Nested Conduit Stiffening for Variable Bend Radius in Steerable Instruments
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Solution Overview
Problem
Existing minimally invasive medical instruments face challenges in navigating small anatomical passageways due to size and flexibility limitations, requiring improved designs for articulation and stiffness adjustment to enhance maneuverability during procedures.
Innovation Solution
The development of a medical instrument with an elongate flexible body featuring nested conduits and actuation tendons, allowing for adjustable axial stiffness and varying bend radii, enabling precise articulation and navigation through small anatomical spaces without additional articulation motors or telescoping designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If additional articulation motors and telescoping structures are added to achieve variable articulable lengths, then maneuverability and ease of use are improved, but device complexity and outer diameter increase
Solution Approach 1:
The patent employs nested conduits where an inner conduit is positioned within an outer conduit, both extending through the flexible body. The control tendon passes through the inner conduit, creating a compact nested structure that enables variable articulable lengths through axial displacement of the inner conduit relative to the outer conduit, without requiring additional motors or telescoping mechanisms that would increase device complexity and outer diameter.
Solution Approach 2:
The patent implements dynamic adjustability by allowing the inner conduit to axially displace within the outer conduit. This dynamic reconfiguration enables the instrument to achieve different articulable lengths on-demand during the procedure, providing variable maneuverability without permanent structural modifications or complex mechanical assemblies.
2Volume of moving object
If the instrument is made smaller and more flexible to fit within small anatomical lumens, then navigability through small passageways is improved, but structural strength and support for remote operation decrease
Solution Approach 1:
The patent applies local stiffening by positioning the nested conduit structure within the flexible body at specific locations. The inner and outer conduits provide localized axial support where needed, while the rest of the flexible body maintains its flexibility for navigation. This allows the instrument to have a small outer diameter for navigability while providing sufficient structural strength at critical regions for remote operation.
Solution Approach 2:
The patent utilizes a composite construction combining flexible material for the body with rigid or semi-rigid nested conduits. This composite structure enables the instrument to exhibit both flexibility (from the flexible body material) and strength (from the nested conduit structure), resolving the contradiction between being small/flexible for navigation and having sufficient structural strength for remote operation.
Data Source
AI summary
A medical instrument comprises an elongate flexible body including a proximal section and a steerable distal section. The instrument also comprises a control tendon extending within the elongate flexible body. The instrument also comprises an axially variable stiffening mechanism including a first conduit extending through a second conduit. The axially variable stiffening mechanism is adjustable between a first state in which an actuation of the control tendon produces a first bend radius in the steerable distal section and a second state in which the actuation of the control tendon produces a second bend radius in the steerable distal section. The second bend radius is different than the first bend radius.