Catheter Electrode Ground Isolation for Position Sensing Accuracy
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Solution Overview
Problem
Existing position-sensing systems for objects within the body face challenges in achieving accurate real-time position determination due to distortion from electrical currents, particularly when functional electrodes interfere with positioning currents.
Innovation Solution
The method involves using distinct electrical grounds for positioning and functional circuitries, with an isolation transformer and inter-ground coupling impedance to minimize interference, ensuring accurate position coordinate determination by isolating the first electrical ground from the second electrical ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If functional electrodes are coupled to the same electrical ground as positioning circuitry, then device complexity is reduced, but measurement precision deteriorates due to current interference
Solution Approach 1:
The electrical ground system is segmented into separate grounds for positioning circuitry and functional electrodes. This segmentation prevents current interference from functional electrodes from affecting position measurements, while still allowing both systems to operate within the same device framework.
Solution Approach 2:
An isolation transformer is introduced as an intermediary component between the positioning circuitry and functional electrodes. The transformer provides galvanic isolation, blocking harmful current paths while allowing signal transmission, thus protecting measurement precision without completely isolating the systems.
2Measurement precision
If isolation transformer is added to separate electrical grounds, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The isolation transformer serves as a compact intermediary component that provides effective galvanic isolation in a space-efficient manner. By placing the transformer at a strategic point in the circuit, complex ground separation is achieved without requiring extensive wiring changes or additional isolation components throughout the entire system.
Solution Approach 2:
The system changes the electrical isolation parameter by introducing the transformer, which provides frequency-dependent isolation characteristics. This allows the system to maintain measurement precision across different operating conditions while managing complexity through a single parameter change rather than multiple structural modifications.
3Measurement precision
If inter-ground coupling impedance is optimized, then measurement precision is maximized, but device complexity increases due to impedance matching requirements
Solution Approach 1:
The system optimizes the inter-ground coupling impedance as a key parameter to balance isolation effectiveness and signal integrity. By selecting an appropriate impedance value, the system achieves maximum measurement precision without requiring complex active impedance matching circuits, as the impedance itself serves as the matching mechanism.
Solution Approach 2:
Rather than attempting to completely eliminate coupling between grounds (which would require complex active circuits), the system discards the harmful direct coupling path and recovers useful signal transmission through the controlled impedance path. This selective discarding and recovering approach simplifies the overall circuit design.
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 accuracy and reliability of position measurements by reducing the impact of functional electrodes on positioning currents, maintaining the validity and accuracy of the positioning process.
Implementation Method 1
isolating the first electrical ground from the second electrical ground
Implementation Method 2
coupling the first electrical ground to the second electrical ground via a predetermined inter-ground coupling impedance
Implementation Method 3
measuring, using first circuitry coupled to at least the first probe-electrode and having a first electrical ground, currents passing between the first probe-electrode and the body-surface electrodes
Data Source
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AI summary
A method for position sensing includes inserting a probe having a first probe-electrode and a second probe-electrode into a body of a subject, and coupling body-surface electrodes to a surface of the body. Currents passing between the first probe-electrode and the body-surface electrodes are measured, using first circuitry coupled to at least the first probe-electrode and having a first electrical ground, and position coordinates of the probe are determined responsively to the measured currents. Second circuitry, having a second electrical ground, is coupled to at least the second probe-electrode, and the first electrical ground is isolated from the second electrical ground.