Annealed Polycarbonate-Urethane Sheath Kink Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing medical articles such as catheters and sheaths often kink when bent, disrupting fluid flow and hindering performance, and are prone to re-kinking at smaller angles, limiting their flexibility and resilience during insertion and use.
Innovation Solution
A method involving the extrusion of polycarbonate-urethane copolymers, followed by annealing at 248° F for one hour to increase flexibility and reduce rigidity, allowing the medical articles to bend up to 120° without kinking, and incorporating a hub and tip formation for improved functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing sheaths and catheters are made with standard rigidity, then they maintain structural integrity, but they kink when bent to certain radii of curvature disrupting fluid flow
Solution Approach 1:
The patent applies parameter changes by heat treating the polymer at temperatures between 150°C and 250°C to permanently alter its physical properties. This heat treatment modifies the polymer's glass transition temperature and reduces its rigidity, enabling the catheter to bend to smaller radii of curvature without kinking while maintaining structural integrity for reliable fluid flow.
Solution Approach 2:
The patent uses composite materials by selecting polymers with specific properties (such as polycarbonate-urethane copolymers) and combining heat treatment with the material's inherent viscoelastic properties. This creates a composite system where the heat-treated polymer exhibits both flexibility for manipulation and structural integrity for maintaining fluid flow continuity.
2Ease of operation
If the catheter is made more flexible to allow manipulation, then ease of insertion improves, but the catheter becomes prone to re-kinking at smaller angles
Solution Approach 1:
The patent applies preliminary action by performing heat treatment on the polymer before the catheter is used in the body. This pre-treatment permanently sets the polymer's physical properties to achieve optimal flexibility-resilience balance, allowing the catheter to be easily manipulated during insertion while resisting re-kinking during use without requiring additional adjustments.
3Ease of operation
If the polymer rigidity is reduced to increase flexibility, then the catheter can bend more easily, but the structural strength decreases
Solution Approach 1:
The patent precisely controls parameter changes by heat treating the polymer within specific temperature ranges (150°C to 250°C) and time periods (30 minutes to 24 hours). This controlled parameter change reduces rigidity to achieve flexibility while maintaining sufficient structural strength, as evidenced by the catheter's ability to withstand pressures up to 300 psi and flow rates up to 130 ml/min.
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 medical articles with enhanced flexibility, memory, kink-resistance, and resilience, enabling them to withstand pressures up to 300 psi and flow rates of 130 ml/min without kinking, improving their performance and comfort during insertion and use.
Implementation Method 1
heat treating the flexible medical article by annealing under conditions of, for example, 248° F. for one hour
Implementation Method 2
heat treating the tubular shaft by annealing under conditions of, for example, 248° F. for one hour
Implementation Method 3
the polymer is selected have the property of reduced rigidity (i.e., increased flexibility) when exposed to heat
Data Source
AI summary
A method of making a flexible medical article or tube, for example, a sheath for a vascular access device, is provided. The method can include extruding a polymer, for example, a polycarbonate-urethane copolymer, to form a tube and annealing the extruded polymer. The method can further include cutting the extruded tube to a desired length before or after annealing, flaring one end of the annealed tube and over-molding the flared portion onto a hub, and forming the other end of the tube into a tip. A sheath formed by such a method is also provided.