Patent ID: 7427278

Claim:
A device for extracting a biological fluid, comprising: a) a first flexible tube including a constriction area and a pre-determined cross-section, the first flexible tube operable to transport a biological fluid; b) a second flexible tube including a constriction area and a pre-determined cross section, the second flexible tube operable to transport an additive solution; c) a collecting bag operable to receive the biological fluid transported by the first flexible tube and the additive solution transported by the second flexible tube, such that the biological fluid and the additive solution are deposited therein; d) at least one peristaltic pump, which is coupled to the first flexible tube and the second flexible tube, and is operable to partially constrict the first flexible tube and to partially constrict the second flexible tube at a substantially uniform rate, wherein the second flexible tube is introduced inside the first flexible tube in a sealed fashion upstream of the constriction area of the first flexible tube; wherein the second flexible tube ends downstream of the constriction area of the first flexible tube, such that the additive solution exits the second flexible tube downstream of the constriction area and is transported by the first flexible tube, and the biological fluid and additive solution are deposited in the collecting bag by way of the first flexible tube; wherein the additive solution and the biological fluid are deposited in the collecting bag in volumes proportionally determined by the ratio between the pre-determined cross-sections of the first flexible tube and the second flexible tube; and wherein the additive solution is substantially restricted from passing upstream of the constriction area of the first flexible tube.