Mixing in an enclosed microfluidic chamber through moving boundary motions
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Mixing in enclosed culture micro-chambers is an important criterion on achieving the long-term cell growth with more consistent characteristics spatially distributed in the microfluidic environments. Here, we report a microfluidic mixer composed of multiple deformable membranes to drive circulation flows within the culture region in a peristaltic manner. This mechanically driven mixing scheme has the advantages over many others existing mixing schemes by inducing negligible shear stress over cells without side effects to the viability and growth characteristics. The membrane movements can induce moving boundary motions of the liquid volume contained in the culture chamber. The flow characteristics such as the velocity profile and shear stress are investigated by lumped-element modeling and computational simulations. Both experiments and simulations are performed to show the effectiveness of the mixing of both soluble substances and sub-microscale particles, including bacteria. The mixing performance under different operation parameters (e.g., membrane size and membrane switching time) is also investigated for the optimized operation. Further, the dental bacteria Streptococcus mutans are cultured for 2 days to demonstrate that the reported mixing scheme can generate a more even distribution of growth, which may be further applied for a uniform dental biofilm development in vitro for the related biofilm research. Additionally, this micro-mixer is highly compatible with the widely used soft lithography technique, and hence, it can be directly integrated with general microfluidic devices for extended biomedical diagnosis and bio-sample processing applications.
KeywordsPDMS Standard Deviation Switching Time Control Channel PDMS Membrane
We sincerely thank for the supports during the early development of this research from Department of Mechanical Engineering in Massachusetts Institute of Technology. We appreciate the invaluable advices from Dr. T. Thorsen. We thank for the financial supports from City University of Hong Kong (Seed Grant; project #7003019), Croucher Foundation Scholarship and General Research Grant of Hong Kong Research Grant Council (project# RGC115813).
- Materne E-M et al (2013) Dynamic culture of human liver equivalents inside a micro-bioreactor for long-term substance testing. In: BMC Proceedings of BioMed Central Ltd. Suppl 6:P72Google Scholar
- Armani D, Liu C, Aluru N (1999) Re-configurable fluid circuits by PDMS elastomer micromachining. In: Twelfth IEEE International Conference on Micro Electro Mechanical Systems, 1999. MEMS’99, Ieee, pp 222–227Google Scholar
- Koh JBY, Marcos (2015) The study of spermatozoa and sorting in relation to human reproduction. Microfluid Nanofluid pp. 1–20Google Scholar
- Loesche WJ (1986) Role of Streptococcus mutans in human dental decay. Microbiol Rev 50:353–380Google Scholar
- Peng Z-C, Hesketh P, Mao W, Alexeev A, Lam W (2011) A microfluidic mixer based on parallel, high-speed circular motion of individual microbeads in a rotating magnetic field. In: Solid-State Sensors, Actuators and Microsystems Conference (TRANSDUCERS), 16th International, 2011. IEEE, pp 1292–1295Google Scholar
- Sayar E, Farouk B (2015) Bulk acoustic wave piezoelectric micropumps with stationary flow rectifiers: a three-dimensional structural/fluid dynamic investigation. Microfluid Nanofluid pp. 1–13Google Scholar
- Senturia SD (2001) Microsystem design, vol 3. Kluwer Academic Publishers, BostonGoogle Scholar
- Timoshenko S, Woinowsky-Krieger S, Woinowsky-Krieger S (1959) Theory of plates and shells, vol 2. McGraw-hill, New YorkGoogle Scholar
- Xia H, Seah Y, Liu Y, Wang W, Toh AG, Wang Z (2014) Anti-solvent precipitation of solid lipid nanoparticles using a microfluidic oscillator mixer. Microfluid Nanofluid pp. 1–8Google Scholar