Steerable Delivery Sheath with Segmented Tubular Members
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Solution Overview
Problem
Current steerable delivery devices face challenges in minimizing tissue injury, navigating tortuous paths, and maintaining stability while providing sufficient torque and compressive support for medical devices within the body, particularly in fluid-filled lumens like blood vessels.
Innovation Solution
The design incorporates a steerable delivery device with an outer and inner tubular member, where the tubular members are axially fixed at a distal location and movable proximally, featuring slots that define spines to impart axial stiffness and allow for steering by applying compressive and tensile forces, along with a floating tubular member for lubricity and a polymeric intermediate for fluid sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the delivery device is made more flexible to navigate tortuous paths, then the ability to track to target destination is improved, but the torque transmission capability and structural stability deteriorate
Solution Approach 1:
The delivery device is divided into multiple tubular members (outer tubular member, inner tubular member, intermediate tubular member) with distinct functional characteristics. Each segment serves a specific purpose: the outer member provides flexibility and tracking, the intermediate member provides torque transmission, and the inner member provides structural support. This segmentation allows the device to simultaneously achieve flexibility for navigation and strength for torque transmission.
Solution Approach 2:
The device employs composite construction with multiple materials having different mechanical properties. The outer tubular member uses a flexible material for tracking, the intermediate tubular member uses a stiffer material for torque transmission, and these are combined in a single device structure. This composite approach resolves the contradiction by allowing different parts of the device to have optimized properties for their specific functions.
2Object-affected harmful factors
If the wall thickness is minimized to reduce tissue injury, then the invasiveness is reduced, but the compressive support and structural integrity deteriorate
Solution Approach 1:
The device is segmented into multiple tubular members, each with optimized wall thickness for its specific function. The outer member has thinner walls for minimal tissue injury, while the intermediate and inner members provide additional structural support through their combined strength, allowing the overall device to maintain compressive support without requiring any single wall to be excessively thick.
Solution Approach 2:
Multiple tubular members are merged concentrically to provide combined structural support. The intermediate tubular member and inner tubular member work together to provide compressive support and structural integrity, allowing the outer member to have minimal wall thickness for reduced tissue injury while the combined structure maintains sufficient strength.
3Object-affected harmful factors
If the delivery device is made more flexible to reduce tissue injury, then the minimally invasive capability is improved, but the ability to maintain stable equilibrium deteriorates
Solution Approach 1:
The device is segmented into flexible outer member for tracking and stiffer intermediate/inner members for stability. This segmentation allows the device to be flexible enough to minimize tissue injury during navigation while the stiffer inner components provide the structural stability needed to maintain stable equilibrium at the target site.
Solution Approach 2:
The composite structure combines flexible material in the outer member with stiffer materials in the intermediate and inner members. This composite construction allows the device to exhibit both flexibility for minimal tissue injury and stability for maintaining equilibrium, as different materials contribute different mechanical properties to the overall system.
4Adaptability or versatility
If slots are added to enable steering by applying compressive and tensile forces, then the steerability is improved, but the structural complexity increases
Solution Approach 1:
The steerable portion is segmented into outer and inner tubular members with slots at different orientations. The outer member has slots oriented in a first direction while the inner member has slots oriented in a second direction, allowing independent control of bending in different planes. This segmentation enables sophisticated steering capability while keeping each individual member's structure relatively simple.
Data Source
Figure 1~2b
Figure 2c
Figure 3~4
AI summary
Steerable medical delivery devices and their methods of use.