Enhanced Microfluidics Mixing Performance in a Grooved Serpentine Microchannel at Different Flow Rates

Abstract

Reliable and efficient mixing in microfluidic systems is crucial for various applications such as molecular diagnostics, DNA hybridization, microreactors and nanoparticle synthesis. However, achieving adequate mixing at the microscale is challenging due to the fact that flow regime in microfluidics is laminar that is characterized by low Reynolds numbers. In an attempt to tackle this challenge, active and passive strategies have been utilized to enhance mixing. Passive techniques mainly rely on the interaction between fluid and channel geometry in order to extend the interface between the components of the fluid by inducing transversal flows. Passive methods have shown their simplicity over the active methods in microfluidics by simply controlling the channel geometry and flow configurations without involving any complex external forces and components. Based on this, our work presents a passive micromixer design with trapezoidal grooves placed at the bottom of the serpentine channels. The grooves induce periodic pressure drops along the channel which create staggered transversal vortices in orthogonal directions which disturbs the symmetries in the flow that results in stirring. These combined effects result in an enhanced mixing performance especially at higher flow rates. The results suggest that the design could be integrated into lab-on-a-chip systems to achieve enhanced mixing of biological or chemical components with reduced footprint, complexity and cost.