e-PTFE Catheter Tip Delamination for Atraumatic Stent Deployment
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Solution Overview
Problem
Catheter systems without an inner shaft face challenges in achieving optimal mechanical properties for the tip during deployment and withdrawal, requiring a material that is stiff enough for delivery but soft enough to minimize trauma and facilitate retraction, while maintaining low friction and flexibility.
Innovation Solution
A catheter system utilizing an e-PTFE laminate with a temporarily bonded adhesive containing fatty acids, which delaminates under strain to change its geometric and mechanical properties from stiff to soft, allowing for atraumatic deployment and easy retrieval, featuring a tip that transitions from frusto-conical to cylindrical or trumpet-shaped during expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the catheter tip is made stiff for delivery, then delivery tube rigidity is improved, but tissue trauma increases and flexibility deteriorates
Solution Approach 1:
The catheter tip is designed to dynamically change its mechanical properties during the procedure. It transitions from a stiff state during delivery to a soft, flexible state after deployment, allowing the same structure to serve both functions optimally
Solution Approach 2:
The mechanical parameters of the catheter tip (stiffness, flexibility) are changed through a phase transition mechanism. The material undergoes a reversible phase change that transforms it from a rigid state suitable for delivery to a compliant state suitable for patient comfort and flexibility
2Adaptability or versatility
If the catheter tip is made soft for flexibility, then flexibility is improved, but delivery tube rigidity deteriorates
Solution Approach 1:
The catheter tip dynamically adjusts its rigidity based on the procedural phase, being rigid during delivery and flexible during/after deployment, eliminating the need to choose between conflicting mechanical properties
3Strength
If the adhesive bond is strong, then structural integrity is improved, but delamination capability deteriorates
Solution Approach 1:
The adhesive bond utilizes a phase transition mechanism where it remains strongly bonded under normal conditions but spontaneously delaminates when triggered by specific conditions (such as temperature change or mechanical stress), enabling controlled release
Solution Approach 2:
The adhesive's bonding parameters are changed through external triggers, transforming it from a strong bonded state to a delaminating state, allowing the system to maintain structural integrity during delivery and then easily separate for deployment
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 system achieves ideal elastic deformation with reduced restoring forces, maintaining mechanical integrity and low friction, enabling effective deployment and retrieval of the stent without causing tissue trauma, and allowing for smaller diameter and greater flexibility.
Implementation Method 1
the e-PTFE laminate is bonded with an adhesive that includes a fatty acid as a functionally essential component... which delaminates under strain to change its geometric and mechanical properties from stiff to soft
Implementation Method 2
The tip opens via plastic deformation when the stent is advanced distally out of the delivery tube... An ideal elastic deformation of the catheter tip is desirable, so that the functional element is released under continuous friction by the elastic recoil force of the catheter tip
Implementation Method 3
the e-PTFE laminate is bonded with an adhesive that includes a fatty acid as a functionally essential component
Data Source
Figure 1
Figure 2a~2c
Figure 2d~2e
AI summary
Catheter system with a distal functional element, in particular a self-expanding stent, a delivery tube surrounding the functional element with its distal end and a sliding element abutting the proximal end of the functional element for advancing the functional element out of the delivery tube, wherein the delivery tube has a tip section that tapers in the delivery state and expands when the functional element is advanced, which is formed from a temporarily bonded, delaminating e-PTFE laminate.