Blood Pump Bearing Geometry for Bearing Wash 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 sleeve and cone bearings that do not effectively enhance fluid flow and maintain pressure-volume characteristics to prevent thrombosis and hemolysis.
Innovation Solution
A modular bearing system incorporating uniquely designed sleeve and cone bearings with modified geometries to promote full washing of bearing surfaces, including features like thrust rings and segmented cone bearings with channels to enhance blood flow and reduce stagnation, combined with a blood flow assist system that includes an impeller assembly and drive unit with curved bearing surfaces to minimize thrombosis and hemolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sleeve or cone bearings are used in blood pumps, then radial and axial confinement of the impeller is achieved, but blood stagnation occurs in bearing areas leading to thrombosis and hemolysis
Solution Approach 1:
The bearing surface is segmented into multiple zones with different geometries (e.g., tapered sections, flat sections, recessed areas) to create varied flow patterns that prevent stagnation while maintaining bearing function
Solution Approach 2:
The bearing design incorporates axial flow components in addition to radial support, creating three-dimensional flow patterns that wash through the bearing interface and prevent blood pooling
2Strength
If bearing surfaces are designed to confine the impeller radially and axially, then mechanical support is provided, but fluid flow enhancement and pressure-volume characteristic maintenance are compromised
Solution Approach 1:
Different regions of the bearing surface have different geometries optimized for specific functions: some areas provide radial confinement, others promote axial flow, and recessed areas create vortices for blood washing
Solution Approach 2:
The bearing design creates dynamic flow conditions through rotational interaction between the impeller and bearing surfaces, generating continuous blood flow and pressure variations that prevent stagnation
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 by ensuring enhanced fluid flow and lubrication in bearing regions, maintaining favorable pressure-volume characteristics, and minimizing forces that lead to adverse blood interactions, thereby improving the performance and safety of blood pumps.
Implementation Method 1
maintaining the pressure-volume characteristics of the bearing interfaces within favorable ranges
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.