Modern fabrication technologies enable the production of microfluidic chips that allow easy and efficient analysis and diagnostics in a wide range of fields. This often requires a mixing process at the microscale, which is difficult due to the highly laminar flows. This thesis presents the basic physical characteristics of microchannel flows, different fabrication methods and types of passive microfluidic mixers, and an inventory of methods for evaluating the quality of mixing in microfluidics. Four passive micromixers were designed, fabricated and tested, and then their performance was evaluated by observing the change in contrast of two dyes through an optical microscope. The evaluation showed that the best mixing is achieved by the mixer with a zigzag shape.
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