Abstract
A micromixer is one of the most significant components in a microfluidic system. A three-dimensional micromixer was developed with advantages of high efficiency, simple fabrication, easy integration, and ease of mass production. The designed principle is based on the concepts of splitting–recombination and chaotic advection. A numerical model of this micromixer was established to characterize the mixing performance for different parameters. A critical Reynolds number (Re) was obtained from the simulation results. When the Re number is smaller than the critical value, the fluid mixing is mainly dependent on the mechanism of splitting–recombination, therefore, the length of the channel capable of complete mixing (complete mixing length) increases as the Re number increases. When the Re number is larger than the critical value, the fluid mixing is dominated by chaotic advection, and the complete mixing length decreases as the Re number increases. For normal fluids, a complete mixing length of 500 µm can be achieved at a very small Re number of 0.007 and increases to 2400 µm as the Re number increases to the critical value of 4.7. As the Re number keep increasing and passes the critical Re number, the complete mixing length continues to descend to 650 µm at the Re number of 66.7. For hard-to-mix fluids (generally referring to fluids with high viscosity and low diffusion coefficient, which are difficult to mix), even though no evidence of strong chaotic advection is presented in the simulation, the micromixer can still achieve a complete mixing length of 2550 µm. The mixing performance of the micromixer was also verified by experiments. The experimental results showed a consistent trend with the numerical simulation results, which both climb upward when the Re number is around 0.007 (flow rate of 0.03 μm/min) to around 10 (flow rate of 50 μm/min), then descend when the Re number is around 13.3 (flow rate of 60 µm/min).
Highlights
A Three-Dimensional MicromixerPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil-
The relationship between complete mixing length and Reynolds number (Re) number is characterized and shown in Figure 4b, based on the information obtained from Figure 4a, where the mixing length has a mixing index of 0.9 and is denoted as complete mixing length
With further increasing of the Re number from 4.7 to 13.33, the complete mixing length decreases to about 1400 μm, and decreases to about 650 μm as the Re number increases to 66.7
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil-. Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have