Abstract: A unified fluid cell circuit assembly for an analytical instrument, such as a clinical hematology, immunoassy or chemistry or a flow cytometry instrument. The assembly includes a unified fluid circuit, a shear valve, a fluid pump assembly, and a plurality of solenoid valves. The unified fluid circuit is made of a plurality of acrylic plates which have formed in the various plate surfaces chamber cavities, pneumatic, hydraulic and vent line, and valve cavities. The plates, when secured together, form a plurality of reaction chambers, a plurality of control valves and various lines as a network for controlling the flow and mixing of aliquots of a sample and fluids (rinse, reagents, etc.) to perform the reactions for analyzing the sample. The fluid pump assembly is connected to the unified flow circuit and has a plurality of diaphragm pumps which pump precise volumes of fluids.

Abstract: A method and apparatus for selecting a subset of a predetermined number of test sample aliquots to mix with respective reagents using a shear valve having a maximum predetermined number of aliquot loops in an analytical instrument, including without limitation a clinical hematology or a flow cytometer instrument. Each aliquot loop can be filled with a test sample aliquot. Selected ones of the aliquot loops can be filled with a rinse solution and, using bypass passages and valves, closed off from the rinse source and a vacuum source used to empty the rinse from the non-closed off aliquot loops. The vacuum source also is used to fill the non-closed off aliquot loops with the sample to be aliquotted, so that the closed off aliquot loop remains filled with rinse. The shear valve can then be shifted to a second position, where the reagents for the non-closed off aliquot loops are pumped through those aliquot loops to mix the selected sample aliquot loops with their respective reagents.