Radiopaque Marker Rivet Structure for Thin Scaffold Struts
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Solution Overview
Problem
Bioresorbable polymer scaffolds lack reliable methods for securely attaching radiopaque markers, which can dislodge during crimping and balloon expansion due to significant plastic deformation, and thicker struts are needed for strength but increase thrombogenicity.
Innovation Solution
The use of reshaped radiopaque rivets, such as platinum beads, secured through a cold-forming process to create a trapezoidal shank, ensures reliable attachment and reduces strut thickness to minimize thrombogenicity and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If radiopaque markers are attached to scaffold struts, then visualization capability is improved, but markers dislodge during crimping and balloon expansion due to plastic deformation
Solution Approach 1:
The marker attachment structure is designed in advance with a retention mechanism that anticipates the plastic deformation forces during crimping and balloon expansion. The strut incorporates features such as holes, grooves, or recesses that are pre-configured to mechanically interlock with the marker, ensuring the marker remains securely attached throughout the delivery and deployment process despite significant radial compression and expansion forces.
Solution Approach 2:
The strut is designed with localized structural features at specific positions where markers will be attached. These local modifications (such as enlarged holes, recesses, or reinforced zones) provide enhanced marker retention precisely at the marker attachment sites, while the rest of the strut maintains its optimized thin profile for low thrombogenicity. This allows different parts of the strut to have different functional properties.
2Strength
If thicker struts are used to provide radial strength, then structural support is improved, but thrombogenicity increases
Solution Approach 1:
The strut design incorporates localized thickening only at specific critical positions where radial strength is most needed (such as at crown regions or marker attachment sites), while the majority of the strut length maintains a thin profile. This allows the scaffold to provide adequate radial support at critical locations without increasing overall thrombogenicity from thicker struts throughout the entire vessel contact surface.
Solution Approach 2:
The scaffold utilizes composite construction combining materials with different properties to achieve optimal balance between radial strength and thrombogenicity. This may involve using a bioresorbable polymer matrix with strategically placed radiopaque marker materials or reinforcing phases that provide enhanced mechanical strength at specific locations without requiring uniform thickening of the entire strut structure.
3Ease of manufacture
If traditional marker attachment methods are used, then manufacturing is simplified, but markers dislodge during plastic deformation
Solution Approach 1:
The marker attachment structure is designed and integrated into the strut manufacturing process itself, rather than requiring separate complex assembly steps. The strut is formed with pre-configured holes, grooves, or recesses that naturally provide marker retention, allowing markers to be attached through simple insertion or bonding processes that are easily automated while ensuring reliable marker retention during subsequent crimping and balloon expansion.
4Reliability
If markers are securely attached through complex processes, then marker retention is improved, but manufacturing complexity and costs increase
Solution Approach 1:
The marker retention functionality is built into the strut structure during the primary manufacturing process, eliminating the need for separate complex marker attachment steps. The strut is formed with integrated features (holes, grooves, recesses) that provide mechanical interlocking for markers, allowing simple marker insertion or bonding that can be easily automated. This approach achieves reliable marker retention while keeping the overall manufacturing process simple and suitable for high-volume production.
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 solution provides secure attachment of radiopaque markers while maintaining a low profile, reducing thrombosis risk and manufacturing costs, and enabling automated assembly.
Implementation Method 1
The use of reshaped radiopaque rivets, such as platinum beads, secured through a cold-forming process to create a trapezoidal shank
Data Source
Figure 1
Figure 2
Figure 2A~2B
AI summary
A scaffold includes a radiopaque marker connected to a strut. The marker is retained within the strut by a head at one or both ends. The marker is attached to the strut by a process that includes forming a rivet from a radiopaque bead and attaching the rivet to the marker including deforming the rivet to enhance resistance to dislodgement during crimping or balloon expansion. The strut has a thickness of about 100 microns.