Voltage Limiter for HF Surgical Arc Stability
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Solution Overview
Problem
Existing HF surgical devices face challenges in igniting and maintaining a stable electric arc in a conductive flushing liquid, leading to excessive heating and thermal tissue damage due to high power output, which degrades cutting properties and prolongs surgery times.
Innovation Solution
A voltage limiter is introduced between the parallel resonant circuit and the output contacts/electrode to limit the HF voltage, preventing excessive energy release and maintaining a stable arc, ensuring efficient cutting properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high power is output to ignite the electric arc quickly, then the ignition time is reduced, but the flushing liquid is excessively heated causing thermal tissue damage
Solution Approach 1:
The system uses periodic pulsed power output with different amplitude levels. During the ignition phase, high-power pulses are applied to quickly form the vapor layer and ignite the arc. Once ignited, the power is reduced to a lower maintenance level. This periodic variation in power delivery allows rapid ignition while preventing excessive heating of the flushing liquid and surrounding tissue.
2Reliability
If high voltage peaks occur to facilitate electric arc discharge, then the arc ignition is improved, but the vapor layer separates from the electrode causing arc collapse
Solution Approach 1:
The system dynamically adjusts the voltage output based on the operational phase. During ignition, voltage peaks are permitted to facilitate arc formation. Once the arc is established, the voltage is dynamically reduced to a stable operating level that maintains the vapor layer attachment to the electrode without causing separation. This dynamic control prevents arc collapse while ensuring reliable ignition.
3Speed
If excessive energy is released during electric arc discharge, then the vapor layer formation is accelerated, but the vapor layer separates from the electrode forming gas bubbles
Solution Approach 1:
The system applies high-energy pulses periodically during the ignition phase to rapidly form the vapor layer. Once formation is achieved, the energy input is reduced to a continuous lower level that maintains the vapor layer without causing excessive growth and separation. This periodic energy delivery ensures fast vapor layer formation while preventing bubble formation that would disrupt the arc.
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 voltage limiter stabilizes the electric arc, reducing tissue heating and improving initial cutting properties by preventing voltage peaks, thus shortening surgery times and maintaining efficient tissue separation.
Implementation Method 1
a parallel resonant circuit which is electrically connected with the output contacts and in which the HF voltage is generated during operations
Implementation Method 2
a voltage limiter which is arranged between the parallel resonant circuit and the output contacts and which limits the HF voltage
Implementation Method 3
the HF voltage is configured to ignite an arc at the electrosurgical instrument
Implementation Method 4
for cutting and/or vaporizing biological tissue
Data Source
AI summary
A high frequency surgical device for generating a high frequency voltage for cutting and/or vaporizing biological tissue within a flushing liquid, in particular a conductive flushing liquid, including two output contacts at which an electrosurgical instrument is connectable and between which the HF voltage is provided during operations; a parallel resonant circuit which is electrically connected with the output contacts and in which the HF voltage is generated during operations, and wherein the HF voltage is configured for igniting an electric arc within the flushing liquid at the electrosurgical instrument. In order to provide an electrosurgical device for applications under a flushing liquid, wherein the flushing liquid is heated less and wherein the electrosurgical device provides better initial cutting properties, it is provided according to the invention that a voltage limiter is arranged between the parallel resonant circuit and the output contacts.