Erosion Fuse for RF Tip Detachment Risk
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Solution Overview
Problem
Legacy RF electrosurgical hand instruments fail both mechanically and electrically during prolonged use, leading to RF tip fragmentation and potential patient injury due to the simultaneous erosion of steel components in RF plasma and saline, resulting in a non-graceful failure.
Innovation Solution
A fail-safe RF electrosurgical hand instrument design where the mechanical retention mechanism is separate from the RF power delivery, with an electrical connection that erodes faster than the RF tip, ensuring RF power cessation before mechanical detachment, thus preventing tip fragments from entering the patient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the RF tip and electrical connection are mechanically integrated, then the device structure is simpler, but both electrical and mechanical failure occur simultaneously causing tip detachment
Solution Approach 1:
The device is divided into separate functional components: the electrical connection (active wire) is separated from the mechanical retention mechanism (RF tip and holder). This segmentation ensures that electrical failure does not necessarily lead to mechanical failure, allowing the RF tip to remain mechanically retained even after the electrical connection erodes.
Solution Approach 2:
The electrical connection function is extracted from the mechanical retention system. The active wire delivering RF power is separated from the RF tip holder that mechanically retains the RF tip. This extraction allows independent failure modes where the electrical connection can fail without compromising the mechanical retention integrity.
2Loss of substance
If the electrical connection erodes at the same rate as the RF tip, then material consumption is uniform, but simultaneous failure occurs causing tip detachment
Solution Approach 1:
The electrical connection is designed with different material properties or geometric characteristics that cause it to erode at a different rate than the RF tip. The active wire may use a more erosion-prone material or have a larger surface area exposed to plasma, creating localized differential erosion where the electrical connection fails before the mechanical components.
Solution Approach 2:
The erosion characteristics of the electrical connection are modified by changing material composition, surface area, or geometric parameters. The active wire is designed to erode faster through parameter adjustments such as using copper instead of stainless steel, or increasing the exposed surface area to plasma, ensuring electrical failure precedes mechanical failure.
3Reliability
If the mechanical retention mechanism is separate from RF power delivery, then failure safety is improved, but device complexity increases
Solution Approach 1:
The device is divided into separate functional components: the electrical connection (active wire) is separated from the mechanical retention mechanism (RF tip and holder). This segmentation ensures that electrical failure does not necessarily lead to mechanical failure, allowing the RF tip to remain mechanically retained even after the electrical connection erodes.
4Reliability
If the electrical connection is made to erode faster, then fail-safe operation is achieved, but the electrical connection lifespan is reduced
Solution Approach 1:
The erosion process, which is normally a harmful degradation mechanism, is converted into a beneficial safety feature. By designing the electrical connection to erode faster, the harmful erosion is transformed into a protective mechanism that ensures electrical failure precedes mechanical failure, preventing tip detachment and converting a potential harm into a safety benefit.
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
The design ensures the device fails safely by ceasing RF function before mechanical detachment, reducing the risk of patient injury from detached tip fragments and maintaining mechanical integrity of the RF tip for safe removal.
Implementation Method 1
the steel components of the RF tip and active inner tube start to erode due to interaction with RF plasma and saline during ablation
Implementation Method 2
The electrical connection used to deliver RF power to the active tip repeatably and reliably erodes at a faster rate than the active tip
Data Source
Figure 1~2A
Figure 2B~2C
Figure 3~4a
AI summary
The present disclosure relates to a RF hand instrument wherein the RF ablation function ceases to operate prior to any RF tip detachment occurs, in order for the hand instrument to fail gracefully and thus be considered fail-safe. This is achieved by ensuring there is a mechanical retention mechanism which is separate to the RF power delivery means such that the power is delivered by a separate electro/mechanical connection. Further, the electrical connection that is used to deliver RF power to the active tip repeatably and reliably erodes at a faster rate than the active tip and the active tip retention mechanism such that the electrical connection geometry erodes to the point where RF power is no longer delivered to the RF tip, and the user will be made aware of this loss in RF function. Thus, the geometry of the used/eroded RF tip, with no remaining electrical connection is still mechanically strong enough to be removed from the patient or cannula without RF tip detachment from the electrode assembly.