Micromixing Within Microfluidic Devices

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

Abstract

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.

Keywords

Active micromixers Microfluidics Micromixing Mixing principles Passive micromixers 

Symbols

A

Cross-sectional area (m2)

Ca

Capillary number

D

Diffusion coefficient (m2 s−1)

Dh

Hydraulic diameter (m)

f

Frequency of the disturbance action

h

Height of the channels (m)

j

Diffusion flux (mol m−2 s−1)

k

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

n

Number of parallel fluid substreams

Pe

Peclét number

Pwet

Wetted perimeter (m)

Q1

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

Q2

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

Q3

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

Qf

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

R

Radius of the particles (or molecules) (m)

Re

Reynolds number

St

Strouhal number

t

Time (s)

T

Absolute temperature

u

Velocity of fluid (m s−1)

v2

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

vf

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

vo

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

w2

Width of central inlet channel (m)

wf

Width of the focused stream (m)

wo

Width of the mixing channel (m)

x

Position of the species (m)

Greek Symbols

γ

Interfacial tension (N m−1)

ϕ

Species concentration (Kg m−3)

ρ

Fluid density (kg m−3)

μ

Fluid dynamic viscosity (Pa s)

ν

Fluid kinematic viscosity (m2 s−1)

Abbreviations

μTAS

Micro total analysis systems

ASM

Asymmetric serpentine micromixer

CDM

Circulation–disturbance micromixer

CGM

Connected-groove micromixer

CMM

Crossing manifold micromixer

EKI

Elecrokinetic instability

EWDO

Electrowetting on dielectrics

LOC

Lab on a chip

MHD

Magneto hydrodynamic

PCR

Polymerase chain reaction

PSM

Planar serpentine micromixer

SAR

Split-and-recombine micromixers, sequential lamination micromixers

SGM

Slanted-groove micromixer

SHM

Staggered-herringbone micromixers

SOC

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
  1. 1.School of Engineering SciencesUniversity of SouthamptonSouthamptonUK

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