Numerical investigation and fabrication of L-turns spiral micromixers for enhanced mixing performance

In this paper, we simulated and fabricated an L-turn spiral passive micromixer design and compared it with a simple spiral design, both of which are particularly effective for improving mixing efficiency in bio-applications. Centrifugal force and secondary flow can be strengthened by the recommended spiral design. Furthermore, the L-turns improved the displacement of the velocity profile across the channel width leading to enhanced mixing efficiency. The micromixer performance was evaluated through a series of simulations and the effects of different parameters such as channel dimensions, inter-channel gaps, and flow rate were assessed. The contact area between the fluids is affected by the mentioned features, resulting in improved mixing efficiency. A mixing quality of over 90% is achieved after 26 mm (approximately one-third of the total channel length) at a flow rate of 25 μl/min, with a molecular diffusion coefficient of 1 × 10⁻¹⁰ m²/s. At last, the proposed fabrication process was presented to show the feasibility of the design.