title: Optical sectioning for microfluidics: secondary flow and mixing in a meandering microchannel.
abstract: Secondary flow plays a critical function in a microchannel, such as a micromixer, because it can enhance heat and mass transfer. However, there is no experimental method to visualize the secondary flow and the associated mixing pattern in a microchannel because of difficulties in high-resolution, non-invasive, cross-sectional imaging. Here, we simultaneously imaged and quantified the secondary flow and pattern of two-liquid mixing inside a meandering square microchannel with spectral-domain Doppler optical coherence tomography. We observed an increase in the efficiency of two-liquid mixing when air was injected to produce a bubble-train flow and identified the three-dimensional enhancement mechanism behind the complex mixing phenomena. An alternating pair of counter-rotating and toroidal vortices cooperated to enhance two-liquid mixing.
authors: Beckman Laser Institute and Department of Biomedical Engineering, University of California, Irvine, CA, USA. ahny@uci.edu z2chen@uci.edu
authors: Yeh-Chan
authors: YC
authors: Ahn
authors: Woonggyu
authors: W
authors: Jung
authors: Zhongping
authors: Z
authors: Chen
mesh_terms: D007368:Interferometry; D008027:Light; D044085:Microfluidics / Q000379:methods*; D008956:Models, Chemical; D011137:Polystyrenes / Q000737:chemistry; D013997:Time Factors; D041623:Tomography, Optical Coherence; D014867:Water / Q000737:chemistry
chemical_list: D011137:Polystyrenes; D014867:Water