Deflectable Access Sheath Handle Locking Mechanism
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Solution Overview
Problem
Current medical devices with deflectable distal ends lack effective control mechanisms for precise deflection and locking, leading to limited maneuverability and user fatigue during procedures like urological interventions.
Innovation Solution
An elongate access sheath with a control handle, tension gear, brake pad, and locking trigger mechanism that allows controlled deflection and incremental locking of the distal end, utilizing a ratchet system to prevent unwanted rotation and enable precise angle adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a simple control mechanism is used for deflecting the distal end, then the device structure is simple, but the control precision and maneuverability are limited
Solution Approach 1:
The control mechanism is segmented into distinct functional components: a control handle for user input, a tension gear for mechanical advantage, a brake pad for friction-based control, and a locking trigger for position fixation. This segmentation allows each component to perform its specific function efficiently, achieving precise control without excessive overall complexity
Solution Approach 2:
The tension gear acts as an intermediary between the control handle and the deflector filament, translating rotational motion into controlled linear tension. The brake pad serves as an intermediary that provides friction-based modulation of the tension, enabling fine-adjustment control. These intermediary components bridge the gap between simple user input and precise deflection control
2Stability of the object's composition
If a locking mechanism is added to prevent unwanted rotation, then the control stability is improved, but the device complexity increases
Solution Approach 1:
The locking trigger mechanism is merged with the existing tension gear and brake pad assembly. The locking trigger utilizes the same rotational path and engagement points as the control mechanism, combining the locking function with the existing structural elements. This merging approach adds stability without proportionally increasing overall device complexity
Solution Approach 2:
The locking mechanism is designed to be self-actuating through the locking trigger, which automatically engages with the tension gear at predetermined positions. The spring-loaded brake pad provides automatic engagement force, eliminating the need for separate actuation mechanisms and reducing the complexity burden of the added locking functionality
3Adaptability or versatility
If incremental angle adjustments are enabled, then the adaptability for various applications is improved, but the operation complexity increases
Solution Approach 1:
The tension gear is designed with periodic engagement features that allow incremental adjustments at regular intervals. Each rotation of the control handle produces discrete, repeatable angular increments at the distal end, enabling systematic exploration of different angles. This periodic action pattern makes incremental adjustment intuitive and easy to operate
Solution Approach 2:
The mechanism allows continuous variation of the deflection angle parameter through controlled rotation of the tension gear. By changing the rotation amount, the user can achieve different deflection angles suitable for various anatomical pathways. The brake pad provides parameter stabilization at desired settings, making parameter adjustment easy and precise
4Reliability
If a ratchet system is used to prevent unwanted rotation, then the reliability of position holding is improved, but the device complexity increases
Solution Approach 1:
The brake pad utilizes friction, which can be considered a harmful force causing resistance, and converts it into a beneficial locking mechanism. The friction between the brake pad and tension gear surfaces provides reliable position holding and prevents unwanted rotation. By embracing friction rather than eliminating it, the design achieves reliable positioning without complex mechanical locks
Solution Approach 2:
The traditional mechanical ratchet and pawl system is replaced with a friction-based brake pad system that achieves similar position-holding reliability. The spring-loaded brake pad provides continuous contact force, substituting discrete mechanical engagement with continuous frictional control. This substitution simplifies the mechanism while maintaining or improving reliability
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
Enhances control and reduces user fatigue by allowing precise deflection and locking of the distal end, facilitating more effective use during medical procedures and enabling incremental adjustments for various applications.
Implementation Method 1
The brake pad is disposed within the hollow center of the tension gear and comprises a slot and an outside engagement portion. Translation of the locking trigger engages the brake pad and the tension gear to prevent rotation of the tension gear in an opposite second direction.
Implementation Method 2
The control handle comprises a lever portion and an engagement portion that comprises input teeth. The input teeth of the engagement portion are meshed with the outside engagement portion of the tension gear such that upward movement of the lever portion causes rotation of the tension gear in a first direction and sliding motion of the deflector filament within the lumen.
Data Source
AI summary
An elongate access sheath comprises a proximal portion and a lumen. The proximal portion supports a control handle, a brake pad, a tension gear, and a locking trigger. A deflector filament extends through the lumen and is coupled to the tension gear. The tension gear includes an outside and an inner engagement portion. The brake pad comprises a slot and an outside engagement portion. The locking trigger includes a pin disposed within the brake pad slot. The control handle includes a lever and an engagement portion. Upward movement of the lever engages the engagement portion with the outside engagement portion of the tension gear to rotate the tension gear in a first direction and slides the deflector filament to bend the lumen distal portion. Translation of the locking trigger engages the brake pad and the tension gear to prevent rotation of the tension gear in an opposite second direction.