Soldered Multilayer Coil Guide Wire Torque Transmission
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Solution Overview
Problem
Conventional coil guide wires face difficulties in transmitting torque consistently and reliably, especially when navigating through the patient's vascular system, as they tend to expand or contract unevenly with applied torque, making it challenging to achieve effective steering during vascular procedures.
Innovation Solution
A guide wire with a multi-layer construction featuring a helically wound stainless steel tube as the outer layer and a wire coil as the inner layer, providing a hollow center channel for a core member, and mechanically ground to achieve a variable diameter distal section for improved pushability, torque transmission, and tactile response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-layer coil is used for the guide wire flexible body, then the guide wire can be manufactured with simpler structure, but torque transmission is inconsistent and unreliable due to uneven expansion and contraction
Solution Approach 1:
The patent applies composite materials by constructing the flexible body as a multi-layer coil structure where an inner coil and an outer coil are soldered together at multiple points. This composite structure ensures that both coils expand and contract uniformly during torque application, providing consistent and reliable torque transmission while maintaining the flexibility needed for navigation through the vascular system.
Solution Approach 2:
The flexible body is segmented into multiple functional layers: an inner coil providing baseline flexibility and an outer coil enhancing torque transmission. The segmentation allows each layer to perform its specific function while working together, with the inner coil handling radial flexibility and the outer coil providing torque stability, thereby resolving the contradiction between reliability and complexity.
2Reliability
If the flexible body is made more rigid to improve torque transmission, then torque reliability improves, but flexibility and pushability deteriorate
Solution Approach 1:
The multi-layer coil composite structure allows the inner coil to maintain flexibility for easy navigation and pushability, while the outer coil provides enhanced torque transmission reliability. The soldered connection points between layers create a composite material system where flexibility and rigidity are distributed across different layers, resolving the contradiction between torque reliability and ease of operation.
Solution Approach 2:
Different regions of the flexible body have different mechanical properties: the inner coil provides localized flexibility for navigation, while the outer coil provides localized rigidity for torque transmission. This local quality differentiation allows the guide wire to exhibit both flexibility and torque reliability simultaneously, addressing the contradiction between ease of operation and torque transmission consistency.
3Reliability
If the outer diameter of the flexible body is increased to improve torque transmission, then torque reliability improves, but the guide wire becomes harder to navigate through narrow vessels
Solution Approach 1:
The multi-layer coil structure provides enhanced torque transmission reliability without requiring an increase in outer diameter. The composite action of the inner and outer coils working together allows for improved torque performance within the same dimensional constraints, maintaining the ability to navigate narrow vessels while achieving reliable torque transmission.
Solution Approach 2:
Instead of increasing torque transmission by increasing the outer diameter (one-dimensional solution), the patent adds a second coil layer (moving to a two-dimensional layered structure). This dimensional change allows torque transmission to be enhanced through the addition of layers rather than through radial expansion, preserving the guide wire's ability to navigate narrow vessels while improving torque reliability.
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 guide wire achieves consistent and reliable torque transmission, maintaining flexibility and stiffness comparable to existing coils while enhancing pushability and tactile feedback, facilitating more precise navigation and procedure execution.
Implementation Method 1
The guide wire achieves consistent and reliable torque transmission
Implementation Method 2
providing a hollow center channel for a core member, and mechanically ground to achieve a variable diameter distal section for improved pushability, torque transmission, and tactile response
Data Source
AI summary
A guide wire includes an elongate core section and a flexible member disposed on the distal end, the flexible member including a first wire wound into an inner helical coil in a first direction and a second wire wound into an outer helical coil wrapped about the first helical coil in the opposite direction. The two combined helical coils add stiffness and torque transmission to the guide wire without sacrificing tactile feedback.