A Sealless Centrifugal Blood Pump with Passive Magnetic and Hydrodynamic Bearings

Wampler, Richard K.; Lancisi, David; Indravudh, V.; Gauthier, R.; Fine, R B

doi:10.1046/j.1525-1594.1999.06422.x

Cited by 25 publications

(15 citation statements)

References 8 publications

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“…However, these active bearings are expensive and complicated; hence, passive bearings are preferred. Some of the recent rotary blood pumps have incorporated passive hydrodynamic bearings in their designs (4,5). The use of passive bearings, such as spiral groove bearings (SGBs), was extensively studied.…”

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confidence: 99%

Numerical and In Vitro Investigations of Pressure Rise in a New Hydrodynamic Blood Bearing

2007

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The reliability and simplicity of rotor bearing are vital to the success of long-term implantation of rotary blood pumps. This article describes both numerical and in vitro studies of the pressure rise in a 5-cm-diameter spiral groove bearing. Results show that the simplified analytical model overpredicts the pressure rise across the bearing while the results from a more comprehensive three-dimensional computational fluid dynamics (CFD) model agree well with the measurements. The discrepancy between the analytical model and the measurements is attributed to the exclusion of the fluid inertia effects in the analytical model. In addition, the assumption of linear pressure variations at the entrance of the groove and the ridge may have oversimplified the analysis. CFD results show that the pressure variation at the entrance of the groove and ridge is nonlinear. A correction factor taking into consideration the fluid inertia effect has been incorporated, and the modified analytical results agreed well with the measurement as well as that of the more comprehensive CFD model. The pressure generated is sufficient to lift the rotor, and this design provides the designer an alternative design for passive bearing.

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confidence: 99%

Numerical and In Vitro Investigations of Pressure Rise in a New Hydrodynamic Blood Bearing

2007

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“…Suspension of the impeller within the pump cavity of the VentrAssist IRBP is performed passively and is achieved through the use of hydrodynamic forces. Hydrodynamic suspension systems have been investigated by other parties (1,2), while others incorporate hydrodynamic bearings working in synergy with magnetic bearings for suspension (3). Total active suspension systems are currently being utilized by other rotary blood pumps (4–6); however, these incorporate complex position sensing and control systems.…”

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confidence: 99%

Impeller Behavior and Displacement of the VentrAssist Implantable Rotary Blood Pump

et al. 2004

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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 microm to 230 microm; 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, theta(x), and theta(y)). The sixth degree of freedom, the rotation about the impeller axis (theta(z)), was determined by the commutation performed by the motor controller. The impeller displacement was found to be within the acceptable range of 8 micro m to 222 microm, 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.

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“…The hemolysis data in most publications are not reported as the NIH value (47,48), and therefore, it is difficult to directly compare our results with the published values. Only a few publications (21,41,49,50) have reported NIH values ranging from 0.001 to 0.1 mg/dL.…”

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confidence: 95%

Design of a Small Centrifugal Blood Pump With Magnetic Bearings

et al. 2009

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Design of a blood pump with a magnetically levitated rotor requires rigorous evaluation of the magnetic bearing and motor requirements and analysis of rotor dynamics and hydraulic performance with attention to hemolysis and thrombosis potential. Given the desired geometric dimensions, the required operating speed, flow in both the main and wash flow regions, and magnetic bearing performance, one of several design approaches was selected for a new prototype. Based on the estimated operating speed and clearance between the rotor and stator, the motor characteristics and dimensions were estimated. The motor stiffness values were calculated and used along with the hydraulic loading due to the fluid motion to determine the best design for the axial and radial magnetic bearings. Radial and axial stability of the left ventricular assist device prototype was verified using finite element rotor dynamic analysis. The analysis indicated that the rotor could be completely levitated and spun to the desired operating speed with low power loss and no mechanical contact. In vitro experiments with a mock loop test setup were performed to evaluate the performance of the new blood pump prototype.

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A Sealless Centrifugal Blood Pump with Passive Magnetic and Hydrodynamic Bearings

Cited by 25 publications

References 8 publications

Numerical and In Vitro Investigations of Pressure Rise in a New Hydrodynamic Blood Bearing

Numerical and In Vitro Investigations of Pressure Rise in a New Hydrodynamic Blood Bearing

Impeller Behavior and Displacement of the VentrAssist Implantable Rotary Blood Pump

Design of a Small Centrifugal Blood Pump With Magnetic Bearings

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