Microfluidic device and method for focusing, segmenting, and dispensing of a fluid stream

• US 20020008028A1
• Filed: 01/12/2001
• Published: 01/24/2002
• Est. Priority Date: 01/12/2000
• Status: Active Grant

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Ramsey, J. Michael, Jacobson, Stephen C.
• Granted Patent: US 6,790,328 B2
• Time in Patent Office: Days
• US Class Current: 204/451
• CPC Class Codes: B01F 33/30 Micromixers
• CPC Class Codes: B01F 33/3011 using a sheathing stream of a fluid surrounding a central stream of a different fluid, e.g. for reducing the cross-section of the central stream or to produce droplets from the central stream
• CPC Class Codes: B01F 33/3031 using electro-hydrodynamic [EHD] or electro-kinetic [EKI] phenomena to mix or move the fluids
• CPC Class Codes: B01L 2200/0605 Metering of fluids
• CPC Class Codes: B01L 2200/0636 Focussing flows, e.g. to laminate flows
• CPC Class Codes: B01L 2200/0673 Handling of plugs of fluid surrounded by immiscible fluid
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2400/0415 electrical forces, e.g. electrokinetic
• CPC Class Codes: B01L 2400/0487 fluid pressure, pneumatics
• CPC Class Codes: B01L 3/5027 by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip B01L3/5023 takes precedence; micromixers B01F33/30; microreactors for synthesis B01J19/0093; microcapillary devices in general B81B1/00
• CPC Class Codes: B01L 3/502776 specially adapted for focusing or laminating flows
• CPC Class Codes: G01N 27/44791 Microapparatus sample containers with integrated microfluidic structures B01L3/5027

Abstract

A microfluidic device for forming and/or dispensing minute volume segments of a material is described. In accordance with one aspect of the present invention, a microfluidic device and method is provided for spatially confining the material in a focusing element. The device is also capable of segmenting the confined material into minute volume segments, and dispensing a volume segment to a waste or collection channel. The device further includes means for driving the respective streams of sample and focusing fluids through respective channels into a chamber, such that the focusing fluid streams spatially confine the sample material. The device may also include additional means for driving a minute volume segment of the spatially confined sample material into a collection channel in fluid communication with the waste reservoir.

Claims

1. An apparatus for the spatial confinement of a material stream, comprising:

a chamber formed in a surface of a substrate;

a sample channel formed in the surface of the substrate for conducting a sample fluid stream therethrough, said sample channel having a first end in fluid communication with a source of a sample fluid and a second end in fluid communication with said chamber;

a focusing channel formed in the surface of the substrate for conducting a focusing fluid stream therethrough, said focusing channel having a first end in fluid communication with a source of focusing fluid and a second end in fluid communication with said chamber;

a waste channel formed in the surface of the substrate, said waste channel having a first end in fluid communication with said chamber and a second end in fluid communication with a waste reservoir; and

means for driving the respective streams of the sample and focusing fluids through the respective channels into said chamber, whereby the focusing fluid stream spatially confines the sample fluid stream within said chamber.

2. An apparatus as set forth in claim 1 further comprising a buffer channel formed in the surface of the substrate for conducting a buffer fluid stream therethrough, said buffer channel having a first end in fluid communication with a source of a buffer fluid and a second end in fluid communication with said chamber;

and

means for driving the buffer fluid through said buffer channel into said chamber such that the buffer fluid acts on the spatially confined sample fluid stream.

3. An apparatus as set forth in claim 2 further comprising a collection channel formed in the surface of the substrate for conducting a fluid stream therethrough, said collection channel having a first end in fluid communication with said chamber and a second end in fluid communication with a waste reservoir, said collection channel being adapted to conduct the buffer fluid from said buffer channel;

and

means for driving the buffer fluid in said collection channel into said chamber such that the buffer fluid acts on the spatially confined sample fluid stream.

