Microchip

A microchip having a fluid circuit therein for passing a liquid, said fluid circuit having:

• a first reservoir and a second reservoir for storing at least a part of said liquid;
• a first path connecting said first reservoir and said second reservoir;
• a second path connecting said first reservoir and said second reservoir at a position different from said first path;
• and
• a portion including therein beads to which an antibody is immobilized, wherein said portion is provided at a bottom of the second reservoir, and wherein a bottom of said portion and a bottom of the first reservoir are connected by the second path,
• wherein the first reservoir and the second reservoir are connected in an upper part thereof by the first path and wherein said first reservoir, said second reservoir, said first path, said second path and said portion constitute a circular path capable of circulating said liquid to reintroduce into said portion the liquid that has been passed through said portion, and
• wherein the microchip is arranged such that said liquid is circulated within said circular path by application of a first centrifugal force in a first direction and by application of a second centrifugal force in a second direction at an angle of about ninety degrees with respect to the first direction, wherein the first centrifugal force and the second centrifugal force are applied to the microchip by revolution of the microchip around a first centrifugal center and a second centrifugal center that are positioned outside the microchip, respectively,
• wherein the liquid can be circulated within the circular path only in an order of the first reservoir, the first path, the second reservoir, the portion including therein beads and the second path, and
• wherein in the fluid circuit, the first reservoir is positioned on a side nearer to the first centrifugal center for the first centrifugal force as compared with the second reservoir, and the first reservoir is positioned on a side farther from the second centrifugal center for the second centrifugal force as compared with the second reservoir.