In Ref.[31], the ratio of the mixing index to the pressure drop (MI/PD) is used as an evaluation criterion. The larger value of MI/PD corresponds to a better overall performance. As shown in Fig. 15(a), the largest value of MI/PD is achieved in micromixer B for Re = 0.1. Then, the MI/PD of micromixer A is the highest when Re is from 1 to 10. When Re increases to 20, the default case is the best as shown in Fig. 15(b). It can be observed that the value of MI/PD is higher than that in Ref.[31] at all Re cases. The optimum design in this paper has a mixing efficiency more than 94% at Re = 0.1 and Re ≥ 40, while the pressure drop is obviously lower than that of the similar micromixer.Besides a good mixing performance, the mixing length of the novel micromixer is less than in many micromixers available in the literature[21-28].