Implant Engagement Member Assembly for Clean Stent Decoupling
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Solution Overview
Problem
Existing delivery devices face challenges in efficiently decoupling stents from pushers due to excessive coupling force, leading to temporary sticking and inefficient deployment.
Innovation Solution
A method involving the creation of recesses in an implant engagement member by pressing the sidewall of a tubular structure into the member's surface, followed by hardening, to facilitate efficient decoupling and deployment of implants like stents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the coupling force between the pusher and the stent is increased to overcome frictional force during delivery, then the stent can be advanced effectively, but the stent may stick to the pusher after deployment and fail to decouple efficiently
Solution Approach 1:
The engagement member features a hardened surface layer (e.g., through nitriding, carburizing, or plasma treatment) that provides high friction for gripping the stent during delivery, while the bulk material remains softer to allow controlled deformation and easy decoupling after deployment. This local differentiation of material properties resolves the contradiction between needing strong coupling force and easy decoupling.
Solution Approach 2:
The engagement member is designed to transition from a rigid gripping state during delivery to a more compliant state after deployment, allowing the stent to decouple naturally. The hardened surface maintains grip during advancement, but after the stent is deployed past the engagement member, the engagement member can deform or release its grip, enabling clean decoupling without sticking.
2Force
If the engagement member surface is made harder to maintain grip and overcome friction, then delivery force is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The engagement member undergoes surface hardening treatments (such as nitriding, carburizing, induction hardening, or plasma spraying) that modify the surface properties without changing the bulk material composition. This allows the same base material to be used throughout, simplifying manufacturing while achieving the required high friction surface for effective stent gripping and delivery.
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 allows for seamless decoupling and immediate expansion of implants, ensuring efficient delivery and deployment without temporary sticking, using grooves that provide sufficient hardness to overcome frictional forces.
Implementation Method 1
heating the implant engagement member
Implementation Method 2
after the recesses are created in the surface of the implant engagement member, hardening the implant engagement member
Data Source
AI summary
A method of assembling an apparatus for delivering an implant to a deployment site in a patient's vasculature, includes: positioning an implant engagement member at least partially within a lumen of a tubular structure, the tubular structure having a sidewall comprising a pattern of wires or struts; heating the implant engagement member; pressing at least a portion of the sidewall of the tubular structure radially inward into a surface of the implant engagement member so that the wires or the struts of the sidewall penetrate into the surface and create corresponding recesses therein; and after the recesses are created in the surface of the implant engagement member, hardening the implant engagement member.