Variable Stiffness Catheter Manufacturing via Continuous Extrusion
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Solution Overview
Problem
Current methods for manufacturing variable stiffness intravascular catheters are labor-intensive, inefficient, and lack design flexibility, often resulting in weak joints and inadequate material transitions, which can lead to kinking and reduced reliability, especially in longer catheters that require narrower diameters for navigation through tortuous vasculature.
Innovation Solution
A system comprising multiple material feeders and a thermally controlled mixer, coupled with a catheter formation mandrel and extruder, allows for the controlled combination and extrusion of materials with varying elasticity and strength characteristics, enabling the formation of catheters with gradual stiffness transitions and improved kink resistance by adjusting feed rates and mandrel rotation, translation, and heating elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple tubular segments with different stiffness are assembled using known methods, then variable stiffness catheters can be manufactured, but the process is labor-intensive and inefficient
Solution Approach 1:
The patent combines multiple material extrusion processes into a single continuous manufacturing operation. Multiple materials are fed simultaneously through separate feeders and extruded in one continuous process to form the variable stiffness catheter, eliminating the need to assemble pre-formed segments and dramatically improving manufacturing efficiency
Solution Approach 2:
The patent prepares multiple materials in advance through separate feeders and pre-heating zones before they are extruded. The materials are conditioned and ready for extrusion in a controlled manner, allowing the main extrusion process to proceed continuously without interruption for material preparation
2Reliability
If tubular segments are shrink-fitted and melt-bonded using heat-shrink tubing, then segments can be joined, but the process requires many different materials and can only fabricate catheters one-at-a-time
Solution Approach 1:
The patent merges the joining function into the extrusion process itself. As materials are extruded continuously, they are heated and bonded together in-line, eliminating the need for separate joining operations and additional materials like heat-shrink tubing. The bonding occurs as part of the single continuous extrusion process
Solution Approach 2:
The patent extracts the joining function from the assembly process and integrates it into the extrusion process. The bonding operation is separated from the segment assembly operation and combined with the material deposition process, reducing the number of distinct steps and materials required
3Adaptability or versatility
If discrete sections of different materials are extruded onto an inner assembly, then variable stiffness regions can be formed, but the joints between sections are weak and prone to kinking
Solution Approach 1:
The patent changes the temperature parameter continuously along the extrusion path. Different zones of the extruder and cooling system are controlled at different temperatures to ensure proper melting and bonding of materials as they are deposited. This temperature control creates strong bonds between successive material sections, eliminating weak joints
Solution Approach 2:
The patent maintains continuous extrusion and continuous bonding action throughout the catheter length. Materials are deposited and bonded in an uninterrupted sequence, ensuring that each section is immediately bonded to the previous section while the material is still in a bonding-appropriate state, creating strong continuous joints throughout the catheter
4Length of moving object
If the distal section diameter is reduced for navigation through narrow vasculature, then catheter length can be increased, but the wall thickness must be thinned which reduces column strength and increases kinking susceptibility
Solution Approach 1:
The patent applies different material properties to different sections of the catheter. The distal section uses materials with appropriate flexibility for navigation, while the proximal section uses stiffer materials for pushability. This local differentiation allows the catheter to have both the length and strength required, as each section is optimized for its specific functional requirements
Solution Approach 2:
The patent uses composite construction with multiple materials having different mechanical properties. By combining materials with varying stiffness, strength, and flexibility characteristics, the catheter achieves both the thin-walled flexibility needed for narrow vessel navigation and the column strength required to prevent kinking, even in the distal section
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 method enables the production of catheters with superior kink resistance and graded stiffness transitions, enhancing navigation through complex vasculature while reducing manufacturing complexity and cost, allowing for more accurate and repeatable production of customized catheters with higher reliability.
Implementation Method 1
thermally controlled mixer coupled to the first and second material feeders, wherein the first material feeder is configured to feed a first material from the first material source into the mixer at a first material feed rate
Implementation Method 2
An extruder is operatively coupled to the mixer and having an output nozzle configured to apply compound material from the mixer onto the catheter formation mandrel
Implementation Method 3
catheter formation mandrel having a longitudinal axis, the mandrel being controllably rotatable about the longitudinal axis at mandrel rotation rate
Data Source
AI summary
A system for manufacturing a catheter includes at least first and second controllable rate material feeders that feed at least first and second materials into a temperature-controlled mixer to form a compound material that varies in flexibility and/or strength with the respective first and second materials and material feed rates. An extruder extrudes the compound material onto a rotating and translating mandrel to thereby form a variable stiffness profile along a length of the catheter that depends on respective rates of rotation and translation of the mandrel.