Apparatus and method for separating cells from biological fluids

• US 5,061,381 A
• Filed: 06/04/1990
• Issued: 10/29/1991
• Est. Priority Date: 06/04/1990
• Status: Expired due to Term

• Current Assignee: Abaxis Incorporated (Zoetis Incorporated)
• Original Assignee: Abaxis Incorporated (Zoetis Incorporated)
• Inventors: Burd, Tammy L.
• Primary Examiner(s): Jones, W. Gary
• Application Number:
  US07/532,524
• Time in Patent Office: 512 Days
• Field of Search: 210/94, 210/95, 210/380.1, 210/514, 210/515, 210/518, 210/782, 210/787, 210/789, 210/198.1, 210/512.1, 210/532.1, 422/64, 422/72, 422/101, 422/102, 494/16, 494/27, 494/29, 494/37, 494/43, 494/17, 436/45, 436/63, 436/177, 436/180
• US Class Current: 210/789
• CPC Class Codes: B01L 2400/0406 capillary forces
• CPC Class Codes: G01N 2035/00237 Handling microquantities of analyte, e.g. microvalves, capillary networks
• CPC Class Codes: G01N 21/07 Centrifugal type cuvettes G01N21/09 takes precedence
• 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
• CPC Class Codes: Y10T 436/25375 Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.]
• CPC Class Codes: Y10T 436/2575 Volumetric liquid transfer

Abstract

A centrifugal rotor for separating plasma from whole blood includes a plurality of internal chambers and passages for combining the plasma with one or more reagents and distributing the plasma to a plurality of individual test wells. The chambers and passages necessary for separating the whole blood into plasma are located on a first, upper level within the rotor and include a measuring chamber, an overflow chamber, a separation chamber, and a reagent chamber. The measuring chamber and overflow chamber have capillary dimensions so that an initial volume of whole blood partitions therebetween, with the measuring chamber filling first to provide a preselected volume. The separation chamber is located radially outward from both the measuring chamber and the reagent chamber to that spinning of the rotor causes both the reagent and the measured blood volume to flow outward into the separation chamber. The separation chamber includes a radially-outward cell trap and a radially-inward drainage port so that spinning of the rotor causes the cellular components of the whole blood to enter the cell trap, while cessation of spinning allows the separated plasma to flow downward through the drainage port. A collection chamber is formed at a lower level than the rotor to receive the plasma through the drainage port. Further spinning of the rotor causes the plasma to flow radially outward into a plurality of test wells formed around the periphery of the collection chamber. Testing of the separated plasma volumes may be performed without removing the plasma from the rotor.

Claims

1. A centrifugal rotor having a separation chamber and means for introducing a fluid including cellular material and a liquid phase to said chamber, wherein the separation chamber includes a receptacle region, a cell trap spaced radially outward from the receptacle region, and a capillary region between the receptacle region and the cell trap, whereby cellular material will separate from the liquid phase in the receptacle and will flow through the capillary region into the cell trap as the rotor is spun, wherein the capillarity of the capillary region is broken at the boundaries with the receptacle region and the cell trap to inhibit back flow of the cellular material into the receptacle after spinning of the rotor ceases.

2. A centrifugal rotor as in claim 1, wherein the capillary region is an annular space having inner and outer arcuate boundaries formed between opposed surfaces.

3. A centrifugal rotor as in claim 2, wherein the cell trap is an annular well contiguous with the outer arcuate boundary of the annular space of the capillary region.

4. A centrifugal rotor as in claim 2, wherein the receptacle region is a tapered compartment having a narrow aperture which is contiguous with the inner arcuate boundary of the annular space of the capillary region.

5. A blood separator comprising:

a rotor having top and bottom surfaces and a central axis;

an application well formed through the top surface of the rotor;

a metering chamber disposed within the rotor and connected to the application well;

a separation chamber disposed within the rotor and connected to the metering chamber, said separation chamber having an axial drainage port and a cell trap wherein the separation chamber is spaced radially outward from the metering chamber and the cell trap is spaced radially outward from the drainage port; and

a collection chamber disposed within the rotor below the drainage port.

6. A blood separator as in claim 5, wherein the rotor is a disk having means for mounting on a driver.

7. A blood separator as in claim 5, further comprising an overflow chamber which is connected to the application well.

8. A blood separator as in claim 7, wherein the flow rate into the overflow chamber is restricted relative to the flow rate into the metering chamber so that the metering chamber will preferentially fill with blood.

9. A blood separator as in claim 5, wherein the cell trap is divided from the remainder of the separation chamber by a capillary barrier which prevents backflow of cells from the cell trap.

