Electrosurgical RF Generator Closed-Loop Control for Tissue Impedance

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Solution Overview

Problem

Existing electrosurgical generators face challenges in providing optimal RF energy for sealing, fusing, and cutting tissues due to dependency on surgeon skill and variability in tissue impedance, with monopolar instruments posing risks of electrical burns and bipolar instruments being highly dependent on surgical expertise.

Innovation Solution

A digital closed-loop control system that regulates voltage, current, and power of RF output using an RF amplifier, feedback system, and microcontroller to adjust RF energy delivery based on real-time measurements and dynamic conditions, ensuring optimal tissue treatment under varying impedance loads and procedural conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If monopolar electrosurgical instruments are used to deliver high current density RF energy, then cutting and sealing efficiency is improved, but the risk of electrical burns to the patient increases

Engineering Contradiction:
Improvecutting and sealing efficiencyVSAvoidrisk of electrical burns
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a return electrode as an intermediary component that safely disperses RF current through a large surface area. This mediator allows the active electrode to deliver high current density for efficient cutting and sealing while the return electrode prevents harmful current concentration on the patient's body, thus resolving the contradiction between surgical efficiency and patient safety

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical parameters of the return electrode by designing it with a large surface area and conductive gel interface. This parameter change transforms the current density distribution, allowing high power delivery through the active electrode while maintaining safe current density at the patient interface through the return electrode, thereby enabling both efficient surgery and patient safety

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If bipolar electrosurgical instruments are used to reduce patient injury risk, then safety is improved, but surgical outcomes become highly dependent on surgeon skill

Engineering Contradiction:
Improvepatient injury riskVSAvoiddependency on surgeon skill
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent implements a feedback control system that continuously monitors tissue impedance and RF power delivery, automatically adjusting energy parameters to maintain optimal surgical conditions. This feedback mechanism reduces dependency on surgeon skill by providing intelligent control that compensates for variations in tissue properties and ensures consistent surgical outcomes while maintaining the safety advantages of bipolar technology

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The electrosurgical system performs self-regulation by automatically monitoring its own performance parameters and adjusting energy delivery accordingly. The system's built-in sensors and control algorithms enable it to self-optimize for different tissue types and surgical conditions, reducing the need for highly skilled manual intervention while maintaining safe and effective operation

Inventive Principle:
Principle #25Self-service

3Ease of operation

If enhanced generators are introduced to reduce dependency on surgeon skill, then ease of operation is improved, but device complexity increases

Engineering Contradiction:
Improvedependency on surgeon skillVSAvoidgenerator complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical adjustment mechanisms with electronic control systems and software algorithms. Instead of requiring multiple physical controls and manual adjustments, the system uses digital signal processing, microcontrollers, and automated feedback loops to manage RF energy delivery, thereby reducing operational complexity while maintaining or enhancing ease of use

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 system enhances surgical outcomes by providing consistent and optimal RF energy delivery, reducing the risk of electrical burns and dependency on surgeon skill, while maintaining focused tissue treatment with reduced risks associated with monopolar instruments.

Implementation Method 1

Electrosurgical instruments may include one or more electrodes that are configured to be supplied with electrical energy from an electrosurgical generator. The electrical energy can be used to fuse, seal, or cut tissue to which it is applied.

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a feedback system to measure voltage and current of the RF output

Methodology Applied
Scientific EffectElectrical measurement: Ohm's Law

Data Source

PatentEP3846717B1Electrosurgical generator control system
Publication Date: 2024.12.18 APPL MEDICAL RESOURCES CORP
  • EP3846717B1 patent drawingFigure 1~2
  • EP3846717B1 patent drawingFigure 3
  • EP3846717B1 patent drawingFigure 4

AI summary

Systems and methods for enhancing surgical outcomes by providing generators having optimal RF output for sealing, fusing and/or cutting tissue or vessels under all dynamic conditions are described. Examples of dynamic conditions may include varying tissue impedance load due to electrosurgical operations or tissue affects, any operational conditions and commands determined by the surgeon, surgical procedure and/or device script. This is achieved by implementing a digital closed-loop control system within the electrosurgical generator to regulate voltage, current, and power of the RF output. The digital closed-loop control system may include an RF amplifier for generating RF energy, a feedback system for constantly monitoring the electrical characteristics, e.g., voltage, current, and power, of the supplied RF energy to a connectable electrosurgical instrument and a microcontroller for processing measurement data from the feedback system and adjusting the output of the RF amplifier to meet a desired regulation target under any varying conditions.