METHOD AND APPARATUS FOR ENTRY OF SPECIMENS INTO A MICROFLUIDIC DEVICE

• US 20080257754A1
• Filed: 04/14/2008
• Published: 10/23/2008
• Est. Priority Date: 06/27/2003
• Status: Abandoned Application

• Current Assignee: Siemens Healthcare Diagnostics Incorporated (Siemens AG)
• Original Assignee: Siemens Healthcare Diagnostics Incorporated (Siemens AG)
• Inventors: Blankenstein, Gert, Peters, Ralf-Peter, Pugia, Michael J., Profitt, James A.
• Application Number:
  US12/102,631
• Publication Number:
  US 20080257754A1
• Time in Patent Office: Days
• US Class Current: 205/792
• CPC Class Codes: B01L 2200/027 for microfluidic devices
• CPC Class Codes: B01L 2200/0684 Venting, avoiding backpressure, avoid gas bubbles
• CPC Class Codes: B01L 2300/0806 Standardised forms, e.g. compact disc [CD] format
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2400/0406 capillary forces
• CPC Class Codes: B01L 2400/0409 centrifugal forces
• CPC Class Codes: B01L 2400/0478 pistons
• 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 2400/086 using baffles or other fixed flow obstructions
• CPC Class Codes: B01L 3/5025 for parallel transport of multiple samples
• CPC Class Codes: B01L 3/502723 characterised by venting arrangements
• CPC Class Codes: B01L 3/50273 characterised by the means or forces applied to move the fluids micropumps F04B19/006, of the membrane type F04B43/043

Abstract

A microfluidic device for analyzing biological samples is provided with a sample inlet section including an inlet port, a capillary passageway communication with the inlet port and with an inlet chamber. The inlet chamber includes means for uniformly distributing the sample liquid across the inlet chamber and purging the air initially contained therein.

Claims

1. A method of supplying liquid to a microfluidic device having an inlet port in fluid communication with an inlet chamber via a capillary passageway, said method comprising;

(a) introducing a portion of said liquid into said inlet port;

(b) transferring by capillary forces said liquid portion of (a) to said inlet chamber via said capillary passageway;

(c) distributing said liquid portion of (a) uniformly across said inlet chamber and purging substantially all air from said inlet chamber with microstructures disposed in said inlet chamber, said microstructures disposed to reduce the capillary forces moving said liquid portion relative to the capillary forces in said capillary passageway.

2. A method of claim 1 wherein said microstructures are an array of posts having a spacing between said posts equal to or greater than the height of said inlet chamber, whereby the capillary forces moving said liquid portion of (a) produced by the base and top of said inlet chamber are greater than the capillary forces produced by the spacing between said posts.

3. A method of claim 1 wherein said microfluidic structures are one or more grooves or weirs disposed at a right angle to the flow of said liquid portion, said groove(s) or weir(s) having width greater than the height of said inlet chamber, whereby the liquid portion of (a) is moved by capillary forces produced by the base and top of said inlet chamber and said groove(s) spread said liquid portion uniformly across said inlet chamber.

4. A method of claim 3 wherein said groove(s) or weir(s) contain wedge-shaped cutouts to facilitate uniform flow of said liquid portion of (a).

5. A method of claim 2 wherein said posts contain wedge-shaped cutouts to facilitate uniform flow of said liquid portion of (a).

6. A method of claim 1 wherein said inlet port is tapered to engage the corresponding shape of a pipette for depositing said liquid portion of (a).

7. A method of claim 1 wherein excess of said liquid portion of (a) is diverted to an overflow chamber after said inlet chamber is filled.

8. A method of claim 7 wherein the presence of said excess of the liquid portion of (a) is detected by an indicator in said overflow chamber.

9. A method of claim 2 wherein the height of said inlet chamber is smaller than the spacing between said posts.

10. A method of claim 1 wherein positive pressure is applied to said liquid portion of (a) to assist said transfer by capillary forces.

11. A method of claim 1 wherein air is purged from a vent that includes a capillary stop to prevent liquid from exiting through said vent.

12. A method of claim 7 wherein capillary stops are provided to force excess liquid into said overflow chamber.

13. A microfluidic device for assaying a liquid biological sample comprising

(a) an inlet port for receiving said sample;

(b) a capillary passageway in fluid communication with said inlet port for moving said sample by capillary forces;

(c) an inlet chamber in fluid communication with the capillary passageway of (b), said inlet chamber containing microstructures disposed to reduce capillary force moving said sample relative to the capillary forces in said capillary passageway of (b), thereby distributing said sample across said inlet chamber and displacing air from said inlet chamber, and

(d) at least one vent passageway for removing air displaced by said liquid sample.

14. A microfluidic device of claim 13 wherein said microstructures are an array of posts having a spacing between said posts equal to or greater than the height of said inlet chamber, whereby the capillary forces moving said sample produced by the base and top of said inlet chamber are greater than the capillary forces produced by the spacing between said array of posts.

15. A microfluidic device of claim 13 wherein said microfluidic structures are one or more grooves or weirs disposed at a right angle to the flow of said sample, said grooves or weirs having a width greater than the height of said inlet chamber, whereby said sample is moved by capillary forces produced by the base and top of said inlet chamber and said groove(s) spread said sample uniformly across said inlet chamber.

16. A microfluidic device of claim 15 wherein said groove(s) or weir(s) contain wedge-shaped cutouts to facilitate uniform flow of said sample.

17. A microfluidic device of claim 14 wherein said posts contain wedge-shaped cutouts to facilitate uniform flow of said sample.

18. A microfluidic device of claim 13 wherein said inlet port is tapered to engage the corresponding shape of a pipette for depositing said sample.

19. A microfluidic device of claim 13 further comprising an overflow chamber in fluid communication with said inlet chamber to receive liquid in excess of said sample.

20. A microfluidic device of claim 19 wherein said overflow chamber contains an indicator to detect presence of said sample.

21. A microfluidic device of claim 14 wherein the height of said inlet chamber is smaller than the spacing between said posts.

22. A microfluidic device of claim 13 wherein said vent passageway includes a capillary stop to prevent liquid from exiting through said vent.

23. A microfluidic device of claim 19 wherein capillary stops are disposed to force liquid into said overflow chamber.