10. A blood separator as in claim 5, wherein the collection chamber is a capillary volume.

11. A blood separator as in claim 5, wherein the collection chamber has dimensions larger than a capillary volume.

12. A blood separator comprising:

a rotor having top and bottom surfaces and a central axis;

an application well formed through the top surface of the rotor;

a metering chamber disposed within the rotor and connected to the application well;

a separation chamber disposed within the rotor and connected to the metering chamber, said separation chamber having an axial drainage port and a cell trap wherein the separation chamber is spaced radially outward from the metering chamber and the cell trap is spaced radially outward from the drainage port;

a collection chamber disposed within the rotor below the drainage port; and

a reagent chamber disposed within the rotor and connected to the separation chamber, wherein the reagent chamber is spaced radially inward from the separation chamber.

13. A blood separator comprising:

a rotor having top and bottom surfaces and a central axis;

an application well formed through the top surface of the rotor;

a metering chamber disposed within the rotor and connected to the application well;

a separation chamber disposed within the rotor and connected to the metering chamber, said separation chamber having an axial drainage port and a cell trap wherein the separation chamber is spaced radially outward from the metering chamber and the cell trap is spaced radially outward from the drainage port; and

a collection chamber disposed within the rotor below the drainage port wherein the collection chamber includes a plurality of examination wells about its periphery.

14. A blood separator and plasma distribution device, said device comprising:

a rotor having top and bottom surfaces and a central axis;

an application well formed through the top surface of the rotor;

means disposed at a first level within the rotor for receiving blood from the application well and separating the blood into plasma and cellular components in response to rotation of the rotor, said receiving and separating means including a drainage port opening downward through the bottom of the first level which allows only the plasma to flow downward when rotation is stopped; and

a collection chamber disposed at a second level within the rotor beneath the drainage port and including a plurality of examination wells about its periphery whereby further rotation of the rotor causes plasma to flow radially outward into said wells.

15. A blood separator and plasma distribution device as in claim 14, wherein the means for separating blood comprises:

a metering chamber disposed within the rotor;

a separation chamber disposed within the rotor and connected to the metering chamber, said separation chamber including the axial drainage port and a cell trap wherein the separation chamber is spaced radially outward from the metering chamber and the cell trap is spaced radially outward from the drainage port.

16. A blood separator and plasma distribution device as in claim 15, wherein the rotor is a disk having means for mounting on a driver.

17. A blood separator and plasma distribution device as in claim 15, further comprising an overflow chamber and an application well formed through the top surface, wherein the application well is connected to both the metering chamber and the overflow chamber.

18. A blood separator and plasma distribution device as in claim 17, wherein the flow rate into the overflow chamber is restricted relative to the flow rate from the application well into the metering chamber so that the metering chamber will preferentially fill with blood.

19. A blood separator and plasma distribution device as in claim 15, wherein the cell trap is divided from the remainder of the separation chamber by a capillary barrier which prevents backflow of cells from the cell trap.

20. A blood separator and plasma distribution device as in claim 15, wherein the collection chamber is a capillary volume.

21. A blood separator and plasma distribution device as in claim 15, wherein the collection chamber has dimensions larger than a capillary volume.

22. A blood separator as in claim 15, further comprising a reagent chamber disposed within the rotor and connected to the separation chamber, wherein the reagent chamber is spaced radially inward from the metering chamber.

23. A blood separator as in claim 14, further comprising means disposed at a first level within the rotor for combining a reagent with the separated plasma in response to rotation of the rotor.

24. A method for separating cells from a biological fluid, said method comprising the following steps:

(a) partitioning the biological fluid between a measuring chamber and an overflow chamber on a rotor;

(b) rotating the rotor to cause the fluid in the measuring chamber to flow radially outward into a separation chamber where cellular components separate into a cell trap leaving separated fluid in the separation chamber; and

(c) stopping rotation of the rotor to allow separated fluid in the separation chamber to flow ;

downward by gravity into a collection chamber.

25. A method as in claim 24, wherein rotation of the rotor in step (b) further causes a reagent in a reagent chamber to flow radially outward into the separation chamber, whereby the reagent combines with the separated fluid.

26. A method as in claim 24, further comprising step (d) including rotating the rotor to cause the separated fluid in the collection chamber to flow radially outward into a plurality of test wells.

27. A method as in claim 26, further comprising step (e) including examining the fluid present in the test wells.

28. A method as in claim 24, wherein step (a) takes place while the rotor is substantially stationary.

29. A method as in claim 28, wherein step (a) includes introducing the biological fluid to an open well intermediate the measuring chamber and the overflow chamber, wherein partitioning takes place by capillary action.