Assay device for liquid sample

• US 20060029924A1
• Filed: 06/26/2003
• Published: 02/09/2006
• Est. Priority Date: 06/27/2002
• Status: Active Grant

• Current Assignee: Alere Switzerland GmbH (Abbott Laboratories)
• Original Assignee: Inverness Medical Switzerland GmbH (Abbott Laboratories)
• Inventors: Brewster, Barry Sinclair, Davies, Robert John, Leslie, Adrian
• Granted Patent: US 8,454,903 B2
• Time in Patent Office: Days
• US Class Current: 435/4
• CPC Class Codes: G01N 33/54306 Solid-phase reaction mechanisms
• CPC Class Codes: G01N 33/54386 Analytical elements
• CPC Class Codes: G01N 33/54388 based on lateral flow
• CPC Class Codes: G01N 33/558 using diffusion or migration of antigen or antibody immunochromatographic test strips G01N33/54387

Abstract

Disclosed is an assay device comprising liquid transport means adapted to take up a liquid sample and conduct the liquid to an analyte detection region operable to provide a test signal indicative of the presence and/or amount of an analyte in the liquid sample; the assay device further comprising a sample presence signal generation means, which is not generated by means of an immunoreaction. This sample presence signal generation means can comprise a coloured portion, which is overlaid by a material (e.g. nitrocellulose) that is opaque, when dry, and translucent or transparent, when wet, to allow the coloured portion to become visible to the user. In another embodiment the signal generation means comprises a colour changing material which under-goes a change in its visible properties upon wetting (eg. pH indication). A third embodiment uses a mobilisable detectable which, when wetted by the sample, is carried along resulting in a streaked line parallel with the flow direction.

Claims

1. An assay device comprising liquid transport means adapted to take up a liquid sample and conduct the liquid to an analyte detection region operable to provide a test signal indicative of the presence and/or amount of an analyte in the liquid sample;

characterised in that the assay device further comprises a sample presence signal generation means.

2. The assay device of claim 1 characterised in that the sample presence signal generation means generates a sample presence signal in the analyte detection region.

3. The assay device of claim 1 wherein the sample presence signal generation means generates a sample presence signal which interacts with the test signal in the presence of analyte to form an interactive symbol representative of a positive result.

4. The assay device of claim 1 wherein the sample presence signal is generated by the transition of an overlay from an opaque state to a transparent or translucent state.

5. The assay device of claim 1 wherein the sample presence signal is in the form of a line oriented substantially parallel with the direction of flow of the liquid sample.

6. The assay device of claim 5 wherein the test signal is a line oriented substantially perpendicular to the sample presence line such that the test signal intersects the sample presence signal.

7. The assay of device of claim 5 wherein the test signal line has a uniform color intensity along its length.

8. The assay device of claim 1 further comprising a casing, the casing having a window therein through which the test signal and sample presence signal are viewable when formed.

9. The assay device of claim 1 further comprising a control signal generation means downstream of the analyte detection region adapted to generate a control signal indicative that one or more reagents present in the assay device are functioning.

10. The assay device of claim 1, further comprising a surface visible to the user, wherein the sample presence signal generation means comprises a coloured portion which is not on the surface visible to the user and which is overlaid by a material which, when dry, is substantially opaque and which initially obscures at least a part of the coloured portion but which, when wet, becomes sufficiently translucent or transparent to allow at least the initially obscured part of the coloured portion to become visible to the user.

11. The assay device of claim 10 wherein the coloured portion is a surface of a protruberance from a casing provided around the liquid transport means.

12. The assay device of claim 10 wherein the liquid transport means comprises a liquid transporting strip functioning as the material which, when dry, is substantially opaque but which, when wet, becomes substantially transparent.

13. The assay device of claim 12, wherein the liquid transporting strip comprises a porous carrier.

14. The assay device of claim 13 wherein the liquid transporting strip comprises a nitrocellulose strip.

15. The assay device of claim 12, wherein the coloured portion comprises part of the liquid transporting strip means.

16. The assay device of claim 12, wherein the coloured portion comprises a sheet applied to the liquid transporting strip means.

17. The assay device of claim 10, wherein the coloured portion presses against the liquid transporting strip.

18. The assay device of claim 1, wherein the sample presence signal generation means comprises a mobilisable detectable material localised on or in the liquid transport means, and which, when wetted by the liquid sample, is carried by it along the liquid transport means resulting in a streaked line substantially parallel with the sample flow direction.

19. The assay device of claim 18 wherein the detectable material is a coloured dye.

20. The assay device of claim 1, wherein the sample presence signal generation means comprises a colour changing material immobilised thereon and which undergoes a change in its visible properties upon wetting.

21. The assay device of claim 20 wherein the colour changing material changes colour in response to wetting by a liquid sample having a specific property to which the colour change material is responsive

22. The assay device of claim 20 wherein the colour changing material is a pH indicator.

23. A method of performing an assay comprising the steps of:

contacting an assay device according to claim 1 with a liquid sample and, if the sample presence signal is generated, determining whether the test result is positive or negative by reference to the presence or absence of the test signal.

24. The assay device of claim 12, wherein the sample presence signal is generated by a line that is printed or deposited on the side of the liquid transporting strip that is not presented to the user using an ink which does not penetrate through the strip.

25. The assay device of claim 24, wherein the liquid transporting strip comprises nitrocellulose, and the line is printed on the strip.

26. The assay device of claim 12, further comprising a layer of mylar or plastic affixed and/or in direct contact with the liquid transporting strip and positioned on the side of the liquid transporting strip that is not presented to the user, and wherein the coloured portion is part of the layer of mylar or plastic.