Steerable Tube Hinge Structure for Medical Instruments
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Solution Overview
Problem
Current steerable medical instruments face challenges with steerability, flexibility, stiffness, and durability, especially for longer instruments, due to high forces exerted on steering and actuation cables, leading to issues like cable cuts, friction, and deformation, which affect their performance and manufacturing complexity, particularly in colonoscopy and gastroscopy applications.
Innovation Solution
A steerable instrument with a tubular body featuring a hinge structure and a corrugated cross-section design that includes a supporting member with a ball-shaped element and a cable fastening mechanism, allowing for high stability and steering capability, while preventing tangential rotation of cables and reducing friction through specific channel designs and materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a plastic extruded tube with integrated channels is used, then the construction becomes simple, but the mechanical properties are too weak for long instruments, causing cable cuts, friction, and deformation
Solution Approach 1:
The patent employs a composite structure combining a flexible polymer sheath with an internal metal reinforcement element (wire or rod). This composite design provides both flexibility and high mechanical strength, preventing cable cuts and deformation while maintaining the simplicity of the extruded tube construction. The metal reinforcement is positioned within the polymer sheath, creating a synergistic structure where each material contributes its advantageous properties.
Solution Approach 2:
The tube element is divided into functional segments: a flexible polymer sheath providing protection and flexibility, and an internal metal reinforcement element providing structural strength. This segmentation allows each component to be optimized for its specific function while working together to solve the contradiction between simplicity and strength.
2Length of moving object
If the instrument length is increased beyond 1 meter, then more reach is achieved, but the steering becomes difficult due to high friction and cable deformation
Solution Approach 1:
The patent changes the material parameters by incorporating a metal reinforcement element with low friction coefficients and high tensile strength. This allows the instrument to maintain steerability even at lengths exceeding 1 meter by reducing cable friction and preventing deformation that would otherwise occur in longer configurations.
Solution Approach 2:
The composite structure of polymer sheath and metal reinforcement provides both the flexibility needed for long instrument lengths and the strength required to maintain steering control. The metal element reduces friction within the channels while the polymer provides the necessary flexibility and protection.
3Force
If high force is exerted on the actuation cable, then the tool can be operated, but the force exceeds the maximum longitudinal force allowed in the extruded plastic tube
Solution Approach 1:
The patent uses a composite structure where the metal reinforcement element bears the high longitudinal forces generated during tool actuation, while the polymer sheath provides flexibility and protection. This distributes the mechanical loads appropriately, allowing high actuation forces without exceeding the strength limits of individual materials.
Solution Approach 2:
The segmentation of forces between the metal reinforcement and polymer sheath allows the system to handle high actuation forces. The metal element handles the longitudinal tensile forces while the polymer handles compression and flexibility requirements.
4Force
If the plastic tube is curved and high force is exerted on the actuation cable, then the tool can be operated, but the channels for steering cables become deformed, clamping them and impeding proper operation
Solution Approach 1:
The metal reinforcement element maintains the structural integrity of the channels even when the tube is curved and high forces are applied. This prevents channel deformation that would otherwise clamp the steering cables, ensuring smooth operation. The polymer sheath provides the necessary flexibility for curvature while the metal preserves channel geometry.
Solution Approach 2:
The separation of functions between the polymer sheath (flexibility and protection) and metal reinforcement (structural integrity and channel maintenance) allows the system to achieve both curvature and force transmission without channel deformation.
Data Source
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AI summary
Tube element including at least one hinge structure for allowing bending of the tube element about the at least one hinge structure, the hinge structure comprising a convex section (77) and a concave section (75) separated from one another by a first slot (73) and connected to one another by a plurality of fracture elements (89); wherein the fracture elements are designed to break once the convex section is rotated relative to the concave section with a predetermined force; the fracture elements are designed such that by rotating the convex section inside the concave section with the predetermined force, the fracture elements will fracture and each fracture element leaves two fracture element portions (89a, 89b); the hinge structure is configured such that the convex section can rotate within the concave section until rotation is blocked by the hinge structure, and the fracture elements have such a width that, after being fractured, the two fracture element portions have surfaces facing one another and contacting one another during the entire maximum possible rotation.