Active micromixers - Micromixers Fundamentals Design and Fabrication - page 251

FIGURE 7.7
Poincar ´ section of mixing with two source-sink pairs for different dimensionless times: (a) t * ¼ 0.15;

(b) t * ¼ 0.5; (c) t * ¼ 0.556; (d) t * ¼ 0.6. The fluid is first pumped from left to right, then from bottom to top.

(Reprinted with permission from [8] .)

7.2.4 Design examples
Due to the established technologies and the advancement of micro electromechanical systems
(MEMS), activemicromixers with pressure-driven disturbance are relatively simple to realize. Figure 7.9
shows the example of an active micromixer with integrated micropumps [10] . The disturbance is
generated by two micropumps operated out of phase. The pulsatile flows cause the instability in the
mixing channel improving transversal transport. Furthermore, the concept leads to the generation of fluid
segments similar to sequential lamination as discussed in Chapter 5. Both transversal transport by
instability and Taylor dispersion contribute to improved mixing performance. Pressure disturbance is
generated by the two integrated micropumps. Each micropump consists of a thermopneumatic actuator
and two micro check valves. The actuator is designed with a 400- m m-diameter actuation chamber and