Fluid delivery system and method

1. A method comprising:

providing a first and a second fluid maintained separately from each other by a third fluid in a common, sealed vessel, wherein the third fluid is adjacent to and substantially immiscible with the first and second fluids;

unsealing the vessel;

transferring the first, third and second fluids in series from the vessel to a reaction site; and

avoiding substantial contact between the first and second fluids, at least until after the fluids have been applied to the reaction site.

2. A method comprising:

unsealing a sealed vessel containing a first and a second fluid maintained separately from each other by a third fluid adjacent to and substantially immiscible with the first and second fluids;

applying in series the first, third, and second fluids to a reaction site, wherein the vessel and the reaction site are formed in a microfluidic chip; and

avoiding substantial contact between the first and second fluids, at least until after the fluids have been applied to the reaction site.

3. A method comprising:

unsealing a sealed vessel containing a first and a second fluid maintained separately from each other by a third fluid adjacent to and substantially immiscible with the first and second fluids;

applying in series the first, third, and second fluids to a reaction site, wherein the vessel and the reaction site are integrally connected to one another; and

avoiding substantial contact between the first and second fluids, at least until after the fluids have been applied to the reaction site.

4. The method of claim 1 further comprising connecting the vessel to a device comprising the reaction site.

5. The method of claim 1 wherein the vessel and reaction site are on a common platform.

6. The method of claim 1 wherein the vessel and reaction site are integrally connected during storage of the first, second and third fluids in the vessel.

7. The method of claim 1 wherein the vessel comprises a tube.

8. The method of claim 1 further comprising applying a pressure differential across the reaction site.

9. The method of claim 8 wherein the pressure differential is provided by suction on a downstream side of the reaction site.

10. The method of claim 8 wherein the pressure differential is provided by a pump on an upstream side of the reaction site.

11. The method of claim 1 wherein the first and second fluids are transferred in series to the reaction site without actuating a valve.

12. The method of claim 1 wherein the first and second fluids are transferred in series to the reaction site without actuation of any device that controls the rate, the order, or timing of introduction of either of the first and second fluids, relative to each other, to the reaction site.

13. The method of claim 4 wherein the device is a microfluidic device.

14. The method of claim 1 wherein at least one of an antibody or an antigen is associated with the reaction site.

15. The method of claim 1 wherein the third fluid is a gas or a gaseous mixture.

16. The method of claim 1 wherein the first fluid and/or second fluid is a rinse solution.

17. The method of claim 4 further comprising disposing a sample in the device prior to applying the first and second fluids to the reaction site.

18. The method of claim 1 wherein the vessel contains a fourth fluid, the method further comprising combining the fourth fluid and the second fluid while transferring the first, third, and second fluids from the vessel to the reaction site.

19. The method of claim 1 wherein the vessel has a length to inner diameter ratio of at least 10:1.

20. The method of claim 1 wherein the vessel has an inner diameter of less than 1 millimeter.

21. The method of claim 1 wherein the vessel has an inner diameter of less than 500 microns.

22. The method of claim 1 wherein one of the fluids comprises a gold conjugated antibody.

23. The method of claim 1 wherein one of the fluids comprises a metal precursor.

24. The method of claim 23 further comprising electrolessly depositing metal at the reaction site to produce an opaque material.

25. The method of claim 24 further comprising determining light absorbance or transmission through the opaque material.

26. The method of claim 1 , wherein the first and second fluids are maintained separately from each other by the third fluid in the common, sealed vessel for greater than one hour.

27. The method of claim 2 wherein at least one of an antibody or an antigen is associated with the reaction site.

28. The method of claim 2 wherein the third fluid is a gas or a gaseous mixture.

29. The method of claim 2 wherein the first fluid and/or second fluid is a rinse solution.

30. The method of claim 2 further comprising disposing a sample in the microfluidic chip prior to applying the first and second fluids to the reaction site.

31. The method of claim 2 wherein the vessel has a length to inner diameter ratio of at least 10:1.

32. The method of claim 2 wherein the vessel has an inner diameter of less than 500 microns.

33. The method of claim 2 further comprising electrolessly depositing metal at the reaction site to produce an opaque material.

34. The method of claim 33 further comprising determining light absorbance or transmission through the opaque material.

35. The method of claim 2 wherein the vessel contains a fourth fluid, the method further comprising combining the fourth fluid and the second fluid while transferring the first, third, and second fluids from the vessel to the reaction site.

36. The method of claim 33 wherein at least one of the first, third, and second fluids comprises a metal precursor.

37. The method of claim 2 wherein the reaction site is adapted for allowing a binding event to occur between at least two binding partners, and wherein at least one of the binding partners comprises an antibody.

38. The method of claim 1 wherein the reaction site is adapted for allowing a binding event to occur between at least two binding partners, and wherein at least one of the binding partners comprises an antibody.

39. The method of claim 3 wherein the third fluid is a gas or a gaseous mixture.

40. The method of claim 39 wherein the first fluid and/or second fluid is a rinse solution.

41. The method of claim 3 wherein the vessel has a length to inner diameter ratio of at least 10:1.

42. The method of claim 41 wherein the vessel has an inner diameter of less than 500 microns.

43. The method of claim 3 wherein at least one of the first, third, and second fluids comprises a metal precursor.

44. The method of claim 43 further comprising electrolessly depositing metal at the reaction site to produce an opaque material.

45. The method of claim 44 further comprising determining light absorbance or transmission through the opaque material.

46. The method of claim 39 wherein the vessel contains a fourth fluid, the method further comprising combining the fourth fluid and the second fluid while transferring the first, third, and second fluids from the vessel to the reaction site.

47. The method of claim 3 wherein the reaction site is adapted for allowing a binding event to occur between at least two binding partners, and wherein at least one of the binding partners comprises an antibody.

48. The method of claim 18 wherein the fourth fluid is stored in the vessel prior to the unsealing step.