Neutral Electrode Temperature Monitoring via Impedance
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Solution Overview
Problem
Current electrosurgical devices lack reliable methods for monitoring temperature at the neutral electrode during high-frequency surgery, leading to potential tissue damage due to increased risk of burning, especially with large HF currents applied over extended periods, and existing solutions are error-prone or complex.
Innovation Solution
An electrosurgical device with a temperature measurement system that utilizes a contacting agent layer with temperature-specific impedance, allowing for impedance measurement to estimate temperature changes at the neutral electrode, incorporating a measurement current generator and hydrogel for improved detail resolution and thermal balance estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistor is coupled into the treatment current to monitor heating, then temperature monitoring is enabled, but the device complexity increases and suitable resistor selection becomes very difficult
Solution Approach 1:
The patent introduces a measuring circuit with oscillators and impedance measurement devices as intermediaries to indirectly monitor temperature through impedance changes of the contacting agent layer, avoiding the need to directly couple resistors into the high-frequency treatment current path
Solution Approach 2:
The patent replaces the physical resistor-based temperature sensing method with an electrical impedance measurement system that uses oscillators and impedance detection circuits to monitor temperature changes through the temperature-dependent impedance of the contacting agent layer
2Measurement precision
If temperature sensors are provided directly on the electrodes, then local temperature detection is improved, but the provision of measurement devices becomes very complex
Solution Approach 1:
The patent uses the contacting agent layer as an intermediary medium that transmits temperature information from the electrode-tissue interface to the measurement circuit through its temperature-dependent impedance characteristics, eliminating the need for direct sensor placement on electrodes
Solution Approach 2:
The patent creates an electrical impedance copy of the temperature conditions at the neutral electrode by measuring the impedance of the contacting agent layer, which varies with temperature, allowing indirect but accurate temperature monitoring without physical sensors at the measurement location
3Productivity
If large HF currents are applied for extended periods, then treatment effectiveness is improved, but the risk of burning tissue at the neutral electrode increases
Solution Approach 1:
The patent implements a feedback mechanism where the impedance measurement device continuously monitors the impedance of the contacting agent layer, and the control device uses this information to detect temperature increases and respond by adjusting or interrupting the HF current to prevent tissue burning
Solution Approach 2:
The patent performs preliminary impedance measurements to establish baseline values before treatment, and continuously monitors impedance changes during treatment to detect temperature rise early, enabling preventive action before tissue damage occurs
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 solution provides a reliable and efficient assessment of temperature conditions at the neutral electrode, preventing tissue damage by detecting temperature changes and adjusting the HF current accordingly, thereby ensuring safer surgical procedures.
Implementation Method 1
a temperature measurement device for determining the temperature and/or the temperature change comprises an impedance measurement device, configured to detect an impedance of the contacting agent layer
Implementation Method 2
electrical energy is fed to the tissue to be treated... The surface of the active electrode, by which the alternating current is conducted into the tissue, is relatively small, so that a high current density and consequently a high level of heat generation arise
Data Source
AI summary
A method for determining a temperature and/or a temperature change at a neutral electrode having a contacting agent layer. The method comprises determining at least one impedance value of the contacting agent layer and calculating a temperature change and/or a temperature at the neutral electrode, at least on the basis of the impedance value. The contacting agent layers may be made from hydrogel and the method uses a correlation that exists between the temperature change and the impedance change.