Novel Variable Radius Spiral⁻Shaped Micromixer: From Numerical Analysis to Experimental Validation.

Area of Science:

• Microfluidics and Fluid Dynamics
• Biomedical Engineering
• Analytical Chemistry

Background:

• Efficient mixing is crucial for microfluidic devices used in point-of-care tests (POCT).
• Low Reynolds number regimes in microchannels often lead to poor mixing due to laminar flow.
• Novel micromixer designs are needed to enhance mixing performance for rapid diagnostics.

Purpose of the Study:

• To develop and evaluate a novel spiral micromixer with expansion and contraction parts.
• To enhance mixing quality in low Reynolds number regimes for POCT applications.
• To investigate the impact of geometric modifications on mixing performance.

Main Methods:

• Numerical simulations using steady-state Navier-Stokes and convection-diffusion equations.
• Analysis of flow behavior and mixing performance across Reynolds numbers from 0.1 to 10.0.
• Fabrication and experimental verification of micromixer designs using image analysis.

Main Results:

• The proposed spiral micromixer with expansion/contraction parts significantly enhances mixing.
• High homogeneity (up to 92%) was achieved at Re = 1.0.
• The mixer generated a pressure drop of 442 Pa, demonstrating a balance between mixing and flow resistance.

Conclusions:

• The novel spiral micromixer design effectively improves mixing efficiency in low Reynolds number regimes.
• The inclusion of expansion and contraction parts is key to disturbing streamlines and enhancing mixing.
• This micromixer is a promising candidate for integration into point-of-care testing devices.