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A Minireview on Inertial Microfluidics Fundamentals: Inertial Particle Focusing and Secondary Flow

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Abstract

In 1961, Segre and Silberberg first reported the tubular pinch effect and numerous theoretical studies were subsequently published to explain the inertial particle migration phenomenon. Presently, as fluid mechanics meets micro- and nanotechnology, theoretical studies on intrinsic particle migration and flow phenomena associated with inertia are being experimentally tested and validated. This collective study on the fluid-particle-structure phenomena in microchannels involving fluid inertia is called, “inertial microfluidics”. Beyond theoretical studies, now inertial microfluidics has been gaining much attention from various research fields ranging from biomedicine to industry. Despite the positive contributions, there is still a lack of clear understanding of intrinsic inertial effects in microchannels. Therefore, this minireview introduces the mechanisms and underlying physics in inertial microfluidic systems with specific focuses on inertial particle migration and secondary flow, and outlines the opportunities provided by inertial microfluidics, along with an outlook on the field.

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References

  1. Segre, G. & Silberberg, A. Radial particle displacements in Poiseuille flow of suspensions. Nature 189, 209–210 (1961).

    Google Scholar 

  2. Ho, B.P. & Leal, L.G. Inertial migration of rigid spheres in two-dimensional unidirectional flows. J. Fluid Mech. 65, 365–400 (1974).

    Google Scholar 

  3. Vasseur, P. & Cox, R.G. The lateral migration of a spherical particle in two-dimensional shear flows. J. Fluid Mech. 78, 385–413 (1976).

    Google Scholar 

  4. Feng, J., Hu, H.H. & Joseph, D.D. Direct simulation of initial value problems for the motion of solid bodies in a Newtonian fluid. Part 2. Couette and Poiseuille flows. J. Fluid Mech. 277, 271–301 (1994).

    Google Scholar 

  5. Cox, R.G. & Brenner, H. The lateral migration of solid particles in Poiseuille flow — I theory. Chem. Eng. Sci. 23, 147–173 (1968).

    Google Scholar 

  6. Zeng, L., Balachandar, S. & Fischer, P. Wall-induced forces on a rigid sphere at finite Reynolds number. J. Fluid Mech. 536, 1–25 (2005).

    Google Scholar 

  7. Di Carlo, D. et al. Particle segregation and dynamics in confined flows. Phys. Rev. Lett. 102, 094503 (2009).

    PubMed  PubMed Central  Google Scholar 

  8. Asmolov, E.S. The inertial lift on a spherical particle in a plane Poiseuille flow at large channel Reynolds number. J. Fluid Mech. 381, 63–87 (1999).

    CAS  Google Scholar 

  9. Di Carlo, D. Inertial microfluidics. Lab Chip 9, 3038–3046 (2009).

    PubMed  Google Scholar 

  10. Amini, H., Lee, W. & Di Carlo, D. Inertial microfluidic physics. Lab Chip 14, 2739–2761 (2014).

    CAS  PubMed  Google Scholar 

  11. Zhang, J. et al. Fundamentals and applications of inertial microfluidics: a review. Lab Chip 16, 10–34 (2016).

    CAS  PubMed  Google Scholar 

  12. Martel, J.M. & Toner, M. Inertial focusing in microfluidics. Annu. Rev. Biomed. Eng. 16, 371–396 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  13. Lu, X., Liu, C., Hu, G. & Xuan, X. Particle manipulations in non-Newtonian microfluidics: A review. J. Colloid Interface Sci. 500, 182–201 (2017).

    CAS  PubMed  Google Scholar 

  14. Kim, G.Y., Han, J.I. & Park, J.K. Inertial microfluidics-based cell sorting. Biochip J. 12, 257–267 (2018).

    Google Scholar 

  15. Karimi, A., Yazdi, S. & Ardekani, A.M. Hydrodynamic mechanisms of cell and particle trapping in microfluidics. Biomicrofluidics 7, 21501 (2013).

    CAS  PubMed  Google Scholar 

  16. Berger, S.A., Talbot, L. & Yao, L.S. Flow in Curved Pipes. Annu. Rev. Fluid Mech. 15, 461–512 (1983).

    Google Scholar 

  17. Rubinow, S.I. & Keller, J.B. The transverse force on a spinning sphere moving in a viscous fluid. J. Fluid Mech. 11, 447–459 (1961).

