Optical flow cytometer and method of investigation

An optical flow cytometer to assay in vitro cellular components in a liquid sample, characterized in that said cytometer comprises

• a flow path extending from a starting point to an end point with a flow direction pointing from said starting point towards said end point, wherein
• the starting point is formed by a first container for storing an auxiliary liquid at a first pressure, the end point is formed by a second container at a second pressure lower than said first pressure;
• said flow path is composed of first and second flow branches formed so as to be capable of transporting said auxiliary liquid from the starting point to the end point, a unifying member (66) is inserted into the flow path that combines the flow branches into a common section and is capable of hydrodinamical focusing, wherein said common section is formed with a given cross-sectional area and so as to allow passing one cellular component of said sample at a time in each cross-sectional area;
• reactors are arranged between the starting point and the unifying element (66) in said first flow branch, said reactors are connected to one another so as to effect transportation in the flow direction, said reactors form parts of separate reagent branches (68-k) of the first flow branch for feeding the sample with cellular components and liquid phase reagents into the first flow branch and said reactors are formed so as to perform one or more reactions of the fed sample with the fed reagents in a controlled way and to transport the thus obtained prepared sample in the flow direction;
• and wherein
• the cross-sectional area is divided into cross-sectional areas of constituent flows of a composite stream according to the ratio of flow impedancies of said first and second flow branches, wherein said composite stream is a layered stream composed of the auxiliary liquid and the prepared sample that enter said common section via the second and first flow branches, respectively, combined by said unifying member (66) through hydrodinamical focusing exerted by the unifying member (66) and flows in said common section laminarly in the flow direction due to the pressure difference prevailing between the starting point and the end point of the flow path;
• a device to illuminate the common section by a shaped coherent beam of light in a given zone thereof from a direction essentially perpendicular to the extension of said common section;
• an optical coupling element capable of collecting beams exiting from the illuminated zone of the common section in a first spatial distribution and transmitting said beams in a spatial distribution identical with said spatial distribution to a sensing surface of at least one optical sensing element (A1, . . . , Ap), wherein
• said illumination device and said optical coupling element exhibit a common optical axis;
• the at least one sensing element (A1, . . . , Ap) is capable of generating at least one electrical signal in conformity with the spatial distribution of the beams incident on said sensing surface, each electric signal being proportional to the detected intensity of a respective incident beam;
• a signal processing unit (54) electrically connected with the at least one optical sensing element (A1, . . . , Ap) and being capable of processing the at least one electric signal generated by the at least one sensing element (A1, . . . , Ap);
• and
• a controlling and evaluating unit electrically connected with an output of said signal processing unit (54) and suitable for at least one of determining properties of the cellular components in the sample based on at least a part of the electrical signals processed and positioning said beam emitted by the illumination device onto the given zone of the common section by employing a part of the electrical signals processed as control parameters.