Hypotube Construction for Catheter Stiffness and Flexibility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current medical devices, such as catheters, face challenges in achieving a balance between flexibility and strength while maintaining a minimal exterior diameter and maximizing interior diameter, which is crucial for minimally-invasive procedures.
Innovation Solution
The development of a hypotube construction with a customizable stiffness profile along its length, featuring a Teflon inner liner and a powdered polymer coat, allowing for a larger interior diameter with a low outer diameter, and incorporating a cut pattern to provide desired stiffness and flexibility, along with a dip-coated polymer for reduced wall thickness and improved maneuverability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the hypotube wall thickness is increased to provide strength and support, then the catheter can resist kinking and maintain structural integrity, but the exterior diameter increases and the interior diameter decreases
Solution Approach 1:
The patent employs a composite construction consisting of a hypotube body with an inner liner and an outer polymer coating. This multi-material approach allows each layer to contribute specific properties: the hypotube body provides structural strength, the inner liner provides flexibility and low friction, and the outer coating provides additional strength and kink resistance. This composite structure achieves the required strength without proportionally increasing the exterior diameter.
2Strength
If the hypotube wall thickness is increased to provide strength and support, then the catheter can resist kinking and maintain structural integrity, but the interior diameter decreases
Solution Approach 1:
The composite construction with inner liner and outer coating allows the hypotube body to be optimized for strength while the liner maximizes the functional interior diameter. The liner layer provides a low-friction surface that effectively increases the usable interior diameter for device passage, while the overall composite structure maintains the required strength properties.
3Ease of operation
If the hypotube is made more flexible to allow easier navigation, then the catheter can navigate vasculature more easily, but the catheter loses pushability and support
Solution Approach 1:
The patent applies different material properties to different regions and layers of the catheter construction. The inner liner provides localized flexibility and low-friction properties where needed for navigation, while the hypotube body and outer coating maintain structural integrity and pushability. This spatial differentiation of material properties allows the catheter to exhibit both flexibility for navigation and pushability for advancement.
Solution Approach 2:
The multi-layer composite structure enables the catheter to combine materials with complementary properties. The flexible liner layer facilitates navigation through vasculature, while the stronger hypotube body and outer coating layers provide the necessary pushability and support during advancement to the target site.
4Shape
If a polymer jacket is added to minimize surface roughness and provide seal, then the exterior surface quality improves, but the device complexity increases
Solution Approach 1:
The patent combines multiple functions into the outer polymer coating layer. This single layer simultaneously provides surface smoothing to minimize roughness, creates a seal between the catheter and surrounding structures, and contributes additional structural strength. By merging these multiple functions into one integrated layer, the design avoids the complexity that would result from adding separate components for each function.
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A medical device such as a catheter may have an elongate shaft that includes a hypotube having a cut formed therein. The elongate shaft may define a lumen that extends within the elongate shaft. A polymer may be disposed over at least a portion of the hypotube. A medical device may include a cut hypotube having a constant pitch and may be configured to reversibly and temporarily alter the pitch of at least a portion of the cut hypotube. In some cases, the medical device may be configured to reversibly and/or temporarily alter a compressive strength of at least a portion of the cut hypotube.