Method and apparatus for separation of particles in a microfluidic device

• US 20040121449A1
• Filed: 12/19/2002
• Published: 06/24/2004
• Est. Priority Date: 12/19/2002
• Status: Active Grant

• Current Assignee: Siemens Healthcare Diagnostics Incorporated (Siemens AG)
• Original Assignee: Bayer Corporation (Bayer AG)
• Inventors: Blankenstein, Gert, Peters, Ralf-Peter, Pugia, Michael J., Profitt, James A., Schulman, Lloyd
• Granted Patent: US 7,094,354 B2
• Time in Patent Office: Days
• US Class Current: 435/287.1
• CPC Class Codes: B01D 21/262 by using a centrifuge
• CPC Class Codes: B01D 2221/10 Separation devices for use in medical, pharmaceutical or laboratory applications, e.g. separating amalgam from dental treatment residues
• CPC Class Codes: B01L 2200/0668 Trapping microscopic beads
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/161 Control and use of surface tension forces, e.g. hydrophobic, hydrophilic
• CPC Class Codes: B01L 2400/0406 capillary forces
• CPC Class Codes: B01L 2400/0409 centrifugal forces
• CPC Class Codes: B01L 2400/0688 surface tension valves, capillary stop, capillary break
• CPC Class Codes: B01L 2400/088 by specific surface properties
• CPC Class Codes: B01L 3/502723 characterised by venting arrangements
• CPC Class Codes: B01L 3/502753 characterised by bulk separation arrangements on lab-on-a-chip devices, e.g. for filtration or centrifugation separation in general B01D; microapparatus for analysis using electrophoresis G01N27/44791; sample preparation G01N1/28
• CPC Class Codes: G01N 33/491 by separating the blood components G01N15/05 takes precedence
• CPC Class Codes: Y10T 436/111666 Utilizing a centrifuge or compartmented rotor

Abstract

A microfluidic device provides separation of particles in a liquid sample, particularly, separation of a sample of whole blood into its components for further analysis. Separation into red blood cells and plasma occurs within a few seconds after the blood sample has been transferred into a separation chamber with the application of centrifugal force of less than one up to about five times gravity. With the application of greater force measurement of hematocrit is possible.

Claims

1. A microfluidic device for separating a mixture of a liquid and particles comprising:

(a) an entry port for receiving a sample of said mixture of a liquid and particles;

(b) a capillary passageway in fluid communication with said entry port, optionally containing a hydrophobic or hydrophilic stop.

(c) a separation chamber in fluid communication with said capillary passageway of (b), said separation chamber comprising

(1) a volume for receiving at least a portion of said sample;

(2) a depth to particle diameter ratio of about 5/1 to 100/1; and

(3) a wall surface having a surface energy equal to or less than the surface energy of said particles to facilitate separation of said sample;

(d) a vent for removing air from the entry port of (a) and the separation chamber of (c) displaced by said sample.

2. A microfluidic device of claim 1 further comprising an outlet capillary in fluid communication with said separation chamber and disposed to receive said liquid separated from said particles.

3. A microfluidic device of claim 1 wherein said surface energy corresponds to a contact angle of 20-80°

relative to water.

4. A microfluidic device of claim 1 wherein said separation chamber includes a lower section having increased depth to accommodate separated particles.

5. A microfluidic device of claim 1 wherein said separation chamber has length:

width;

depth ratios of about 6;

1;

0.5.

23. A method of separating samples of whole blood comprising:

(a) introducing a sample of whole blood into the entry port of the microfluidic device of claim 1;

(b) rotating said microfluidic device at a predetermined speed with said separation chamber positioned radially outward of the center of rotation relative to said entry port to transfer the blood sample into the separation chamber and to separate said blood sample into red blood cells and plasma.

24. A method of claim 23 wherein said blood separation takes place in about 1 to 10 seconds with an centrifugal force of less than one to about 5 times gravity.

25. A method of claim 23 wherein said blood separation takes place within about 2 minutes with a centrifugal force of about 35 to 350 times gravity, thereby enabling hematocrit to be measured.

6. A microfluidic device for separating whole blood into red blood cells and plasma comprising:

(a) an entry port for receiving a sample of whole blood;

(b) a capillary passageway in fluid communication with said entry port, said passageway optionally containing a hydrophobic or hydrophilic stop;

(c) a separation chamber in fluid communication with said capillary passageway of (b), said separation chamber comprising;

(1) a volume for receiving at least a portion of said sample,

(2) a depth to red blood cell diameter ratio of about 5/1 to 100/1; and

(3) a wall surface having a contact angle relative to water of about 20°

to 80°

to facilitate separation of said sample

(d) a vent for removing air from the entry port of (a), and the separation chamber of (c) displaced by said sample.

7. A microfluidic device of claim 6 further comprising an outlet capillary in fluid communication with said separation chamber and disposed to receive plasma separated from said whole blood.

8. A microfluidic device of claim 6 wherein said separation chamber has a volume of about 0.2 to 10 μ

L.

9. A microfluidic device of claim 8 wherein said volume is about 0.3 to 2 μ

L.

10. A microfluidic device of claim 6 wherein said separation chamber has a length:

width;

depth ratio of about 6;

1;

0.5.

11. A microfluidic device of claim 10 wherein the separation chamber has a greater depth at the end furthest from the center of rotation to provide additional volume for separated red blood cells.

12. A microfluidic device of claim 7 further comprising wells in fluid communication with said outlet capillary for receiving plasma separated from said whole blood.

13. a microfluidic device of claim 12 wherein said wells in communication with said outlet capillary of (d) contain reagents for interaction with said plasma.

14. A microfluidic device of claim 13 wherein said reagents precondition said plasma for subsequent reaction to detect presence of an analyte.

15. A microfluidic device of claim 13 wherein said reagents interact with said plasma to detect presence of an analyte.

16. A microfluidic device of claim 7 wherein said outlet capillary has a smaller cross-sectional area than said separation chamber such that said plasma is prevented from entering said capillary until centrifugal force is applied.

17. A microfluidic device of claim 7 wherein a blood sample is separated within 1 to 10 seconds when subjected to a force of less than 1 to about 5 times gravity.

18. A microfluidic device for measuring hematocrit of whole blood samples comprising:

(a) an entry port for receiving a sample of whole blood;

(b) a capillary passageway in fluid communication with said entry port, said passageway containing a hydrophobic or hydrophilic stop;

(c) a separation chamber in fluid communication with said capillary passageway of (b), said separation chamber comprising;

(1) a volume for receiving at least a portion of said sample,

(2) depth to red blood cell diameter ratio of about 5/1 to 100/1; and

(3) a wall surface having a contact angle relative to water of about 20°

to 80°

to facilitate separation of said sample;

(d) a vent from the entry port of (a) and the separation chamber of (c) for removing air displaced by said sample.

19. A microfluidic device of claim 18 wherein said separation chamber has a volume of about 0.2 to 10 μ

L.

20. A microfluidic device of claim 19 wherein said separation chamber has a volume of about 0.3 to 2 μ

L

21. A microfluidic device of claim 18 wherein said separation chamber has length:

width;

depth ratios of about 6;

1;

0.5.

22. A microfluidic device of claim 18 wherein a blood sample is separated within 2 minutes when subjected to a force of 35 to 350 times gravity.