Active micromixing

Yang, Z., Goto, H., Matsumoto, M., Maeda, R., Active micromixer for microfluidic systems using lead-zirconate-titanate(PZT)-generated ultrasonic vibration. Electrophoresis 2000, 21, 116-119. 

Choi, J.-W., Hong, C.-C., Ahn, C.H., An electrokinetic active micromixer. Micro Total Analysis Systems, Proceedings 5th pTAS Symposium, Monterey, CA, Oct. 21-25, 2001, 621-622. 

Various active micromixers using 2-D time-dependent flow to achieve chaotic advection have been developed [16-19]. Since electroosmosis is very attractive for manipulating fluids in LOC devices, a chaotic electroosmotic stirrer developed by Qian and Bau [20] is described as an example to achieve chaotic advection and mixing by 2-D time-dependent electroosmotic flow. 

Keywords Active micromixers Microfluidics Micromixing Mixing principles Passive micromixers... 

As described previously, active micromixers rely on an external energy input to introduce perturbation within the fluid streamlines to achieve mixing. Therefore, they are categorized with respect to the type of external perturbation energy ... 

One of the simple ways to achieve active mixing is to induce a pressure field disturbance. Active micromixers relying on this strategy have been reported from different authors [43, 156-159], Deshmuck et al. [156, 157] proposed a T-junction microfluidic chip with an integrated micropump that alternatively drives and stops the flow within the microdevice to create a segmented flow. 

Active micromixers use an external energy source to introduce perturbation in the fluid stream and are then categorized with respect to the type of energy source used. Pressure field, elecrokinetic, dielectrophoretic, electrowetting shaking, magneto-hydrodynamic, ultrasound, and thermal-assisted micromixers have been presented and discussed. 

The term active mixer or active micromixer refers to a microfluidic device in which species mixing is enhanced by the application of some form of external energy disturbance. Typically, this disturbance is generated either by moving... 

In typical microfluidic applications, the Reynolds number is much lower than unity (i.e.. Re = PfUlIp 1), and hence the flow can be approximated as a creeping flow (i.e., Stokes flow). Therefore, the convection term in Eq. 2 can be neglected, and the time-dependent flows in active micromixers are then governed by Eqs. 1 and 3, i.e.. 

Numerical studies relating to active micromixers generally visualize the mixing process and evaluate the mixing performance by solving the following convection-diffusion equation ... 

Yu S, Jeon TJ, Kim SM (2012) Active micromixer using electrokinetic effects in the mitao ianochannel junction. Chem Eng J 197 289-294... 

In contrast to the presented passive mixers, active micromixers rely on external power input to introduce perturbations within the laminar flow to accelerate mixing. A selection of different external perturbation sources are summarized in Table 4.1 and are discussed briefed here. 

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