Stent Surface Roughness for Balloon Retention and Vessel Trackability
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Solution Overview
Problem
Preferentially electropolished stent systems face challenges with poor retention on balloon catheters due to smooth surfaces, which enhance trackability but lead to dislodgment during delivery.
Innovation Solution
A stent delivery system with an abluminal surface roughness of ≤0.030 microns and a luminal surface roughness ≥0.036 microns, achieved through selective electropolishing using a DC source, electrolyte bath, and electrode setup, maintaining surface roughness on the luminal surface while smoothing the abluminal surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stent surface is polished to be smooth, then trackability is improved, but retention on balloon is worsened
Solution Approach 1:
The patent applies different surface roughness characteristics to different surfaces of the stent: the abluminal surface is electropolished to a smooth finish (Ra ≤ 0.030 microns) to improve trackability, while the luminal surface maintains a rougher texture (Ra ≥ 0.036 microns) to improve retention on the balloon catheter during delivery. This local differentiation of surface properties resolves the contradiction between trackability and retention.
2Object-affected harmful factors
If the abluminal surface is electropolished, then biocompatibility is improved, but manufacturing complexity increases
Solution Approach 1:
The electropolishing process is applied selectively only to the abluminal surface of the stent, which is the surface that contacts the blood vessel wall and requires high biocompatibility. The luminal surface is excluded from electropolishing and maintains its rougher, more manufacturable state. This localized application of the complex electropolishing process improves biocompatibility while minimizing the increase in manufacturing complexity.
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 approach significantly increases stent trackability and retention force, reducing the force required for delivery while maintaining biocompatibility and preventing dislodgment.
Implementation Method 1
operating the electropolishing apparatus to preferentially remove surface material from the abluminal surface without removing surface material from at least a portion of the luminal surface to electropolish the abluminal surface
Data Source
AI summary
The preferentially electropolished stent system and method of manufacture includes a stent delivery system including a catheter; a balloon operably attached to the catheter; and a stent disposed on the balloon. The stent includes an elongate body having an abluminal surface and a luminal surface; wherein the abluminal surface has an abluminal average roughness less than or equal to 0.030 microns; and the luminal surface has at least one rough portion having an luminal average roughness greater than or equal to 0.036 microns.