Electrosurgical Generator Power Calibration Using Signal Equalizers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrosurgical generators face inaccuracies in power measurements due to parasitics in cables and analog processing circuitry, leading to improper control of electrosurgical energy applied to tissue, which can result in inconsistent tissue heating during procedures.
Innovation Solution
The implementation of equalizers, such as LMS adaptive filters and bandpass parametric equalizers, within the electrosurgical generator system to accurately calibrate power measurements by correcting voltage and current signals, ensuring precise power calculation and delivery to the tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage and current measurements are taken at the output of the electrosurgical generator, then power can be calculated for control purposes, but measurement errors occur due to parasitics in cables and analog processing circuitry
Solution Approach 1:
The patent replaces direct physical measurement of voltage and current at the output with a computational model that calculates expected measurements based on known system characteristics (cable parasitics, amplifier gains, phase shifts). This substitution of physical measurement with mathematical modeling eliminates measurement errors while avoiding additional complex hardware
Solution Approach 2:
The patent introduces an intermediary computational layer that processes the relationship between generator output and load measurements. By using a mathematical model as an intermediary, the system accounts for parasitic effects without requiring direct measurement, thus improving accuracy without proportionally increasing device complexity
2Measurement precision
If measurement errors are corrected using complex equalization algorithms, then power measurement accuracy improves, but computational complexity and processing time increase
Solution Approach 1:
The patent performs preliminary characterization of the system during manufacturing or initial setup, storing calibration data about cable parasitics, amplifier characteristics, and phase shifts. This preliminary action allows the runtime algorithm to use pre-determined correction factors rather than performing complex real-time optimization, reducing computational complexity while maintaining high measurement accuracy
3Reliability
If real-time power calculation is performed to control electrosurgical energy, then tissue heating control is achieved, but measurement inaccuracies lead to improper power delivery
Solution Approach 1:
The patent implements a feedback mechanism where the calculated power measurement (corrected for parasitic effects) is used to adjust the generator output to match the desired power level. The system continuously monitors and adjusts based on the corrected measurements, improving reliability of tissue heating control by compensating for measurement inaccuracies through active feedback control
Data Source
AI summary
The disclosed electrosurgical systems and methods accurately determine the power actually applied to a load by using equalizers to calibrate the power measurements. The electrosurgical systems include an electrosurgical generator and an electrosurgical instrument coupled to the electrosurgical generator through an electrosurgical cable. The electrosurgical generator includes an electrical energy source, voltage and current detectors, equalizers that estimate the voltage and current applied to a load, and a power calculation unit that calculates estimated power based upon the estimated voltage and current. The methods of calibrating an electrosurgical generator involve applying a resistive element across output terminals of the electrosurgical generator, applying a test signal to the resistive element, measuring the magnitude and phase angle of voltage and current components of the test signal within the electrosurgical generator, estimating the magnitude and phase angle of the voltage and current at the resistive element using equalizers, and determining gain correction factors and minimum phase angles for the equalizers.