FIG. 4.

(a) Low-cost fluidic switch for fluid routing. When the switch is turned “off,” it prevents the sample from flowing backward from one cryotube and into another. (b) Two laminar liquids flow side-by-side at equal flow rates in a microfluidic T-channel. (c) The switch for the “red” stream is turned off and the “green” stream follows the path of least resistance. (d) The switching is reversed. (e) Two samples with different cryotube volumes are delivered to a microfluidic T-channel. (f) Without a capillary the hydraulic head of the “green” stream is greater than the “red,” resulting in the “green” stream having a faster flow rate and the interface is not centered. (g) When the capillary is introduced to the same system both flow rates become equal and the interface becomes centered. The effect of the hydraulic head is eliminated as the flow rate is bottlenecked at the high resistive capillary.