Patent ID: 7656146
Filing Date: 2010-02-02
Classification: G01N

Abstract:
1. A particle analyzer based on sheath flow impedance method, comprising: a flow cell; and a counting circuit; the flow cell includes a front chamber and a back chamber, the front chamber includes a particle suspension liquid inlet and a front sheath liquid inlet, the back chamber includes a back sheath liquid inlet and a waste liquid outlet, an aperture being provided between the front and back chambers so as to form a fluid passage between the front and back chambers, each of the front and back chambers being connected to the counting circuit via an electrode respectively; wherein the particle analyzer further comprising: a back sheath liquid isolating chamber, whose upper end communicates with the atmosphere on one hand and is connected to a sheath liquid storing chamber through a pipeline on the other hand, and whose lower end is connected to the back chamber through a pipeline, the back sheath liquid being stored on the bottom of the back sheath liquid isolating chamber; during a non-detection period, the back sheath liquid is supplied to the back sheath liquid isolating chamber from the sheath liquid storing chamber; during a detection period, the liquid passage for supplying liquid to the back sheath liquid isolating chamber is cut off, the supply of the back sheath liquid from the sheath liquid storing chamber to the back sheath liquid isolating chamber is terminated, and the back sheath liquid in the back sheath liquid isolating chamber flows to the back chamber, with a result that air enters into the back sheath liquid isolating chamber via an interface on its top to form isolation air, causing air isolation of the internal fluid passage connecting the inlet and the outlet of the back sheath liquid isolating chamber; and during the detection period, the level of the back sheath liquid in the back sheath liquid isolating chamber is always maintained higher than the level of the back chamber.