Chapter 2
Active and Passive Micromixers
Abstract Micromixers are classified into two types: active and passive micromixers.
Active micromixers promote mixing using moving parts or some external agitation/energy to stir the fluids. Magnetic energy, electrical energy, pressure disturbance,
and ultrasonic are examples of the external energies to enhance mixing. Passive
micromixers use geometrical modification to cause chaotic advection or lamination to promote the mixing of the fluid samples, and allow easy fabrication and
integration with lab-on-a-chip and μ-TAS. In this chapter, both active and passive
micromixers are discussed, but the major emphasis is laid on passive micromixer
designs and mechanisms. Extensive referencing on active and passive micromixers
is not possible due to the limited length of the book, but the diversity of micromixers
is introduced as much as possible.
Keywords Active micromixers · Electrokinetics · Time pulsing · Passive
micromixers · Multi-lamination · Chaotic advection
2.1 Active Micromixers
Active micromixers promote mixing using external energy sources such as pressure
disturbance, acoustics, vibrations, impellers, and electric and magnetic fields. Based
on the type of external energy, the flows in active micromixers can be categorized as:
• Pulsed flow
• Electro-kinetic flow
• Magneto-hydrodynamic flow
• Acoustic induced flow
• Coriolis force induced flow
Glasgow and Aubry [1, 2] conducted a series of extensive studies on pulsed flows
by pressure disturbance through T-mixers with different configurations and operating
parameters using CFD and experiments. The pulsing was performed using a low
frequency sinusoidal flow superimposed upon a steady flow. In one of these studies
[2], they investigated the mixing behaviors in ribbed and 3D twisted micromixers
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
A. Afzal and K.-Y. Kim, Analysis and Design Optimization of Micromixers,
SpringerBriefs in Computational Mechanics,
https://doi.org/10.1007/978-981-33-4291-0_2
11
Active and Passive Micromixers
Abstract Micromixers are classified into two types: active and passive micromixers.
Active micromixers promote mixing using moving parts or some external agitation/energy to stir the fluids. Magnetic energy, electrical energy, pressure disturbance,
and ultrasonic are examples of the external energies to enhance mixing. Passive
micromixers use geometrical modification to cause chaotic advection or lamination to promote the mixing of the fluid samples, and allow easy fabrication and
integration with lab-on-a-chip and μ-TAS. In this chapter, both active and passive
micromixers are discussed, but the major emphasis is laid on passive micromixer
designs and mechanisms. Extensive referencing on active and passive micromixers
is not possible due to the limited length of the book, but the diversity of micromixers
is introduced as much as possible.
Keywords Active micromixers · Electrokinetics · Time pulsing · Passive
micromixers · Multi-lamination · Chaotic advection
2.1 Active Micromixers
Active micromixers promote mixing using external energy sources such as pressure
disturbance, acoustics, vibrations, impellers, and electric and magnetic fields. Based
on the type of external energy, the flows in active micromixers can be categorized as:
• Pulsed flow
• Electro-kinetic flow
• Magneto-hydrodynamic flow
• Acoustic induced flow
• Coriolis force induced flow
Glasgow and Aubry [1, 2] conducted a series of extensive studies on pulsed flows
by pressure disturbance through T-mixers with different configurations and operating
parameters using CFD and experiments. The pulsing was performed using a low
frequency sinusoidal flow superimposed upon a steady flow. In one of these studies
[2], they investigated the mixing behaviors in ribbed and 3D twisted micromixers
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
A. Afzal and K.-Y. Kim, Analysis and Design Optimization of Micromixers,
SpringerBriefs in Computational Mechanics,
https://doi.org/10.1007/978-981-33-4291-0_2
11