Skip to main content
Log in

A review on microdroplet generation in microfluidics

  • Review
  • Published:
Journal of the Brazilian Society of Mechanical Sciences and Engineering Aims and scope Submit manuscript

Abstract

Micro-nanofluidic technology is widely used in food safety testing, drug screening, new material synthesis and bioengineering. Droplet microfluidic technology is an important branch of micro-nanofluidic technology. The microdroplet technology can produce high-throughput monodisperse droplets. The droplet technology overcomes many problems of continuous flow, such as small sample reagent volume, no cross-contamination, and rapid chemical reaction. So microdroplets have an important position in the fields of single cell analysis, gene sequencing, and real-time diagnosis. This review focuses on the different methods and applications of microdroplet generation in microfluidics. The droplet generation methods are passive and active methods. The passive method does not require external force, while the active method requires external force such as external electric field, magnetic field, acoustic field, and laser field. It is predicted that the quantitative generation of droplets on demand in microfluidics will be the important direction for future research. This review provides new ideas for the applications of the quantitative generation of microdroplets on demand in microfluidics.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7

Similar content being viewed by others

References

  1. Zhu P, Wang L (2017) Passive and active droplet generation with microfluidics: a review. Lab Chip 17(1):34–75

    Article  Google Scholar 

  2. Cybulski O, Garstecki P, Grzybowski BA (2019) Oscillating droplet trains in microfluidic networks and their suppression in blood flow. Nat Phys 15(7):706–713

    Article  Google Scholar 

  3. Han W, Chen X, Wu Z et al (2019) Three-dimensional numerical simulation of droplet formation in a microfluidic flow-focusing device. J Braz Soc Mech Sci Eng 41(6):265

    Article  Google Scholar 

  4. Chen PC, Wu MH, Wang YN (2014) Microchannel geometry design for rapid and uniform reagent distribution. Microfluid Nanofluid 17(2):275–285

    Article  Google Scholar 

  5. Li X, Li D, Liu X, Chang H (2016) Ultra-monodisperse droplet formation using PMMA microchannels integrated with low-pulsation electrolysis micropumps. Sens Actuators B Chem 229:466–475

    Article  Google Scholar 

  6. Han W, Chen X (2019) New insights into the pressure during the merged droplet formation in the squeezing time. Chem Eng Res Des 145:213–225

    Article  Google Scholar 

  7. Theberge AB, Courtois F, Schaerli Y, Fischlechner M, Abell C, Hollfelder F, Huck W (2010) Microdroplets in microfluidics: an evolving platform for discoveries in chemistry and biology. Angew Chem Int Ed 49(34):5846–5868

    Article  Google Scholar 

  8. Agresti JJ, Antipov E, Abate AR, Ahn K, Rowat AC, Baret J, Marquez M, Klibanov AM, Griffiths AD, Weitz DA (2010) Ultrahigh-throughput screening in drop-based microfluidics for directed evolution. Proc Natl Acad Sci 107(9):4004–4009

    Article  Google Scholar 

  9. Köster S, Angile FE, Duan H, Agresti JJ, Wintner A, Schmitz C, Rowat AC, Merten CA, Pisignano D, Griffiths AD, Weitz DA (2008) Drop-based microfluidic devices for encapsulation of single cells. Lab Chip 8(7):1110–1115

    Article  Google Scholar 

  10. Thorsen T, Roberts RW, Arnold FH, Quake SQ (2001) Dynamic pattern formation in a vesicle-generating microfluidic device. Phys Rev Lett 86(18):4163

    Article  Google Scholar 

  11. Nisisako T, Torii T, Higuchi T (2002) Droplet formation in a microchannel network. Lab Chip 2(1):24–26

    Article  Google Scholar 

  12. Cramer C, Fischer P, Windhab EJ (2004) Drop formation in a co-flowing ambient fluid. Chem Eng Sci 59(15):3045–3058

    Article  Google Scholar 

  13. Garstecki P, Fuerstman MJ, Stone HA, Whitesides GM (2006) Formation of droplets and bubbles in a microfluidic T-junction-scaling and mechanism of break-up. Lab Chip 6(3):437–446

    Article  Google Scholar 

  14. Van der Graaf S, Nisisako T, Schroen C, van der Sman R, Boom R (2006) Lattice Boltzmann simulations of droplet formation in a T-shaped microchannel. Langmuir 22(9):4144–4152

