UNIVERSITY OF CINCINNATI
University of Cincinnati – Dean Flow Dynamics and Cell Separations in Low-Aspect Ratio Spiral Microchannels
This research activity, involving Dr. Ligrani, is in collaboration with Professor Ian Papautsky, and associated graduate students, of the BioMicroSystems Laboratory of the University of Cincinnati. Of interest are spiral inertial microfluidic devices for continuous blood cell separations 1, as well as microfluidic inertial, continuous SPLITT, and field-flow fractionation technologies for separations of whole blood components 2. More recently, secondary Dean vortices 3-4 in spiral microchannels are investigated 5, and used to advantage for cell separations 6. Recent attention is focused on curvilinear channel geometries because of the presence of secondary flows, which, with appropriate configurations and flow conditions, can be employed to promote cell separations. In general, such devices are designed with the assumption that there are two counter rotating Dean vortices, present in the curved rectangular channels, which exist in the state of steady rotation and amplitude. Within the collaborative effort, these secondary Dean flows are investigated in low aspect ratio spiral rectangular microchannels, including their development with respect to the channel aspect ratio and Dean number. Dean vortex flows are shown to be present when Dean number exceeds a critical value. Multiple vortex vortices (>2) are also considered, including their effects on particle and cell focusing. Overall, results from these studies offer new insights into secondary flow instabilities for low-aspect ratio, spiral microchannels, with improved flow models for design of more precise and efficient microfluidic devices for applications, which include cell sorting and micromixing 5-6.
1 Spiral Inertial Microfluidic Devices For Continuous Blood Cell Separation (N. Nivedita, P. M. Ligrani, and I. Papautsky), Invited Paper, Paper Number 8251-26, MOEMS-MEMS Conference on Micro- and Nano-Fabricated Electromechanical and Optical Components, SPIE – International Society for Optics and Photonics, San Francico, California, USA, January 21-26, 2012.
2 Microfluidic Inertial, Continuous SPLITT, and Field-Flow Fractionation Developments for Separation of Whole Blood Components, (M. Jennerjohn, N. Nivedita, L. Carlson, P. M. Ligrani, I. Papautsky, J. Eslick, R. Sprague, and E. Bowles), 16th International Symposium on Field- and Flow-Based Separations, FFF2013 – PAU, University de Pau et des Pays de l’Adour, IPREM and Faculty of Sciences Pau, France, June 30-July 4, 2013.
3 Flow Visualization of Dean Vortices in a Curved Channel with 40 to 1 Aspect Ratio (P. M. Ligrani and R. D. Niver), Physics of Fluids, Vol. 31, No. 12, pp. 3605-3617, December 1988.
4 Experimental Surface Heat Transfer and Flow Structure in a Curved Channel With Laminar, Transitional, and Turbulent Flows, (P. M. Ligrani, and C. R. Hedlund), ASME Transactions-Journal of Turbomachinery, Vol. 126, No. 3, pp. 414-423, July 2004.
5 Dean Flow Dynamics in Low-Aspect Ratio Spiral Microchannels (N. Nivedita, P. M. Ligrani, and I. Papautsky), Nature – Scientific Reports, Vol. 7, Article Number 44072, pages 1-10, March 2017.
6 Evolution of Secondary Dean Vortices in Spiral Microchannels for Cell Separations (N. Nivedita, P. M. Ligrani, and I. Papautsky), Invited Lecture, Miniaturized Systems for Chemistry and Life Sciences MicroTAS 2013, University of Freiburg, Freiburg, Germany, October 27-31, 2013.