Flow control in multi-stream microfluidic devices

• US 20020153046A1
• Filed: 09/25/2001
• Published: 10/24/2002
• Est. Priority Date: 04/20/2001
• Status: Active Grant

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Nanostream, Inc.
• Inventors: Patel, Paren P., Dantsker, Eugene, Pezzuto, Marci, Hobbs, Steven E., Karp, Christoph D.
• Granted Patent: US 6,499,499 B2
• Time in Patent Office: Days
• US Class Current: 137/833
• CPC Class Codes: B01L 2300/0681 Filter
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/0864 comprising only one inlet and multiple receiving wells, e.g. for separation, splitting
• CPC Class Codes: B01L 2300/087 Multiple sequential chambers
• CPC Class Codes: B01L 2300/0887 Laminated structure
• CPC Class Codes: B01L 2400/0418 electro-osmotic flow [EOF]
• CPC Class Codes: B01L 2400/0487 fluid pressure, pneumatics
• CPC Class Codes: B01L 2400/0688 surface tension valves, capillary stop, capillary break
• CPC Class Codes: B01L 2400/084 Passive control of flow resistance
• CPC Class Codes: B01L 3/502707 characterised by the manufacture of the container or its components by shaping or joining plastic parts B29C59/00, B29C65/00; by laminating B32B37/00; manufacture of microstructural devices in general B81C
• CPC Class Codes: B01L 3/502738 characterised by integrated valves microvalves F16K99/0001
• CPC Class Codes: F16K 2099/0074 using photolithography, e.g. etching
• CPC Class Codes: F16K 2099/0076 using electrical discharge machining [EDM], milling or drilling
• CPC Class Codes: F16K 2099/008 Multi-layer fabrications
• CPC Class Codes: F16K 99/0001 Microvalves microdevices B81B1/00; manufacture or treatment of devices or systems in or on a substrate B81C1/00; microfluidic structures B01L3/5027; micropumps F04B19/006
• CPC Class Codes: F16K 99/0025 Valves using microporous membranes
• CPC Class Codes: F16K 99/0028 Valves having multiple inlets or outlets
• CPC Class Codes: F16K 99/0036 operated by temperature variations
• CPC Class Codes: F16K 99/0057 the fluid being the circulating fluid itself, e.g. check valves
• CPC Class Codes: Y10T 137/0318 Processes
• CPC Class Codes: Y10T 137/206 : Flow affected by fluid contact, energy field or coanda effect [e.g., pure fluid device or system]
• CPC Class Codes: Y10T 137/2196 : Acoustical or thermal energy
• CPC Class Codes: Y10T 137/2224 : Structure of body of device

Abstract

Microfluidic devices for splitting an established fluidic flow through a microfluidic channel among multiple downstream microfluidic channels include a plurality of elevated flow resistance regions to promote precise and predictable splitting. Each elevated resistance region imparts a flow resistance that is substantially greater than the characteristic resistance to established flow of its associated downstream channel. Elevated flow resistance regions may include one or more porous materials and/or alterations to the channel geometry of at least a portion of a downstream channel.

Claims

1. A device for precisely splitting a first established microfluidic stream into a plurality of microfluidic streams in predictable proportions, the splitting device comprising:

an upstream microfluidic channel containing a first established microfluidic flow;

a plurality of downstream microfluidic channels in fluid communication with the upstream channel, each downstream channel having a characteristic flow resistance; and

a plurality of regions of permanently elevated resistance to established flow, each resistance region being associated with one of said plurality of downstream channels and providing a flow resistance substantially greater than the characteristic resistance to established flow of its associated downstream channel.

2. The device of claim 1 wherein at least one of said plurality of elevated resistance regions provides a flow resistance at least about 2 times greater than the characteristic resistance to established flow of its associated downstream channel.

3. The device of claim 1 wherein at least one of said plurality of elevated resistance regions provides a flow resistance at least about 5 times greater than the characteristic resistance to established flow of its associated downstream channel.

4. The device of claim 1 wherein at least one of said plurality of elevated resistance regions provides a flow resistance at least about 10 times greater than the characteristic resistance to established flow of its associated downstream channel.

5. The device of claim 1 wherein at least one flow resistance region includes a porous material.

6. The device of claim 1 wherein the porous material is selected from the group consisting of:

a sandwiched porous device layer, an interference-fit porous element, an in-plane porous element, a porous polymerized material, a porous sol-gel, and a plurality of beads.

7. The device of claim 1 wherein the device is a multi-layer microfluidic device, the upstream channel being disposed in a first layer and at least one of the plurality of downstream channels being disposed in a second layer.

8. The device of claim 7 wherein the device is fabricated from a plurality of sandwiched stencil layers defining microfluidic channels therein.

9. The device of claim 7 wherein the channels are formed within device layers by micromachining techniques.

10. The device of claim 1 wherein at least one elevated flow resistance region is formed by altering the channel geometry of at least a portion of one channel of the plurality of downstream channels.

11. The device of claim 1 wherein at least one elevated flow resistance region is characterized by a reduced cross-sectional flow area.

12. The device of claim 1 wherein the elevated flow resistance region includes a flow-limiting aperture between the upstream channel and at least one downstream channel.

13. The device of claim 1 wherein at least one elevated flow resistance region includes a capillary.

14. The device of claim 1 wherein at least one elevated flow resistance region includes a collapsed channel section.

16. The method of claim 15 wherein the flow resistance of each downstream channel is elevated by at least about 5 times its characteristic resistance to established flow.

17. The method of claim 15 wherein flow resistance of each downstream channel is elevated by a region characterized by a reduced cross-sectional flow area.

18. The method of claim 15 wherein, following permanent elevation, the flow resistance of each downstream channel is substantially equal.

19. The method of claim 15 wherein, following permanent elevation, the flow resistance of each downstream channel is substantially unequal.

20. The method of claim 15 wherein the flow resistance of at least one downstream channel is elevated using a porous material.

21. The method of claim 15 wherein the flow resistance of at least one downstream channel is elevated by altering the channel geometry of at least a portion of said downstream channel.

22. The method of claim 15 wherein the flow resistance of at least one downstream channel is elevated by collapsing at least a portion of the downstream channel.

23. The method of claim 15 wherein the input channel and at least one downstream channel are provided in different non-adjacent layers of a multi-layer microfluidic device.

24. The method of claim 21 wherein the flow resistance of at least one downstream channel is elevated by providing a flow-limiting aperture between the upstream channel and the at least one downstream channel.

25. The method of claim 23 wherein the upstream channel is defined in a first layer, at least one downstream channel is formed in a second layer, and the flow resistance of said at least one downstream channel is elevated by providing a porous material layer disposed between the first layer and the second layer.

26. The method of claim 15 wherein the upstream channel and at least one downstream channel are disposed in different adjacent layers of a multi-layer microfluidic device, and the flow resistance of the at least one downstream channel is elevated by providing a flow-limiting overlap region between the upstream channel and the at least one downstream channel.

15. A method for precisely splitting an established fluidic flow through a microfluidic channel among a plurality of microfluidic channels, the method comprising the steps of:

providing an upstream channel containing a first flow of fluid;

providing a plurality of downstream channels in fluid communication with the input channel, each downstream channel having a characteristic resistance to established flow; and

permanently elevating the flow resistance of each downstream channel by at least about 2 times its characteristic resistance to established flow.