    Article  Google Scholar 

  15. Xu JH, Li SW, Tan J, Wang YJ, Luo GS (2006) Preparation of highly monodisperse droplet in a T-junction microfluidic device. AIChE J 52(9):3005–3010

    Article  Google Scholar 

  16. Xu JH, Li SW, Wang YJ, Luo GS (2006) Controllable gas-liquid phase flow patterns and monodisperse microbubbles in a microfluidic T-junction device. Appl Phys Lett 88(13):133506

    Article  Google Scholar 

  17. Xu JH, Li SW, Tan J, Luo GS (2008) Correlations of droplet formation in T-junction microfluidic devices: from squeezing to dripping. Microfluid Nanofluid 5(6):711–717

    Article  Google Scholar 

  18. De Menech M, Garstecki P, Jousse F, Stone HA (2008) Transition from squeezing to dripping in a microfluidic T-shaped junction. J Fluid Mech 595:141–161

    Article  MATH  Google Scholar 

  19. Wang W, Liu Z, Jin Y, Cheng Y (2011) LBM simulation of droplet formation in micro-channels. Chem Eng J 173(3):828–836

    Article  Google Scholar 

  20. Abate AR, Weitz DA (2011) Air-bubble-triggered drop formation in microfluidics. Lab Chip 11(10):1713–1716

    Article  Google Scholar 

  21. Yan Y, Guo D, Wen SZ (2012) Numerical simulation of junction point pressure during droplet formation in a microfluidic T-junction. Chem Eng Sci 84:591–601

    Article  Google Scholar 

  22. Tarchichi N, Chollet F, Manceau JF (2013) New regime of droplet generation in a T-shape microfluidic junction. Microfluid Nanofluid 14(1–2):45–51

    Article  Google Scholar 

  23. Shi Y, Tang GH, Xia HH (2014) Lattice Boltzmann simulation of droplet formation in T-junction and flow focusing devices. Comput Fluids 90:155–163

    Article  MathSciNet  MATH  Google Scholar 

  24. Wehking JD, Gabany M, Chew L, Kumar R (2014) Effects of viscosity, interfacial tension, and flow geometry on droplet formation in a microfluidic T-junction. Microfluid Nanofluid 16(3):441–453

    Article  Google Scholar 

  25. Bashir S, Rees JM, Zimmerman WB (2014) Investigation of pressure profile evolution during confined microdroplet formation using a two-phase level set method. Int J Multiph Flow 60:40–49

    Article  Google Scholar 

  26. Zeng W, Li S, Wang Z (2015) Closed-loop feedback control of droplet formation in a T-junction microdroplet generator. Sens Actuators A: Phys 233:542–547

    Article  Google Scholar 

  27. Surya HPN, Parayil S, Banerjee U, Chander S, Sen AK (2015) Alternating and merged droplets in a double T-junction microchannel. BioChip J 9(1):16–26

    Article  Google Scholar 

  28. Ngo IL, Dang TD, Byon C, Joo SW (2015) A numerical study on the dynamics of droplet formation in a microfluidic double T-junction. Biomicrofluidics 9(2):024107

    Article  Google Scholar 

  29. Malekzadeh S, Roohi E (2015) Investigation of different droplet formation regimes in a T-junction microchannel using the VOF technique in OpenFOAM. Microgravity Sci Technol 27(3):231–243

    Article  Google Scholar 

  30. Bai L, Fu Y, Zhao S, Cheng Y (2016) Droplet formation in a microfluidic T-junction involving highly viscous fluid systems. Chem Eng Sci 145:141–148

    Article  Google Scholar 

  31. Li X, Li D, Liu X, Chang H (2016) Ultra-monodisperse droplet formation using PMMA microchannels integrated with low-pulsation electrolysis micropumps. Sens Actuators B Chem 229:466–475

    Article  Google Scholar 

  32. Soh GY, Yeoh GH, Timchenko V (2016) Numerical investigation on the velocity fields during droplet formation in a microfluidic T-junction. Chem Eng Sci 139:99–108

    Article  Google Scholar 

  33. Wong VL, Loizou K, Lau PL, Graham RS, Hewakandamby NB (2017) Numerical studies of shear-thinning droplet formation in a microfluidic T-junction using two-phase level-SET method. Chem Eng Sci 174:157–173

