Catheter Braid Recessed Region Design for Tip Bonding
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Solution Overview
Problem
Existing catheters face challenges with reduced pushability and torque transfer capability due to the cutting of the braid at the distal end, leading to potential penetration of the braid into the distal tip, especially when the tip is small or short, compromising its flexibility and bonding strength.
Innovation Solution
The catheter design features recessed regions in the braid's distal end with longer recess and protruding sides, increasing the bonding area with the distal tip and reducing the number of peaks, thereby enhancing tensile strength and preventing braid penetration during insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the braid is cut at the distal end portion to provide flexibility, then the distal end flexibility is improved, but the pushability and torque transfer capability are reduced
Solution Approach 1:
The braid is configured with different structures at different locations: the proximal portion has a continuous structure for pushability and torque transfer, while the distal end portion has cut wires providing flexibility. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The braid is segmented into different functional zones along its length, with the distal end portion having cut wires separated into discrete segments while the proximal portion maintains continuous connectivity. This segmentation allows the distal end to be flexible while the proximal portion maintains structural integrity for force transmission.
2Reliability
If the distal tip bonding area is increased by oblique cutting, then the bonding reliability is improved, but the tensile strength improvement is negligible due to braid presence
Solution Approach 1:
The wires of the braid are completely cut and removed from the distal end portion, eliminating the obstacle that prevented effective bonding between the distal tip and the inner layer. This extraction of the braid wires from the bonding zone allows the distal tip to bond directly to the inner layer, significantly improving tensile strength.
Solution Approach 2:
The braid wires are cut at different lengths in the axial direction, creating a stepped configuration that increases the bonding surface area in multiple dimensions. This dimensional approach allows both improved bonding reliability and enhanced tensile strength by maximizing the contact area between the distal tip and inner layer.
3Shape
If the distal end portion of the braid is cut by laser beam, then the distal end shape is formed, but fine projections and depressions are created causing braid penetration into the distal tip
Solution Approach 1:
The harmful effect of laser cutting creating projections that cause penetration is converted into a benefit by carefully controlling the cut depth and pattern. The projections are designed to engage with corresponding features in the distal tip, providing mechanical interlocking that prevents pullout while the cut wires themselves prevent penetration during insertion.
Solution Approach 2:
The laser cutting parameters are optimized to create specific projection heights and patterns that prevent penetration. By adjusting the cutting depth, speed, and pattern, the projections are formed to provide beneficial mechanical engagement rather than harmful penetration, resolving the contradiction between shape formation and penetration prevention.
4Volume of moving object
If the catheter size is reduced for patient treatment, then the treatment burden is reduced, but the distal tip becomes more susceptible to braid penetration due to small thickness and length
Solution Approach 1:
The braid wires are pre-cut and removed from the distal end portion before the distal tip is attached. This preliminary action eliminates the source of potential penetration problems, allowing the distal tip to be made small and thin without the risk of braid penetration, thus enabling miniaturization while maintaining safety.
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 design improves the catheter's pushability, torque transfer capability, and tensile strength, allowing for a smaller and more reliable distal tip with reduced risk of detachment, even in meandering blood vessels.
Implementation Method 1
as illustrated in Fig. 7, since the distal end portion of an existing braid is cut by a laser beam or the like
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A catheter (1) includes an inner layer (24), a braid (26), an outer layer (28), and a distal tip (12). A recessed region (100) having a first side (101) and a second side (102) is formed in a distal end portion (27) of the braid (26), the first side being longer than the sum of a wire width (X1) of a first wire (26a) and a distance (X2) between two adjacent first wires, the second side being longer than the sum of a wire width (Y1) of a second wire (26b) and a distance (Y2) between two adjacent second wires. The distal tip (12) is bonded to the inner layer (24) in the recessed region (100). By providing the recessed region (100), the number of peaks (30) formed in the distal end portion (27) of the braid (26) is made smaller than that in the existing case.