Electrosurgical Forceps Knife Deployment Mechanism
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Solution Overview
Problem
Existing electrosurgical forceps lack an efficient mechanism for selectively and reliably deploying a knife through an end effector assembly for tissue severing after treatment, which can lead to inconsistent tissue cutting.
Innovation Solution
The design incorporates a pair of pivotably coupled shaft members with a knife deployment mechanism that includes a crank and biasing members, allowing the knife to translate between retracted and extended positions, with a biasing member configured to resiliently bias the knife toward the retracted position and a stop to prevent overextension, enabling precise control and deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a knife deployment mechanism is added to electrosurgical forceps, then tissue severing capability is improved, but device complexity increases
Solution Approach 1:
The knife deployment mechanism is integrated within the existing electrosurgical forceps structure, combining the knife deployment function with the shaft members and end effector assembly. The crank is coupled to the trigger mechanism, and the knife is guided through the shaft members, merging multiple functions into a unified device rather than adding a separate independent system.
Solution Approach 2:
The trigger mechanism serves dual purposes: it activates the end effector closure and simultaneously drives the knife deployment through the crank linkage. The shaft members serve both as structural support and as guides for the knife translation. This multi-functionality reduces the need for additional separate components.
2Measurement precision
If a biasing member is used to resiliently bias the knife toward the retracted position, then knife control precision is improved, but device complexity increases
Solution Approach 1:
The biasing member automatically provides the restoring force to retract the knife after deployment without requiring additional active control mechanisms. The spring-loaded system self-regulates the knife position, providing consistent biasing force throughout the knife's travel range and ensuring reliable return to the retracted position.
Solution Approach 2:
The biasing member acts as a mechanical counterforce system, providing a resilient bias that counteracts forces attempting to extend the knife beyond the desired position. This passive counterbalancing mechanism simplifies control by automatically opposing unwanted knife movement.
3Reliability
If a stop mechanism is added to prevent knife overextension, then cutting reliability is improved, but device complexity increases
Solution Approach 1:
The stop mechanism is pre-positioned within the shaft member or end effector assembly to define the maximum extension position of the knife before deployment occurs. This preliminary positioning ensures that the knife cannot overextend regardless of the forces applied during operation, providing inherent protection against unreliable cutting.
Solution Approach 2:
The stop mechanism acts as a pre-established mechanical limit that cushions against excessive knife travel. By providing a physical barrier before overextension can occur, the system prevents potential damage and ensures consistent cutting depth without requiring active sensing or control systems.
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 mechanism allows for precise and controlled deployment of the knife through the end effector assembly, enhancing the reliability and efficiency of tissue severing post-treatment, while preventing knife overextension and ensuring consistent cutting performance.
Implementation Method 1
a biasing member disposed around the knife and configured to resiliently bias the knife toward the retracted position
Data Source
AI summary
An electrosurgical forceps includes a pair of first and second shaft members pivotably coupled to one another, an end effector assembly coupled to the pair of first and second shaft members, a knife, and a biasing member. The biasing member is disposed about the knife and configured to resiliently bias the knife toward a retracted position.