Table 2.

Performance of passive micromixers in recent five years [13–25].

Categories	Mixing Technique	Mixing Time (ms)	Mixing Length (μm)	Mixing Index	Reference
Lamination	Wedged shaped inlets	1	1	0.9	[13]
	90° rotation	-	-	0.95	[14]
Zigzag channels	Elliptic-shape barriers	-	10,000	0.96	[15]
3-D serpentine structure	Folding structure	489	-	0.01	[16]
	Creeping structure	-	-	0.015	[17]
	Stacked shim structure	-	-	-	[18]
	Multiple splitting, stretching and recombining flows	-	-	-	[19]
	Unbalanced driving force	-	815ψ	0.91	[20]
Embedded barriers	SMX	-	-	-	[21]
	Multidirectional vortices	-	4255	0.72	[22]
Twisted channels	Split-and-recombine	730	96,000	∼1	[23]
Surface-chemistry	Obstacle shape	-	1000	0.98	[24]
	T-/Y- mixer	-	1000	0.95	[25]