Abstract

Computational fluid dynamics modeling at Reynolds numbers ranging from 10 to 100 was used to characterize the performance of a new type of micromixer employing a serpentine channel with a grooved surface. The new topology exploits the overlap between the typical Dean flows present in curved channels due to the centrifugal forces experienced by the fluids, and the helical flows induced by slanted groove-ridge patterns with respect to the direction of the flow. The resulting flows are complex, with multiple vortices and saddle points, leading to enhanced mixing across the section of the channel. The optimization of the mixers with respect to the inner radius of curvature (Rin) of the serpentine channel identifies the designs in which the mixing index quality is both high (M > 0.95) and independent of the Reynolds number across all the values investigated.

Highlights

  • Microfluidic devices and lab-on-a-chip systems are widely used nowadays in chemical and biological sciences [1,2,3,4] for applications ranging from the synthesis of nanoparticles and colloidal systems [5,6,7] to molecular diagnostics [8,9] and cell biology [10,11], owing to their reduced consumption of reactants [12], better control over reaction variables such as the reactant concentration and temperature [13,14], and the ability to spatially control liquid composition with cellular resolution [11,15]

  • Mixing components is one of the fundamental and critical blocks in the development of microfluidic devices. It is one of the difficult functionalities to achieve, as the fluid flow is laminar, characterized by low Reynolds numbers at the length scales involved, and the turbulent mixing techniques employed in macroscale systems are not typically applicable [18]

  • At the fluid velocities used, guiding the fluid along curved channels induces vertically stacked transversal vortices, while the slanted groove-ridges with respect to the direction of the flow are associated with horizontally stacked vortices

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Summary

Introduction

Microfluidic devices and lab-on-a-chip systems are widely used nowadays in chemical and biological sciences [1,2,3,4] for applications ranging from the synthesis of nanoparticles and colloidal systems [5,6,7] to molecular diagnostics [8,9] and cell biology [10,11], owing to their reduced consumption of reactants [12], better control over reaction variables such as the reactant concentration and temperature [13,14], and the ability to spatially control liquid composition with cellular resolution [11,15]. Mixing components is one of the fundamental and critical blocks in the development of microfluidic devices It is one of the difficult functionalities to achieve, as the fluid flow is laminar, characterized by low Reynolds numbers at the length scales involved, and the turbulent mixing techniques employed in macroscale systems are not typically applicable [18]. Active strategies integrate external drivers in the mixer design such as moving membranes [21,22], rotating magnetic particles [23], and electromagnetic [24,25] or acoustic [26,27,28] fields, in an effort to stir and mix the inhomogeneous fluid solution. For all set-ups, the depth of the grooves was kept the same as for the SHB design, i.e., hSgHrooBved=es3i3gnμ,mi..eT., hhegropovae r=am33etμemrs.aTghaienpstawrahmicehtetrhseapgearinfosrtmwahnicceh otfhtehpeedrefosirgmnawncaes oefvathlueadteedsiagrne wthaes ienvnaelruraatdediuasroeftchuerivnanteurrera(dRiiun)saonfdcuthrveaRtueyreno(Rldins) nanudmtbheer.Reynolds number

Numerical Modeling
Conclusions

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