Stent Loading Mechanism With Compliant Tube Gripping
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Solution Overview
Problem
The existing stent loading process faces challenges such as high force requirements that can damage stents, limited stent dimensions due to deformation of delivery catheters, and alignment issues during radial compression, which affect the precision and efficiency of stent loading.
Innovation Solution
A translating radial compression mechanism with radially movable dies and a compliant tube holding mechanism that allows for variable diameter accommodation and precise alignment, reducing the force needed to insert stents into catheters without deformation, using a sequenced lateral movement of dies and axial compression of the compliant tube to grip and align the catheter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rod-like device is used to push the stent through the compression mechanism into the catheter, then the stent can be loaded into the catheter, but the force required can be quite high and the stent can be easily damaged
Solution Approach 1:
A tapered intermediate section is introduced between the compression mechanism and the catheter, acting as a mediator that gradually transitions the stent from compressed to uncompressed state. This intermediate tapered section distributes the pushing force over a longer distance and reduces stress concentration, preventing stent damage while enabling successful loading.
Solution Approach 2:
The catheter is pre-positioned within the compression mechanism before stent loading, and the compression mechanism is pre-adjusted to the correct diameter. This preliminary positioning ensures proper alignment and reduces the force required during the actual stent pushing operation.
2Adaptability or versatility
If a hinged clamp with V-shaped grooves is used to hold the catheter, then a wide range of diameters can be accommodated, but the catheter is deformed into a square shape
Solution Approach 1:
A flexible bellows-like structure with multiple circumferential folds is used to replace the rigid V-shaped clamp. This flexible structure can conform to catheters of various diameters while maintaining uniform radial support, preventing square deformation. The multiple folds allow the structure to expand and contract smoothly to accommodate different catheter sizes.
3Shape
If precisely cut semi-circles are used to hold the catheter, then the product remains round, but the clamp must be customized for each diameter and small variations greatly affect the holding force
Solution Approach 1:
The bellows structure is designed to be dynamically adjustable, with folds that can expand and contract to match different catheter diameters. This dynamic flexibility eliminates the need for multiple customized clamps while maintaining proper circular support. The structure automatically adapts to the catheter diameter through its flexible geometry.
4Measurement precision
If an adjustable mechanism is used to align the catheter clamp with the radial compression mechanism, then alignment can be achieved, but it is difficult to precisely adjust and the alignment may change over time
Solution Approach 1:
The system is designed with self-aligning features where the flexible bellows structure naturally conforms to the compression mechanism's geometry. The catheter clamp automatically positions itself in the correct alignment through the flexible folds, eliminating the need for manual adjustment mechanisms that are difficult to operate and prone to drift.
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
This solution enables the safe and efficient loading of stents into catheters without damage, accommodating a range of diameters while maintaining the cylindrical shape of the catheter, reducing the required force, and ensuring precise alignment, thus overcoming the limitations of prior art.
Implementation Method 1
compressing mechanism associated with one end of the compliant tube and designed to compress the compliant tube along the longitudinal axis to reduce the diameter of the central opening for gripping a second article residing therein
Data Source
AI summary
A translating radial compression and holding mechanism includes radially movable dies defining a cylindrical cavity with movable radius. Apparatus coupled to the dies for sequenced lateral movement of the dies in a first direction and an opposite direction, substantially parallel to the central cavity to convey the compressed article along the axis of the central cavity. A compliant tube with a central opening larger than an article to be held, a case surrounding the tube along the longitudinal axis, and a plurality of cylindrical bushings positioned between the outer case and the tube. Mechanism associated with the tube for compressing the tube along the longitudinal axis to reduce the diameter of the central opening for gripping a second article residing therein, and the cylindrical cavity of the dies being positioned in axial alignment with the central opening of the tube.