Low-Diameter Axial Shaft Coupling for Stable Impeller Gap
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Solution Overview
Problem
Current ventricular assist devices face challenges in efficiently pumping blood and minimizing hemolysis due to the design of the impeller and its coupling to the axial shaft.
Innovation Solution
The use of a coupling element made of shape-memory material with slits to securely attach the impeller to the axial shaft, allowing for radial expansion and contraction, thereby enhancing the efficiency of blood pumping and reducing hemolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the impeller is rigidly coupled to the axial shaft, then the structural strength is improved, but the efficiency of blood pumping deteriorates due to inconsistent gap between impeller blades and inner lining
Solution Approach 1:
The coupling element is designed with elastic properties allowing it to dynamically adjust the impeller's position relative to the axial shaft. This dynamic adjustment maintains a consistent gap between the impeller blades and the inner lining during rotation, optimizing blood pumping efficiency while preserving structural integrity through the elastic connection.
Solution Approach 2:
The coupling element changes its physical state between elastic deformation and rigid locking. During assembly, it deforms elastically to accommodate the impeller, then locks into a rigid position that maintains optimal spacing. This parameter change allows the system to achieve both structural strength and pumping efficiency.
2Productivity
If the coupling element is made of shape-memory material with slits, then the efficiency of blood pumping is improved through consistent gap maintenance, but the device complexity increases
Solution Approach 1:
The shape-memory coupling element with slits is designed to self-adjust and self-lock into the optimal position. The slits allow the element to deform and conform to the impeller, while the shape-memory material automatically returns it to its predetermined geometry, maintaining consistent spacing without external control mechanisms.
Solution Approach 2:
The coupling element utilizes shape-memory material that combines elastic deformation capabilities with rigid locking properties. This composite material behavior allows a single component to provide both the flexibility needed for consistent gap maintenance and the structural integrity required for reliable operation.
3Strength
If welding is used to couple the coupling element to the axial shaft, then the structural strength is improved, but the reliability deteriorates due to heat-induced weakening of components
Solution Approach 1:
The invention replaces the thermal welding process with a mechanical interference fit and elastic locking mechanism. The coupling element is inserted in a deformed state and then elastically locks onto the axial shaft, achieving strong mechanical coupling without thermal exposure that could weaken the components.
Solution Approach 2:
The coupling element acts as an intermediary component between the axial shaft and the impeller. It provides the mechanical connection and force transmission without requiring direct welding between the shaft and impeller, thereby protecting both components from heat-induced weakening while maintaining structural strength.
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 configuration improves the efficiency of blood pumping and reduces hemolysis by maintaining a consistent gap between the impeller blades and the inner lining, ensuring effective blood flow and minimizing tissue damage.
Implementation Method 1
the coupling element includes a first portion, which is disposed around the axial shaft, is made of a shape-memory material, is shaped to define one or more slits that facilitate a radial expansion of the first portion
Data Source
AI summary
Apparatus and methods are described including a solid axial shaft having a shaft diameter that is less than 0.8 mm, an impeller configured for insertion into a left ventricle of a heart of a subject and coupled to the axial shaft, and a hollow drive cable coupled, at a distal end of the drive cable, to the axial shaft, and configured to rotate so as to rotate the axial shaft, thereby causing the impeller to pump blood of the subject from the left ventricle. Other applications are also described.