    Article  Google Scholar 

  34. Liu Z, Zhang L, Pang Y, Wang X, Li M (2017) Micro-PIV investigation of the internal flow transitions inside droplets traveling in a rectangular microchannel. Microfluid Nanofluid 21(12):180

    Article  Google Scholar 

  35. Fu H, Zeng W, Li S (2017) Quantitative study of the production rate of droplets in a T-junction microdroplet generator. J Micromech Microeng 27(12):125020

    Article  Google Scholar 

  36. Sontti SG, Atta A (2017) CFD analysis of microfluidic droplet formation in non–Newtonian liquid. Chem Eng J 330:245–261

    Article  Google Scholar 

  37. Riaud A, Zhang H, Wang X, Wang K, Luo GS (2018) Numerical study of surfactant dynamics during emulsification in a T-junction microchannel. Langmuir 34(17):4980–4990

    Article  Google Scholar 

  38. Saqib M, Şahinoğlu OB, Erdem EY (2018) Alternating DROPLET formation by using tapered channel geometry. Sci Rep 8(1):1606

    Article  Google Scholar 

  39. Arias S, Montlaur A (2018) Influence of contact angle boundary condition on CFD simulation of T-junction. Microgravity Sci Technol 30(4):435–443

    Article  Google Scholar 

  40. Freytes VM, Rosen M, D’Onofrio A (2018) Capillary film and breakup mechanism in the squeezing to dripping transition regime at the mesoscale between micro and milli-fluidics. Chaos Interdiscip J Nonlinear Sci 28(10):103104

    Article  Google Scholar 

  41. Sun L, Fan M, Li P, Yu H, Zhang Y, Xu J, Jiang W, Qian S, Sun G (2019) Microbubble characteristic in a T-junction microchannel in microfluidic chip. Mol Phy 117(18):2535–2545

    Article  Google Scholar 

  42. Dendukuri D, Tsoi K, Hatton TA et al (2005) Controlled synthesis of nonspherical microparticles using microfluidics. Langmuir 21(6):2113–2116

    Article  Google Scholar 

  43. Anna SL, Bontoux N, Stone HA (2003) Formation of dispersions using “flow focusing” in microchannels. Appl Phys Lett 82(3):364–366

    Article  Google Scholar 

  44. Dreyfus R, Tabeling P, Willaime H (2003) Ordered and disordered patterns in two-phase flows in microchannels. Phys Rev Lett 90(14):144505

    Article  Google Scholar 

  45. Garstecki P, Fuerstman MJ, Whitesides GM (2005) Nonlinear dynamics of a flow-focusing bubble generator: An inverted dripping faucet. Phys Rev Lett 94(23):234502

    Article  Google Scholar 

  46. Takeuchi S, Garstecki P, Weibel DB, Whitesides GM (2005) An axisymmetric flow-focusing microfluidic device. Adv Mater 17(8):1067–1072

    Article  Google Scholar 

  47. Yobas L, Martens S, Ong WL, Nagarajan RN (2006) High-performance flow-focusing geometry for spontaneous generation of monodispersed droplets. Lab Chip 6(8):1073–1079

    Article  Google Scholar 

  48. Romero PA, Abate AR (2012) Flow focusing geometry generates droplets through a plug and squeeze mechanism. Lab Chip 12(24):5130–5132

    Article  Google Scholar 

  49. Fu T, Wu Y, Ma Y, Li HZ (2012) Droplet formation and breakup dynamics in microfluidic flow-focusing devices: from dripping to jetting. Chem Eng Sci 84:207–217

    Article  Google Scholar 

  50. Derzsi L, Kasprzyk M, Plog JP, Garstecki P (2013) Flow focusing with viscoelastic liquids. Phys Fluids 25(9):092001

    Article  Google Scholar 

  51. Gol B, Tovar-Lopez FJ, Kurdzinski ME, Tang SY, Petersen P, Mitchell A, Khoshmanesh K (2015) Continuous transfer of liquid metal droplets across a fluid–fluid interface within an integrated microfluidic chip. Lab Chip 15(11):2476–2485

    Article  Google Scholar 

  52. Huang H, He X (2015) Fluid displacement during droplet formation at microfluidic flow-focusing junctions. Lab Chip 15(21):4197–4205

