Micromixing Within Microfluidic Devices

  • Lorenzo Capretto
  • Wei Cheng
  • Martyn Hill
  • Xunli ZhangEmail author
Part of the Topics in Current Chemistry book series (TOPCURRCHEM, volume 304)


Micromixing is a crucial process within microfluidic systems such as micro total analysis systems (μTAS). A state-of-art review on microstructured mixing devices and their mixing phenomena is given. The review first presents an overview of the characteristics of fluidic behavior at the microscale and their implications in microfluidic mixing processes. According to the two basic principles exploited to induce mixing at the microscale, micromixers are generally classified as being passive or active. Passive mixers solely rely on pumping energy, whereas active mixers rely on an external energy source to achieve mixing. Typical types of passive micromixers are discussed, including T- or Y-shaped, parallel lamination, sequential, focusing enhanced mixers, and droplet micromixers. Examples of active mixers using external forces such as pressure field, electrokinetic, dielectrophoretic, electrowetting, magneto-hydrodynamic, and ultrasound to assist mixing are presented. Finally, the advantages and disadvantages of mixing in a microfluidic environment are discussed.


Active micromixers Microfluidics Micromixing Mixing principles Passive micromixers 



Cross-sectional area (m2)


Capillary number


Diffusion coefficient (m2 s−1)


Hydraulic diameter (m)


Frequency of the disturbance action


Height of the channels (m)


Diffusion flux (mol m−2 s−1)


Boltzmann’s constant (k = 1.381·10−23J K−1)


Number of parallel fluid substreams


Peclét number


Wetted perimeter (m)


Volumetric flow rates for the lateral channels (m3 s−1)


Volumetric flow rates of the central inlet channel (m3 s−1)


Volumetric flow rates for the lateral channels (m3 s−1)


Volumetric flow rates of the focused stream (m3 s−1)


Radius of the particles (or molecules) (m)


Reynolds number


Strouhal number


Time (s)


Absolute temperature


Velocity of fluid (m s−1)


Average flow velocity of the flow within central inlet channel (m s−1)


Average flow velocity of the flow within focused stream (m s−1)


Average flow velocities of the flow within the mixing channel (m s−1)


Width of central inlet channel (m)


Width of the focused stream (m)


Width of the mixing channel (m)


Position of the species (m)

Greek Symbols


Interfacial tension (N m−1)


Species concentration (Kg m−3)


Fluid density (kg m−3)


Fluid dynamic viscosity (Pa s)


Fluid kinematic viscosity (m2 s−1)



Micro total analysis systems


Asymmetric serpentine micromixer


Circulation–disturbance micromixer


Connected-groove micromixer


Crossing manifold micromixer


Elecrokinetic instability


Electrowetting on dielectrics


Lab on a chip


Magneto hydrodynamic


Polymerase chain reaction


Planar serpentine micromixer


Split-and-recombine micromixers, sequential lamination micromixers


Slanted-groove micromixer


Staggered-herringbone micromixers


Staggered overlapping crisscross micromixer


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Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  • Lorenzo Capretto
    • 1
  • Wei Cheng
    • 1
  • Martyn Hill
    • 1
  • Xunli Zhang
    • 1
    Email author
  1. 1.School of Engineering SciencesUniversity of SouthamptonSouthamptonUK

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