Patent ID: 6916116

Claim:
An article comprising: a housing enclosing: (a) a first fluid reservoir at least partially filled with a first fluid; (b) a substrate comprising a plurality of channels; (c) a second fluid reservoir in fluid communication with at least one channel of the substrate; and (d) a barrier located between the first fluid reservoir and the second fluid reservoir; wherein the article can be manipulated at a desired point in time by opening the barrier to allow at least a portion of the fluid to flow from the first reservoir to the second reservoir and to contact at least one channel of the substrate; wherein the article is designed to provide an indication of the progress of the fluid as it moves through the channels of the substrate; and wherein the second reservoir has a volume that is greater than a volume of the first reservoir, and is a sufficient to prevent the fluid from the first reservoir from being forced directly into the substrate upon opening the barrier.