Ceramic Thrust Bearing and Inlet Guard for Blood Pump Shaft Stability
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Solution Overview
Problem
Existing ventricular assist devices face challenges in efficiently managing axial motion and flow direction of blood due to variations in pressure gradients, leading to potential damage and inefficiencies in blood pumping.
Innovation Solution
The device incorporates an inlet guard shaped to define holes, a frame with a toric inlet guard perpendicular to the axial shaft, and a thrust bearing with ceramic surfaces to stabilize the axial shaft, reducing axial motion and optimizing blood flow direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a traditional bearing system is used to support the axial shaft, then the device structure is simple, but axial motion of the shaft is not effectively controlled leading to inefficiencies in blood pumping
Solution Approach 1:
The patent employs a composite bearing system combining ceramic materials (for low-friction surfaces) with metallic components (for structural support). The ceramic-coated axial shaft and ceramic thrust bearing surfaces create a low-friction interface that reduces axial motion, while the overall bearing housing and support structures use metallic materials for strength and stability.
Solution Approach 2:
The patent replaces traditional high-friction mechanical bearing surfaces with ceramic-ceramic contact surfaces that utilize low-friction material properties. This substitution of material characteristics fundamentally changes the friction dynamics of the bearing system, reducing axial shaft motion without requiring complex active control mechanisms.
2Productivity
If the inlet guard is positioned to optimize blood flow direction, then flow efficiency is improved, but the device occupies more space within the ventricle
Solution Approach 1:
The inlet guard is designed as a flat, planar structure with a toric shape that optimizes blood flow direction through its geometric configuration rather than through volumetric bulk. The flow direction control is achieved through the two-dimensional arrangement of holes and the toric curvature, minimizing the third-dimensional volume occupied by the component.
Solution Approach 2:
The inlet guard employs a toric (doubly curved) geometry that smoothly guides blood flow through its curved surfaces. This spherical/curved geometry efficiently directs flow patterns while maintaining a compact form factor, as the curvature achieves flow optimization without requiring large linear dimensions.
3Productivity
If the axial shaft is constrained to prevent axial motion, then pumping efficiency is improved, but the shaft cannot accommodate guidewire insertion and purging fluid channels
Solution Approach 1:
The bearing support system is segmented into distinct functional zones: the ceramic thrust bearing provides axial constraint for pumping efficiency, while the hollow axial shaft structure maintains internal lumens for guidewire and purging fluid functions. The bearing housing is also segmented to accommodate these multiple functions without compromising axial stability.
Solution Approach 2:
The axial shaft is designed as a multi-functional component that simultaneously serves as the rotational drive shaft, contains internal channels for guidewire insertion and purging fluid flow, and interfaces with the ceramic bearing system for axial constraint. This universal design allows multiple functions within a single component without compromising any individual function.
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 provides low-friction stabilization of the axial shaft, maintaining efficient blood flow and preventing damage, while allowing for guidewire insertion and purging fluid channels.
Implementation Method 1
a thrust bearing with ceramic surfaces to stabilize the axial shaft, reducing axial motion
Implementation Method 2
an impeller coupled to the axial shaft, and a frame surrounding the impeller. As the axial shaft rotates, the impeller pumps blood proximally
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
An apparatus, comprising: a blood pump, comprising: an axial shaft (92) configured for insertion into, and rotation within, a body of a subject; an impeller (50) coupled to the axial shaft (92) such that, as the axial shaft (92) rotates, the impeller (50) pumps blood of the subject; a thrust bearing (270) comprising a proximally-facing ceramic surface (271) and disposed distally from the axial shaft (92) so as to inhibit distal movement of the axial shaft (92) beyond the thrust bearing (270); a distal radial bearing (118) configured to radially stabilize the axial shaft (92) while the axial shaft (92) rotates; a distally-facing ceramic cover (273) that covers a distal end of the axial shaft (92), such that the ceramic cover (273) contacts the ceramic surface (271) as the axial shaft (92) rotates; and a ceramic sleeve (240) that is configured to cover a distal portion of the axial shaft (92) that rotates within the distal radial bearing as the axial shaft (92) rotates.