Humidity-Controlled Crimping of Bioabsorbable Polymeric Stents

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Solution Overview

Problem

Current stent crimping technologies damage polymeric stents and their coatings due to shear forces, stress cracking, and variability in strut and balloon dimensions, leading to potential stent dislodgment during delivery and compromised coating integrity.

Innovation Solution

A crimping process and device that utilize high and controlled humidity, and a plasticizing agent to reduce the glass transition temperature and shore hardness of polymeric stents, minimizing shear forces and stress, and maintaining humidity during the crimping process to absorb moisture and reduce brittleness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional crimping methods (roll crimper, collet crimper, iris crimper) are used, then stent crimping can be performed, but polymeric coatings are damaged due to shear forces and stress cracking

Engineering Contradiction:

Improvestent crimping capabilityVSAvoidcoating damage

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical-chemical parameters of the polymeric coating by exposing it to humidity or plasticizing agents before crimping. This reduces the glass transition temperature and shore hardness of the polymer, making it more ductile and less prone to cracking and delamination during the crimping process.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies a preliminary treatment to the polymeric stent or coating before crimping by exposing it to humidity or plasticizing agents. This pre-treatment modifies the polymer properties in advance, reducing brittleness and preventing damage during the subsequent crimping operation.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If standard crimping processes are used, then stent delivery can proceed, but stent retention is compromised due to dislodgment and stripping

Engineering Contradiction:

Improvestent delivery efficiencyVSAvoidstent retention

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

By modifying the polymeric material properties through humidity or plasticizing agent exposure, the crimping process achieves better stent retention without compromising delivery efficiency. The reduced glass transition temperature and shore hardness enable more effective crimping that prevents stent dislodgment during delivery.

Inventive Principle:

Principle #35Parameter changes

3Strength

If polymeric stents with high glass transition temperature are crimped, then structural integrity is maintained, but brittleness increases causing cracking and delamination

Engineering Contradiction:

Improvepolymer structural integrityVSAvoidstress cracking

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent temporarily changes the physical-chemical parameters of the polymeric material by reducing its glass transition temperature through humidity or plasticizing agent exposure. This transformation makes the normally brittle polymer ductile during crimping, preventing cracking and delamination while maintaining structural integrity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent exploits a phase transition in the polymeric material by inducing a temporary shift from a glassy, brittle state to a more ductile state through humidity or plasticizing agent exposure. This phase change enables the polymer to withstand crimping stresses without cracking, after which it returns to its original state.

Inventive Principle:

Principle #36Phase transitions

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 method effectively minimizes damage to polymeric stents and coatings by reducing shear forces and stress, enhancing stent retention and coating integrity during crimping, while allowing for controlled release of drugs and maintaining vascular compatibility.

Implementation Method 1

utilize high and controlled humidity, and a plasticizing agent to reduce the glass transition temperature and shore hardness of polymeric stents

Methodology Applied

Scientific EffectGlass transition temperature reduction:

Implementation Method 2

maintaining humidity during the crimping process to absorb moisture and reduce brittleness

Methodology Applied

Scientific EffectMoisture absorption: Absorption (physical)

Implementation Method 3

utilize high and controlled humidity, and a plasticizing agent to reduce the glass transition temperature and shore hardness of polymeric stents

Methodology Applied

Scientific EffectShore hardness reduction:

Data Source

PatentUS9375334B2Crimping method

Publication Date: 2016.06.28 ABBOTT CARDIOVASCULAR SYSTEMS INC

AI summary

A method for crimping a bioabsorbable stent in a humid environment is disclosed.