Polymer Scaffold Crimping Temperature Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polymeric scaffolds used in drug-eluting medical devices face challenges in retaining structural integrity during crimping and deployment due to their brittle nature and anisotropic properties, leading to potential crack formation and loss of strength, as well as issues with retention on balloons during transit through tortuous anatomy.
Innovation Solution
A process for crimping a polymer scaffold to a balloon involves heating the scaffold to a temperature range just below its glass transition temperature, optimizing crimping parameters such as temperature, pressure, and hold time to enhance retention force while minimizing structural damage, and using deionization to prevent electrostatic charges that cause irregular deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the scaffold is crimped at room temperature, then the structural integrity is maintained, but the retention force on the balloon is insufficient
Solution Approach 1:
The patent applies parameter changes by heating the polymeric scaffold to a temperature range of 37°C to 70°C (optimally 45°C to 65°C) before crimping. This temperature elevation modifies the polymer's mechanical properties, increasing its ductility and allowing it to conform to the balloon surface for improved retention while maintaining structural integrity through controlled thermal activation.
2Force
If the scaffold is crimped at elevated temperature, then the retention force is improved, but cracking and loss of strength occur
Solution Approach 1:
The patent precisely controls the temperature parameter within 37°C to 70°C (optimally 45°C to 65°C) to achieve the desired balance. This controlled thermal parameter change softens the polymer sufficiently for crimping and balloon conformation while avoiding temperatures that would cause excessive softening, cracking, or permanent structural damage.
Solution Approach 2:
The patent applies preliminary heating to the scaffold before the crimping process. This preliminary thermal action prepares the polymer material by increasing its ductility and conformability, allowing the subsequent crimping to proceed without causing cracking or structural damage while still achieving adequate retention force.
3Strength
If the scaffold is made from thicker struts to improve strength, then the structural integrity is enhanced, but the scaffold becomes more prone to cracking during crimping
Solution Approach 1:
The patent changes the temperature parameter to 37°C-70°C before crimping, which temporarily modifies the mechanical properties of the polymer. This thermal parameter change increases ductility and reduces cracking susceptibility during crimping, allowing thicker struts to be crimped without the same level of damage risk, while maintaining their enhanced strength characteristics.
4Force
If the crimping pressure is increased to improve retention, then the retention force is enhanced, but irregular deformations and cracking increase
Solution Approach 1:
The patent applies a two-parameter change strategy: heating to 37°C-70°C and maintaining it during crimping. This thermal parameter modification allows higher crimping pressures to be applied without causing irregular deformations or cracking, as the softened polymer can accommodate the increased mechanical stress more uniformly.
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 process significantly improves the retention force of the scaffold on the balloon without causing unacceptable cracking or loss of strength, reducing rejection rates and ensuring the scaffold's structural integrity during deployment.
Implementation Method 1
heating the scaffold to a temperature range just below its glass transition temperature
Implementation Method 2
using deionization to prevent electrostatic charges that cause irregular deformations
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A medical device includes a polymer scaffold crimped to a catheter having an expansion balloon. The scaffold is crimped to the balloon by a process that includes heating the scaffold to a temperature below the polymer's glass transition temperature to improve scaffold retention without adversely affecting the mechanical characteristics of the scaffold when later deployed to support a body lumen. Additionally, before crimping begins the scaffold is placed on a support by an alignment carriage and deionized to remove any static charge buildup on the scaffold before placing the scaffold within the crimping mechanism.