4. An apparatus as set forth in claim 1 wherein said means for driving the streams of the sample and focusing fluids through the respective channels into said chamber comprises electromotive means for providing electrokinetic transport of the sample and focusing fluids through their respective channels.

5. An apparatus as set forth in claim 2 wherein said means for driving the streams of the sample and focusing fluids through the respective channels into said chamber and said means for driving the buffer fluid through said buffer channel into said chamber comprise electromotive means for providing electrokinetic transport of the sample, focusing, and buffer fluids through said sample, focusing, and buffer channels, respectively.

6. An apparatus as set forth in claim 3 wherein said means for driving the streams of the sample and focusing fluids through the respective channels into said chamber, said means for driving the buffer fluid through said buffer channel into said chamber, and said means for driving the buffer fluid and the spatially confined sample fluid stream through said collection channel comprise electromotive means for providing electrokinetic transport of the sample, focusing, buffer, and spatially confined sample fluids through said sample, focusing, buffer, and collection channels, respectively.

7. An apparatus as set forth in claim 1, 2, 3, 4, 5, or 6 further comprising a second focusing channel formed in the surface of the substrate for conducting a second focusing fluid stream therethrough, said second focusing channel having a first end in fluid communication with a source of focusing fluid and a second end in fluid communication with said chamber, said second end of said second focusing channel being positioned and arranged to provide said focusing fluid into said chamber such that the sample fluid can be spatially confined in said chamber;

and means for driving the focusing fluid in said first and second focusing channels such that said sample fluid is spatially confined in said chamber.

8. An apparatus as set forth in claim 7 wherein said means for driving the focusing fluid in said second focusing channel comprises electromotive means for providing electrokinetic transport of the focusing fluid through said second focusing channel.

9. An apparatus as set forth in claim 7 wherein said focusing fluid driving means comprises means for controlling the flow of the focusing fluid in said first and second focusing channels such that the sample fluid is spatially confined substantially along the center axis of said chamber.

10. A method of spatially confining a fluidic material in a channel comprising the steps of:

providing a microfluidic device that includes a body having a first microchannel formed therein, said first microchannel being operatively connected to a source of a first material;

providing a focusing channel in said microfluidic device having one end in fluid communication with a source of a focusing material and a second end in fluid communication with said first channel;

transporting a stream of the first material through said first channel, said stream of first material having a width; and

transporting a stream of the focusing material through said focusing channel into said first channel such that the width of the stream of first material in said first channel is narrowed.

11. A method as set forth in claim 10 further comprising the steps of providing a second microchannel formed in said body such that said second microchannel communicates with said first channel at a first intersection;

and

transporting the narrowed stream of the first material through said second channel.

12. A method as set forth in claim 10 or 11 wherein the step of transporting the stream of the first material through said first channel comprises the step of transporting the first material by electrokinetic transport means;

and

said step of transporting the stream of the focusing material through said focusing channel comprises the step of transporting the focusing material by electrokinetic transport means.

13. A method as set forth in claim 11 wherein the step of transporting the narrowed stream of the first material through said second channel comprises the step of transporting the narrowed stream of the first material by electrokinetic transport means.

14. A method as set forth in claim 10 or 11 further comprising the steps of

providing a second focusing channel in said microfluidic device having one end in fluid communication with a source of a focusing material and a second end in fluid communication with said first channel;

and

transporting a stream of the focusing material through said second focusing channel into said first channel such that the width of the stream of first material in said first channel is narrowed in said first channel.

15. A method as set forth in claim 14 comprising the step of controlling the transport of the focusing material through said focusing channels such that the width of the stream of the first material is narrowed substantially along the center axis of said first channel.

16. A method as set forth in claim 15 wherein said step of transporting the streams of the focusing material through the focusing channels comprises the step of transporting the focusing material by electrokinetic transport means.

