Reagent zone deposition pattern

1. An assay device comprising:

a liquid sample zone;

a reagent zone downstream and in fluid communication with the sample zone comprising a reagent cell having a line of symmetry in the direction of fluid flow;

a reagent material in the reagent cell, wherein the reagent material includes a first reagent material located at the axis of symmetry and is left-right symmetric, and a second and third reagent material having a substantially identical shape and volume and located in mirror locations from the line of symmetry;

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

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

2. An assay device as claimed in claim 1 , wherein the first reagent material has a shape and volume such that it is the last reagent material to be completely dissolved by the fluid flow.

3. An assay device as claimed in claim 2 , wherein the first reagent material has a larger shape and volume than the second and third reagent materials such that it is the last reagent material to be completely dissolved by the fluid flow.

4. An assay device as claimed in claim 1 , wherein the first reagent material is located upstream from the second and third reagent material.

5. An assay device as claimed in claim 1 , wherein the first reagent material is located downstream from the second and third reagent material.

6. An assay device as claimed in claim 1 , wherein the reagent zone has a single reagent cell.

7. An assay device as claimed in claim 1 , wherein the reagent zone has at least two reagent cells arranged symmetrically in the reagent zone.

8. An assay device as claimed in claim 1 , wherein the detection zone has a substrate and projections which extend substantially vertically from the substrate, wherein the projections have a height, cross-section and a distance between one another that defines a capillary space between the projections capable of generating capillary flow parallel to the substrate surface.

9. An assay device as claimed in claim 1 , wherein the reagent material comprises a labeled reagent material, and the detection zone has capture elements bound thereto.

10. An assay device as claimed in claim 1 , wherein the width of the fluid flow path through the detection zones is in the range of about 0.5 to 1.2 mm.

11. An assay device as claimed in claim 1 , wherein at least one of the first, second and third reagent materials has the same composition.

12. An assay device as claimed in claim 1 , wherein at least one of the first, second and third reagent materials has a different composition.

13. An assay device as claimed in claim 12 , wherein the first reagent material has a first composition and the second and third reagent materials have a different, second composition.

14. A method of performing an assay on a liquid sample for the presence or concentration of one or more analyte(s) of the liquid sample or control(s) on the assay device according to claim 1 , comprising:

depositing a liquid sample containing the analyte(s) of interest onto a sample addition zone of the assay device;

moving the sample by capillary action through a fluid flow path into a reagent zone of the assay device where the sample dissolves one or more reagents;

flowing the sample away from the reagent zone having a dissolved reagent plume containing one or more reagents and into detection zone(s) of the assay device by capillary action through the fluid flow path, wherein signal(s) representative of the presence or concentration of analyte(s) of the sample or control(s) of the assay device is produced; and

reading the signal(s) that are produced in the detection zone(s) to determine the presence or concentration of the analyte(s) of the sample or control(s) of the assay device.