Teilchendetektor, Vorrichtung zur Detektion von Teilchen und ein Verfahren zum Betreiben enes Teilchendetektor

摘要

A particle detector (10) is designed to detect particles such as cells and blood corpuscles and includes means (14, 16, 18, 30, 32) for passing through an orifice (12) and recovering a multilayer flow consisting of an inner layer (A) of conductive liquid specimen, a middle layer (B) of conductive first sheath liquid, and an outer layer (C) of nonconductive second sheath liquid surrounding the inner and middle layers (A, B), and a pair of electrodes (16, 30) disposed upstream and downstream of the orifice (12) and in electrical contact with the conductive liquids. A particle detecting apparatus incorporates the particle detector (10) and a detector circuit (44) connected to the pair of electrodes (16, 30) so as to detect particles in the conductive liquid specimen of the inner layer (A) by detecting changes in the electrical impedance between the electrodes. An electric current flows from one electrode (16) to the other electrode (30) through the conductive liquids of the inner layer (A) and middle layer (B). Because the outer layer (C) is nonconductive, the current does not flow through that layer. Thus, the effective diameter of the orifice (12) is substantially the diameter (b) of the middle layer (B). By varying the flow rate balance of the conductive liquids and nonconductive liquid, the diameter (b) of the middle layer (B) may be easily changed. Thus, the effective diameter (b) of the orifice (12) may be changed to optimize the detection of large or small particles in the conductive liquid specimen of the inner layer (A).