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Investigation of mass transport in a spiral microfluidic network with an expansion chamber

In this work, we proposed the new design of two spiral networks interconnected with an expansion chamber to create vortex and disruption of the laminar boundary of intermingled streams which can efficiently boost mass transport in the microchannel. Confocal microscope is used to observe the mixing and fluid motion in the microchannel. We observed the evolution of Dean vortices along the spiral inlet channel and the disruption of stream boundary at the expansion chamber which are further pulled along the outlet spiral channel resulting in higher mixing efficiency compared to that without chamber. Laminar flow of two fluids still maintained at the end of the normal spiral networks but the perfect mixing can be achieved at a given flow rates (Re of 15 to 45) from our design. Furthermore, uniform mixing can be obtained even at the spiral channel with shorter channel length. Unlike other complex designs, the design of the expansion chamber does not increase the pressure drop of the microchannel system and its dimension is larger than that of the main channel allowing to be fabricated by using conventional fabrication approach.