Drug-Polymer Coating Fracture Resistance via Staged Crimping
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Solution Overview
Problem
Current drug-eluting medical devices face challenges in maintaining coating integrity under external loads, leading to cracking and peeling issues that can compromise drug dosage control and release, with existing methods failing to predictably prevent these issues without extensive device-specific testing.
Innovation Solution
A method involving forming a polymer stent body, reducing its diameter, applying a drug-polymer coating, and crimping in stages with relaxation periods, followed by baking to increase fracture resistance, which reduces instances of cracking and peeling without altering the stent's functionality or drug release profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a drug-polymer coating is applied to a stent and then the stent is crimped to delivery diameter, then the stent can be delivered through catheters, but the coating may crack or peel due to mechanical deformation
Solution Approach 1:
The patent applies preliminary action by coating the stent with the drug-polymer coating BEFORE the crimping process, and then performing controlled baking to pre-set the coating's mechanical properties. This preliminary preparation ensures the coating is properly adhered and conditioned before undergoing the mechanical deformation of crimping, thereby preventing crack and peel formation during delivery.
Solution Approach 2:
The patent employs parameter changes by controlling the baking temperature and time parameters after coating application. By adjusting these thermal parameters, the coating's fracture resistance is modified to match the mechanical demands of subsequent crimping and deployment, resolving the contradiction between deliverability and coating integrity.
2Manufacturing precision
If the stent diameter is reduced to an intermediate diameter before coating, then the coating process is improved, but additional processing steps are required
Solution Approach 1:
The stent diameter is reduced to an intermediate diameter before coating application as a preliminary action. This intermediate state provides optimal geometric characteristics for uniform coating deposition, allowing the coating process to be performed more effectively before the final crimping to delivery diameter.
3Reliability
If the stent is crimped in multiple stages with relaxation periods, then coating fracture resistance is increased, but manufacturing time is extended
Solution Approach 1:
The crimping process is segmented into multiple stages with intermediate relaxation periods. This segmentation allows the coating and stent structure to progressively adapt to deformation, reducing stress concentration and preventing crack formation. The multi-stage approach divides the total deformation into manageable increments, each followed by a relaxation period that enables stress dissipation.
Solution Approach 2:
The crimping process employs periodic action through alternating cycles of deformation and relaxation. Each crimping stage is followed by a relaxation period, creating a rhythmic process that allows the material to periodically recover and redistribute stresses, thereby enhancing coating fracture resistance without excessive time extension.
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 method significantly reduces cracking and peeling in the drug-polymer coating, enhancing the stent's fracture resistance and maintaining the integrity of the polymer scaffolding and drug release characteristics, potentially avoiding the need for additional clinical trials.
Implementation Method 1
baking the polymer coating and scaffolding to increase fracture resistance in the coating and scaffolding
Implementation Method 2
After each reduction in diameter a relaxation period is used to relieve stress/strain in the coating and scaffolding
Data Source
AI summary
Methods for increasing the fracture resistance of a polymer stent's drug-polymer coating and scaffolding including applying a coating and crimping using techniques that increase the resistance to fracture in the coating layer and scaffolding and scaffolding.