High speed microturbine mixer for kinetically controlled synthesis.

Area of Science:

• Microfluidics
• Nanoparticle Synthesis
• Chemical Engineering

Background:

• Rapid mixing is crucial for controlling kinetically-limited chemical reactions.
• Traditional synthesis methods for ultra-small nanoparticles often lack size control and reproducibility.
• Microfluidic devices offer potential for precise control over reaction conditions.

Purpose of the Study:

• To design, fabricate, and characterize a microfluidic microturbine mixer for rapid mixing.
• To utilize the mixer for optimizing the synthesis of ultra-small, monodisperse silver nanoparticles (AgNPs).
• To demonstrate a scalable and reproducible method for nanoparticle production.

Main Methods:

• Microfabrication of a silicon-based microturbine mixer using photolithography and deep reactive ion etching (DRIE).
• Fluidic-driven operation where reagent inlets drive a microturbine via momentum transfer.
• Experimental and computational determination of microturbine rotational velocities based on flow rates.
• Analysis of mixing profiles using fluorescence colocalization.
• Optimization of silver nanoparticle synthesis using the microturbine mixer.

Main Results:

• The microturbine mixer achieved rapid mixing (<1 ms).
• Microturbine rotational velocities were accurately determined through systematic variation of reagent flow rates.
• The mixer enabled the optimized synthesis of ultra-small (1-3 nm) monodisperse silver nanoparticles (AgNPs).
• Demonstrated precise control over nanoparticle size and distribution.

Conclusions:

• The microfluidic microturbine mixer is an effective tool for rapid mixing and precise control of chemical reactions.
• This technology provides a scalable and reproducible method for producing ultra-small AgNPs with excellent size control.
• The developed method overcomes limitations of traditional synthesis routes for nanoparticles.