    Article  Google Scholar 

  53. Nooranidoost M, Izbassarov D, Muradoglu M (2016) Droplet formation in a flow focusing configuration: Effects of viscoelasticity. Phys Fluids 28(12):123102

    Article  Google Scholar 

  54. Castro-Hernandez E, Kok MP, Versluis M, Rivas DF (2016) Study of the geometry in a 3D flow-focusing device. Microfluid Nanofluid 20(2):40

    Article  Google Scholar 

  55. Van Loo S, Stoukatch S, Kraft M, Gilet T (2016) Droplet formation by squeezing in a microfluidic cross-junction. Microfluid Nanofluid 20(10):146

    Article  Google Scholar 

  56. Gulati S, Vijayakumar K, Good WW, Tamayo WL, Pate AR, Niu X (2016) Microdroplet formation in rounded flow-focusing junctions. Microfluid Nanofluid 20(1):2

    Article  Google Scholar 

  57. Chen X, Ren CL (2017) Experimental study on droplet generation in flow focusing devices considering a stratified flow with viscosity contrast. Chem Eng Sci 163:1–10

    Article  Google Scholar 

  58. Wang X, Zhu C, Fu T, Qiu T, Ma Y (2017) Critical condition for bubble breakup in a microfluidic flow-focusing junction. Chem Eng Sci 164:178–187

    Article  Google Scholar 

  59. Wu J, Yan Q, Cui Y, Xuan S, Gong X (2017) Geometry-confined bifurcation at low flow rate in flow-focusing droplet generator[J]. Microfluid Nanofluid 21(7):119

    Article  Google Scholar 

  60. Rostami B, Morini GL (2018) Generation of Newtonian and non-Newtonian droplets in silicone oil flow by means of a micro cross-junction. Int J Multiph Flow 105:202–216

    Article  Google Scholar 

  61. Islam MM, Loewen A, Allen PB (2018) Simple, low-cost fabrication of acrylic based droplet microfluidics and its use to generate DNA-coated particles. Sci Rep 8(1):1–11

    Article  Google Scholar 

  62. Umbanhowar PB, Prasad V, Weitz DA (2000) Monodisperse emulsion generation via drop break off in a coflowing stream. Langmuir 16(2):347–351

    Article  Google Scholar 

  63. Utada AS, Lorenceau E, Link DR, Kaplan PD, Stone HA, Weitz DA (2005) Monodisperse double emulsions generated from a microcapillary device. Science 308(5721):537–541

    Article  Google Scholar 

  64. Shao T, Feng X, Jin Y, Cheng Y (2013) Controlled production of double emulsions in dual-coaxial capillaries device for millimeter-scale hollow polymer spheres. Chem Eng Sci 104:55–63

    Article  Google Scholar 

  65. Gordillo JM, Sevilla A, Campo-Cortés F (2014) Global stability of stretched jets: conditions for the generation of monodisperse micro-emulsions using coflows. J Fluid Mech 738:335–357

    Article  Google Scholar 

  66. Deng C, Wang H, Huang W, Cheng S (2017) Numerical and experimental study of oil-in-water (O/W) droplet formation in a co-flowing capillary device. Colloids Surf A 533:1–8

    Article  Google Scholar 

  67. Zahoor R, Belšak G, Bajt S, Šarler B (2018) Simulation of liquid micro-jet in free expanding high-speed co-flowing gas streams. Microfluid Nanofluid 22(8):87

    Article  Google Scholar 

  68. Shams Khorrami A, Rezai P (2018) Oscillating dispersed-phase co-flow microfluidic droplet generation: Multi-droplet size effect. Biomicrofluidics 12(3):034113

    Article  Google Scholar 

  69. Zhang J, Xu W, Xu F et al (2021) Microfluidic droplet formation in co-flow devices fabricated by micro 3D printing. J Food Eng 290:110212

    Article  Google Scholar 

  70. Li Y, Jain M, Ma Y, Nandakumar K (2015) Control of the breakup process of viscous droplets by an external electric field inside a microfluidic device. Soft Matter 11(19):3884–3899

    Article  Google Scholar 

  71. Xi HD, Guo W, Leniart M, Chong ZZ, Tan SH (2016) AC electric field induced droplet deformation in a microfluidic T-junction. Lab Chip 16(16):2982–2986

