode against a ferri-ferrocyanide probe, while working as a functionalized electrode in the sensing of thiocyanate ions.