Patent ID: 8248604

Claim:
An apparatus for measuring a particle in a liquid, the apparatus comprising: a stage with a flow cell mounted thereon, the flow cell including a first flow channel into which a sample liquid containing a particle is introduced, second and third flow channels into which a sheath liquid is introduced, the second and third flow channels being arranged on opposite sides of the first flow channel, and a fourth flow channel in which the first to third flow channels are joined, the first to fourth flow channels being formed on a substrate; laser light application means for applying laser light to the particle flowing in the fourth flow channel; and means for detecting and analyzing scattered light or fluorescence generated from the particle, the flow cell further including: fifth to seventh flow channels provided downstream of the fourth flow channel, the fifth to seventh flow channels being symmetrical to the first to third flow channels provided upstream of the fourth flow channel; and a first liquid storage tank and a second liquid storage tank provided upstream of the first to third flow channels and downstream of the fifth to seventh flow channels, respectively, wherein: the second and third flow channels into which the sheath liquid is introduced are connected to the first liquid storage tank; the first flow channel into which the sample liquid is introduced is connected to a third liquid storage tank provided inside the first liquid storage tank; the second and third flow channels share a same liquid surface in the first liquid storage tank, the third liquid storage tank is independent from the first liquid storage tank and has a structure preventing the sheath liquid and the sample liquid from being mixed in the first liquid storage tank; the fifth flow channel at the center of the downstream flow channels is connected to a fourth liquid storage tank provided inside the second liquid storage tank, and the sixth and seventh separated flow channels on opposite sides of the fifth flow channel are connected to the second liquid storage tank; a gas with a constant pressure higher than an atmospheric pressure is introduced into the first liquid storage tank using a detachable cap structure, a flow rate of the sample liquid is controlled to be constant by controlling the pressure of the gas, the sample liquid is collected into the fourth liquid storage tank on the downstream side, and the sheath liquid is collected into the second liquid storage tank.