A pump for moving a fluid, as blood, having a body and end members forming a cylindrical chamber. A free floating piston located in the chamber is moved along the length of the chamber with a solenoid to pump blood into and out of opposite ends of the chamber. The end members containing inlet and outlet...http://www.google.es/patents/US4221548?utm_source=gb-gplus-sharePatente US4221548 - Dual action solenoid pump
