Method of improving liquid sample flow in assay device

1 . A method of improving flow of a liquid sample in an assay device, the method comprising:

providing a liquid sample addition zone;

providing a reagent zone downstream and in fluid communication with the sample addition zone containing a reagent material;

providing a detection zone in fluid communication with the reagent zone;

providing a wicking zone in fluid communication with the detection zone having a capacity to receive liquid sample flowing from the detection zone, wherein the sample addition zone, the reagent zone, the detection zone and the wicking zone define a fluid flow path;

further providing a reagent addition zone along and in fluid communication with the fluid flow path downstream of the sample addition zone and upstream of the detection zone;

adding a reagent to the reagent addition zone, wherein the reagent flows upstream toward the sample addition zone and downstream toward the wicking zone, wetting the fluid flow path; and

adding a liquid sample to the sample addition zone, wherein the sample moves through the fluid flow path that has been wetted with the reagent, and wherein flow of the sample through the fluid flow path that has been wetted with the reagent is improved over flow of the sample through the fluid flow path when no reagent is used.

2 . The method of claim 1 , wherein the reagent added to the reagent addition zone is a wash reagent.

3 . The method of claim 1 , wherein the liquid sample is whole blood.

4 . The method of claim 1 , further comprising providing at least a portion of the fluid flow path with a plurality of adjacent projections, the plurality of projections having a height, width and distance or distances between the projections such that lateral capillary flow is achieved.

5 . The method of claim 4 , further comprising providing the plurality of projections over the entire fluid flow path.

6 . The method of claim 5 , wherein the flow path is open such that a lid or cover is not required at a capillary distance.

7 . The method of claim 5 , wherein the plurality of projections provide for capillary flow of the applied reagent to flow upstream toward the sample addition zone and downstream toward the wicking zone to wet the fluid flow path.

8 . The method of claim 4 , further comprising giving the plurality of projections a chemical, biological, or physical functionality.

9 . The method of claim 4 , wherein the detection zone includes the plurality of adjacent projections.

10 . The method of claim 9 , further comprising attaching capture elements to the projections in the detection zone.

11 . A method of performing an assay on a liquid sample for the detection of one or more analytes of interest, comprising:

providing a liquid sample addition zone;

providing a reagent zone downstream and in fluid communication with the sample addition zone containing a reagent material;

providing a detection zone in fluid communication with the reagent zone;

providing a wicking zone in fluid communication with the detection zone having a capacity to receive liquid sample flowing from the detection zone, wherein the sample addition zone, the reagent zone, the detection zone and the wicking zone define a fluid flow path;

further providing a reagent addition zone along and in fluid communication with the fluid flow path downstream of the sample addition zone and upstream of the detection zone;

adding a reagent to the reagent addition zone, wherein the reagent flows upstream toward the sample addition zone and downstream toward the wicking zone, wetting the fluid flow path;

adding a liquid sample containing an analyte of interest to the sample addition zone, wherein the sample moves through the fluid flow path that has been wetted with the reagent, and wherein flow of the sample through the fluid flow path that has been wetted with the reagent is improved over flow of the sample through the fluid flow path when no reagent is used;

moving the sample by capillary action into the reagent zone wherein the sample dissolves the reagent material;

flowing the sample away from the reagent zone with the dissolved reagent material therein into the detection zone by capillary action, wherein the analyte of interest is detected in the detection zone by reading a signal that is generated; and

flowing the sample and any unbound material into the wicking zone.

12 . The method of claim 11 , further comprising providing at least a portion of the fluid flow path with a plurality of adjacent projections, the plurality of projections having a height, width and distance or distances between the projections such that lateral capillary flow is achieved.

13 . The method of claim 12 , further comprising providing the plurality of projections over the entire fluid flow path.

14 . The method of claim 13 , wherein the flow path is open such that a lid or cover is not required at a capillary distance.

15 . The method of claim 13 , wherein the plurality of projections provide for capillary flow of the applied reagent to flow upstream toward the sample addition zone and downstream toward the wicking zone to wet the fluid flow path.

16 . The method of claim 13 , further comprising giving the plurality of projections a chemical, biological, or functional functionality.

17 . The method of claim 13 , wherein the detection zone includes the plurality of adjacent projections and including the further step of attaching capture elements to the projections in the detection zone.

18 . The method of claim 11 , wherein the reagent added to the reagent addition zone is a wash reagent.

19 . The method of claim 11 , wherein the liquid sample is whole blood.

20 . The method of claim 11 , wherein a volume of the reagent is less than a volume of the liquid sample.