Shape-Memory Steerable Tip for Tight Catheter Curvature
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Solution Overview
Problem
Existing steerable devices, such as those using shape memory alloy wires, face challenges with wide curvature radii, difficulty in assembly, wear-out issues, and limited bending ability, making them cumbersome and difficult to navigate through complex anatomies or tubes.
Innovation Solution
An elongated steerable device with a flexible member and a shape memory alloy wire secured at one extremity, activated by an actuator, allowing for a curvature angle of 0 to 360°, featuring a U-shaped configuration for enhanced strength and ease of assembly, and incorporating elastic elements for stability and precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If shape memory alloy wires are used with low contraction rate (below 8%), then the device structure is simple, but the curvature radius is wide and bending ability is limited
Solution Approach 1:
The patent applies curvature by pre-forming the shape memory alloy wire into a U-shape configuration with a predetermined curvature radius. When activated, the wire achieves a high curvature angle (90° to 180°) by returning to its memorized shape, enabling tight bending without requiring high contraction rate. This resolves the contradiction by using geometric curvature design rather than relying solely on material contraction properties.
2Reliability
If shape memory alloy wires are crimped at both extremities, then the wire is firmly maintained, but the assembly is difficult and wear-out occurs quickly
Solution Approach 1:
The patent extracts the crimping operation from one end of the wire and eliminates it entirely by securing the shape memory alloy wire at only one extremity (the apex of the U-shape) to the elongated flexible member. The other extremity remains free, simplifying assembly while maintaining reliable fixation through the single securement point combined with the wire's elastic properties.
3Adaptability or versatility
If high curvature angle (90° to 180°) is achieved, then navigation in tortuous conducts is improved, but the device requires stronger actuation force
Solution Approach 1:
The patent applies preliminary action by pre-memorizing the desired curved configuration in the shape memory alloy wire during manufacturing. The wire is trained to return to this predetermined U-shape with high curvature angle when heated, eliminating the need for real-time high-force actuation. The geometric design and pre-conditioning of the material enable high curvature achievement with minimal activation force.
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 device provides improved navigation and handling, enabling access to hard-to-reach locations with high curvature angles, reducing the need for exchange guides and ensuring durability through controlled activation of the shape memory alloy wire.
Implementation Method 1
at least one shape memory alloy wire presenting at least one activable zone and secured to the distal extremity of the elongated flexible member, an actuator configured to activate the at least one shape memory alloy wire from the proximal extremity of the elongated flexible member
Data Source
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AI summary
The invention relates to an elongated steerable device for guiding a catheter or an endoscope comprising an elongated flexible member, at least one shape memory alloy wire (16) presenting at least one activable zone, and an actuator configured to activate the at least one shape memory alloy wire, wherein the activable zone (17) of the at least one shape memory alloy wire (16) is configured to present a resting configuration and an activated configuration, the activated configuration displaying at least one predetermined curvature (C1, C2), wherein the activable zone (17) of the at least one shape memory alloy wire (16) is configured to adopt the activated configuration when activated by the actuator, thus inducing the predetermined curvature (C1, C2) to the distal extremity (12D) of the elongated flexible member (12).