Retractable Catheter Embedded Pull Element Friction Reduction
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Solution Overview
Problem
Conventional implant catheter delivery systems face challenges with increased friction forces due to longer implants, requiring higher retracting forces that can lead to deflection or breakage of the inner shaft, and thicker diameters that limit treatment options and increase the risk of injury in narrow bodily lumens.
Innovation Solution
A retractable catheter with an elongate tubular sheath made of flexible material and a pull element with an end portion embedded within, where the thickness is less than its length, reducing the need for additional connecting elements and allowing for improved force transmission without increasing the overall diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the implant length is increased, then the treatment capability is improved, but the friction force between the implant and outer sheath increases, requiring higher retracting forces
Solution Approach 1:
The invention extracts the connection mechanism from the conventional external ring configuration and embeds it within the outer sheath material. The pull element's end portion is embedded in the flexible material of the outer sheath, with at least its thickness being substantially less than its length, creating a low-profile connection that reduces friction and allows easier retraction of longer implants
Solution Approach 2:
The invention transitions from a two-dimensional external connection (rings on the outside of the sheath) to a three-dimensional embedded connection within the sheath material. This dimensional change allows the pull element to be integrated within the sheath structure, reducing the overall device profile and minimizing friction forces during retraction
2Force
If the retracting force is increased to handle longer implants, then the friction force is overcome, but the inner shaft may deflect or move under compression
Solution Approach 1:
The invention removes the need for thick external rings and complex connection mechanisms by embedding the pull element directly within the outer sheath material. This extraction of the connection mechanism reduces the overall force requirements and eliminates the stability issues associated with high retracting forces
3Strength
If additional connecting elements like outer rings are added to connect the pull wire to the sheath, then the connection strength is improved, but the device diameter increases
Solution Approach 1:
The invention merges the pull element connection with the outer sheath structure by embedding the end portion of the pull element within the flexible material of the outer sheath. This integration eliminates the need for separate external rings and connecting elements, maintaining connection strength while minimizing device diameter
Solution Approach 2:
The pull element's end portion is nested within the outer sheath material, with the thickness of the end portion being substantially less than its length. This nesting arrangement allows the connection mechanism to be contained within the sheath structure, avoiding external additions that would increase device diameter
4Reliability
If the outer rings are clamped onto the inner ring to prevent relative movement, then the connection reliability is improved, but the thickness of the device increases
Solution Approach 1:
The invention combines the connection function with the outer sheath structure itself, eliminating the need for separate clamping rings. The pull element is directly embedded in the flexible material of the outer sheath, creating a reliable connection without the additional thickness required for external clamping mechanisms
Data Source
AI summary
A retractable catheter for use in an implant delivery system, the catheter including an elongate tubular sheath made of a relatively flexible material, and a pull element for transmitting a pull force to the sheath to retract it longitudinally. The pull element includes an end portion disposed in the relatively flexible material, at least the thickness of the end portion being substantially less than its length.