Micromixers based on chaotic advection - Micromixers Fundamentals Design and Fabrication - page 233

where Pe ¼W u / D is the Peclet number, and L * ¼ L / W is the dimensionless droplet length normalized
by the channel width. Taking the algorithm of both sides of (6.46) and assuming a large Peclet number,
so that log( n ) log( l ), result in relation [45] :

(6.47)
Substituting the above value of n into (6.44) results in the required residence time of the microplug:

n z log ðPeÞ:

L
u log ð Pe Þ:

t res ¼ (6.48)

Compared to diffusive mixing with parallel lamination, the improvement of mixing time is [45]
t lamination
t chaotic

Pe
L log ð Pe Þ :

¼ (6.49)

Because of the passive microfluidic network, the droplet-based micromixer can be easily implemented
with any micromachining technology. Most of the reported droplet-based micromixers are made of
PDMS using soft lithography [45] .

FIGURE 6.40

Micromixers based on gas/liquid flow: (a) Mixer design with repeated turns and (b) Chaotic advection with loop
design.