Figure 5.

Production of different flow profiles in the same device using composite pumping lids. (A) Schematics of the setup used for the experiments. The microfluidic device has three cups, each dedicated to a different aqueous solution (from left to right: green, transparent, and red). A composite lid controls the pressure at each of the three inlets, thus controlling the flow rate of each solution. (B) Micrograph of the junction at which the three inlet branches combine into a single channel and the streams from the three inlets produce parallel laminar flow. (C) Different composite lids can be used to produce different flow profiles. The top row shows the cross-section of five different lids, cut along the red dashed line in panel A. The middle row shows the experimental flow profiles obtained with these five lids in the same microfluidic device. The sketches (bottom row) show the expected flow profiles based on the pressures produced by the lids and the device geometry. For the channel used in these experiments the width (1.5 mm) was more than 35 times bigger than the channel height (40 μm), so the effect of parabolic flow near the lateral walls was negligible¹⁶