Stent Locking Mechanism Using Rotational Tab Engagement
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Solution Overview
Problem
Current drainage stent delivery systems lack effective locking mechanisms that allow for controlled positioning and deployment of stents in body lumens without premature release, necessitating alternative embodiments for secure attachment and detachment.
Innovation Solution
The development of a stent delivery system with a locking mechanism that includes an elongate shaft with a tab or radially extending protrusion, which engages with the stent through rotational motion, allowing for selective coupling and decoupling of the stent from the shaft, ensuring secure attachment and controlled deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flexible thread or suture is used for releasably connecting the drainage stent to the delivery system, then the stent can be releasably connected to the delivery system, but the connection reliability is insufficient and premature deployment may occur
Solution Approach 1:
The locking mechanism is segmented into distinct components: a locking feature on the shaft (such as a tab or protrusion) and a corresponding engagement feature on the stent (such as an opening or receptacle). This segmentation allows for a more reliable mechanical interlock compared to a simple suture connection, while keeping each individual component relatively simple in structure.
Solution Approach 2:
The locking mechanism incorporates rotational motion as the key dynamic element. The shaft can rotate relative to the stent to engage or disengage the locking feature with the engagement feature. This dynamic rotational action provides a secure, positive lock that prevents premature deployment, while still allowing controlled release when needed.
2Ease of operation
If a locking mechanism with rotational motion is implemented, then controlled positioning and deployment of the stent is achieved, but the ease of operation is reduced
Solution Approach 1:
The mechanism uses rotational motion as the primary dynamic element. The shaft can rotate relative to the stent to engage or disengage the locking feature with the engagement feature. This rotational action provides intuitive tactile feedback to the operator, making it easy to determine when the stent is properly locked or released, thereby maintaining ease of operation while ensuring reliability.
Solution Approach 2:
The locking mechanism is designed to be self-indicating through its mechanical design. As the shaft rotates into the locked position, the geometry of the locking feature and engagement feature naturally guides the components into proper alignment and provides tactile feedback. This self-service design reduces the need for additional indicators or complex control systems, maintaining operational simplicity.
3Reliability
If the stent is securely locked to the shaft, then premature deployment is prevented, but the ability to easily detach the stent from the delivery system is reduced
Solution Approach 1:
The mechanism uses rotational motion to both engage and disengage the lock. To detach the stent, the operator simply rotates the shaft in the opposite direction or continues rotation, which automatically disengages the locking feature from the engagement feature. This same rotational action that provides secure attachment also enables easy detachment, resolving the contradiction between secure locking and ease of assembly/disassembly.
Solution Approach 2:
Instead of using a complex release mechanism to detach the stent, the design inverts the approach: the same simple rotational motion that engages the lock also releases it. By making the engagement and disengagement actions symmetric and equally simple, the design achieves both secure attachment and ease of detachment without requiring separate complex mechanisms.
Data Source
AI summary
A drainage stent delivery system including an elongate shaft of a medial device, a drainage catheter or stent, and a locking mechanism for selectively coupling the drainage stent to the elongate shaft. The drainage stent is selectively coupled to a distal portion of the elongate shaft such that the proximal end of the stent is positioned proximal of the distal end of the elongate shaft. The locking mechanism includes an engaging feature of the elongate shaft which engages a portion of the stent such that the stent may be selectively coupled to the elongate shaft through rotational motion of the elongate shaft relative to the stent. In some instances, the engaging feature of the elongate shaft may be a tab which extends into an opening of the stent.