Nonexpandable Stent with Shape Memory Alloy Anchoring
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Solution Overview
Problem
Current biliary and pancreatic stents are limited to thermoplastic materials for ease of fabrication, restricting the use of polymers with desirable properties like biocompatibility and low durometer, which are not thermoplastic.
Innovation Solution
A nonexpandable stent design featuring a tubular body with a shape memory alloy reinforcement member that changes configuration from a delivery to a deployment state, allowing the stent to be formed from a wide range of polymers, including non-thermoplastic ones like Thoralon, using a method involving heat treatment, mandrel formation, and sequential polymer layering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the stent is made of thermoplastic material to facilitate fabrication and heat forming, then ease of manufacture is improved, but the ability to use polymers with desirable properties like biocompatibility and low durometer is limited
Solution Approach 1:
The stent is divided into two functional components: a polymer tubular body providing biocompatibility and low durometer properties, and a separate shape memory alloy reinforcement member providing structural support and shape memory functionality. This segmentation allows each component to be optimized independently for its specific function.
Solution Approach 2:
The stent combines two different materials with complementary properties: a biocompatible polymer (non-thermoplastic) for the tubular body and a shape memory alloy for the reinforcement member. This composite structure enables the stent to achieve both desirable polymer properties and metal structural advantages without being limited to thermoplastic materials only.
2Reliability
If the stent uses non-thermoplastic polymer to achieve desirable properties like biocompatibility and low durometer, then material performance is improved, but ease of fabrication is worsened
Solution Approach 1:
The stent is divided into two functional components: a polymer tubular body providing biocompatibility and low durometer properties, and a separate shape memory alloy reinforcement member providing structural support and shape memory functionality. This segmentation allows each component to be optimized independently for its specific function.
Solution Approach 2:
The shape memory alloy reinforcement member acts as an intermediary that enables the non-thermoplastic polymer tubular body to achieve proper structural support and shape memory functionality. The reinforcement member compensates for the limitations of non-thermoplastic polymers in providing structural integrity.
3Ease of operation
If the stent uses shape memory material for anchoring configuration change, then deployment functionality is improved, but device complexity is worsened
Solution Approach 1:
The stent is divided into two functional components: a polymer tubular body providing biocompatibility and low durometer properties, and a separate shape memory alloy reinforcement member providing structural support and shape memory functionality. This segmentation allows each component to be optimized independently for its specific function.
Solution Approach 2:
The shape memory alloy reinforcement member utilizes temperature-induced phase changes to transition between different structural configurations. By changing the temperature parameter, the material transforms between martensitic and austenitic phases, enabling automatic deployment of the pigtail anchoring elements without complex mechanical mechanisms.
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
Enables the use of polymers with desirable properties for biliary and pancreatic stents, providing effective anchoring and drainage while maintaining a nonexpandable diameter, thus overcoming the limitations of existing thermoplastic material constraints.
Implementation Method 1
The securing element includes a reinforcement member comprising a shape memory material. The securing element comprises a first configuration of the reinforcement member for delivery to a treatment site within a body vessel and a second configuration of the reinforcement member for deployment at the treatment site.
Data Source
Figure 1~2B
Figure 3~5B
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AI summary
Disclosed herein is a nonexpandable stent and a method of making and deploying the stent. The stent includes a tubular body having a distal portion, a proximal portion, a central longitudinal portion between the distal and proximal portions, and a substantially nonexpandable diameter. The stent includes at least one securing element. The securing element includes a reinforcement member comprising a shape memory material. The securing element comprises a first configuration of the reinforcement member for delivery to a treatment site within a body vessel and a second configuration of the reinforcement member for deployment at the treatment site.