Electrosurgical Generator Voltage Control for Stable Plasma Ignition
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Solution Overview
Problem
Existing electrosurgical generators face challenges in reliably igniting plasma for tissue cutting due to unstable conditions during the initial phases of plasma ignition, leading to inconsistent and potentially prolonged attempts before achieving a stable plasma arc.
Innovation Solution
The electrosurgical generator includes an impedance determination unit and an output voltage control unit to regulate AC output voltage based on different maximum values for the evaporation, ignition, and equilibrium phases, ensuring a stable plasma arc by maintaining a constant current density and detecting phase transitions through impedance and DC component detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single maximum output voltage value is used for all phases, then the device complexity is reduced, but the reliability of plasma ignition is worsened due to unstable conditions during initial phases
Solution Approach 1:
The maximum output voltage value is made dynamic by adjusting it according to the detected phase (evaporation, ignition, or equilibrium). The control unit changes the voltage parameter based on real-time impedance measurements, allowing optimal voltage for each phase while maintaining a unified control structure.
Solution Approach 2:
The system uses impedance determination to detect the current phase and provides feedback to the output voltage control unit. This closed-loop feedback mechanism enables automatic adjustment of the maximum output voltage value to match the appropriate phase, improving ignition reliability without requiring complex manual intervention.
2Reliability
If the electrosurgical generator attempts to ignite plasma under unstable initial conditions, then the speed of plasma ignition may be improved, but the reliability is worsened due to inconsistent results and prolonged attempts
Solution Approach 1:
The system performs preliminary action by detecting the evaporation phase through impedance measurement and adjusting the maximum output voltage value before attempting plasma ignition. This preparatory voltage adjustment ensures optimal conditions for subsequent ignition attempts, reducing the need for multiple tries.
Solution Approach 2:
The system employs periodic action by continuously monitoring impedance and periodically adjusting the maximum output voltage value according to the detected phase. This periodic adaptation ensures that each ignition attempt occurs under appropriately optimized conditions, improving consistency and reducing wasted attempts.
3Reliability
If the AC output voltage is not regulated during the evaporation phase, then the productivity is improved by faster ignition, but the reliability is worsened due to potential instability and failed attempts
Solution Approach 1:
The system changes the voltage parameter dynamically based on the detected phase. During the evaporation phase, the maximum output voltage value is adjusted to appropriate levels, and during the ignition and equilibrium phases, different voltage values are applied. This parameter adaptation ensures stable plasma arc formation while maintaining efficient ignition speed.
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 approach enhances the reliability and speed of plasma ignition, stabilizing the plasma arc more effectively, reducing the number of attempts required and ensuring consistent tissue cutting performance.
Implementation Method 1
the electrically conductive liquid around the active electrode is heated and evaporated by current flow
Implementation Method 2
If the electric field is sufficiently strong, a gas discharge, also known as an arc, occurs as a result of the ionization of the gas in the vapor bubble, thus creating a plasma (ionized gas)
Data Source
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AI summary
According to the invention, an electrosurgical generator (12) is proposed which is configured to supply a high-frequency alternating current to an electrosurgical instrument (14) for plasma cutting of body tissue (52) during operation. The electrosurgical generator (12) has outputs (18) for connecting an electrosurgical instrument (14), for supplying an electrosurgical instrument (14) connected to the outputs (18) with a high-frequency alternating current, and for determining the impedance of a load connected to the outputs (18). The electrosurgical generator (12) comprises an impedance determination unit and a voltage sensing unit (40) as well as an output voltage control unit (36).The output voltage control unit (36) is designed to control the output AC voltage as a function of a maximum output voltage value, which is set during operation as a function of an output value of the impedance determination unit and/or as a function of an output value of the voltage sensing unit (40) such that the maximum output voltage value in an evaporation phase specifies a lower output AC voltage than in an ignition phase following the evaporation phase.