Laparoscopic Forceps Four-Bar Linkage Mechanism
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Solution Overview
Problem
Existing forceps used in laparoscopic surgery lack a mechanism to efficiently control the amount of force required to move the working arms, particularly in initiating movement and reducing the force needed for clamping or cutting once a predetermined position or force is achieved.
Innovation Solution
The introduction of an electrosurgical device with a four-bar mechanism that includes a first link connected to a fourth link via a first pivot, and to a second link at a second pivot, allowing movement of the first link to move the second link relative to the fourth link, thereby assisting in the movement of the jaws between open and closed positions with reduced initial input force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a cam mechanism is used to close the jaws, then the jaws can be forced together to create gripping force, but the initial input force required to begin movement is high
Solution Approach 1:
The patent applies a four-bar linkage mechanism that transforms the static cam-follower relationship into a dynamic system with controlled motion paths. The linkage allows the jaws to follow a predetermined trajectory during closure, reducing the initial force spike characteristic of cam mechanisms while maintaining effective gripping force at closure.
Solution Approach 2:
The four-bar linkage mechanism changes the geometric parameters of the jaw closure path. By adjusting the linkage dimensions and pivot points, the system optimizes the force distribution throughout the motion range, reducing initial input force while ensuring sufficient gripping force is achieved at the closed position.
2Force
If a cam mechanism is used to close the jaws, then the jaws can be forced together to create gripping force, but the force required to complete the cut or clamp is excessive
Solution Approach 1:
The four-bar linkage creates a dynamic force transmission system that reduces energy loss during the cutting or clamping process. The mechanism allows for a more efficient force profile where the input force is better matched to the resistance encountered during tissue cutting, reducing excessive force requirements and associated energy loss.
Solution Approach 2:
The four-bar linkage acts as an intermediary mechanism between the user's input force and the jaw closing action. This intermediate mechanism optimizes the force transmission, reducing energy loss that would otherwise occur in direct cam-follower systems by providing a more gradual and controlled force application throughout the motion range.
3Force
If the shaft captures the jaws and acts as a cam, then the jaws are moved together to create gripping force, but the device complexity increases
Solution Approach 1:
The four-bar linkage mechanism serves multiple functions within a single integrated structure: it guides the jaw motion path, transmits the input force, and controls the timing of jaw closure. This multi-functionality reduces the need for separate components that would otherwise be required, thereby managing device complexity while achieving the desired gripping force.
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
This solution allows for a low initial input force to begin moving the working arms and reduces the amount of force required to complete a cut or clamp once the predetermined position or force is reached, enhancing the efficiency and precision of surgical procedures.
Implementation Method 1
a four-bar mechanism that includes a first link connected to a fourth link via a first pivot, and to a second link at a second pivot, allowing movement of the first link to move the second link relative to the fourth link, thereby assisting in the movement of the jaws between open and closed positions with reduced initial input force
Data Source
AI summary
An electrosurgical device comprising: (a) a stylet including: (i) a first jaw; (ii) a second jaw that is movable relative to the first jaw from a first position where the first jaw and the second jaw are open to a second position where the first jaw and the second jaw move towards each other to grasp tissue therebetween; and (iii) one or more jaw support rods connected to the first jaw, the second jaw, or both; and (b) a housing connected to the stylet and the stylet extending from the housing, the housing including: (i) an operable mechanism including: (1) a fourth link; (2) a second link; (3) a first link being connected to the fourth link via a first pivot and being rotatable relative to the first pivot, and connected to the second link at a second pivot so that movement of the first link moves the second link relative to the fourth link; and (4) a third link being connected to the second link at a third pivot so that movement of the second link moves the third link, and the fourth link being connected to the third link at a fourth pivot, the third link moving about the fourth pivot to move the one or more jaw supports so that the first jaw and the second jaw are moved between the first position and the second position; and wherein the fourth link is the housing and the first link is a clamp lever that extends outside of the housing and is actuated by a user.