    Article  Google Scholar 

  72. Brandenbourger M, Caps H, Vitry Y, Dorbolo S (2017) Electrically charged droplets in microgravity. Microgravity Sci Technol 29(3):229–239

    Article  Google Scholar 

  73. Timung S, Chaudhuri J, Borthakur MP, Mandal TK, Biswas G, Bandyopadhyay D (2017) Electric field mediated spraying of miniaturized droplets inside microchannel. Electrophoresis 38(11):1450–1457

    Article  Google Scholar 

  74. Hatami M, Ramiar A, Ranjbar AA (2018) Numerical assessment of different parameters affecting droplet production in an electro-hydrodynamic flow focusing device. Chem Eng Process Process Intensif 131:190–202

    Article  Google Scholar 

  75. Teo AJT, Tan SH, Nguyen NT (2019) On-demand droplet merging with an AC electric field for multiple-volume droplet generation. Anal Chem 92(1):1147–1153

    Article  Google Scholar 

  76. Liu J, Tan SH, Yap YF, Ng MY, Nguyen NT (2011) Numerical and experimental investigations of the formation process of ferrofluid droplets. Microfluid Nanofluid 11(2):177–187

    Article  Google Scholar 

  77. Zhang Q, Li H, Zhu C, Fu T, Ma Y, Li HZ (2018) Micro-magnetofluidics of ferrofluid droplet formation in a T-junction. Colloids Surf A 537:572–579

    Article  Google Scholar 

  78. Chaudhuri J, Mandal TK, Bandyopadhyay D (2018) Steady and oscillatory Lorentz-force-induced transport and digitization of two-phase microflows. Phys Rev Appl 10(3):034057

    Article  Google Scholar 

  79. Ray A, Varma VB, Jayaneel PJ et al (2017) On demand manipulation of ferrofluid droplets by magnetic fields. Sens Actuators B Chem 242:760–768

    Article  Google Scholar 

  80. Schmid L, Franke T (2013) SAW-controlled drop size for flow focusing. Lab Chip 13(9):1691–1694

    Article  Google Scholar 

  81. Collins DJ, Alan T, Helmerson K et al (2013) Surface acoustic waves for on-demand production of picoliter droplets and particle encapsulation. Lab Chip 13(16):3225–3231

    Article  Google Scholar 

  82. Jin S, Wei X, Liu Z, Ren J, Jiang Z, Abell C, Yu Z (2019) Focused surface acoustic waves induced microdroplets generation and its application for microgels. Sens Actuators B Chem 291:1–8

    Article  Google Scholar 

  83. Li P, Ma Z, Zhou Y et al (2019) Detachable acoustophoretic system for fluorescence-activated sorting at the single-droplet level. Anal Chem 91(15):9970–9977

    Article  Google Scholar 

  84. de Saint VMR, Delville JP (2016) Fragmentation mechanisms of confined co-flowing capillary threads revealed by active flow focusing. Phys Rev Fluids 1(4):043901

    Article  Google Scholar 

  85. de Saint VMR, Chraïbi H, Delville JP (2015) Optical flow focusing: Light-induced destabilization of stable liquid threads. Phys Rev Appl 4(4):044005

    Article  Google Scholar 

  86. Wang Z, Chen R, Zhu X, Liao Q, Ye D, Zhang B, He X, Li W (2018) Control of the droplet generation by an infrared laser. AIP Adv 8(1):015302

    Article  Google Scholar 

  87. Zhang H, Palit P, Liu Y et al (2020) Reconfigurable Integrated Optofluidic Droplet Laser Arrays. ACS Appl Mater Interfaces 12(24):26936–26942

    Article  Google Scholar 

Download references

Acknowledgement

This work was supported by Young Taishan Scholars Program of Shandong Province of China (tsqn2020), Shandong Provincial Natural Science Foundation (ZR2021JQ), Key Research and Development Projects of Shandong Province (2018GGX103046).

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Xueye Chen.

Ethics declarations

Conflict of interest

The authors declare no conflicts of interest.

Additional information

Technical Editor: Daniel Onofre de Almeida Cruz.

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Han, W., Chen, X. A review on microdroplet generation in microfluidics. J Braz. Soc. Mech. Sci. Eng. 43, 247 (2021). https://doi.org/10.1007/s40430-021-02971-0

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1007/s40430-021-02971-0

Keywords

Navigation