Effect of Bending Direction on Mixing Performance of Zigzag Microchannels

Zigzag microchannels have been commonly used in microreactors and micro total analysis systems (mu TAS). In the present study, the mixing performance of four special types of zigzag channels was compared. These channels had m successive 90 degrees bends in the same direction, followed by m successive 90 degrees bends in the opposite direction; this pattern was repeated numerous times. The mixing efficiencies (as Reynolds number, Re) under various flow conditions of the zigzag channels (having m = 1, 2, 3, or 4) were experimentally determined in the following two ways. First, the mixing patterns were visualized by means of laser-induced fluorometry (LIF). Second, the required length for complete mixing was measured by means of a decolorizing reaction. The results revealed that the mixing efficiency became high with an increase in m, and the effect of convective flow by bending in the same direction is large for 150<Re<250.