Modelling, fabrication and characterization of a polymeric micromixer based on sequential segmentation

Area of Science:

• Microfluidics
• Chemical Engineering
• Biotechnology

Background:

• Efficient mixing is crucial for microfluidic applications but often limited by molecular diffusion in laminar flow.
• Reducing mixing path length is key to improving mixing time and quality, as per scaling laws.
• Sequential segmentation offers a method to decrease mixing path by axially dividing fluids.

Purpose of the Study:

• To develop and validate a time-dependent analytical model for sequential segmentation in microfluidic mixing.
• To design, fabricate, and experimentally evaluate a novel micromixer utilizing sequential segmentation.
• To investigate the influence of switching frequency and flow velocity on mixing performance.

Main Methods:

• Development of a 1D analytical model incorporating sequential segmentation, Taylor-Aris dispersion, and variable mixing ratios.
• Fabrication of a polymer-based micromixer using CO(2) laser micromachining and lamination of four layers.
• Implementation of fluid flow switching using two piezoelectric valves and optical evaluation of mixing experiments.

Main Results:

• The analytical model qualitatively predicts the concentration profile along the mixing channel.
• Experimental results demonstrate the feasibility of controlling mixing ratio via pulse width modulation and flow velocity.
• Mixing quality was observed to decrease with increasing switching frequency due to system dynamics.

Conclusions:

• Sequential segmentation is an effective technique for enhancing mixing in microfluidic devices.
• The developed analytical model provides a useful tool for designing and optimizing such micromixers.
• Further research is needed to mitigate the negative impact of high switching frequencies on mixing efficiency.