Helicoidal Stent Platinum Strand Length Control
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Solution Overview
Problem
Stents formed by helicoidally braiding metal strands, particularly those made of materials like stainless steel, Co—Cr alloy, and Ni—Ti alloy, are not visible under X-ray, making it difficult to confirm their implantation position in patients, and strands made of platinum alloy tend to protrude from the stent due to differences in material properties.
Innovation Solution
The stent is designed with some strands made of a platinum alloy material, specifically platinum-iridium alloy, having a non-transmissive property under X-rays, with these strands being shorter than others to prevent protrusion, and strategically placed to ensure even extension and consistent cross-sectional shape, with two strands in the same winding direction used to maintain structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If platinum alloy strands are used in the stent, then X-ray visibility is improved, but strand protrusion from stent ends occurs
Solution Approach 1:
The patent applies local quality by making the platinum alloy strands shorter than the other strands. Specifically, the platinum alloy strands have a length that is 0.5mm to 2.0mm shorter than the non-platinum strands, creating a localized length difference that prevents protrusion while maintaining X-ray visibility in the critical regions where platinum strands are needed for imaging.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and pre-setting the strand lengths during manufacturing to account for the protrusion tendency of platinum alloy material. The strand lengths are determined in advance based on the expected protrusion amount, so that when the stent is deployed and extends, the platinum strands do not protrude from the ends.
2Manufacturing precision
If platinum alloy strands are made shorter to prevent protrusion, then protrusion is prevented, but stent structural integrity may be compromised
Solution Approach 1:
The patent applies parameter changes by carefully controlling the length parameter of platinum alloy strands within a specific range (0.5mm to 2.0mm shorter than other strands). This parameter optimization ensures that the strands are short enough to prevent protrusion but not so short as to compromise the structural integrity and mechanical strength of the stent framework.
3Stability of the object's composition
If even-numbered strands are used for platinum alloy, then even extension is achieved, but strand configuration complexity increases
Solution Approach 1:
The patent applies asymmetry by strategically positioning platinum alloy strands at specific even-numbered locations (2nd, 4th, 6th, 8th strands) rather than using a symmetric alternating pattern. This asymmetric configuration achieves even extension during stent deployment while simplifying the overall strand arrangement compared to more complex symmetric patterns.
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 allows for the prevention of platinum alloy strands from protruding from the stent, ensures even extension, and maintains a consistent cross-sectional shape, enabling accurate X-ray visualization and effective deployment of the stent.
Implementation Method 1
the strand made of the platinum alloy material has a probability by nature to protrude from both ends of the stent when the stent extends... a strand made of a platinum alloy material which is the transmissive property with respect to the X ray
Data Source
AI summary
A strand made of a platinum alloy material is prevented from protruding from both ends of a stent when some strands of the stent are disposed using the strand made of the platinum alloy material. In a stent (10) which is formed by helicoidally braiding a plurality of strands, some strands among the plurality of strands are disposed using a strand made of a platinum alloy material, and a length of the strand made of the platinum alloy material is made shorter than lengths of other strands by a length of the strand made of the platinum alloy material which is estimated to protrude from the stent.