Microfluidic assay devices

• US 20060137434A1
• Filed: 12/23/2004
• Published: 06/29/2006
• Est. Priority Date: 12/23/2004
• Status: Active Grant

• Current Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Original Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Inventors: Feaster, Shawn Ray, Cohen, David Samuel
• Granted Patent: US 7,682,817 B2
• Time in Patent Office: Days
• US Class Current: 73/61.430
• CPC Class Codes: B01L 2300/069 Absorbents; Gels to retain a fluid
• CPC Class Codes: B01L 2300/0803 Disc shape
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/0864 comprising only one inlet and multiple receiving wells, e.g. for separation, splitting
• CPC Class Codes: B01L 2400/0406 capillary forces
• CPC Class Codes: B01L 3/502746 characterised by the means for controlling flow resistance, e.g. flow controllers, baffles B01L3/502738 takes precedence

Abstract

A microfluidic assay device for determining the presence or absence of an analyte within a fluid test sample is provided. The present invention provides a technique for achieving continuous flow in a microfluidic device by using at least one input channel, an analysis zone, and a plurality of wicking channels disposed about the perimeter of the analysis zone. In one embodiment, for example, the wicking channels extend radially from the analysis zone. As a result of the particular configuration of the microfluidic device, an assay may performed in a “single step” without the need for active forces, such as a pressure source, electrokinetic force, etc., to induce flow of the fluid test sample through the device. Likewise, flow rate is controlled so that the dwell time of the fluid test sample within the analysis zone is long enough to allow for the desired reactions and/or detection.

Claims

1. An assay device for detecting the presence or concentration of an analyte within a fluid test sample, said assay comprising:

an input channel;

an analysis zone in fluid communication with said input channel, said analysis zone defining a periphery, wherein said analysis zone serves as a location for detecting the analyte; and

a plurality of microfluidic wicking channels extending outwardly from the periphery of said analysis zone, wherein the assay device is configured so that the fluid test sample is capable of flowing through said input channel and said analysis zone primarily via capillary action.

2. The assay device of claim 1, wherein said input channel has a cross-sectional area of less than about 20 square millimeters.

3. The assay device of claim 1, wherein said analysis zone is of a size sufficient to accommodate substantially the entire volume of the fluid test sample applied to the assay device.

4. The assay device of claim 1, wherein said analysis zone has a substantially circular shape.

5. The assay device of claim 4, wherein said wicking channels extend radially from the periphery of said analysis zone.

6. The assay device of claim 1, wherein the fluid test sample is capable of flowing sequentially from said input channel to said analysis zone.

7. The assay device of claim 1, wherein said wicking channels taper inwardly toward said analysis zone.

8. The assay device of claim 1, wherein said wicking channels have an aspect ratio of from about 0.1 to about 10.

9. The assay device of claim 1, wherein said wicking channels have an aspect ratio of from about 0.25 to about 5.

10. The assay device of claim 1, wherein said wicking channels have an aspect ratio of from about 0.5 to about 1.5.

11. The assay device of claim 1, wherein said wicking channels have a cross-sectional area of less than about 20 square millimeters.

12. The assay device of claim 1, wherein said wicking channels have a cross-sectional area of from about 0.001 to about 10 square millimeters.

13. The assay device of claim 1, wherein said wicking channels have a cross-sectional area of from about 0.01 to about 5 square millimeters.

14. The assay device of claim 1, wherein the assay device comprises from about 3 to about 500 of said wicking channels.

15. The assay device of claim 1, wherein the assay device comprises from about 15 to about 200 of said wicking channels.

16. The assay device of claim 1, further comprising an overflow zone that is in fluid communication with said wicking channels.

17. The assay device of claim 1, further comprising a substrate on or within which said input channel, said analysis zone, and said wicking channels are disposed.

18. The assay device of claim 17, wherein a separation medium is laminated to said substrate, said separation medium containing a receptive material that is capable of binding to the analyte or a complex thereof.

19. The assay device of claim 18, wherein said separation medium includes a polymer film having a metal coating.

20. An assay device for detecting the presence or concentration of an analyte within a fluid test sample, said assay comprising:

an input channel;

a substantially circular analysis zone in fluid communication with said input channel, said analysis zone defining a periphery, wherein said analysis zone serves as a location for detecting the analyte;

a plurality of wicking channels extending radially from the periphery of said analysis zone, wherein said wicking channels have an aspect ratio of from about 0.1 to about 10 and a cross-sectional area of less than about 20 square millimeters; and

an overflow zone that is in fluid communication with said plurality of wicking channels, wherein the assay device is configured so that the fluid test sample is capable of flowing through said input channel and said analysis zone primarily via capillary action.

21. A method for performing an assay, said method comprising:

introducing into an input channel a fluid test sample suspected of containing an analyte;

allowing the fluid test sample to flow via capillary action from said input channel to an analysis zone that defines a periphery;

detecting the presence or absence of the analyte; and

drawing the fluid test sample from the analysis zone using a plurality of microfluidic wicking channels, said wicking channels extending outwardly from the periphery of said analysis zone.

22. The method of claim 21, wherein the fluid is applied to a sample well that is in fluid communication with said input channel, the fluid flowing from said sample well to said input channel via capillary action.

23. The method of claim 21, wherein said analysis zone has a substantially circular shape.

24. The method of claim 21, wherein said wicking channels extend radially from the periphery of said analysis zone.

25. The method of claim 21, wherein said wicking channels have an aspect ratio of from about 0.1 to about 10.

26. The method of claim 21, wherein said wicking channels have an aspect ratio of from about 0.5 to about 1.5.

27. The method of claim 21, wherein said wicking channels have a cross-sectional area of less than about 20 square millimeters.

28. The method of claim 21, wherein said wicking channels have a cross-sectional area of from about 0.01 to about 5 square millimeters.

29. The method of claim 21, wherein the fluid test sample flows through said wicking channels into an overflow zone.