Uniform Expansion of Thin-Walled Scaffolds via Protective Crimping
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Solution Overview
Problem
Existing methods for crimping polymer scaffolds to balloon catheters result in non-uniform expansion, structural damage, and reduced retention force, particularly for thin-walled scaffolds, leading to potential failure and reduced fatigue life.
Innovation Solution
A crimping process using a polymer material as a protective sheet between the scaffold and crimper blades, with intermittent adjustments and re-setting of the polymer material, along with controlled balloon pressurization to maintain small folds and ensure uniform radial pressure, thereby preventing excessive strain and ensuring structural integrity and uniform expansion.
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 treatment site, but the scaffold expands non-uniformly and suffers structural damage
Solution Approach 1:
The patent applies preliminary action by pre-coating the scaffold with a protective polymer material before crimping. This protective coating is applied in advance to prevent structural damage during the crimping process and ensure uniform expansion during deployment. The coating is applied before the scaffold is crimped to the balloon catheter, preparing the scaffold to withstand the mechanical stresses of delivery and deployment.
Solution Approach 2:
The patent implements beforehand cushioning by using a protective polymer coating that cushions the scaffold struts during crimping. This protective layer absorbs and distributes the mechanical stresses applied during crimping, preventing direct contact between the crimper blades and the scaffold structure. The cushioning effect is maintained throughout the delivery and deployment process, protecting the scaffold from structural damage while ensuring uniform expansion.
2Reliability
If the scaffold wall thickness is reduced to improve biocompatibility, then healing is improved, but the scaffold becomes more prone to fracture during crimping
Solution Approach 1:
The patent applies beforehand cushioning by coating thin-walled scaffolds with a protective polymer material before crimping. This protective coating cushions the delicate thin walls during the crimping process, distributing mechanical stresses and preventing fracture. The cushioning layer compensates for the reduced inherent strength of thin-walled scaffolds, enabling them to withstand crimping forces while maintaining their thin-wall design for improved biocompatibility and healing.
Solution Approach 2:
The patent employs composite materials by combining the polymer scaffold with an additional protective polymer coating. This creates a composite structure where the scaffold provides the structural framework for vascular support while the protective coating enhances fracture resistance during crimping and deployment. The composite approach allows the scaffold to maintain thin walls for biocompatibility while gaining the mechanical protection needed for safe delivery.
3Length of moving object
If crimping pressure is increased to reduce scaffold diameter for delivery, then the crossing profile is improved, but the scaffold suffers structural damage
Solution Approach 1:
The patent applies beforehand cushioning by pre-coating the scaffold with a protective polymer material that cushions the struts during high-pressure crimping. This protective layer allows higher crimping pressures to be applied to achieve smaller crimped diameters for improved crossing profiles, while the cushioning coating prevents direct transmission of damaging forces to the scaffold structure. The coating absorbs and distributes the compressive forces, enabling aggressive crimping without structural damage.
Solution Approach 2:
The patent uses an intermediary protective polymer coating that mediates between the crimper blades and the scaffold structure during high-pressure crimping. This intermediary layer allows the transmission of crimping force to achieve small crimped diameters while protecting the scaffold from direct contact with the crimper blades. The protective coating acts as a buffer that enables high crimping pressures to be applied safely, reducing the scaffold diameter for improved deliverability without causing structural damage.
4Force
If the scaffold is crimped tightly to the balloon to improve retention force, then retention is enhanced, but uniform expansion is compromised
Solution Approach 1:
The patent applies preliminary action by pre-coating the scaffold with a protective polymer material that enables tight crimping without compromising expansion uniformity. This protective coating is applied before crimping, allowing the scaffold to be compressed tightly against the balloon to maximize retention force. The coating maintains its protective function throughout the tight crimping process and during subsequent expansion, ensuring that the scaffold expands uniformly despite the aggressive crimping that maximizes retention.
Solution Approach 2:
The patent implements beforehand cushioning by coating the scaffold with a protective polymer material that cushions the struts during tight crimping to the balloon. This protective layer allows the scaffold to be compressed tightly against the balloon to maximize retention force while preventing direct contact forces that would cause non-uniform expansion. The cushioning coating distributes the compressive forces evenly, enabling tight crimping for enhanced retention while maintaining the potential for uniform expansion during deployment.
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 enhances the structural integrity and uniformity of scaffold expansion, reduces the risk of fracture, and maintains a high retention force between the scaffold and balloon, ensuring safe delivery and effective deployment.
Implementation Method 1
The polymer material is disposed between the struts of the scaffold and the faces of the crimper blades... preventing excessive strain and ensuring structural integrity
Implementation Method 2
controlled balloon pressurization to maintain small folds and ensure uniform radial pressure, thereby preventing excessive strain and ensuring structural integrity and uniform expansion
Data Source
AI summary
A medical device includes a balloon expanded scaffold (or stent) crimped to a catheter having a balloon. The scaffold is crimped to the balloon by a process that includes using protective polymer sheaths or sheets during crimping, and resetting 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. Balloon pressure is adjusted when the polymer material is reset.