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Impeller Behavior and Displacement of the VentrAssist Implantable Rotary Blood Pump
Author(s) -
Chung Michael K.H.,
Zhang g,
Tansley Geoff D.,
Woodard John C.
Publication year - 2004
Publication title -
artificial organs
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.684
H-Index - 76
eISSN - 1525-1594
pISSN - 0160-564X
DOI - 10.1111/j.1525-1594.2004.47269.x
Subject(s) - impeller , centrifugal pump , rotodynamic pump , progressive cavity pump , rotor (electric) , reciprocating pump , displacement (psychology) , variable displacement pump , slip factor , mechanics , mechanical engineering , materials science , acoustics , engineering , physics , psychology , psychotherapist
The VentrAssist implantable rotary blood pump, intended for long‐term ventricular assist, is under development and is currently being tested for its rotor‐dynamic stability. The pump is of the centrifugal type and consists of a shaftless impeller, also acting as the rotor of the brushless DC motor. The impeller remains passively suspended in the pump cavity by hydrodynamic forces, resulting from the small clearances between the impeller outside surfaces and the pump cavity. In the older version of the pump tested, these small clearances range from approximately 50 µm to 230 µm; the displacement of the impeller relative to the pump cavity is unknown in use. This article presents two experiments: the first measured displacement of the impeller using eddy‐current proximity sensors and laser proximity sensors. The second experiment used Hall‐effect proximity sensors to measure the displacement of the impeller relative to the pump cavity. All transducers were calibrated prior to commencement of the experiments. Voltage output from the transducers was converted into impeller movement in five degrees of freedom (x, y, z, θ x , and θ y ). The sixth degree of freedom, the rotation about the impeller axis (θ z ), was determined by the commutation performed by the motor controller. The impeller displacement was found to be within the acceptable range of 8 µm to 222 µm, avoiding blood damage and contact between the impeller and cavity walls. Thus the impeller was hydrodynamically suspended within the pump cavity and results were typical of centrifugal pump behavior. This research will be the basis for further investigation into the stiffness and damping coefficient of the pump's hydrodynamic bearing.