17. A method of forming and dispensing minute volume segments of a material in a microfluidic device, said method comprising the steps of:

providing a microfluidic device that includes a body having first, second, third, and fourth microchannels formed therein, said first, second, third, and fourth microchannels communicating at a first intersection and said first microchannel being connected to a source of a first material;

providing a first focusing channel in said body having one end in fluid communication with a source of a focusing material and a second end in fluid communication with said first channel between said source of the first material and the first intersection;

transporting a stream of the first material through said first channel toward second channel, said stream of first material having a width; and

transporting a stream of the focusing material from the first focusing channel into said first channel, such that the width of the stream of first material in said first channel is narrowed.

18. A method as set forth in claim 17 comprising the step of transporting a buffer material in said third and fourth channels such that said buffer material acts on said narrowed stream of the first material.

19. A method as set forth in claim 17 or 18 comprising the step of dispensing a volume segment of the narrowed first material stream into the fourth channel.

20. A method as set forth in claim 19 wherein the step of dispensing the volume segment of the narrowed first material stream into the fourth channel comprises the steps of:

transporting a first buffer fluid through said third channel toward the first intersection;

transporting the volume segment of the narrowed first material stream through the fourth channel; and

reversing the direction of the stream of the first material through said first channel.

21. A method as set forth in claim 17 or 18 further comprising the steps of:

providing a second focusing channel in said body having one end in fluid communication with the focusing fluid and a second end in fluid communication with said first channel between the source of the first material and the first intersection; and

transporting a second stream of the focusing material from the second focusing channel into said first channel such that the width of the stream of the first material in said first channel is narrowed substantially along the center axis of said first channel.

22. A method as set forth in claim 21 comprising the step of dispensing a volume segment of the narrowed first material stream into the fourth channel.

23. A method as set forth in claim 22 wherein the step of dispensing the volume segment of the narrowed first material stream into the fourth channel comprises the steps of:

transporting a first buffer fluid through said third channel toward the first intersection;

transporting the volume segment of the narrowed first material stream through the fourth channel; and

reversing the direction of the stream of the first material through said first channel.

30. An apparatus as set forth in claim 22 wherein the means for dispensing the volume segment of the narrowed first material stream into the fourth channel comprises:

means for transporting a first buffer fluid through said third channel toward the first intersection;

means for transporting the volume segment of the narrowed first material stream through the fourth channel; and

means for reversing the direction of the stream of the first material through said first channel.

24. An apparatus for forming and dispensing minute volume segments of a material in a microfluidic device, the apparatus comprising:

a substrate having first, second, third, and fourth microchannels formed therein, said microchannels communicating at a first intersection and said first microchannel being connected to a source of a first material;

a focusing channel formed in said substrate and having one end in fluid communication with a source of a focusing material and a second end in fluid communication with said first channel between said source of the first material and the first intersection;

means for transporting a stream of the first material through said first and second channels, said stream of first material having a width;

means for transporting a stream of the focusing material into said first channel, whereby the width of the stream of first material in said first channel is narrowed, and

25. An apparatus as set forth in claim 24 further comprising means for transporting a buffer material in said third and fourth channels such that said buffer material acts on said narrowed stream of the first material.

26. An apparatus as set forth in claim 24 or 25 comprising means for dispensing a volume segment of the narrowed first material stream into the fourth channel.

27. An apparatus as set forth in claim 26 wherein the means for dispensing the volume segment of the narrowed first material stream into the fourth channel comprises:

means for transporting a first buffer fluid through said third channel toward the first intersection;

means for transporting the volume segment of the narrowed first material stream through the fourth channel; and

means for reversing the direction of the stream of the first material through said first channel.

28. An apparatus as set forth in claim 24 or 25 further comprising:

a second focusing channel in said body having one end in fluid communication with the focusing fluid and a second end in fluid communication with said first channel between the source of the first material and the first intersection; and

means for transporting a second stream of the focusing material from the second focusing channel into said first channel such that the width of the stream of the first material in said first channel is narrowed substantially along the center axis of said first channel.

29. An apparatus as set forth in claim 28 comprising means for dispensing a volume segment of the narrowed first material stream into the fourth channel.