Catheter Articulation Joint with Interlinked Springs
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Solution Overview
Problem
Existing elongate flexible systems, such as catheters, face challenges in optimizing axial stiffness for resistance to compression while maintaining low bending stiffness for navigational flexibility, and achieving a balance between instrument passage and anatomical access.
Innovation Solution
The design incorporates an articulation joint with pairs of links and springs, where the springs are positioned between radially extending arcuate segments of the links, allowing for bending in multiple planes and reduced overall cross-sectional dimensions, enabling efficient navigation and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If axial stiffness is increased to resist compression, then resistance to compression is improved, but bending stiffness increases reducing navigational flexibility
Solution Approach 1:
The catheter shaft is divided into multiple segments or elements arranged in series, where each segment can bend independently relative to the others. This segmentation allows the distal tip to be steered through anatomical passageways while the proximal segments maintain structural integrity and resist compression forces during insertion and manipulation.
Solution Approach 2:
Different portions of the catheter shaft are designed with different mechanical properties - the proximal portion has higher stiffness for compression resistance, while the distal portion has lower stiffness for bending flexibility. This local variation in mechanical properties resolves the contradiction between axial stiffness and bending flexibility.
2Adaptability or versatility
If central channel size is increased to allow instrument passage, then versatility is improved, but outer diameter increases reducing access to narrow passageways
Solution Approach 1:
Multiple concentric catheters or nested tubular elements are used, where a smaller inner catheter with a larger central channel for instrument passage is positioned within a larger outer catheter with a smaller outer diameter for navigating narrow passageways. The nested configuration allows both functions to coexist without compromising either capability.
Solution Approach 2:
The solution moves from a single-dimension trade-off (channel size vs. outer diameter) to a multi-dimensional configuration by adding the nested layer structure. This allows independent optimization of inner channel dimensions for instrument access and outer diameter for anatomical access.
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 enhances axial stiffness for resistance to compression while maintaining low bending stiffness for flexibility, allowing for precise steering and access to narrow anatomical passageways with reduced articulation forces, thus improving the device's navigational capabilities and clinical effectiveness.
Implementation Method 1
spring members that may be coupled between the links and that may provide axial stiffness
Implementation Method 2
The spring members may be bendable to allow articulation of the links along a first plane
Data Source
AI summary
A catheter system may comprise an articulation joint including a first pair of links and a second pair of links. Each link may include a central channel enclosed at least in part by radially extending arcuate segments. The first pair of links may include a first link and a second link, and the second pair of links may include the second link and a third link. The system may also comprise a first pair of springs coupled between the first and second links. The system may also comprise a second pair of springs coupled between the second and third links. The system may also include control wires extending through the first pair of springs and a control wires extending through the second pair of springs. The spring walls may share a radial dimension with the link walls.