Blood Pump Bearing Geometry for Thrombosis-Resistant Flow
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Solution Overview
Problem
Blood pumps face challenges such as blood clots and hemolysis due to stagnation in bearing areas, which existing designs fail to adequately address, particularly with regards to fluid flow and pressure-volume characteristics.
Innovation Solution
A modular bearing system incorporating unique sleeve and cone bearing designs with modified geometries to enhance fluid flow, reduce thrombosis, and promote full washing of bearing surfaces, including features like thrust rings and segmented cone bearings to minimize contact points and ensure continuous blood flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sleeve bearings are used to provide radial confinement, then bearing support function is achieved, but blood stagnation and clotting occur in bearing areas
Solution Approach 1:
The bearing surface is segmented into multiple zones with different geometries (e.g., tapered sections, stepped configurations) to create varying flow patterns that prevent stagnation while maintaining radial confinement. This segmentation allows blood to flow through bearing regions rather than stagnate, eliminating clotting risks.
Solution Approach 2:
Different regions of the bearing have locally optimized geometries tailored to specific functional requirements. For example, certain zones have smoother surfaces for reduced friction, while other zones have flow-enhancing features. This local differentiation ensures both reliable support and continuous blood flow.
2Object-affected harmful factors
If bearing geometries are modified to enhance fluid flow, then thrombosis risk is reduced, but pressure-volume characteristics of bearing interfaces deteriorate
Solution Approach 1:
The bearing geometry incorporates dynamic flow features that adapt to operating conditions. For example, the bearing surfaces are designed to create hydrodynamic lubrication films that self-regulate pressure distribution, maintaining favorable pressure-volume characteristics while ensuring continuous blood flow through the bearing region.
Solution Approach 2:
The bearing design utilizes hydraulic principles to generate and maintain lubricating fluid layers. The geometry is optimized to create pressure gradients that drive blood flow through the bearing, ensuring both thrombosis prevention and maintenance of pressure-volume characteristics through fluid dynamic effects.
3Device complexity
If conventional bearings are used with point or line contact, then structural simplicity is maintained, but pressure-velocity characteristics are inferior
Solution Approach 1:
The bearing design transitions from point or line contact to two-dimensional surface contact. The bearing interfaces are designed as extended surfaces that provide both radial and axial confinement, creating favorable pressure-velocity characteristics while maintaining reasonable structural complexity through geometric optimization.
4Object-affected harmful factors
If bearing surfaces are designed for full washing by blood, then hemolysis risk is reduced, but bearing confinement capability deteriorates
Solution Approach 1:
The bearing geometry employs asymmetric configurations where different surfaces have different degrees of openness to blood flow. One surface may be more exposed to ensure washing, while the opposing surface provides stronger confinement. This asymmetric design balances hemolysis prevention with adequate confinement capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces thrombosis and hemolysis risks by improving fluid dynamics and lubrication within the bearing regions, enhancing the safety and efficiency of blood circulation in blood pumps.
Implementation Method 1
maintaining the pressure-volume characteristics of the bearing interfaces within favorable ranges, and minimizing forces on the blood that can lead to thrombosis or hemolysis
Data Source
AI summary
A blood flow assist system can include an impeller assembly including an impeller shaft and an impeller on the impeller shaft, a primary flow pathway disposed along an exterior surface of the impeller. The system can include a rotor assembly at a proximal portion of the impeller shaft. A secondary flow pathway can be disposed along a lumen of the impeller shaft. During operation of the blood flow assist system, blood can be pumped proximally along the primary flow pathway and the secondary flow pathway. The system can include a sleeve bearing distal the impeller. The system can include a drive unit having a distal end disposed distal a proximal end of the second impeller. The drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly.