Polyamide Introducer Sheath Kink Resistance
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Solution Overview
Problem
Existing introducer sheaths face a challenge in achieving a balance between a large inner diameter for smooth catheter insertion and minimal outer diameter for reduced insertion resistance, while maintaining sufficient kink resistance to prevent deformation during medical procedures.
Innovation Solution
The introducer sheath is designed with a tubular body made of polyamide resin containing a structural unit derived from a cyclic aliphatic hydrocarbon, featuring a wall thickness/inner diameter ratio of 1/14 or less and a kink radius/outer diameter ratio of less than 10, enhancing kink resistance while allowing for a larger inner diameter and thinner wall thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the wall thickness of the tubular body is decreased to achieve a large inner diameter and small outer diameter, then the insertion resistance is reduced and catheter introduction is facilitated, but the kink resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight distribution of the polyamide resin, specifically setting the weight average molecular weight between 10,000-100,000 and the number average molecular weight between 5,000-50,000, with a ratio of 2.0-5.0. This molecular parameter optimization enables the tubular body to achieve both thin wall thickness (improving insertion properties) and sufficient kink resistance simultaneously
Solution Approach 2:
The patent uses composite material strategy by formulating a specific polyamide resin composition containing structural units derived from cyclic aliphatic hydrocarbons (10-50 mol%) combined with aliphatic dicarboxylic acid units and aliphatic diamine units. This composite resin structure provides both the flexibility needed for thin-walled construction and the structural integrity for kink resistance
2Strength
If a rigid material is used to increase the kink resistance of the tubular body, then the kink resistance is improved, but the flexibility deteriorates leading to poor followability to body lumen
Solution Approach 1:
The patent applies parameter changes by optimizing the molecular weight parameters of the polyamide resin, specifically controlling the weight average molecular weight (10,000-100,000), number average molecular weight (5,000-50,000), and their ratio (2.0-5.0). These parameter adjustments create a material with balanced rigidity and flexibility, enabling both kink resistance and followability to body lumen
3Adaptability or versatility
If a flexible material is used to improve the followability to body lumen, then the flexibility is improved, but the kink resistance deteriorates
Solution Approach 1:
The patent applies composite material principle by creating a polyamide resin with a specific composition: structural units from cyclic aliphatic hydrocarbons (10-50 mol%), aliphatic dicarboxylic acid units (30-70 mol%), and aliphatic diamine units (20-60 mol%). This composite structure provides the flexibility for followability while maintaining kink resistance through the crystalline regions formed by the dicarboxylic acid and diamine units
Data Source
AI summary
An introducer sheath includes a tubular body configured to be percutaneously inserted into a body lumen and a hub that is connected to a proximal portion of the tubular body, wherein the tubular body contains a polyamide resin having a structural unit derived from a cyclic aliphatic hydrocarbon, and a wall thickness/inner diameter ratio of the tubular body is 1/14 or less, and a kink radius/outer diameter ratio of the tubular body is less than 10.