Abstract: An apparatus for detecting changes in a property of a liquid/reagent mixture comprises a cartridge having a fluid receiving/dispensing reservoir, one or more fluid-receiving chambers, one or more conduit(s) that permit(s) fluid communication between the fluid receiving/dispensing reservoir and the fluid-receiving chamber(s) and wherein the one or more conduits have a constricted passage for increasing the velocity of fluid flow through said constricted passage and thereby more thoroughly mixing the liquid (e.g., human blood) and a reagent (e.g., protamine).

Abstract: An apparatus for detecting changes in a property of a liquid/reagent mixture comprises a cartridge having a fluid receiving/dispensing reservoir, one or more fluid-receiving chambers, one or more conduit(s) that permit(s) fluid communication between the fluid receiving/dispensing reservoir and the fluid-receiving chamber(s) and wherein the one or more conduits have a constricted passage for increasing the velocity of fluid flow through said constricted passage and thereby more thoroughly mixing the liquid (e.g., human blood) and a reagent (e.g., protamine).

Abstract: An apparatus for detecting changes in the viscosity of a fluid comprises a cartridge having a fluid receiving/dispensing reservoir, one or more fluid-receiving chambers, and a conduit that permits fluid communication between the fluid receiving/dispensing reservoir and the fluid-receiving chamber. Fluid is introduced into the cartridge through an injection port and fills the reservoir, moving from the reservoir through the conduit into the chamber. An air vent/fluid plug device in fluid communication with the chamber permits air to exit while the fluid enters the system but prevents the fluid from leaving after the chamber is filled. A freely movable ferromagnetic material is placed within the fluid-receiving chamber and is caused to move by an electromagnet. Changes in the viscosity of the fluid are detected by determining the position of the ferromagnetic material in the fluid-receiving chamber.