Blood Pump Bearings with Segmented Contact Surfaces
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Solution Overview
Problem
Existing rotary blood pumps face challenges with thrombus formation and mechanical bearing durability, particularly in mechanical blood immersed bearings, which can lead to wear and thrombus accumulation due to high friction and stasis areas, and magnetic levitation systems are complex and unreliable.
Innovation Solution
The solution involves a rotor supported by mating portions of the tips of streamlined support blades close to the center of rotation, with axial restraint to prevent disengagement, and a conical bearing surface made of hard wear-resistant material, eliminating continuous circumferential bearing material that can support thrombus growth, while minimizing friction and thrombus formation through optimal blood flow washing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If mechanical blood immersed bearings are used to support the rotor, then the pump structure can be compact and simple, but thrombus formation and wear occur due to high friction and stasis areas
Solution Approach 1:
The bearing surface is segmented into discrete contact zones rather than continuous circumferential contact. The rotor has localized bearing surfaces that contact the housing at specific points, creating separate contact regions that eliminate continuous stasis areas where thrombus could form.
Solution Approach 2:
The continuous circumferential bearing surface is removed and replaced with discrete contact points. This extraction of the continuous surface eliminates the stasis areas that cause thrombus formation while maintaining the necessary mechanical support function.
2Reliability
If magnetic levitation is used to support the rotor, then thrombus formation is reduced due to eliminated mechanical contact, but the system becomes large and complex requiring active electromagnetic feedback control
Solution Approach 1:
The patent replaces the complex magnetic levitation system with a simplified mechanical bearing design. By using localized mechanical contact points instead of continuous contact or magnetic fields, the system achieves reliability without requiring active electromagnetic feedback control.
3Use of energy by moving object
If small diameter bearings are used to reduce friction and wear, then power consumption and heat generation are reduced, but the bearing load capacity may be limited
Solution Approach 1:
The bearing design concentrates load support at specific localized zones with optimized material properties and geometry. The localized contact surfaces are engineered with enhanced load-bearing characteristics while maintaining small overall diameter, allowing high load capacity in a compact configuration.
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
This design minimizes thrombus accumulation, enhances mechanical bearing durability, and allows for the miniaturization of blood pumps, achieving reliable and efficient operation with reduced risk of thrombosis and mechanical failure.
Implementation Method 1
high flow washing of the junction of the rotating and stationary parts of the bearings
Implementation Method 2
mechanical bearings, using fluid film lubrication or hydrodynamic fluid support
Implementation Method 3
a spinning impeller imparts hydrodynamic energy to the fluid
Data Source
Figure 1~1D
Figure 2~2D
Figure 3~7
AI summary
Rotary hydrodynamic blood pumps have been used to treat over a thousand patients. The Jarvik 2000 has supported a patient for seven years and uses blood immersed bearings washed by high flow to avoid excessive thrombus formation. This permits the pump to be very simple and small. Nonetheless, the present Jarvik 2000 bearings and all other mechanical blood immersed bearings of the prior art have a supporting structure that predisposes to thrombus adjacent to the bearings. The present invention provides a bearing structure that eliminates this predilection site for thrombus formation, and may provide indefinite thrombus free operation. The rotor of the preferred embodiment includes a tapered hub fabricated of wear resistant material supported by three posts at each end of the rotor, upon which the rotor rotates. Blood washes the unobstructed spaces between the posts to prevent the accumulation of a torus of thrombus that could enlarge excessively.