Low Complexity Flow Control in a Microfluidic Mixer
The present invention provides a microfluidic mixing platform having a bulk, the platform including an inlet well, a microchannel, a passive capillary valve a mixing feature and an outlet. The passive capillary valve prevents unwanted capillary flow along the microchannel. The passive capillary valve comprises a widening of the microchannel relative to the direction of fluid flow, and the angle has a graduated profile. The mixing platform bulk comprises a rigid matrix capable of machine manufacture. A method of preventing backflow in a microfluidic mixer is also provided.
1 . A microfluidic mixing platform having a bulk, comprising:
(a) an inlet well,
(b) a microchannel having a length,
(c) a passive capillary valve at a point in said length,
(d) a mixing feature, and
(e) an outlet,
and wherein said passive capillary valve prevents capillary flow along the microchannel.
2 . The mixing platform of claim 1 , wherein the bulk comprises a rigid matrix capable of machine manufacture.
3 . The mixing platform of claim 1 , wherein said passive capillary valve comprises a widening of the microchannel at an angle of at least 90 degrees and up to 179 degrees relative to the direction of overall fluid flow in the microchannel.
4 . The mixing platform of claim 1 , wherein said passive capillary valve comprises a widening of the microchannel at an angle of at least 95 degrees and up to 160 degrees relative to the direction of overall fluid flow in the microchannel.
5 . The mixing platform of claim 1 , wherein said passive capillary valve comprises a widening of the microchannel at an angle of at least 100 degrees and up to 150 degrees relative to the direction of fluid flow.
6 . The mixing platform of claim 1 , wherein said passive capillary valve comprises a widening of the microchannel at an angle of at least 105 degrees and up to 145 degrees relative to the direction of fluid flow.
7 . The mixing platform of claim 1 , wherein said passive capillary valve comprises a widening of the microchannel at an angle of at least 110 degrees and up to 140 degrees relative to the direction of fluid flow.
8 . The mixing platform of claim 1 , wherein said passive capillary valve comprises a widening of the microchannel at an angle of at least 120 degrees, and up to 130 degrees relative to the direction of fluid flow.
9 . The mixing platform of claim 1 , wherein said passive capillary valve comprises a widening of the microchannel relative to the direction of fluid flow, and wherein said angle is graduated and has a minimum radius of curvature of from 0.015 to 0.05 mm.
10 . The mixing platform of claim 1 , wherein said passive capillary valve comprises a widening of the microchannel relative to the direction of fluid flow, and wherein said angle is graduated and has a minimum radius of curvature of about 0.08 mm.
11 . The mixing platform of claim 1 , wherein said passive capillary valve is plural.
12 . The mixing platform of claim 1 , wherein said passive capillary valve is upstream from a mixing feature.
13 . The mixing platform of claim 1 , wherein said passive capillary valve is downstream from a mixing feature.
14 . The mixing platform of claim 1 , wherein said passive capillary valve is upstream from a mixing feature.
15 . A method of preventing back flow in a microfluidic mixing platform, by incorporating a segment of negative microchannel wall at a point in a microchannel.
16 . The method of claim 15 , wherein said segment of negative microchannel is plural.
17 . The method of claim 15 , wherein said segment of negative microchannel wall is upstream from a mixing feature.
18 . The method of claim 15 , wherein said segment of negative microchannel wall is downstream from a mixing feature.