    Google Scholar 

  18. Saffman, P.G. The lift on a small sphere in a slow shear flow. J. Fluid Mech. 22, 385–400 (1994).

    Google Scholar 

  19. Di Carlo, D., Irimia, D., Tompkins, R.G. & Toner, M. Continuous inertial focusing, ordering, and separation of particles in microchannels. Proc. Natl. Acad. Sci. U. S. A. 104, 18892–18897 (2007).

    PubMed  PubMed Central  Google Scholar 

  20. Chung, A.J. et al. Microstructure-induced helical vortices allow single-stream and long-term inertial focusing. Lab Chip 13, 2942–2949 (2013).

    CAS  PubMed  Google Scholar 

  21. Hur, S.C., Tse, H.T. & Di Carlo, D. Sheathless inertial cell ordering for extreme throughput flow cytometry. Lab Chip 10, 274–280 (2010).

    CAS  PubMed  Google Scholar 

  22. Braff, W.A., Bazant, M.Z. & Buie, C.R. Inertial effects on the generation of co-laminar flows. J. Fluid Mech. 767, 85–94 (2015).

    CAS  Google Scholar 

  23. Gossett, D.R. et al. Inertial manipulation and transfer of microparticles across laminar fluid streams. Small 8, 2757–2764 (2012).

    CAS  PubMed  Google Scholar 

  24. Liu, C., Hu, G., Jiang, X. & Sun, J. Inertial focusing of spherical particles in rectangular microchannels over a wide range of Reynolds numbers. Lab Chip 15, 1168–1177 (2015).

    CAS  PubMed  Google Scholar 

  25. Dean, W.R. Fluid motion in a curved channel. Proc. Royal Soc. A 121, 402–420 (1928).

    Google Scholar 

  26. Nivedita, N., Ligrani, P. & Papautsky, I. Dean flow dynamics in low-aspect ratio spiral microchannels. Sci. Rep. 7, 44072 (2017).

    PubMed  PubMed Central  Google Scholar 

  27. Amini, H. et al. Engineering fluid flow using sequenced microstructures. Nat. Commun. 4, 1826 (2013).

    PubMed  Google Scholar 

  28. Chung, A.J., Gossett, D.R. & Carlo, D. Three dimensional, sheathless, and high-throughput microparticle inertial focusing through geometry-induced secondary flows. Small 9, 685–690 (2013).

    CAS  PubMed  Google Scholar 

  29. Mach, A.J. et al. Automated cellular sample preparation using a centrifuge-on-a-chip. Lab Chip 11, 2827–2834 (2011).

    CAS  PubMed  Google Scholar 

  30. Hur, S.C., Mach, A.J. & Di Carlo, D. High-throughput size-based rare cell enrichment using microscale vortices. Biomicrofluidics 5, 22206 (2011).

    PubMed  Google Scholar 

  31. Haddadi, H. & Di Carlo, D. Inertial flow of a dilute suspension over cavities in a microchannel. J. Fluid Mech. 811, 436–467 (2017).

    CAS  Google Scholar 

  32. Bretherton, F.P. The motion of rigid particles in a shear flow at low Reynolds number. J. Fluid Mech. 14, 284–304 (1962).

    Google Scholar 

  33. Gossett, D.R. & Di Carlo, D. Particle focusing mechanisms in curving confined flows. Anal. Chem. 81, 8459–8465 (2009).

    CAS  PubMed  Google Scholar 

  34. Martel, J.M. & Toner, M. Inertial focusing dynamics in spiral microchannels. Phys. Fluids 24, 32001 (2012).

    Google Scholar 

  35. Burke, J.M., Zubajlo, R.E., Smela, E. & White, I.M. High-throughput particle separation and concentration using spiral inertial filtration. Biomicrofluidics 8, 024105 (2014).

