Active micromixers - Micromixers Fundamentals Design and Fabrication - page 253

FIGURE 7.9

Concept of an active micromixer based on pressure-driven disturbance. The fluids are delivered by integrated
micropumps. Thermopneumatic actuators drive the pump and generate the pressure disturbance (after [10] ).

actuator. The inlet and outlet of the micro pump are designed as structures with different fluidic
resistances. Liquid is driven to the direction of the outlet with lower fluidic resistance. By adjusting the
actuation times of the pumping and supply modes, a bi-directional operation can be realized with this
pump. The micropump can deliver a flow rate from 20 nl/s to 200 nl/s, and pressure up to 5.0 kPa. The
mixing channel has a cross section of 150

m m

m. Each inlet is equipped with passive capillary
valve, which is simply a constriction. The constriction allows the synchronous introduction of the two
liquids into the microchannel during priming. Similar to sequential segmentation concept, the two
pumps at the inlet are turned on and off alternately. Mixing is achieved with both pressure-driven
disturbance and Taylor-dispersion.

m 150

FIGURE 7.10
Concept of an active micromixer based on pressure-driven disturbance. The fluids are delivered by hybrid-
integrated piezoelectric micropumps (after [11] ).