title: Rapid circular microfluidic mixer utilizing unbalanced driving force.
abstract: This paper proposes a novel rapid circular microfluidic mixer for micro-total-analysis-systems (mu-TAS) applications in which an unbalanced driving force is used to mix fluids in a circular chamber at low Reynolds numbers (Re). The microfluidic mixer has a three-layered structure and is fabricated on low-cost glass slides using a simple and reliable fabrication process. Using hydrodynamic pumps, fluids are driven from two inlet ports into a circular mixing chamber. Each inlet port separates into two separate channels, which are then attached to opposite sides of the 3-dimensional (3-D) circular mixing chamber. The unequal lengths of these inlet channels generate an unbalanced driving force, which enhances the mixing effect in the mixing chamber. Numerical simulations are performed to predict the fluid phenomena in the mixing chamber and to estimate the mixing performance under various Reynolds number conditions. The numerical results are verified by performing flow visualization experiments. A good agreement is found between the two sets of results. The numerical and experimental results reveal that the mixing performance can reach 91% within a mixing chamber of 1 mm diameter at a Reynolds number of Re=3. Additionally, the results confirm that the unbalanced driving force produces a flow rotation in the circular mixer at low Reynolds numbers, which significantly enhances the mixing performance. The novel micromixing method presented in this study provides a simple solution for mixing problems in Lab-on-a-chip systems.
authors.affiliation: Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan, 804.
authors.forename: Che-Hsin
authors.initials: CH
authors.lastname: Lin
authors.forename: Chien-Hsiung
authors.initials: CH
authors.lastname: Tsai
authors.forename: Chih-Wen
authors.initials: CW
authors.lastname: Pan
authors.forename: Lung-Ming
authors.initials: LM
authors.lastname: Fu
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000295:instrumentation* / Q000379:methods; D045424:Complex Mixtures / Q000737:chemistry*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods; D009038:Motion; D013314:Stress, Mechanical
chemical_list: D045424:Complex Mixtures