Reaction vessel with a rocking base

A fluid circuit reaction vessel for detecting a target substance contained in a minute amount in a fluid sample, wherein said vessel comprises:

• (A) a body structure, said body structure comprising an upstream portion on one side of a center of gravity of the body structure and a downstream portion on the other side of the center of gravity of the body structure;
• (B) a fluid circuit defined in said body structure, said fluid circuit comprising,
• (a) at least one fluid inlet for introducing at least one fluid including the fluid sample containing the target substance, said fluid inlet being provided in the upstream portion of the body structure,
• (b) at least one fluid sump provided in the downstream portion of the body structure,
• (c) at least one fluid channel connecting said fluid inlet and said fluid sump,
• (d) at least one reagent-immobilized area provided in said fluid channel, said reagent-immobilized area having a reagent fixedly immobilized thereto, said reagent being able to specifically react with said target substance contained in the sample,
• (e) at least one reagent-attached area provided in said fluid channel between said fluid inlet and said reagent immobilized area, said reagent-attached area having a reagent reversibly attached thereto, and
• (f) a vent mechanism comprising at least one ventilatory outlet provided in said fluid circuit for venting said fluid circuit;
• and
• (g) a rocking means for allowing said body structure to become inclined with said downstream portion of the body structure including said fluid sump moving downward to indicate substantial completion of the detection, said inclination being induced by the movement of the fluid into said fluid sump.