US Patent 7947007 Bubble trap

A bubble trap for removing bubbles from blood flowing through an extracorporeal circuit includes device body possessing blood inlet and outlet ports, and a negative-pressure chamber at the upper part of the device body that is adapted to be connected to a gas evacuator at a gas outlet port so that a negative-pressure state can be kept therein. Two communication passages provide communication between the gas outlet port and the device body. On the first communication passage, a liquid-repellant or water-repellent filter is provided in a manner crossing the passage. On the second communication passage, a valve member is arranged. Within the device body, a buoyant float is provided. A mechanism is provided to remove bubbles from the blood by the cooperation of the float and the valve member.