Fig. 3.

a Normalized concentrations along the X-X’ line across the center of the micromixer for the four integrated vortex-type micromixers; b The relationship between the mixing time and mixing index while operated at different driving frequencies. A mixing index of 96 % is achieved in 1 s while mixing at 4.0 Hz frequency and −70 kPa; c The relationship between the applied negative pressure and the flow pumping rate. Note that when the transportation frequency is set as 0.67 Hz (1.5 s/cycle), the flow pumping rate can be as high as 516.5 ± 13.5 μL/min at −70 kPa vacuum pressure