RF Power Generator Phase-Angle Control for Electrosurgical Cutting Filament
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Solution Overview
Problem
Electrosurgical generators face challenges in maintaining uniform power density along the length of exposed cutting filaments during tissue resection, particularly due to varying tissue impedance and power factor fluctuations, which can lead to inefficient cutting and potential tissue damage.
Innovation Solution
The implementation of a phase-angle measurement circuit and impedance load discriminator circuit in an RF power generator to regulate the power delivered to the cutting electrode, ensuring uniform real-power density and adapting to changing tissue impedance, along with a controller that adjusts the RF energy output based on measured current and voltage signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power delivered to the cutting electrode is regulated based on measured tissue impedance, then the cutting arc can be sustained under varying operational conditions, but the power density along the length of exposed filament becomes non-uniform
Solution Approach 1:
The patent applies local quality by varying the power delivered to different segments of the cutting electrode based on their individual impedance characteristics. The controller divides the cutting electrode into multiple segments and independently controls the power density to each segment, ensuring uniform power distribution along the entire length despite variations in tissue impedance at different locations.
Solution Approach 2:
The system dynamically adjusts the power delivery to the cutting electrode in real-time based on measured impedance values. As the instrument forms the receptacle and the exposed filament length changes, the controller continuously modifies the power distribution to maintain uniform power density, making the system adaptive to changing operational conditions.
2Productivity
If the exposed filament length changes during instrument deployment, then the tissue resection capability is improved, but the power density along the filament becomes non-uniform
Solution Approach 1:
The system dynamically adapts power delivery as the instrument deploys and the exposed filament length changes. The controller receives real-time feedback on the state of instrument deployment and adjusts the power distribution accordingly, ensuring that each segment of the filament receives appropriate power density regardless of the changing overall length.
Solution Approach 2:
The patent applies local quality by treating different segments of the cutting electrode differently based on their exposure state. As segments become exposed or retracted during deployment, the controller independently controls the power delivered to each segment, ensuring uniform power density is maintained along the entire exposed length throughout the deployment process.
3Adaptability or versatility
If the power factor fluctuates during tissue resection, then the cutting performance adapts to different tissue types, but the power readout becomes erroneous
Solution Approach 1:
The system uses feedback by continuously measuring the actual power factor during tissue resection and using this information to adjust the power delivery. The controller compares the measured power factor against expected values and compensates for deviations, ensuring accurate power delivery and readout despite variations in tissue type and impedance characteristics.
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 solution maintains consistent power density along the cutting filament, improving tissue resection efficiency and reducing the risk of tissue damage or instrument failure by compensating for fluctuations in tissue impedance and power factor.
Implementation Method 1
a phase-angle measurement circuit to determine the average real power delivered (also called "average active-power") to the cutting filament
Implementation Method 2
the electrosurgical instrument uses the delivered energy to form a cutting arc for ablating a tissue mass
Implementation Method 3
form a cutting arc for ablating a tissue mass
Implementation Method 4
an impedance load discriminator circuit to tune the output power to match the average tissue impedance of the target tissue
Data Source
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AI summary
The disclosed technology is directed to a RF power generator and feedback control system used to regulate the electrical power delivered to a cutting filament (i.e., a cutting electrode) of an electrosurgical instrument. The electrosurgical instrument uses the delivered energy to form a cutting arc for ablating a tissue mass to access a target tissue therein. The instrument forms a basket-like receptacle around the target tissue to excise the target tissue from the ablated tissue mass. As the instrument forms the receptacle, the length of exposed filament ablating the tissue changes. To this end, the RF power generator described herein is configured to vary the total power delivered during the deployment of the instrument based on a measurement of output power derived from a differential phase angle between a current sense output and a voltage sense output, in some embodiments, to maintain a uniform power density along the length of exposed filament.