Secondary flow restrictors

In order to reduce variations in flow due to secondary forces such as capillary forces within reservoirs, the flow resistance at each port is increased by using a long serpentine path as a flow restrictor (see Figure 2.37). This chip design also contains the so-called pair-well design so that two channels from the pair wells (e.g., wells 1 and 8) are connected to a common node. Since the pair channels have the same flow resistance, the change of flow in one channel could be easily compensated by that from another channel and so keeping the main channel flow constant. For instance, a 40% flow in the main channel can be achieved by either -4% from well 1 and +44% from well 8, or 4% from well 1 and 36% from well 8 [295],... 

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