Concept Designs of Nonrotating–type Centrifugal Blood Pump and Basic Study on Output Characteristics of the Oscillating Disk–type Centrifugal Pump

Abstract: When designing a turbo–type blood pump as an artificial heart, the gap between a rotating shaft and a pump housing should be perfectly sealed to prevent any leakage or contamination through a seal. In addition, blood coagulation in a blood chamber must be avoided. To overcome these problems, we proposed five different nonrotating–type turbo pumps: a caudal–fin–type axialflow pump, a caudal–fin–type centrifugal pump, a nutating–column–type centrifugal pump, a nutating–collapsibletube–type centrifugal pump, and an oscillating–disk–type centrifugal pump. We selected and developed the oscillating–disk–type centrifugal pump that consists of a disk, a driving rod, a seal, an oscillation mechanism, and a pump housing. The disk is mounted on the end of the rod, which is connected to a high–speed DC motor through an oscillation mechanism. The rod and the disk do not rotate, but they oscillate in the pump housing. This movement of the disk generates forward fluid flow around the axis (i. e., the rotational fluid flow). Centrifugal force due to fluid rotation supports the pressure difference between the outlet and the inlet. The diameter of the disk is 39 mm, the maximum inner diameter of the pump housing is 40 mm, and the volume of the blood chamber for 25 degrees' oscillation is 16. 9 ml. The performance of the pump was tested in a mock circulatory system. Using the disk, in which two holes were bored and a blood chamber designed for 25 degrees' oscillation, output flow rate of 6 and 14 L/min were obtained under motor rotational speeds of 2, 700 and 3, 000 rpm, respectively, at 100 mm Hg mean aortic pressure.