Bioabsorbable Composite Stent with Elastomeric Struts
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Solution Overview
Problem
Existing stents, particularly those made from polymers, face challenges such as brittle fracture, reduced radial strength, and limited ability to collapse and expand, making them unsuitable for dynamic loading conditions in arteries like the superficial femoral artery (SFA).
Innovation Solution
A composite stent structure is fabricated using one or more layers of bioabsorbable polymers, with high-strength polymeric ring structures connected by elastomeric polymeric substrates. This structure is designed to withstand complex, multi-axial loading conditions through precise geometric tolerances and controlled molecular orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polymeric stents are fabricated through extrusion or injection molding, then manufacturing process is simple, but the stent has reduced wall thickness and imprecise geometric tolerances making it susceptible to brittle fracture
Solution Approach 1:
The patent employs a composite structure consisting of a polymeric stent framework reinforced with a metallic mesh or braid layer. The metallic reinforcement provides tensile strength and fracture resistance to the polymeric material, which otherwise suffers from brittleness when fabricated through conventional molding processes. This composite construction allows the stent to maintain thin wall thickness while achieving the mechanical reliability needed for vascular implantation.
2Ease of operation
If stent wall thickness is reduced, then flexibility and ability to collapse for delivery is improved, but radial strength and resistance to fracture are reduced
Solution Approach 1:
The thin-walled polymeric stent is reinforced with a metallic mesh or braid that provides the necessary radial strength and fracture resistance. The metallic reinforcement layer acts as an exoskeleton that enables the thin polymeric walls to withstand compressive forces during delivery and maintain structural integrity during expansion, resolving the contradiction between wall thickness reduction and strength maintenance.
Solution Approach 2:
The stent structure is divided into two functional components: a thin polymeric framework that provides flexibility and collapse capability, and a metallic reinforcement layer that provides radial strength. This segmentation allows each material to perform its optimal function without compromising the other.
3Manufacturing precision
If stent is made from brittle material, then manufacturing precision can be achieved, but the stent has limited ability to deform and expand without failure
Solution Approach 1:
The combination of polymeric material with controlled geometric precision and metallic reinforcement creates a composite structure that maintains precise manufacturing tolerances while gaining the ductility and deformability needed for successful stent delivery and expansion. The metallic layer accommodates deformation stresses that would cause brittle failure in the polymeric material alone.
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 composite stent structure achieves enhanced radial strength, flexibility, and durability, allowing it to maintain its position securely within the vessel while accommodating the vessel's range of motion without impeding physiological compression and bending.
Implementation Method 1
elastomeric polymeric substrates. This structure is designed to withstand complex, multi-axial loading conditions
Data Source
AI summary
A bioabsorbable composite stent structure, comprising bioabsorbable polymeric ring structures which retain a molecular weight and mechanical strength of a starting substrate and one or more interconnecting struts which extend between and couple adjacent ring structures. The ring structures can have a formed first diameter and being radially compressible to a smaller second diameter and re-expandable to the first diameter. The ring structures can comprise a base polymeric layer. The interconnecting struts can be formed from a polymer blend or co-polymer of poly-L-lactide (PLLA) and an elastomeric polymer. The interconnecting struts each can have a width that is less than a circumference of one of the ring structures. The adjacent ring structures can be axially and rotationally movable relative to one another via the interconnecting struts. The interconnecting struts can also be bioabsorbable.