    PubMed  PubMed Central  Google Scholar 

  36. Martel, J.M. & Toner, M. Particle focusing in curved microfluidic channels. Sci. Rep. 3, 1–8 (2013).

    Google Scholar 

  37. Xuan, X.C., Zhu, J.J. & Church, C. Particle focusing in microfluidic devices. Microfluid Nanofluid 9, 1–16 (2010).

    Google Scholar 

  38. Li, M. et al. Inertial focusing of ellipsoidal Euglena gracilis cells in a stepped microchannel. Lab Chip 16, 4458–4465 (2016).

    CAS  PubMed  Google Scholar 

  39. Wu, Z., Chen, Y., Wang, M. & Chung, A.J. Continuous inertial microparticle and blood cell separation in straight channels with local microstructures. Lab Chip 16, 532–542 (2016).

    CAS  PubMed  Google Scholar 

  40. Lee, W., Amini, H., Stone, H.A. & Di Carlo, D. Dynamic self-assembly and control of microfluidic particle crystals. Proc. Natl. Acad. Sci. U. S. A. 107, 22413–22418 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  41. Kahkeshani, S., Haddadi, H. & Di Carlo, D. Preferred interparticle spacings in trains of particles in inertial microchannel flows. J. Fluid Mech. 786, R3 (2016).

    Google Scholar 

  42. Deng, Y. et al. Inertial microfluidic cell stretcher (iMCS): Fully automated, high-throughput, and near real-time cell mechanotyping. Small 13, 1700705 (2017).

    Google Scholar 

  43. Chen, Y. et al. Pulsed laser activated cell sorting with three dimensional sheathless inertial focusing. Small 10, 1746–1751 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  44. Amini, H., Sollier, E., Weaver, W.M. & Di Carlo, D. Intrinsic particle-induced lateral transport in microchannels. Proc. Natl. Acad. Sci. U. S. A. 109, 11593–11598 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  45. Lee, D. et al. Active control of inertial focusing positions and particle separations enabled by velocity profile tuning with coflow systems. Anal. Chem. 90, 2902–2911 (2018).

    CAS  PubMed  Google Scholar 

  46. Mutlu, B.R., Edd, J.F. & Toner, M. Oscillatory inertial focusing in infinite microchannels. Proc. Natl. Acad. Sci. U. S. A. 115, 7682–7687 (2018).

    CAS  PubMed  PubMed Central  Google Scholar 

  47. Chan, S.T., Haward, S.J. & Shen, A.Q. Microscopic investigation of vortex breakdown in a dividing Tjunction flow. Phys. Rev. Fluids 3, 072201 (2018).

    Google Scholar 

  48. Kim, J.A. et al. Size-dependent inertial focusing position shift and particle separations in triangular microchannels. Anal. Chem. 90, 1827–1835 (2018).

    CAS  PubMed  Google Scholar 

  49. Kazerooni, H.T., Fornari, W., Hussong, J. & Brandt, L. Inertial migration in dilute and semidilute suspensions of rigid particles in laminar square duct flow. Phys. Rev. Fluids 2, 084301 (2017).

    Google Scholar 

  50. Masaeli, M. et al. Continuous inertial focusing and separation of particles by shape. Phys. Rev. X 2, 031017 (2012).

    Google Scholar 

  51. Stoecklein, D. & Di Carlo, D. Nonlinear microfluidics. Anal. Chem. 91, 296–314 (2018).

    PubMed  Google Scholar 

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Acknowledgments

A.J.C. thanks Prof. Ian Papautsky at University of Illinois at Chicago and Dr. Kevin Paulsen at Rensselaer Polytechnic Institute (presently at Lawrence Livermore National Laboratory) for their useful comments. A.J.C. acknowledges funding from Korea University Grant, and National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2018R1D1A1B07045538).

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Authors and Affiliations

  1. School of Biomedical Engineering, Korea University, Seoul, 02841, Korea

    Aram J. Chung

  2. Department of Bioengineering, Korea University, Seoul, 02841, Korea

    Aram J. Chung

  3. Department of Bio-convergence Engineering, Korea University, Seoul, 02841, Korea

    Aram J. Chung

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  1. Aram J. Chung
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Correspondence to Aram J. Chung.

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Chung, A.J. A Minireview on Inertial Microfluidics Fundamentals: Inertial Particle Focusing and Secondary Flow. BioChip J 13, 53–63 (2019). https://doi.org/10.1007/s13206-019-3110-1

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