Thin-Walled Scaffold Crimping Using Polymer Sheaths
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Solution Overview
Problem
Existing methods for crimping polymer scaffolds to balloon catheters result in unsatisfactory uniformity, structural integrity, and retention issues, particularly for thin-walled scaffolds, leading to twisted, cracked, or fractured struts and non-uniform expansion.
Innovation Solution
A crimping process using polymer material between the scaffold and crimper blades, with intermittent adjustments and re-setting of polymer sheets to minimize interference and ensure uniform crimping, maintaining structural integrity and retention force while avoiding balloon over-stretch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer scaffold is crimped to a balloon catheter using conventional methods, then the scaffold can be delivered to the target site, but the scaffold struts become twisted, cracked, or fractured and expansion is non-uniform
Solution Approach 1:
The polymer material is positioned between the scaffold and crimper blades before crimping begins. This preliminary placement of the polymer cushioning material prevents direct contact between the blades and scaffold struts, eliminating the mechanism that causes strut twisting, cracking, and fracturing during the crimping process.
Solution Approach 2:
A layer of polymer material is placed between the crimper blades and the scaffold struts to provide cushioning during compression. This cushioning layer distributes the compressive forces uniformly across the scaffold surface, preventing stress concentration that would otherwise cause strut damage and non-uniform expansion.
2Reliability
If polymer material is placed between the scaffold and crimper blades, then strut damage is prevented, but the polymer material may interfere with the crimping process
Solution Approach 1:
The polymer material is discarded after a single use in the crimping process. This disposable approach eliminates the need for complex removal mechanisms or cleaning procedures, simplifying the overall process while maintaining scaffold integrity. The polymer is placed before crimping and then discarded with the crimper assembly after use.
3Length of moving object
If the scaffold is crimped to reduce the crossing profile, then delivery through narrow vessels is enabled, but the scaffold may dislodge or separate from the balloon
Solution Approach 1:
The polymer material is positioned in advance between the scaffold and crimper blades to ensure uniform compression during crimping. This preliminary placement prevents localized stress concentrations that could cause scaffold distortion or detachment from the balloon, ensuring reliable retention while achieving the reduced crossing profile.
Data Source
AI summary
A medical device includes a balloon expanded scaffold crimped to a catheter having a balloon. The scaffold has a network of rings formed by struts connected at crowns and links connecting adjacent rings. The scaffold is crimped to the balloon by a process that includes using protective polymer sheaths or sheets during crimping, and adjusting the sheaths or sheets during the crimping to avoid or minimize interference between the polymer material and scaffold struts as the scaffold is reduced in size.