Electrode Assembly Lead-In Feature for RF Safety

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Solution Overview

Problem

Prior RF electrosurgical instruments with a return electrode configured as an outer shaft often have a blunt edge at the distal end due to insulating sleeves, which can catch on cannulas, cause trauma, and lead to material erosion or increased RF current density.

Innovation Solution

Incorporating a lead-in feature on the return electrode assembly with a gradual diameter increase to match the insulating sleeve, preventing edge catching and reducing insertion force, and using metal injection molding for cost-effective manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an insulating sleeve is provided around the return electrode to limit the exposed area, then the RF current density is controlled and safety is improved, but a blunt edge is created that can catch on cannulas and cause trauma

Engineering Contradiction:

ImprovesafetyVSAvoidtrauma

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The return electrode is designed with a curved, tapered surface that transitions smoothly from the insulating sleeve to the distal end. This curvature eliminates the blunt edge created by conventional flat-ended insulating sleeves, preventing the edge from catching on cannulas or port entry sites during insertion.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Stability of the object's composition

If the insulating sleeve is tightly fitted over the return electrode, then mechanical stability is improved, but the blunt edge catches on surfaces increasing insertion force and risk of damage

Engineering Contradiction:

Improvemechanical stabilityVSAvoidinsertion force

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

The tapered, curved surface of the return electrode allows the insulating sleeve to be fitted smoothly without creating a protruding edge. This curvature enables the assembly to pass through cannulas and port sites with reduced friction and insertion force while maintaining mechanical stability.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Object-affected harmful factors

If the insulating sleeve material is thin to reduce trauma, then patient safety is improved, but pinholes can be created leading to increased RF current density

Engineering Contradiction:

ImprovetraumaVSAvoidRF current density control

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The curved, tapered design distributes mechanical stresses more evenly across the insulating sleeve material during insertion, reducing the likelihood of pinhole formation. This geometry allows the use of thinner, more flexible insulating materials without compromising the integrity of the RF current path.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS20230363815A1Electrode assembly

Publication Date: 2023.11.16 GYRUS MEDICAL LTD

AI summary

The present disclosure relates to an electrode assembly provided with a lead-in feature that gradually increases the diameter of the outer shaft to that of the insulation sleeve. In doing so, there is no blunt edge formed by the insulation used to secure the electrode assembly to the instrument handle. This prevents a user catching this edge on the cannula, therefore reducing the force needed to insert the device, and the risk of causing damage to the insulation or entry site of the patient.