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

• US 7,422,669 B2
• Filed: 01/16/2004
• Issued: 09/09/2008
• Est. Priority Date: 01/12/2000
• Status: Expired due to Term

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Ramsey, J. Michael, Jacobson, Stephen C.
• Primary Examiner(s): NOGUEROLA, ALEXANDER STEPHAN
• Application Number:
  US10/758,718
• Publication Number:
  US 20040144648A1
• Time in Patent Office: 1,698 Days
• Field of Search: 204600-605, 204450-455, 422/99, 422/100
• 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 and method for forming and dispensing minute volume segments of a material are described. In accordance with the present invention, a microfluidic device and method are provided for spatially confining the material in a focusing element. The device is also adapted for 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. 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 the first intersection, said stream of first material having a width;

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; and

dispensing a volume segment of the narrowed first material stream into the fourth channel.

2. A method as set forth in claim 1 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.

3. A method as set forth in claim 1 or 2 further comprising the steps of:

providing a second focusing channel in said body having one end in fluid communication with a source of focusing material 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.

4. A method as set forth in claim 3 wherein the step of dispensing the volume segment of the narrowed first material stream into the fourth channel comprises the steps of:

transporting buffer material through said third channel toward the first intersection; and

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

5. A method as set forth in claim 4 which further comprises the step of reversing the direction of the transporting of the stream of the first material in the first channel.

6. A method as set forth in claim 3 wherein the step of transporting the second stream of the focusing material comprises transporting the second stream of the focusing material from the focusing channel into the first channel such that the width of the stream of the first material in the first channel is narrowed substantially along the center axis of the first channel.

7. A method as set forth in claim 2 wherein the step of transporting the buffer material in the third and fourth channels comprises the step of controlling the flow of the buffer material in the third and fourth channels such that the buffer material expands, maintains, or further confines the stream of first material.

8. A method as set forth in claim 1 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 material through said third channel toward the first intersection; and

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

9. A method as set forth in claim 8 which further comprises the step of reversing the direction of the transporting of the stream of the first material in the first channel.

10. 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 channel toward said first intersection, 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

means for dispensing a volume segment of the narrowed first material stream into the fourth channel.

11. An apparatus as set forth in claim 10 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.

12. An apparatus as set forth in claim 10 or 11 further comprising:

a second focusing channel in said body having one end in fluid communication with a source of focusing material 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.

13. An apparatus as set forth in claim 12 wherein the means for transporting the stream of the first material, the means for transporting the stream of focusing material, the means for transporting the buffer material, and the means for transporting the second stream of focusing material comprise a means selected from the group consisting of electrokinetic means for effecting the transporting of the respective materials, pressure driven means for effecting the transporting of the respective materials, and a combination thereof.

14. An apparatus as set forth in claim 12 wherein the means for transporting the second stream of the focusing material comprises means for transporting the second stream of the focusing material from the focusing channel into the first channel such that the width of the stream of the first material in the first channel is narrowed substantially along the center axis of the first channel.

15. An apparatus as set forth in claim 11 wherein the means for transporting the stream of the first material, the means for transporting the stream of the focusing material, and the means for transporting the buffer material comprise a means selected from the group consisting of electrokinetic means for effecting the transporting of the respective materials, pressure-driven means for effecting the transporting of the respective materials, and a combination thereof.

16. An apparatus as set forth in claim 10 wherein the means for dispensing the volume segment of the narrowed first material stream into the fourth channel comprises:

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

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

17. An apparatus as set forth in claim 16 wherein the means for transporting the stream of the first material, the means for transporting the stream of focusing material, the means for transporting the buffer material, and the means for transporting the volume segment of the narrowed first material comprise a means selected from the group consisting of electrokinetic means for effecting the transporting of the respective materials, pressure driven means for effecting the transporting of the respective materials, and a combination thereof.

18. An apparatus as set forth in claim 16 which further comprises means for reversing the direction of the transporting of the stream of the first material in the first channel.

19. An apparatus as set forth in claim 10 wherein the means for transporting the stream of the first material and the means for transporting the stream of the focusing material comprise a means selected from the group consisting of electrokinetic means for effecting the transporting of the respective materials, pressure-driven means for effecting the transporting of the respective materials, and a combination thereof.